"Women with a family history of breast cancer should be screened in their thirties," says The Daily Telegraph.

The news relates to an ongoing study that aims to look at the effects of mammography screening in women with a family history of breast cancer when they are between the ages of 35 and 39. 

National guidelines currently recommend that women identified as being at increased risk of breast cancer because of a family history of the disease are offered annual mammography screening from the age of 40. Women at very high risk, such as those with BRCA1 or 2 mutations, are already offered annual MRI screening from the age of 30.

This report covers the first stage of the study, which looked back at the type of screening offered to women in this category at 33 centres across the UK. It found that the majority of the centres surveyed offered mammography, with most offering it on an annual basis.

In the five centres with the most rigorous follow-up, 47 cancers were identified in women, with almost half identified through screening and about a third identified between mammograms.

Comparison of these cancers with results reported in previous studies in unscreened women suggested that in the women offered screening, the cancers identified were smaller and less likely to have spread to the lymph nodes at the time of diagnosis.

The current study gives a snapshot of existing surveillance measures in the UK for women aged 35-39 who have an increased risk of breast cancer because of their family history. But as the centres surveyed were not specifically collecting information in order to analyse the effectiveness of mammography screening, they did not have enough information for a thorough analysis.

Therefore, the second part of this study plans to follow 2,800 high-risk women offered mammography screening on an annual basis up to 2016. These results will give a better idea of the potential benefits, risks and costs of screening in this younger age group.

Where did the story come from?

The study was carried out by researchers from the Genesis Breast Cancer Prevention Centre at the University Hospital of South Manchester NHS Trust and other hospitals and research centres in the UK.

It was funded by Breast Cancer Campaign and was published in the peer-reviewed medical journal, Familial Cancer.

The Daily Telegraph's headline doesn't convey the preliminary nature of these findings, but it does report later on in the story that a larger study is planned and that changes to recommendations are only likely if the larger study confirms the results.

What kind of research was this?

The researchers were reporting on part of a study of breast cancer screening in younger women with a family history of breast cancer (the FH02 study). The first part of the study was a retrospective analysis of the type of breast cancer surveillance that has been offered to these women in the past and what their outcomes were.

In the UK, all women between the ages of 50 and 70 are currently offered mammography. Women whose family history indicates that they are at increased risk are offered annual mammograms from the age of 40 as a form of "surveillance" for the disease. Women at very high risk, including those who are known to carry mutations in one of the BRCA1/BRCA2/TP53 genes, are offered annual MRI screening from the age of 30.

The researchers report that a previous study looked at mammography for women aged 40-49 in the UK with a significant family history of the disease (the FH01 study), but the effects of mammography in women aged 35-39 has not yet been assessed.

The National Institute for Health and Care Excellence (NICE) has produced guidelines on how doctors should classify breast cancer risk in women with a family history of the disease, and how they should be assessed and treated.

The researchers state that in the second part of this study, they will carry out a prospective study to look at the effects of breast cancer surveillance in these younger women. A previous study suggested that the health professionals caring for these women feel that such surveillance is likely to be of benefit. For this reason, it was decided that it would not be ethical to carry out a randomised controlled trial and that the study would compare the participants' results with those from previous studies instead.

What did the research involve?

Retrospective study

The researchers sent a survey to the 33 centres taking part in the study. The survey asked whether they had previously carried out mammographic surveillance in women under the age of 40 with an increased familial risk of breast cancer.

If they answered yes, the survey then asked about exactly how they selected women for surveillance and what this consisted of. They also asked about the outcomes of this surveillance, including the number and type of cancers identified.

The researchers compared these results with the types of cancer reported in studies published previously looking at women:

• aged 40-49 years with a family history of breast cancer who had annual mammography (the FH01 study)
• aged 40-49 years with a family history of breast cancer
• a series of women aged 30-49 having breast cancer surgery
• women aged 35-39 years with a family history of breast cancer who had not been screened

Prospective study

The researchers reported in detail the planned approach for their prospective study. This study aims to identify the likely benefit of annual mammography for women aged 35-39 with a family history of breast cancer.

They will compare the results in this group with results from the preceding study in older women with a family history of the disease (the FH01 study) and the UK Age Trial, a randomised controlled trial that assessed the effects of annual mammography screening in women from the age of 40 (not selected on the basis of family history). This study will also assess the cost of surveillance, so it can estimate its cost effectiveness.

The researchers say they have recruited 2,280 women from 33 centres, and should have reached the target of 2,800 by the end of June 2013. The study is expected to continue until June 2016.

What were the basic results?

In their survey, the researchers found that among the 33 centres:

• mammography screening in women aged 35-39 at increased risk of breast cancer was already carried out in 27 centres
• almost all of this screening was reported to use film mammography, rather than the newer digital mammography
• these 27 centres record a three generation family history and carry out a risk assessment in these women to determine their risk level
• 25 of the centres record the women's lifetime risk of cancer and 22 record whether they have the known genetic mutations which predispose women to breast cancer (BRCA1, BRCA 2 and TP53)
• 26 of the centres offered the women annual mammograms and one centre offered them screening every two years
• 17 centres offered MRI scanning
• 14 centres offered routine physical examinations
• none of the centres routinely offered ultrasound

Five centres had robust systems to reliably identify whether any breast cancers were identified in these women in the period between mammograms (called interval cancers), as well as any detected in the mammogram.

There were 47 breast cancers in the women attending these centres between 1994 and 2010. Ten of these cancers (21%) were already known when the women attended the centres, 22 were new cancers (47%) identified through screening, and 15 (32%) were detected between mammograms.

Compared with two groups of unscreened women with breast cancer – one who had a similar family history and one without a family history – the cancers among the screened women were significantly smaller and less likely to have spread to the lymph nodes.

More of the screened women were alive with no spread of the disease in the screened group than in the two groups of unscreened women with breast cancer. However, the number of deaths from breast cancer was too small to carry out a robust analysis.

How did the researchers interpret the results?

The researchers say that this is the first study to assess the effects of mammography alone in women aged under 40 who are at increased risk of breast cancer.

They say that the results are "encouraging", but that the prospective part of their study is needed to assess the effects of digital mammography in moderate and high-risk women in order to inform cost effectiveness analyses.

Conclusion

The current study gives a snapshot of existing surveillance measures in the UK for women aged 35 to 39 with an increased risk of breast cancer due to their family history.

There are some points to note, which the authors themselves highlight:

• As this first part of the study is retrospective, the centres will not have collected all the relevant information that would allow thorough evaluation of the effects of mammography.
• The number of cancers in women receiving screening described in detail in the current study is small (just 47). The larger prospective part of the study is needed to get better estimates of the rates of cancer in these women.
• Most previous screening in the centres used film mammography, but the newer technique of digital mammography may offer better results. 
• In addition, the comparisons performed in the current part of the study against results in other studies may be affected by differences between the groups of women other than the screening offered. For example, the studies covered different time periods, and breast cancer management may have differed over these periods and could affect the chances of survival.

Overall, the current study gives some background information, but the second part of the study will shed more light on the potential effects of mammography surveillance in younger women at increased risk of breast cancer.
 

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Family history of breast cancer should mean screening earlier. The Daily Telegraph, June 17 2013

'Screen women aged 30 for breast cancer': Half a million at risk because of family history could be offered mammograms. Daily Mail, June 17 2013

Call for more breast cancer screening. The Times website, June 17 2013

Links To Science

Evans DG et al. Mammographic surveillance in women aged 35–39 at enhanced familial risk of breast cancer (FH02). Familial Cancer. Published online June 4 2013

“Anti-baldness drug can cause men to lose interest in alcohol,” reports the Mail Online.

This report is based on a small survey of young men who had been taking the drug, finasteride, for hair loss. Impotence and decreased libido are recognised side effects of this anti-male-hormone drug, and all 83 men in this study had experienced sexual side effects that lasted at least three months after they stopped taking it.

The survey found that the men reported drinking less at the time of the survey than before they started taking the drug. However, this was on average five years earlier, so it is not clear how well these men could remember what they drank so far in the past.

Also, as the study had no control group who didn’t take the drug, it’s not possible to say that these changes wouldn’t have happened naturally over time as the men aged. The results may also not be representative of what might be seen in older men, men taking the drug for its other use (enlarged prostate), or men who do not experience the sexual side effects of the drug.

Overall, these findings are inconclusive. Larger studies, ideally with a control group, are needed to assess the effects of the drug on alcohol consumption.

Where did the story come from?

The study was carried out by a single researcher from The George Washington University in the US. No sources of funding were reported. It was published in the peer-reviewed journal Alcoholism: Clinical and Experimental Research.

The Mail Online reports the results of the study, but not any of its fairly extensive limitations.

What kind of research was this?

This was a cross-sectional study reporting on the alcohol consumption among men taking the drug finasteride. This anti-male-hormone drug is licensed to treat benign (non-cancerous) enlargement of the prostate and male pattern hair loss.

The recognised side effects of the drug include sexual problems such as decreased libido, impotence and erectile dysfunction. It may also have effects on the nervous system. The researchers reported that finasteride has been shown to reduce alcohol intake in male mice, but no studies have assessed this in humans.

This study relied on men reporting their own alcohol consumption before and after taking the drug in a single survey. This is likely to be less reliable as men may not accurately remember their consumption in the past. Asking the men to keep an alcohol diary before and after they started taking the drug would be a more reliable approach.

The study also didn’t include a comparison group not taking the drug. Therefore, the result cannot conclusively show that the drug itself is definitely causing a change in alcohol consumption.

What did the research involve?

The researchers surveyed the alcohol consumption habits in 83 men aged under 40, who had been taking finasteride to treat or prevent male pattern hair loss. These men had experienced persistent sexual side effects but were otherwise healthy.

The men were reported to be recruited from the author’s previous studies on persistent sexual side-effects of finasteride. These men had side-effects for at least three months despite stopping finasteride. Men who had sexual dysfunction before taking finasteride, had chronic medical conditions, current or past psychiatric conditions, or had taken psychiatric medication were excluded.

The survey asked about their average weekly alcohol consumption before they started taking finasteride, and at the time of the interview. A glass of wine, can of beer, or shot of hard liquor was considered a standard drink.

What were the basic results?

Sixty-three of the men reported drinking at least one alcoholic drink per week before starting finasteride. Among these men, at the time of the survey:

• 65% reported reduced alcohol consumption 
• 32% reported no change in their alcohol consumption
• 3% reported an increase in their alcohol consumption

On average, of the men who reported drinking alcohol, the average number of drinks per week reduced significantly – from 5.2 before finasteride to 2.0 after finasteride. As the men had stopped taking finasteride, they were not taking the drug at the time of assessment.

The authors reported that although they were not asked about this specifically, some men volunteered the information that they could not tolerate alcohol as well after starting to take finasteride. Eighteen men reported giving up alcohol entirely.

How did the researchers interpret the results?

The researchers concluded that among men who developed persistent sexual side effects from finasteride and stopped taking the drug, almost two-thirds reported reduced alcohol consumption.

Conclusion

This relatively small study in a very select group of men provides only limited evidence of the effects of finasteride on alcohol consumption in men. Its limitations include:

• The study didn’t include a comparison group not taking the drug. Therefore, the result cannot conclusively show that the drug itself is definitely causing a change in alcohol consumption, rather than the men just having changing alcohol tolerance as they got older.
• The study asked men to remember what their alcohol consumption was before taking the drug – on average about five years previously. This is likely to be less reliable as men may not accurately remember their consumption in the past. Asking the men to keep an alcohol diary before and after they started taking the drug would be a more reliable approach.
• The study only used a crude assessment of the number of drinks consumed, the size and alcohol content of these drinks may vary and this could affect comparison of before and after findings.
• The study did not say exactly how men were selected to take part, or whether they knew the purpose of the study. The men’s responses may have altered if they knew that finasteride may have an effect on alcohol consumption.
• The men all had persistent sexual dysfunction following taking finasteride for male pattern hair loss. The results may not apply to other men taking the drug, for example those without these side effects, or those taking it for an enlarged prostate.
• The author reported that many of the men in the study experienced depressive symptoms, and this may have affected their alcohol consumption.

As the author acknowledges, more research would be needed to determine the effects of finasteride on the nervous system and alcohol consumption.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Anti-baldness drug can cause men to lose interest in alcohol. Mail Online. June 17 2013

Links To Science

Irwig MS. Decreased Alcohol Consumption Among Former Male Users of Finasteride with Persistent Sexual Side Effects: A Preliminary Report. Alcoholism: Clinical and Experimental Research. Published online June 13 2013

“'Cradle snatchers' cause menopause, says biologist,” is the bizarre headline in The Guardian today.

The menopause has always been a bit of an evolutionary puzzle. Evolution is about one thing only – reproducing genes. So why would genes that cause a woman to lose fertility halfway through her life survive?

Two main theories have been previously suggested:

• one theory suggests the menopause is a trade-off in increased fertility versus prolonged survival 
• the second theory is known as the “grandmother effect”, whereby older, post-menopausal women are no longer fertile so they can instead help out with raising their grandchildren

A new study has provided a third theory. Humans started off with prolonged fertility, but if men theoretically preferred mating with younger women there would be no pressure to weed out the mutations that cause infertility in later life. According to this theory, over time mutations affecting fertility in older women accumulate – leading to most, and then all, women experiencing menopause.

Researchers used a complicated computer model to run a number of evolutionary cycles and found that the model was consistent with their theory. But it’s not possible to say conclusively that this model accurately represents what has happened in human evolution, and other factors may contribute.

The findings are interesting but they have no direct health implications. Menopause – for whatever reason it may occur – is a natural part of human female life, to which no blame should be attached.

Where did the story come from?

The study was carried out by researchers from McMaster University, Ontario, Canada, and was funded by the Origins Institute and Shared Hierarchical Academic Research Computing Network at McMaster University, and the Natural Sciences and Engineering Research Council of Canada.

The study was published in the peer-reviewed open access scientific journal PLoS Computational Biology.

The media reporting of the theory is broadly accurate but it is just that, a theory. This complex computer modelling research can only suggest certain scenarios that could potentially explain the observations seen. It is not possible to say conclusively that these models do represent what truly happened.

Headlines that suggested men are “to blame for the menopause” are a bit silly. Evolutionary forces are not something anyone has any control over. Blaming men for the menopause is like blaming someone other hereditary conditions that have evolved in humans over time, say, sickle cell anaemia.

A number of the news sources carry a quote from another expert critical of the theory. Dr Maxwell Burton-Chellew, an evolutionary biologist in the department of zoology at the University of Oxford, was quoted as saying: “This [theory] is probably the wrong way round - the human male preference for younger females is likely to be because older females are less fertile.”

What kind of research was this?

This was a computer modelling study trying to determine why women undergo menopause.

As the authors note, survival beyond the menopause is a characteristic that appears almost unique to humans with only odd exceptions (such as whales, and chimps in captivity). Evolutionary theories suggest that natural selection should operate against living beyond reproductive age and it is not clear (theoretically) why women live beyond the menopause.

At least two possibilities have been put forward to explain this phenomenon: a trade-off favouring longer lifespan over reproduction in women (because giving birth when older may increase mortality risk); and that menopause increases the reproductive success of the woman’s offspring (that is, the “grandmother effect” of older women being able to assist their children in rearing their own children).

Other researchers have suggested that living beyond menopause could be down to an influence from males. They suggest that the fact that men remain fertile throughout their lifespan would prevent accumulation of lifespan-shortening mutations, allowing men and women to live longer. However, this does not explain why women undergo menopause.

The current research aimed to test the effect of male mating preference on the evolution of the menopause. In particular, they were interested in the effect a male mating preference for younger females would have.

What did the research involve?

The research involved a complex computer model that looked at the effect on a population of male lifelong fertility and of male mating preference on female fertility.

The researchers modelled a population of a fixed size, which initially had pre-set fertility and survival probabilities. Each individual started the model in one of 18 increasing age classes. Survival probability for each age group (determined by the number and type of mortality-causing mutations introduced) was assessed at five-year intervals.

The different computer models then introduced mutations into the population that separately affected mortality and fertility – mutations that affected fertility did not affect survival, and mutations that affected survival did not affect fertility.

This determined whether any individual in each age group died or went into the next age bracket. All individuals that reached the oldest age class (class 18) died in the model.

Deaths in the model were replaced by new births assigned to the first age category. The births were simulated by randomly selecting a male from the surviving male population, and a female from the surviving female population. Male and female fertility probabilities in the model were influenced by the number and type of fertility-affecting mutations that had been introduced into the population.

The researchers used their model to look at two scenarios.

First scenario

In their first scenario, men retained lifelong fertility, while women underwent menopause. In this scenario men did not have an age-specific mating preference. The researchers looked at the effect of introducing into the population theoretical genetic mutations that reduced lifespan but did not affect fertility.

Second scenario

In their second scenario, the researchers started out with men and women being fertile all their lives. They then introduced mutations that caused reducing fertility, and mutations that affected survival. They looked at the impact on this scenario of men having a preference for mating with younger females.

What were the basic results?

In their first scenario – where men did not have an age-specific mating preference and women underwent menopause – the researchers found that if men retained lifelong fertility this did prevent
mortality-causing mutations from accumulating in females. However, this does not explain why menopause came about.

In their second scenario - where both sexes started with lifelong fertility and men preferred to mate with younger females – over time the mutations reducing female fertility with age accumulated in the population, causing a decline in female fertility with age; effectively the menopause. 

However, a similar effect was not seen if male mating preference was not influenced by women’s age.

How did the researchers interpret the results?

The researchers say that their model suggests that male mating preference for younger females could have driven the evolution of menopause. Their model did not need the presence of the other suggested explanations for the menopause to be present in order to work (the trade-off between fertility and lifespan and the “grandmother effect”). Instead they say that these explanations “may be insufficient factors in elucidating the origin of menopause”.

Conclusion

This computer modelling study has suggested that a male preference for mating with younger females could be the reason why menopause evolved in humans. However, whether this is truly the reason, or whether other factors some into play is not possible to say.

While this may be of interest to sociologists and others interested in the possibilities of human evolution, it has no direct health implications.

Unless someone comes up with a working time machine there is little we can do about the genetic cards that evolution has dealt us.

If you are experiencing the menopause, tempting as it may be to start blaming the men in your life, you are better off seeking support from your doctor, who may be able to offer treatment for particular symptoms of menopause.

A commonly used treatment is hormone replacement therapy (HRT), although there are also alternatives for women are not suited to HRT.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

'Cradle snatchers' cause menopause, says biologist. The Guardian, June 13 2013

Men 'to blame for the menopause'. BBC News, June 14 2013

Men may be to blame for the menopause. The Daily Telegraph, June 13 2013

Did man's yearning for young women create the menopause? Research suggests that men's wandering eyes may have caused middle-age loss of fertility in women. Mail Online, June 14 2013

Links To Science

Morton RA, Stone JR, Singh RS. Mate Choice and the Origin of Menopause. PLoS Computational Biology. Published online June 13 2013

“New AIDS prevention pill could cut infection rates in IV drug users by 50%,” the Mail Online reports, as the US Centers for Disease Control and Prevention (CDC) is set to approve the medication for injecting drug users.
 
The drug proved its worth in a large, well-conducted randomised control trial in Thailand. In this study, over 2,000 injecting drug users were given either placebo tablets or the ‘new’ drug tenofovir – which has been used to treat HIV since 2006.
 
The participants also attended monthly clinics to have blood tests to check for HIV infection, assess adverse events and to give them risk-reduction counselling. They were followed, on average, for four years to see if they contracted HIV.
 
The trial found that daily oral tenofovir reduced the drug users’ risk of catching HIV during the trial by about half: seven to eight per 1,000 would develop HIV per year without taking tenofovir, reducing to three to four per 1,000 per year if they did take tenofovir. Side effects for tenofovir were tolerable.
 
These are promising results though there are many other factors that would need to be considered before implementing an effective strategy on a wider scale outside of the context of a clinical trial.
 
While the obvious message in terms of HIV prevention is to stop injecting drugs, this type of pragmatic harm reduction approach could save many lives.

Where did the story come from?

The study was carried out by researchers from Bangkok Tenofovir Study Group, Bangkok, Thailand, and additional researchers from Centers for Disease Control and Prevention (CDC), Atlanta, and Johns Hopkins University, Baltimore, in the US. Funding was provided by the US CDC and Bangkok Metropolitan Administration.
 
The study was published in the peer-reviewed medical journal The Lancet.
 
The Mail Online's reporting of the study is accurate. However, there are additional issues that may need to be considered before the drug is licensed for this use, which the Mail does not describe.   

What kind of research was this?

This was a randomised controlled trial that aimed to assess whether daily use of the antiretroviral (anti-HIV) drug, tenofovir, could reduce HIV transmission in injecting drug users.
 
Injecting drug users are at high risk of getting HIV due to needle sharing. Tenofovir is currently licensed for the treatment of people who have HIV infection, usually taken in combination with other antiretrovirals.
 
The researchers suggest that use of antiretrovirals to prevent HIV infection could be ‘a promising new strategy to end the HIV/AIDS epidemic’. Previous studies in animals and humans have suggested the drugs can prevent transmission of the virus. They are currently used to reduce the risk of mother-to-child transmission of HIV, and to reduce risk among healthcare workers who may have been exposed to HIV (for example, through a ‘needlestick’ injury).
 
The current study is a phase III trial, meaning the research has already progressed through the earlier stages of clinical trials. This study investigated tenofovir's effects and safety compared with inactive placebo in a large sample of injecting drug users. 

What did the research involve?

The trial assessed whether giving tenofovir to injecting drug users reduced their chances of getting HIV over an average of four years.
 
It enrolled 2,413 injecting drug users from 17 drug-treatment clinics in Bangkok, Thailand. The clinics offer a wider range of services including HIV counselling and testing, risk-reduction counselling, social services, medical care, methadone treatment, condoms, and materials to clean injecting equipment (clinics cannot provide fresh needles under Thai law).
 
Participants were eligible if they were aged between 20 and 60 years, were HIV-negative, and reported injecting drugs during the previous year. The researchers excluded those positive for hepatitis B, and pregnant or breastfeeding women.
 
Participants were given contraception and hepatitis B vaccine, and were randomised to receive either daily oral tenofovir 300mg or identical placebo pills. Participants could choose either to be observed daily taking their treatment (this ensures the participants do actually take their pills), or could just attend the monthly visits. All participants attended monthly clinic visits where they received HIV blood testing, were assessed for adverse effects, and were counselled on risk-reduction and adherence to treatment.
 
Risk behaviour was assessed in more depth every three months.
 
The trial was long term, and lasted up to seven years. The average duration of follow-up was four years. The researchers assessed the number who remained in treatment each year. 

What were the basic results?

Of the 2,413 randomised participants, 80% were men, 43% were in their 20s, 38% were in their 30s, and the remainder were older. The majority (63%) had injected drugs within the past three months.
 
Drugs used included heroin (22%), methamphetamine (33%), midazolam – a sedative which can give feelings of euphoria if injected at high doses (23%), and 22% were currently in a methadone programme. 
 
For the first year, the proportion of participants retained in the trial was high (88% of the tenofovir group and 89% of the placebo group). However, this gradually declined each year up to seven years.
 
Overall, 34% of both groups withdrew from the study during the course of the seven years. Dropout during the course of the trial was for various reasons including loss to follow-up, death, pregnancy and contracting HIV. Participants took the drugs for an average 84% of treatment days, with no difference in adherence between the groups. Overall, 8% of participants reported sharing their drugs in some way.
 
HIV was acquired by 50 people during the trial:

• 17 in the tenofovir group – an incidence of 3.5 cases per 1,000 person-years of follow-up (if 1,000 people were followed for one year, three to four would develop HIV while taking tenofovir)
• 33 in the placebo group – an incidence of 6.8 per 1,000 person-years of follow-up (if 1,000 people who were not taking preventative treatment were followed for one year, six to eight would develop HIV)  

This meant that taking tenofovir cut the risk of contracting HIV by about half (48.9% reduction, 95% confidence interval [CI] 9.6 to 72.2%).
 
There was no significant difference in the risk of any adverse events between groups. The most frequent adverse events were:

• abdominal pain
• nausea
• vomiting
• weight loss
• diarrhoea
• rash
• fractures 

Between 5% and 20% of people in both groups experienced these events. The only event that was significantly more common with tenofovir was nausea and vomiting, which affected 8% of the tenofovir group and 5% of the placebo group. 

How did the researchers interpret the results?

The researchers concluded that daily oral tenofovir reduced the risk of HIV infection in people who inject drugs. They suggest that preventative treatment with tenofovir ‘can now be considered for use as part of an HIV prevention package for people who inject drugs’. 

Conclusion

This was a well-conducted trial which has many strengths, including its very large sample size, long duration of follow-up, and regular and thorough assessments of HIV outcomes, adherence to treatment, adverse effects and risk counselling.
 
It found that daily oral tenofovir, when taken by injecting drug users, causes an almost 50% reduction in their relative risk of contracting HIV. It found that about seven to eight per 1,000 would develop HIV per year without taking tenofovir, reducing to three to four per 1,000 per year if they did take tenofovir. 
 
Although the drug has been demonstrated to be effective, it is not yet licensed by drug regulators for this use. They will need to review a submission from the manufacturer on the evidence of efficacy and safety of the drug in injecting drug users before this can be granted. If tenofovir is licensed for this use, when considering whether it should be widely offered for this purpose, there are many factors to be taken into account. This includes the number of people that would need to be treated and duration of treatment, and the cost of this treatment. 
 
For injecting drug users there are other important considerations. This includes that injecting drug–users’ often chaotic lives mean that they can find it difficult to access health services and may only be in contact with health professionals sporadically. This trial included only those who were currently attending drug treatment clinics. However, there are likely to be many other vulnerable groups of injecting drug users in the community who are not attending clinics, or who attend but then are lost to follow-up. Therefore, ensuring that all drug users are able to access care, and receive continued care and treatment may be issues that would need to be considered.
 
Another potential concern, is that preventative HIV treatment could possibly give false reassurance that the person is fully protected and would not be harmed by practices such as sharing needles or other injecting equipment, or having unprotected sex. It would still be important to ensure that people receive full information and guidance on the risks of blood borne infections (and other sexually transmitted infections), and the need to follow safe practices such as using single use needles and equipment and using condoms.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

New AIDS prevention pill could cut infection rates in IV drug users by 50%. Mail Online, June 13 2013

Links To Science

Choopanya K, Martin M, Suntharasamai P, et al. Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomised, double-blind, placebo-controlled phase 3 trial. The Lancet. Published online June 13 2013