Here an Australian expert responds.

*Acute cannabis consumption and motor vehicle collision risk: A systematic review of observational studies, Asbridge et al., BMJ, 2012; 344, doi: 10.1136/bmj.e536

Feel free to use these quotes in your stories.  If you would like to speak to an expert, please don’t hesitate to contact us on (08) 7120 8666 or by email.

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Prof Mathew Martin-Iverson is Professor of psycho-pharmacology at the School of Medicine & Pharmacology, University of Western Australia

“There are some issues with this research as the authors only state the relative risk of an accident given the presence of tetrahydrocannabinol (THC; the active ingredient of marijuana) in people that have had serious accidents – they do not state the absolute risk. They describe the risk as ‘doubling’ but that is not particularly helpful – does it mean that the risk of an accident went from 50% to 100% chance or from 0.0001% to a 0.0002% chance? The former would be very significant but the latter would not be.

Random road-side testing in Victoria Australia in 2007 found 0.66% of the drivers were positive for THC (87/13176 tests). The risk of Victorians suffering an injury or fatal motor vehicle accident in a year is about 0.11%. So, I suppose that 0.66% of the drivers of Victoria have a risk of a serious accident going up from 0.11% to 0.22% if they use cannabis frequently when driving during the year. Is this a significant issue?

Of course, one supposes that it depends on the level of intoxication rather than a positive THC screen (which may remain positive well after intoxication is no longer an issue). I wouldn’t recommend anyone to drive while intoxicated on any substance.”

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In the ongoing debate over the benefits and harms of hormone replacement therapy, an international team of researchers has suggested that findings from the Million Women Study, which were used to establish that hormone replacement therapy (HRT) causes breast cancer, do not in fact prove a causal link.

The Million Women Study (MWS) is the largest study of its kind on the topic and has produced four reports (2003, 2004, 2006 and 2011). It was one of three major pieces of research that prompted a rethink of the long-term safety of HRT and its proponents state the findings have been replicated in many other studies.

Today’s paper is co-authored by Australian Prof Henry Burger, Emeritus Director of Prince Henry’s Institute of Medical Research, Melbourne, and Past President of the International and Australasian Menopause Societies.

Australian and UK experts respond below.

Feel free to use these quotes in your stories. Any further comments will be posted here. If you would like a copy of the paper or to speak to an expert, please don’t hesitate to contact us on (08) 7120 8666 or by email.

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Dr Andrew Penman is Chief Executive Officer of Cancer Council NSW

“This research review offers no new conclusions when it comes to assessing the well-established link between hormonal replacement therapy (HRT) and breast cancer.

The reality is that the overwhelming body of global evidence confirms a link between HRT and breast cancer. Cancer Council NSW research conducted in 2008 added to this evidence with our study showing that Australian women lowered their use of hormone replacement therapy (HRT) by more than half since 2001, and this resulted in sustained reductions in the number of women developing breast cancer.

Our research reveals that HRT use dropped 55 per cent between 2001 and 2005. During the same period there was also a nine per cent drop in breast cancer rates among women aged 50 years and older, which is the equivalent of 800 fewer cases. No changes were seen in breast cancer rates in women aged under 50 years, who do not usually use HRT.

These results are consistent with other evidence that women can reduce their risk of breast cancer quickly by stopping or reducing use of HRT. So, by reducing their use of HRT, women and their doctors have had a very positive impact on breast cancer in Australia.”

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Prof Ian Fraser is Professor in Reproductive Medicine at the University of Sydney

“These authors rightly draw attention to the problems inherent in the so-called “Million Women Study”. For reasons well addressed by these authors the title of the study has inappropriately given the MWS analysis a measure of authority which size alone does not justify.

Tiny statistical differences, as promoted by the Million Women study, cannot be convincingly demonstrated by the techniques used, even though the authors attempted to ‘control’ for some of the recognized biases. It is not possible to control for all known and unknown biases in such studies, and this is well demonstrated by the authors of this latest article in the Journal of Family Planning and Reproductive Health Care. Sadly, the Million Women study did not add anything valid to the debate on HRT existing at the time it was published.

The present authors are very well respected endocrinologists and epidemiologists who have undertaken a new and critical analysis of the data presented in ‘Million Women’ and have clearly demonstrated biases, which could not be allowed for in making the conclusions which ‘Million Women’ published.

Any statistical analysis is only as good as the quality of the data analysed. Breast cancer epidemiology is so complex, and so many factors have been shown or suspected to influence incidence rates, that data analyses have to be extraordinarily comprehensive to allow for all relevant and known factors (and, when statistical differences are tiny, they must also take into account possible unknown confounding factors). The current authors have highlighted this fallacy clearly.

This detailed critique is long overdue, and is an important contribution to the ongoing debate on the well-recognized benefits of hormone replacement therapy contrasted with a small number of uncertain disadvantages. The debate raised by the Million Women study merely frightened women without giving them a clear view of the potentially valuable benefits balanced against a theoretical risk. Women need clear, balanced, accurate and unemotional information about the quality of published scientific recommendations. The Million Women study failed to do this, and the current article goes a long way to remedying this.”

Prof Fraser has limited availability for interviews today

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The following comments were compiled by our colleagues at the UK Science Media Centre

Comments from Valerie Beral, Professor of Epidemiology and Director of the Cancer Epidemiology Unit, University of Oxford, and Richard Peto, Professor of Medical Statistics & Epidemiology University of Oxford:

“HRT is one of the most important causes of breast cancer in the world and women can easily change their risk by stopping.” Professor Valerie Beral and Professor Richard Peto, Oxford

Prof Dame Valerie Beral:

This paper is a re-statement of views held by many consultants to HRT manufacturers (as these authors are) attempting to dispute evidence about the adverse effects of HRT. The issues raised are not new and have been refuted previously.
The authors omit to say that Million Women Study findings, of an increased risk of breast cancer in users of HRT, especially of oestrogen-progestagen combinations, have been replicated in over 20 other studies. The totality of the worldwide evidence is now overwhelming.
In line with the findings from these studies, the recent large decrease in HRT use has been followed in many countries by a nationwide decline in the incidence of breast cancer.

Prof Sir Richard Peto:

A. Changes in hormonal stimulation of invisibly small clumps of hormone-sensitive breast cancer cells can have a BIG effect on cancer rates within just ONE OR TWO years.
Ordinary breast cells can be stimulated to divide by the female hormone, estrogen. Even when one cell from the breast has gone wrong and has turned into the seed of a growing cancer, that cancer can still be dependent on the continued stimulation by the body’s own oestrogen. Hormone-sensitive breast cancers can, however, be shrunk (and sometimes cured completely) by drugs such as tamoxifen, which block the action of oestrogen on the breast cancer cells.
In women who have had a hormone-sensitive breast cancer apparently completely removed from their breast, invisibly small deposits of cancer cells may remain either nearby or in distant parts of the body that, without drug treatment, would cause breast cancer recurrence and eventually death.
Our review of the randomized trials of daily tamoxifen vs no tamoxifen (Lancet 2011, 378: 771-84) showed that daily tamoxifen halves breast cancer recurrence rate during the first year or two, and that these rapid gains persist. These trials also showed that tamoxifen prevents one-third of the deaths from breast cancer.
A few breast cancers are not hormone sensitive, and tamoxifen does not help patients with this type of cancer.

B. Hormone replacement therapy (HRT) was supposed to replace the body’s own oestrogen after the menopause, and many non-randomized studies have produced strong evidence that it can cause a substantial risk of breast cancer.
The Million Women Study has shown that oestrogen-progestagen HRT, the type most commonly used in the UK, substantially increases the risk of developing a hormone-sensitive breast cancer. As is biologically plausible, in view of the rapidity of the benefit from tamoxifen, the HRT-associated risks fall rapidly after use stops.
In the Million Women Study participants were recruited just before they attended a breast screening clinic, at which some cancers were detected. But, even if attention is restricted to cancers that were detected only later, hormone-sensitive cancers are still three times as common in HRT users as in non-users or ex-users.

Thus, the Million Women Study provides strong, biologically plausible evidence of causality, i.e. of an increased probability of getting breast cancer among otherwise similar women (and a rapid decrease after they stop).

Hazel Nunn, head of health information at Cancer Research UK, said:

“Women shouldn’t be unduly worried by this latest review of HRT and breast cancer risk. HRT can be an effective short-term treatment for menopausal symptoms – women taking it should try and use the lowest dose possible for as short a time as they need it.

“If you are considering starting or stopping HRT, or using it for a long time, you should discuss it with your doctor. The issues are different for every woman and your doctor will be able to help you weigh up the benefits and risks of different types of HRT and make the right choice based on your own circumstances.

“In the UK, HRT use has been falling since the start of the Millennium. Studies suggest that in 2005 there were 1,400 fewer cases of breast cancer in the UK among women aged 50-59 than would have been if there had been no drop in HRT use.”

Comments from the International Menopause Society:

President-Elect of the International Menopause Society, Professor Rod Baber (Sydney) said:

“This review of The Million Women Study (MWS) highlights the problems associated with any observational study regardless of size. Potential biases inherent in any observational study make it difficult for such studies to accurately comment on relative risks of less than 2 and this paper identifies them in a clear concise manner. In the MWS identified biases including time order, information and detection bias, confounding, internal and external consistency may all have contributed to the excess risk of breast cancer with HRT use found in this study. HRT may contribute to increased breast cancer risk but the evidence from this study is flawed and does not assist in the decision making process.
“Every woman has individual risk factors for breast cancer, a number of which are modifiable and she should discuss these with her physician when considering whether or not to use hormone replacement therapy so that an accurate assessment of risks and benefits may be made”

International Menopause Society Board member, Professor Anne Gompel (Paris) said:

“This paper is a meaningful analysis of the MWS by an expert in Epidemiology, and puts forward the fact that the numbers of patients included in a study does not guarantee the accuracy of results. I would advise everyone to read this paper closely, since it highlights some of the important requirements of a good quality epidemiological study. For example, Professor Shapiro shows that the real relative risk is actually difficult to evaluate when it is under 2.
“There are other studies which do show risks and benefits for HRT, so I believe that the take home message is that, for a given woman, the important evaluation is her own risk. Recent papers on breast density, alcohol, obesity and exercise suggest that taking all these factors into account should help to identify which patients are at risk. HRT does not carry the same risk and benefit for each woman; some women will have increased risks, some will have only benefits, and this also applies to breast cancer.”

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* Does hormone replacement therapy cause breast cancer? An application of causal principles to three studies Part 4. The Million Women Study, Shapiro et al., Journal of Family Planning and Reproductive Health Care, doi: 1136/jfprhc-2011-100229

The journal has made a special concession for Australian media on this occasion, allowing Australian newspapers to run the story on Friday as long as nothing appears online before 11am AEDT on Fri 6 Jan)

ONLINE NEWS BRIEFING – Thu Jan 5 at 10.30 AM AEDT

A series of papers to be published in the medical journal The Lancet this week puts a spotlight on the use of illicit drugs throughout the world. Focussing especially on amphetamines, cannabis, cocaine, and opioids, the three part series pulls together the latest research into the social and economic costs of illicit drug abuse and the effectiveness of government policies and international treaties intended to stem the production and use of illicit drugs. The series was initiated by Australian scientists from the University of Queensland, UNSW and The Macfarlane Burnet Institute for Medical Research and Public Health in Melbourne and involves experts from the UK, Canada and the US.

Papers in the series:

Addiction part 1: Extent of illicit drug use and dependence, and their contribution to the global burden of disease

Addiction part 2: Drug policy and the public good: evidence for effective interventions

Addiction part 3: How well do international drug conventions protect public health?

The briefing discuss the following issues:

• Patterns of global drug abuse and their contribution to the global burden of disease, including mortality
• How effective are national drug policies in reducing harm to individuals and the community from drug abuse?
• Have global treaties helped or hindered efforts to control the production and use of illicit drugs?

SPEAKERS:

• Professor Wayne Hall, The Centre for Clinical Research and Centre for Youth Substance Abuse Research, University of Queensland, Australia | Wayne and Louisa’s powerpoint
• Professor Louisa Degenhardt, National Drug and Alcohol Research Centre, Faculty of Medicine, University of New South Wales, Sydney, NSW, and Burnet Institute and Centre for Health Policy, Programs and Economics, School of Population Health, University of Melbourne, Victoria, Australia | Wayne and Louisa’s powerpoint
• Professor John Strang, King’s College London, National Addiction Centre, London, UK | John’s powerpoint
• Professor Robin Room, Centre for Alcohol Policy Research, Turning Point Alcohol and Drug Centre and School of Population Health, University of Melbourne, Victoria, Australia | Robin’s powerpoint

Follow the full presentations (powerpoints and audio) by clicking here |  To listen to the audio only click here

BRIEFING DETAILS:

DATE:  Thursday 5 January 2012
START TIME: 10.30am AEDT
DURATION: 58 min
VENUE:  Online

For further information, please contact the AusSMC on 08 7120 8666 or email info@aussmc.org.

NB:  The AusSMC generally runs two different types of media briefings:
NEWS BRIEFINGS – Where new research or data will be released as part of the briefing
BACKGROUND BRIEFINGS – Where experts discuss an issue which is in the news or an issue we consider newsworthy, but no new research or data is being released

UK authors used a 1970 cohort study to suggest a link between a high childhood IQ and subsequent illegal drug use, particularly among women. Below an Australian expert who is independent of the research responds.

Feel free to use these quotes in your stories. Any further comments will be posted here. If you would like a copy of the research paper or to speak to an expert, please don’t hesitate to contact us on (08) 7120 8666 or by email.

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Associate Professor Jayne Lucke is Principal Research Fellow in the UQ Centre for Clinical Research at the The University of Queensland

“There are multiple factors that determine whether someone tries an illegal drug during adolescence, and whether they will be using them at the age of 30. Whether your friends use drugs, social and family attitudes, and the availability of drugs in your neighbourhood are important factors that are difficult to include in longitudinal analyses such as this one.

People with high IQs are not necessarily any better at making sensible decisions about their health than the rest of us. Everyone needs to be well informed about the potential dangers involved in using illegal drugs. This study raises interesting questions about the relationship between IQ and illegal drug taking, but the main finding is that more research is needed.

IQ is a contested concept in itself – sometimes referred to as ‘whatever IQ tests measure’. The finding that IQ in childhood may be related to later drug use is not necessarily helpful in designing health promotion messages.

It is also important to note that there are aspects of drug use that have not been considered, such as frequency of use (the analysis examined whether someone had ever used at age 16 and whether someone had used at any time in the last 12 months). People have different reasons and patterns of drug use, and further research is needed to know how intelligence fits into the picture.”

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*Intelligence across childhood in relation to illegal drug use in adulthood: 1970 British Cohort Study, White et al., Journal of Epidemiology and Community Health, doi:10.1136/jech-2011-200252

US researchers examine a reported link between using a type of drug to treat high blood pressure (angiotensin converting enzyme inhibitors) during the first trimester of pregnancy and the risk of birth defects in the baby. The authors suggest it is likely high blood pressure itself in pregnant women increases the risk of birth defects, rather than drugs prescribed to treat high blood pressure in the first trimester. Editorial available.

The research was published online at bmj.com at 9.30am AEDT Wed 19 October.

Feel free to use these quotes in your stories.  Any further comments will be posted here. If you would like to speak to an expert, please don’t hesitate to contact us on (08) 7120 8666 or by email.

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Professor Alastair MacLennan is Professor and Head of Discipline of Obstetrics & Gynaecology at The University of Adelaide

“The Kaiser Permanente Californian database is a respected epidemiological tool for examining possible associations between pharmacy prescriptions and health outcomes. Such an observational study cannot show cause and effect and is potentially open to confounding factors. In this case, the confounding factors included that the users of drugs in early pregnancy to control high blood pressure were older, were more overweight and had more pre-existing diabetes than the control group without hypertension.

However, after allowing for these confounding factors it was concluded that the small absolute increase in congenital heart defects was likely to be due to the underlying high blood pressure rather than the medications.

The health message from this study is that the 3 out of 1000 women who need treatment for high blood pressure in early pregnancy can continue its use.

For the general public, the message is that to reduce the risks from high blood pressure and diabetes in early pregnancy they should not leave having their family too late in reproductive life i.e. over age 35, they should avoid obesity and, if diabetic, they should have good glucose control before trying to get pregnant.”

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* Maternal exposure to angiotensin converting enzyme inhibitors in the first trimester and risk of malformations in offspring: a retrospective cohort study, Li et al., BMJ, 343, 2011