Cannabis and testicular cancer
Daling JR, Doody DR, Sun X et al. Association of marijuana use and the incidence of testicular germ cell tumors. Cancer 2009 Feb 9. doi 10.1002/cncr.24159
Smoking cannabis increases a man's risk of developing testicular cancer, a study suggests. US researchers found that current cannabis users had a 70 per cent higher risk of testicular germ cell tumour. Most of the association appeared to be because of a more than doubled risk of developing a nonseminoma or mixed histology tumour. Dr Janet Daling and colleagues from the University of Washington conducted interviews on cannabis use with 369 men aged 18 to 44 years who had been diagnosed with a testicular germ cell tumour.
The researchers compared the men's answers with those from interviews with 979 age-matched controls. They said the results were 'the first inkling' that cannabis use might be associated with testicular cancer. Dr Daling and her team will now examine how cannabis might act on cannabinoid receptors to increase tumour risk. Tom Moberly
The effect on cancer risk of drinking a pint a day
WCRF/AICR Expert Report. Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective
Drinking a pint of beer, a large glass of wine or a couple of measures of spirits a day increases the risk of liver and bowel cancer by a fifth, according to researchers.
Research by the World Cancer Research Fund (WCRF) has shown that two units of alcohol a day increases the risk of bowel cancer by 18 per cent and the risk of liver cancer by 20 per cent. In the UK every year, liver cancer kills about 3,000 people and more than 36,000 people are diagnosed with bowel cancer.
In 2007, the WCRF produced a report looking at the effect on cancer incidence of food, drink and physical activity. The report looked at all available research on cancer prevention. Over the course of six years, researchers from nine universities reviewed thousands of studies and made a series of recommendations, including a limit on alcohol consumption. From an initial 500,000 studies, 7,000 were deemed to meet the standards required for inclusion in the report. It found there was convincing evidence that alcoholic drinks were a cause of bowel cancer and probably a cause of liver cancer.
WCRF science programme manager Dr Rachel Thompson has since reviewed the evidence in the report. Dr Thompson converted the relative risks, which are presented in the report in units 'per 10g per day', into more meaningful terms.
She calculated that having one pint of beer a day, or two smaller drinks containing more than 10g of alcohol each, increases the risk of bowel cancer by 18 per cent and the risk of liver cancer by 20 per cent.
However, research suggests that few people understand the risks. In Britain, 64 per cent of people are unaware of the link between alcohol and cancer, she said. 'For cancer prevention, WCRF recommends not drinking alcohol at all,' Dr Thompson added. 'Modest amounts of alcohol may have a protective effect for heart disease but the benefits only outweigh the risk in those particularly at risk of heart disease, such as men aged over 40 and postmenopausal women.' The WCRF recommends that if people drink, they should limit themselves to two drinks a day for a man or one for a woman, she added.
Ed Yong, health information manager at Cancer Research UK, said that the WCRF analysis was consistent with other research into links between alcohol intake and cancer risk. 'The WCRF report was comprehensive,' he said. 'It fits with established evidence that drinking more than three units of alcohol a day can significantly increase the chance of developing cancer - particularly in the mouth, oesophagus, breast, bowel and larynx.' Tom Moberly
HRT and breast cancer
Chlebowski RT, Kuller LH, Prentice RL et al; WHI Investigators. N Engl J Med 2009; 360: 573-87
GPs should advise women to continue taking HRT, despite claims linking it to breast cancer, according to an expert on the menopause. Concerns about HRT began in 2002 when the Women's Health Initiative (WHI) study was halted after it found that HRT use could increase breast cancer risk by 26 per cent.
These claims were later dismissed by an international panel of menopause experts who examined data from 42 published studies on HRT use, including the WHI study and a reanalysis from 2007. The panel found that among women taking HRT, there were seven fewer breast cancers per 100,000 women than those given placebo.
But in a recently published study, US researchers monitored 15,000 women from the WHI study who stopped using HRT after 2002 and 41,449 women in an observational study.
They found that incidence of breast cancer was much higher in women taking combined estrogen and progestin HRT in the five years up to 2002. When they stopped taking HRT, their breast cancer risk fell by 28 per cent in 12 months.
Among women in the observational study, a 50 per cent decrease in HRT use coincided with a 43 per cent fall in breast cancer between 2002 and 2003.
Cornwall GP Dr Sarah Gray, a member of the British Menopause Society, said that the study should not change HRT use. It is important to tell patients that breast cancer risk from HRT use is low, she added. Sanjay Tanday