Tuesday June 16 2009
Diet and fitness are linked with cancer risk
Men are 16% more likely to develop cancer and 40% more likely to die from cancer than women, newspapers have reported. The BBC said, “there is no known biological reason for this but it may be because women take better care of themselves.” The Daily Mail reports a cancer expert as saying there is a divide because “the NHS prefers saving women”.
The news stories are based on a report that found that men are more likely to develop and to die from cancer than women. The researchers say, “the reasons men seem to be so much more at risk of so many cancers are complex and still only partially understood.” While lifestyle, genes, immunity and knowledge and behaviour (such as knowing of family members with cancer and “help-seeking behaviour”) are given as possible contributors, the full reason is unknown. The report does not suggest that the NHS is biased in favour of women.
Optimistically, the report also found that, while the cancer rate in UK men rose between 1975 and 2006, the rate of cancer death fell by about a quarter, which was mainly attributed to earlier diagnosis, better diagnostic methods and improvements in treatment and care.
What is the basis for these current reports?
These news stories are based on a report prepared by the National Cancer Intelligence Network (NCIN), Cancer Research UK (CRUK), Leeds Metropolitan University and the Men's Health Forum as part of Men's Health Week. The report used data from the CRUK Cancerstats webpages.
It was already known that men are generally at greater risk than women for almost all common cancers that affect both men and women (except breast cancer). The current report looked at recent figures to see how common cancer is in men in the UK and whether there are differences in cancer rates and deaths from cancer between men and women.
What did the report find?
The report carried out many analyses and key results include the following:
- The number of new cancer cases diagnosed in the UK in 2006 was similar for men and women: about 146,000 men and 147,000 women (non-melanoma skin cancers were excluded from all analyses). However, when these figures were adjusted to take age into account (age-standardisation), the rate of cancer was higher in men (409.7 per 100,000 men) than in women (354.6 per 100,000 women). The researchers say that this difference is because women generally live longer than men.
- In 2007, cancer caused 29% of all deaths in men and 25% of all deaths in women. The age-standardised rate of cancer death was higher in men (211.3 per 100,000 men) than in women (153.1 per 100,000 women). This difference was reportedly due to women’s longer life expectancy and the greater likelihood that men will develop more fatal cancers.
- The rate of cancer diagnosis in men in the UK rose from 353.7 per 100,000 in 1975 to 409.5 per 100,000 in 2006. However, the rate of cancer death in men dropped from 278.5 per 100,000 to 211.3 per 100,000 in the same period. A similar trend was seen in women. This is because earlier diagnosis, better diagnostic methods and improvements in treatment and care have resulted in more people surviving cancer.
- The most common cancers in men in 2006 were prostate cancer (24% of all cancers), lung cancer (15%) and bowel cancer (colorectal cancer) (14%). These three types of cancer were also the most common causes of cancer death in men in 2007, with lung cancer the most common cause (24% of cancer deaths), followed by prostate cancer (13%) and bowel cancer (10%). This leaves 53% of cancer deaths caused by other less common cancers.
- Overall, the rate of death from cancer in 2007 was 1.38 times higher in men than in women (which is the same as saying that cancer deaths were 38% more common in men than women). This difference was most pronounced among people aged 65 years and over, where cancer deaths were 1.57 times higher in men than in women. The rate was 1.05 times greater in men than in women in the younger (15 to 64) age group. This increased risk in men was seen for a range of different cancers.
- When the researchers excluded lung cancer deaths (as men have tended to smoke more than women over the past 60 years), they found that the difference in the ratio of deaths between men and women was smaller. The overall difference in the death rate between men and women was 1.31. In those aged 65 and above it was 1.51, and in those aged 15 to 64 it was 0.98. The researchers suggest that the higher overall death rate in men for all cancers in the younger age group could, therefore, be due to lung cancer.
- When the researchers excluded deaths from breast cancer and cancers that only occur in either men or women, overall cancer deaths were 69% more common in men than women. Cancers in men aged 15 to 64 were 60% more common than in women, and in men aged 65 or over they were 73% more common. The researchers suggest that these figures can be explained by the fact that cancer deaths in younger women are largely due to breast cancer and other genital cancers, whereas deaths among men due to male-specific cancers in this age group are uncommon.
- Overall, men were 16% more likely than women to have a new diagnosis of cancer in the UK in 2006. More women than men in the 15 to 64 age group were diagnosed with cancer, but in the 65 and over group, new diagnoses of cancer were more common in men. Once breast cancer and female- or male-specific cancers were excluded, the overall rate of new cancer diagnoses was 62% higher in men than women, and 44% higher in men than women in the 15 to 64 age group.
Why are men’s cancer rates worse than women’s?
The researchers report that, “the reasons men seem to be so much more at risk of so many cancers are complex and still only partially understood.” They say that differences in the levels of smoking and alcohol consumption in men and women will affect the rates of related cancers (such as lung cancer and bladder cancer). They say that other factors probably contribute to the differences, such as other lifestyle factors, genetics and immunity. Health knowledge and behaviours, such as knowledge of cancer and genetic links within families, uptake of available cancer screening and willingness to seek help, may also have an effect. They say that more research is needed to investigate how these and other factors affect differences in risk.
Does this show that men and women have different quality cancer treatment?
This study did not look at whether the quality of cancer treatment differs between men and women, and the researchers do not suggest that this is a possible reason for these differences. To investigate this and other possible reasons for the differences in cancer rates and deaths between men and women, further data about the characteristics of individuals diagnosed with cancer and their outcomes will be needed.
What can people do to reduce their risk of cancer?
Men as well as women can reduce their exposure to the lifestyle factors that are known to influence cancer risk, such as smoking, high alcohol consumption, being overweight or obese and having an unhealthy diet.
The NHS offers help with quitting smoking and also free screening programmes for certain types of cancer, and men and women who are eligible should consider taking part in this screening. Men can also monitor their health and be aware of any changes that may be possible signs of cancer. The earlier a cancer is detected, the better the chance of curing it, and people who have any symptoms they are worried about should see their doctor sooner rather than later.