Cancer death rates are falling in Australia even as incidences rise of lung cancer in women and prostate cancer in men, according to research published today in the Asia-Pacific Journal of Clinical Oncology.
In “Cancer in Australia: Actual incidence and mortality data from 1982 to 2007 and projections to 2010,” the researchers from the Australian Institute of Health and Welfare report that “overall, 5-year relative survival has improved markedly from 41% for males diagnosed in 1982-1986 to 58% for those diagnosed in 1998-2004 … [with] a similar improvement for females diagnosed in these periods - from 53% to 64%.” Yet, survival rates in brain cancer and lung cancer have not changed much, and patients “continue to have poor relative survival”.
Female lung cancer rates are climbing due to the rising popularity of smoking among young women, said Jake Najman, Professor of Population Health at the University of Queensland. While lung cancer is highly lethal and tobacco consumption is to be avoided, the rising incidence of prostate cancer in men is less alarming, Professor Najman said.
“Most prostate cancers are slow growing and relatively benign. Autopsies of men who died from unrelated causes often show that they had prostate cancer,” he said. “By the time men get to their 70s, about 70% of them will have it. The aggressive prostate cancers are a rarer event.” The smart thing to do if a man finds out he has the cancer is to find out what kind it is and then sort out the appropriate treatment, said Dr Najman, whose father died in his 90s after having a tumour removed a decade or so earlier.
Other factors behind the greater rate of cancer in men than women were lifestyle related, Professor Najman said. Men tended to expose themsevles to the sun more, and their diets were worse. There was less of a risk of developing bowel cancer if one eats high fibre food and plenty of vegetables, but many men don’t do so. “Women worry about those things more,” Professor Najman said.
The report found that 108,368 new cases of cancer were diagnosed in 2007, excluding non-melanoma skin cancers.
The Clinical Professor on Oncology of Cancer Council Australia, Ian Olver, saw other trends in the report, saying that “much of the increase in incidence is due to the ageing of the population, with more people living into the age groups where cancer is more common. Increases in incidence of particular cancers can sometimes be temporary such as when screening is introduced and initially the numbers are swelled by cancers being detected earlier. Although there is no population screening for prostate cancer because of the inaccuracy of the test, a rise in the number of men choosing PSA testing is probably responsible for the increased incidence.”
Professor Olver said the far greater incidence of cancer than a subsequent death rate was good news, as it showed “increasing success in cancer control. This can be both due to better treatments but also early detection of those cancers with population screening programs; breast, cervix and bowel cancer. The participation rates for cervix and breast cancer which have proven successful in reducing cancer deaths are still lower than the ideal. The bowel screening program has the lowest participation rate of all but that is because it really only consists of sporadic testing of three age groups and this highlights that it should be a priority for Government to complete this program and drive the bowel cancer death rates down further.”
An overview from Ray Lowenthal, Professor of Oncology, University of Tasmania
The overall incidence is increasing largely due to ageing of the population (cancer on the whole being a disease of older persons). However the death rate is not increasing, indeed it is falling, suggesting that treatment is getting better – in other words more people are living on despite a diagnosis of cancer.
The strange pattern of prostate cancer incidence is largely explained by an increase in diagnoses due to ‘screening’ using the PSA test in the period 1988-96. It is well known that a substantial proportion of cases‘diagnosed’ by the PSA test are indolent or minimally invasive cancers that never would have caused problems or death and thus would have been better not diagnosed! The value of the PSA test for prostate cancer screening is hotlydebated amongst the medical/scientific community.
The more recent ‘secondary’ rise in prostate cancer incidence is unexplained but may be due to recent prominence given in the media to the pro-PSA lobby in persuading men to undergo PSA screening and again, this leading to what might be called ‘over diagnosis’.
The improvement in the outlook for breast cancer is particularly pleasing given its high incidence. The great majority of womengiven a diagnosis of breast cancer will not die from it.
On the other hand the dismal outlook for lung cancer, pancreatic cancer, and of cancer of unknown primary is disappointing, the more so in that many such cases are due to cigarette smoking; indeed 85% of lung cancer cases can be attributed to smoking and thus are entirely preventable.
The figures for indigenous people are intriguing. They indicate that overall cancer incidence is lower amongst indigenous people, but that mortality rates are higher. There are several explanations. Firstly, although having a lower cancer incidence rate overall, indigenous people tend to get the ‘worst’ cancers, that is cancers with the highest mortality rates such as lung and pancreatic cancers and (in women) cancer of the cervix. Secondly, cancer survival is worse in Indigenous people compared with non-indigenous, even with the same cancers, partly because they present to medical attention with more advanced disease and because they are less likely to begiven the most effective treatment. This in turn is partly for cultural reasons and partly because many live in remote locations where administration of the most effective treatments may be difficult or impossible.