The latest report from Public Health Scotland on cancer incidence indicates more evidence for the benefits of early diagnosis and improved treatments but also shows upward trends in incidence of several major lifestyle related cancers. It is so easy to point to an ageing population and longer lives as reasons for greater number of cases but we also need to think of lifestyle related cancers that are increasing at a younger age (e.g. colorectal cancer). It is also notable that the risk of cancer diagnosis is higher in females aged 25 to 59 and higher in males aged over 60.
Women haven’t fared so well with recent decreases in colorectal cancer where the incidence in men has decreased by 21% (even though they are less likely to return screening tests) compared to a decrease of 11.9% in women. These findings are probably explained by the fact that the screening test (FIT, or faecal immunochemical test) has a higher positive predictive value for pre-malignant polyps in men than it does in women.
With respect to lung cancer, women have also benefited less than men from decreased tobacco use . In the decade under study, lung cancer in men has decreased by 18.7% but in women there has been an increase in 1.8%. Current smoking amongst women (reported in the Scottish Health Survey) is 17% compared to 21% in men. Clearly, all efforts to maintain smoke free environments and prohibit people starting tobacco use need to be continued. Tobacco control is not yet a “done deed”.
The other most striking results are for liver cancer – up 54% in women and 37% in men. Ask the person in the street about causes of liver cancer in Scotland and alcohol is likely to be the first response. The main lifestyle cause is in fact excess body fat. Current estimates by The World Cancer Research Fund suggest an increase of 30% per 5kg/m2 (e.g. 5 BMI units). Add in 3 alcoholic drinks per day and risk starts to increase further. Whilst there are great reasons for being as physically active as possible (not least to improve weight management) as an independent risk factor this is unlikely to improve risk of liver cancer.
Finally, a comment about cancer by socio-economic circumstances. The disease is prevalent across all social groupings. There is 28% greater chance of being diagnosed in people from most deprived areas and for lung cancer it is 3 times higher than for people from more affluent areas. For women, breast cancer rates are higher in least deprived as is prostate cancer in men. Both of these may be related to higher screening and testing rates. In terms of deprivation differences – malignant melanoma is 85% higher in people from least deprived areas and the reasons for this are far from clear.
Public health action for cancer prevention remains relevant across Scotland and the need for communicating how to decrease risk from screening to lifestyle change remains imperative.
Prof Annie S. Anderson Prof Bob Steele – SCPN Co-Directors