Years of Life Lost from Cancer and Applications to Research Funding

Abstract:

Different measures of mortality can be used to focus attention on different aspects of disease. Cancer statistics provide a useful example of this. Crude mortality is a simple method of expressing the proportion or percentage of deaths attributable to any particular cancer type. It is relatively influenced by common tumours in older patients. ‘Years of life lost’ (YLL) provides a measure of disease burden to society, and average years of life lost (AYLL) represents the measure burden of disease to the individual patient. These different parameters show different aspects of mortality, and are complementary. Calculation of YLL must be done with an appropriate algorithm to avoid misleading results. Using these YLL and AYLL reveals interesting and important differences in mortality from different tumours. Analysis of this type can identify tumour types with extreme impact, either on society or individual patients.

YLL indicates a relatively higher burden of disease on society from cancers of the cervix and CNS, despite a screening programme for cervix cancer, and a rather low burden from prostate cancer. AYLL reveals striking differences between tumours. Prostate cancer has the lowest individual burden of death, measured as AYLL, at only 6.1 years. Brain and CNS tumours cause over 3 times as much loss of life per affected individual, at just over 20 years, higher than any other adult cancer.

These parameters can be used for comparison to research spending. In the cancer area, such a comparison demonstrates a mis-match between disease burden and funding. In the UK, research spending is very high on leukaemia, colo-rectal (+ anus) and breast cancer, which has the highest level of relative spending. By contrast, research spending is relatively low on several tumour types, including lung cancer, which are typically the less well-publicised cancers. The research spend per year of life lost is over thirty times higher for leukaemia than it is for lung cancer, which is relatively under-funded. There is clear evidence of inequity in research spending, which goes beyond the under-provision for lung cancer research. Better levels of funding are typically associated with well-publicised cancers. Comparing AYLL to research spending reveals 4 ‘Cinderella’ cancers, with individual burden of mortality higher and spending lower than average. These are kidney, melanoma, cervix, and brain and CNS cancers, and of these CNS is the most extreme. Such extreme tumour types, expressed by either statistic, may need special consideration.

Measures of mortality and disease burden may have to develop to include a component related to disease morbidity and treatment toxicity. Comprehensive use of mortality statistics, including YLL and AYLL, would be useful in considering allocation of research funding, and in debates on public health issues.