Colorectal cancer mortality is decreasing but not the average person-years of life loss: Findings from a population-based study

Purpose: Colorectal cancer death rate decreased by about 2 percent per year in the 1990s and this decline accelerated to about 3 percent per year during 2001 to 2010 in the US. The objective of this study was to investigate whether the average person-years of life loss (APYLL) has improved in a similar fashion over time. We also investigated the effects of cancer stage at diagnosis on person-years of life loss (PYLL) since it is one of the major factors that influences the survival of cancer patients. Methods: A total of 509,738 patients diagnosed with only colorectal cancer in their lifetime in 1988-2012 were identified from the Surveillance, Epidemiology, and End Results (SEER) registries. We used life expectancy from the US population life table adjusted by year of death, sex, and race to estimate person-years of life loss. PYLL were calculated for 111,704 patients, who died during the follow up period due to colorectal cancer, by subtracting age at death from expected years of life at that age. To estimate the effect of early diagnosis on PYLL by controlling the effects of sex, race, and marital status, we have fitted a multiple linear regression. Results: Average PYLL was 16.3 years and showed an increasing trend from 14.6 years in 1988 to 17.4 years in 2012. Effects of stage at diagnosis on PYLL were significantly different between stages, and it varied from 10.8 years at stage 0 to 18.2 years at stage IV. Estimated APYLL for White, Black, and Other races were 15.5, 17.4, and 17.8 years respectively. After adjusting sex, race, and marital status we had found that asymptomatic diagnosis of colorectal cancer (stage 0) could save, on an average, 6.8 years of life loss in comparison to diagnosis at stage IV. Diagnosis at stage I, II, and III could save, on an average, 5.5, 4.3, and 2.3 years of life loss, respectively, in comparison to stage IV. Conclusion: Average person-years of life loss has been increasing steadily over the last two decades for colorectal cancer patients in the US. This increasing trend might be attributed to diagnosis at later stage and transition of the disease at younger age. It is evident from our study that early diagnosis might be one of the most effective ways to save person-years of life loss due to colorectal cancer.