ImportanceIn the United States (US) in 2017, nearly half a million adults aged 75 and older were diagnosed with cancer. Cancer survival has improved since the 1990s, but to different extents across age groups, with a disadvantage for older adults. Documenting age-related differences in cancer survival in the US can help to inform prioritization efforts to narrow the age-related gap in cancer survival.
ObjectiveTo quantify age-related differences in relative survival by stage at diagnosis for 10 cancer types.
DesignRetrospective population-based observational study of cancers diagnosed between 2012-2016 with follow-up through December 31, 2017
Setting18 US Surveillance Epidemiology and End Results cancer registries
Participants844,296 individuals aged 50 and over with first primary cancers of the prostate, breast, rectum, colon, ovary, esophagus, stomach, liver, lung, and pancreas.
ExposureAge at cancer diagnosis (50-64, 65-74, 75-84, 85-99) and stage at diagnosis (localized, regional, distant, and unknown/unstaged).
Main Outcome(s) and Measure(s)One-year relative survival (RS). We estimated the absolute difference in 1-year RS between the 50 to 64 age group and the 75 to 84 age group.
ResultsThe smallest age-related differences were observed for prostate and breast cancers (1.8%-points [95% confidence interval (CI): 1.5-2.1] and 1.9%-points [95% CI: 1.5-2.3], respectively). The largest was for ovarian cancer (27 points, 95%CI: 24-29). For other cancers, differences ranged between 7 (95% CI: 5-9, esophagus) and 18%-points (95% CI: 17-19, pancreas). With the exception of pancreatic cancer, cancer type and stage combinations with either very high (e.g., >95%) or very low (e.g., <40%) 1-year RS tended to have smaller age-related differences in survival than those with mid-range prognoses.
Conclusions and RelevanceThe broad age-related variation in survival across cancer types and stages may reflect the degree to which cancers are amenable to anti-cancer treatment. Future work to measure the extent of age-related differences that are avoidable, and identify how to narrow the survival gap, may have most benefit by prioritizing cancers with relatively large age-related differences in survival, especially at earlier stages (e.g., stomach, esophagus, liver and pancreas).
Key PointsO_ST_ABSQuestionC_ST_ABSAfter accounting for background differences in mortality, how big are differences in one-year cancer survival between older and younger adults and how does the magnitude vary by cancer site and stage?
FindingsIn this analysis of population-based cancer registry data, age-related differences in cancer survival varied widely, ranging from less than 1% absolute difference in localized breast and prostate cancer survival to over 30% absolute difference in localized pancreatic cancer survival.
MeaningFocused efforts to reduce age-related differences in cancer survival may have greatest impact by prioritizing cancer site and stage combinations with the widest differences.
