Age-related differences in cancer relative survival in the US: a SEER-18 analysis

Abstract

Importance: In 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. Objective: To quantify age-related differences in relative survival by stage at diagnosis for 10 cancer types. Design: Retrospective population-based observational study of cancers diagnosed between 2012-2016 with follow-up through December 31, 2017 Setting: 18 US Surveillance Epidemiology and End Results cancer registries Participants: 844,296 individuals aged 50 and over with first primary cancers of the prostate, breast, rectum, colon, ovary, esophagus, stomach, liver, lung, and pancreas. Exposure: Age 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. Results: The 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 Relevance: The 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).

Age-related differences in colon and rectal cancer survival: An analysis of United States SEER-18 data

“…3 Consistent with our findings, increasing age-related differences in colon and rectal cancer survival with worsening stage of diagnosis and large differences for unstaged diseases have been observed in ICBP and other countries, 5,3,13 which have also been shown for other cancer types in the US. 19 Regarding sex, the greater age-related differences in colon cancer survival in females with distant disease than males were also observed in New Zealand and Finland. 5,20 Some authors have suggested a possible involvement of sex hormones, but no causal mechanisms have been identified so far.…”

“…Consistent with our findings, increasing age-related differences in colon and rectal cancer survival with worsening stage of diagnosis and large differences for unstaged diseases have been observed in ICBP and other countries, 5,3,13 which have also been shown for other cancer types in the US. 19…”