Regional variation in survival following the diagnosis of cancer

Recent studies have documented substantial geographical variation in patterns of treatment of cancer and other diseases. Because cancer treatment is not uniform nationwide, survival following the diagnosis of cancer might also be expected to vary geographically. Survival data from the nine population-based registries in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program were analyzed for cancers of the stomach, colon, rectum, lung, breast, uterus, ovary, prostate, and bladder (n = 401,861). The patients included all non-Hispanic white patients diagnosed with cancer of one of the selected sites during 1983-1991. Regional variation in crude five-year survival rates across the nine SEER areas was most marked for cancers of the uterus and prostate. For uterine cancer, for example, five-year survival ranged from 73.2% in Connecticut to 84.0% in Hawaii. Less marked variation was observed for cancers of the colon, rectum, and breast. For cancers of the bladder, ovary, stomach, and lung, survival rates five years after diagnosis were relatively invariant across the SEER areas. Observed differences in survival rates, although statistically significant, were relatively modest from the standpoint of the practicing physician. Nonetheless, the general pattern of regional variation was unchanged after adjustment for sex, age, stage, and surgical treatment and when analysis was limited to patients younger than 70 years, who would be anticipated to have the least comorbidity.