Social class and cancer patient survival in Finland

The effect of social class on survival was assessed in a cohort of cancer patients identified from the nationwide population-based Finnish Cancer Registry. The cohort consisted of all reported cases of the 12 most common types of cancer occurring in Finland between 1971 and 1985 among persons born in 1906-1945 (n = 106,661). Social class information based on occupation was obtained individually for each patient from the population census of 1970. Both observed and corrected (i.e., cause of death-specific) 5-year survival rates were used in the analyses. A statistically significant linear effect of social class on age-adjusted relative risk of cancer death was observed in six of 12 cancer types among men and in nine of 12 among women; and the risk was highest for those in the lowest social class. The relative risk of death due to cancer for social class I (highest) relative to social class IV (lowest) was lowest in bladder cancer (relative risk (RR) = 0.46, 95% confidence interval (CI) 0.34-0.61) and kidney cancer (RR = 0.61, 95% CI 0.48-0.78) among men and in corpus uteri (RR = 0.51, 95% CI 0.36-0.72) and rectum cancer (RR = 0.56, 95% CI 0.42-0.74) among women. The differences between results obtained using corrected and observed survival rates were small. These findings indicate that social class is an important determinant of cancer patient survival. Additional research is required to clarify the etiology of the social class differences and to identify factors that could be used for developing strategies to diminish such inequalities.