Associations between lifestyle factors and excess mortality of cancer patients in Finland: A pooled analysis of seven population‐based cohort studies

Modifiable risk factors, such as smoking, alcohol consumption, and excess weight, are associated with cancer incidence but data on their associations with population-based mortality among cancer patients are limited. Pooled data from seven health studies conducted in Finland during 1972-2015 were used to assess the associations of smoking, alcohol consumption, body mass index, physical inactivity, and education on mortality among 224,820 participants, of whom 10,637 were diagnosed with colorectal, lung, pancreatic, prostate or breast cancer. We estimated age-standardized relative survival and relative excess risks of death (RER) using piecewise constant excess hazard models. Current smoking was associated with increased excess mortality in male pancreatic cancer (RER compared with never-smokers 1.54, 95% CI 1.08-2.19) and prostate cancer patients (1.55, CI 1.08-2.23), as well as in female lung cancer patients (1.44, CI 1.07-1.92). Obesity was associated with increased excess mortality in prostate cancer patients (1.56, CI 1.06-2.30) and physical inactivity in colorectal cancer (1.33, CI 1.01-1.76 in men; 1.36, CI 1.06-1.74 in women) and male lung cancer patients (1.15, CI 1.02-1.30). Excess mortality was systematically elevated among patients with low education with statistically significant associations for male lung and female pancreatic cancer. Several lifestyle-related factors were associated with increased excess mortality among cancer patients but not consistently over all cancer sites or in both sexes. It is notable that even in a Nordic welfare state with potentially equal healthcare, marked socioeconomic inequalities persist in mortality among cancer patients.