Smoking is one of the most attributable risk factor for cancer in worldwide. The purpose of this study was to estimate the risk of second primary cancers(SPCs) according to Pre-diagnosis smoking status among cancer survivors and the risk of primary cancers to Pre-diagnosis smoking status among total cohort population.
This study was a retrospective cohort study of male cancer survivors from January 2004 to December 2008, which there after were examined for SPCs until the end of 2013 from the National Health Insurance Corporation Study cohort in Korea. We included 244,079 patients in total cohort and 9,618 patients who survived for at least five years after cancer diagnosis. Cox proportional hazard models were used to calculate association between pre-diagnosis smoking status and primary cancer and SPCs.
Follow-up duration was 69,884 person-years, 580 patients presented with SPCs. Incidence rates of cancer were higher in cancer survivor than total cohort in smoking related cancer, head and neck cancer, respiratory cancer, urinary system cancer, colorectal cancer, pancreas cancer, bladder cancer, lung cancer.
Current smoker had 1.76(CI, 1.13-2.73) and 1.79(CI, 1.15-2.80) times higher risk for respiratory system cancer and lung cancer, and Current heavy smoker had 2.78(CI, 1.05-7.42) and 2.05(CI, 1.16-3.29) times higher risk for pancreas cancer and lung cancer than never smoker. The hazard ratio of smoking was higher in cancer survivors than total cohort in head and neck cancer, colorectal cancer, pancreas cancer. There were no statistical significance between the risk of SPCs and Age, BMI, Physical activity, alcohol consumption, CCI.
Pre-diagnosis smoking status was risk factors for respiratory cancer and lung cancer in current smoker. And pre-diagnosis smoking status was risk factors for pancreas cancer and lung cancer in current heavy smoker.