Excessive risk of second-cancer incidence and cancer mortality in patients with esophageal cancer

Background: Second primary cancers have impact on survival in patients who achieved cure for the first esophageal cancer. We, therefore, assessed the risk of incidence and mortality for second primary cancer by calculating standardized incidence ratio (SIR) and standardized mortality ratio (SMR) in patients with superficial or localized esophageal cancer without lymph node metastases as the first cancer (index cancer). Methods: Data on cancer development and subsequent causes of deaths were collected from integrated database of the Osaka Cancer Registry and the Vital Statistics of Japan. Records with information on patients with index esophageal cancer diagnosed between 2004 and 2013 were extracted from the database. Then, SIR and SMR for second primary cancers that developed in other organ were calculated with the reference to the general population during the same period. All probability values are two-tailed. Results: Of 473,784 case records, 3022 cases of patients with index esophageal cancer were identified. Significantly higher SMRs/SIRs for cancers in mouth/pharynx, larynx, pancreas, and leukemia were confirmed with the values of 10.78/16.16, 8.56/6.44, 2.33/2.31, and 3.96/4.42, respectively. Significantly, higher SIRs for stomach, lung, and skin cancers were confirmed with the values of 2.84, 2.36, and 3.38, respectively, while SMRs were not significantly higher in these cancers. Conclusions: Significantly higher risks for mouth/pharynx, larynx, pancreas, and leukemia as second cancers were clarified. Careful surveillance for these cancers is required for esophageal cancer patients.