Clinical features of second other-site primary cancers among sporadic colorectal cancer patients - A hospital-based study of 3,722 cases

Background/Aims: Although synchronous and metachronous colorectal cancers are now well known to all colorectal surgeons, second other-site primary cancers following colorectal cancer are unfamiliar to most colorectal physicians. Knowledge of the clinical characteristics of these second other-site primary cancers becomes important especially during their follow-up surveillance. Methodology: Information from a computer database was retrieved. Medical records were reviewed and all histopathological data were confirmed. Results: Forty-seven (1.26%) patients developed second other-site primary cancers. Of these patients, 22 (46.8%) patients were diagnosed concordantly while 25 (53.2%) patients were discordant cases. Twelve of 25 (45%) discordant cases were found within one year postoperatively. Regarding the clinical features of these 47 patients, male patients more frequently develop discordant cases (p=0.031). A significantly higher proportion of Dukes' B patients developed second other-site primary cancer than that of patients of other stages (p=0.017). Liver, 8 (17%) cases, was the most common site followed by the prostate, 6 (13%), stomach, 6 (13%), lung, 5 (11%), head and neck cancers, 5 (11%), and kidney, 3 (6.4%). However, there was not a significantly increased risk for these sporadic colorectal patients statistically. Conclusions: We described clinical features of second other-site primary cancers and emphasized that knowledge of these is important for their postoperative surveillance.