Risk of second primary malignancies in young patients with colorectal cancer.

e14533 Background: Colorectal cancer (CRC) is one of the most common cancers. Because of the increase in long survivors of CRC, second primary cancer (SPC) became a major issue. Methods: We searched the database of Taiwan Cancer Registry for patients who have histology-proven primary colon cancer or rectal cancer from 1995 to 2005. We observed SPC events which had to be histology-proven except for liver cancers until 2009. We calculated the standardized incidence ratios (SIRs), which were the numbers of observed SPC events divided by the expected numbers of cancers occurrences in general population. Results: A total of 65,648 patients were enrolled. With median follow-up of 4.4 years, 3,810 SPC events were identified. In the entire cohort, the SIR was 1.03 (95% confidence interval [CI]: 0.99-1.06). Patients who aged u003c 50 and 50-69 years had significantly increased SIRs of 2.52 (95% CI: 2.28-2.78) and 1.18 (95% CI: 1.12-1.23), respectively. For young patients who aged u003c 50 years, the significantly increase...