ABSTRACT
BACKGROUND/AIMS: Colorectal cancer and thyroid cancer are common diseases with relatively higher survival rates compared with other cancers. The number of patients identified with colorectal cancer or thyroid cancer who develop multiple primary malignancy during long-term follow-up is increasing with advances in diagnostic techniques and treatment modalities. However, the association between colorectal cancer and thyroid cancer is uncertain, and few data have been reported in Korea. This study examined the association between thyroid cancer and colorectal neoplasm. METHODS: We retrospectively investigated 363 patients who underwent a colonoscopy, among patients diagnosed with thyroid cancer between January 2004 and December 2008 at Samsung Medical Center. The control group was comprised of 2,494 patients who underwent screening colonoscopy for the first time within the study period at the center for health promotion at Samsung Medical Center between March 2004 and December 2005. RESULTS: The detection rates in patients with thyroid cancer were 4.7% (17/363) for advanced adenomas and 2.8% (10/363) for colorectal cancer. In the control group, it was 3.2% (79/2,494) for advanced adenomas and 0.3% (7/2,494) for colorectal cancer. A multivariate analysis revealed that the presence of thyroid cancer had an odds ratio of 1.893 (95% confidence interval, 0.868-4.128, P=0.109) in favor of finding at least one advanced colorectal neoplasm. CONCLUSIONS: The results indicate that thyroid cancer is not associated with advanced colorectal neoplasm. Survivors of thyroid and colorectal cancer live longer and hence are at risk for second primary cancers. Therefore, further studies that prospectively evaluate the association between thyroid cancer and colorectal advanced neoplasm are needed.