Related Experiment Video
Updated: Jun 18, 2026
Competing-Risk Nomogram for Predicting Cancer-Specific Survival in Multiple Primary Colorectal Cancer Patients after Surgery
Published on: September 27, 2024
Second primary cancer in patients with colorectal cancer after a curative resection
Shingo Noura1, Masayuki Ohue, Yosuke Seki
1Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan. noura-si @ mc.pref.osaka.jp
Background:
Colorectal cancer (CRC) patients have an increased risk of developing other malignancies. Understanding the characteristics of the second primary cancer is important to establish an effective surveillance program.
Methods:
This study investigated 301 CRC patients to assess the risk factors for postoperative primary cancers arising from organs distinct from the colorectal area (extracolorectal cancers). The observed/expected ratio (O/E ratio) was calculated using the Osaka Cancer Registry, to determine the rate of increase in extracolorectal cancers.
Results:
The frequency of postoperative extracolorectal cancers was 12.6%. A logistic regression analysis showed only age to be an independent risk factor for postoperative extracolorectal cancer development. The O/E ratio of overall postoperative extracolorectal cancer was significantly higher than one (O/E ratio 2.6, p < 0.01). In each organ, the frequency of lung and gastric cancers were significantly higher than one, with O/E ratios of 3.2 and 2.7 (p < 0.01 and p < 0.05, respectively).
Conclusion:
The frequency of postoperative extracolorectal cancers in CRC patients was significantly higher than that in the normal population, especially for lung and gastric cancers. Clinicians should carefully follow patients for a possible recurrence of CRC and educate CRC patients with regard to the high risk of a second primary cancer.
