Construction and validation of a simple scoring system for stage III colorectal cancer recurrence (SiS-SCORE). A case control study.

Background: Stage III colorectal cancer is an indication for adjuvant chemotherapy; however, there is no definite view on the selection of regimen. If the recurrence can be predicted, it can serve as the indicator of regimen selection. The present study aimed to predict the recurrence of stage III colorectal cancer by constructing a simple scoring system.

Methods: The information of stage III cases that underwent curative surgery was obtained from two facilities and analyzed. A scoring system was constructed from the analysis results and evaluated based on the cases from a different facility.

Results: Five factors were extracted by multivariate analysis: age > 65, male, rectum, ≥pN2 and CA19-9 > 37. When these parameters were scored as 1 point each, the score was correlated with the cumulative recurrence rate. Additionally, when cases were divided into three groups (≤1 point, 2 points, ≥3 points), the 5-year recurrence rate was as follows:, ≤1 point: 33.3%, 2 points: 42.1%, ≥3 points: 78.6%. The cumulative recurrence rate of ≥3 points was significantly higher than that of ≤1 point (P < 0.001). Similar results were obtained by evaluating that cases at a different facility (P = 0.032). Both cases with 2 points were located between ≤1 point and ≥3 points, reflecting the average recurrence rate of each institution.

Conclusion: As the SiS-SCORE presented the same result in the facility that was different from the base facility, it can be used widely. However, a prospective study is required to prove the usefulness of the SiS-SCORE.