Population based study of prognostic factors in stage II colon cancer

Abstract

3619 Background: Guidelines for the use of adjuvant chemotherapy in stage II colorectal cancer state this treatment may be considered to patients whose tumours show features of poor prognosis. The aim of the current study was to evaluate the prognostic significance of commonly reported clinical and pathological features of this disease. Methods: A population-based observational study encompassing all stage II colon cancer patients diagnosed in the state of Western Australia from 1993–2003 inclusive. A total of 1306 cases treated by surgery alone were identified and had a median follow-up of 59 months (range 0–145). Results: Multivariate analysis revealed the only independent prognostic factors for disease-specific survival were T4 stage (HR=1.75, 95%CI [1.32–2.32], P<0.0001) and vascular invasion (HR=1.63, 95%CI [1.15–2.30], P<0.0001). In the younger patient group (≤75 yrs) who are more likely to be considered for chemotherapy, the same two features showed independent prognostic significance but with higher HR values (1.96 and 2.73 respectively). T4 and/or the presence of vascular invasion identified a “poor” prognosis group comprising 26% of younger cases and having a 5-year survival rate of 71%. The remaining “good” prognosis group showed 84% survival at 5 years follow-up. Conclusion: This study highlights the importance of accurate pathological assessment of T stage and vascular invasion for the prognostic stratification of stage II colon cancer and their subsequent consideration for adjuvant chemotherapy. No significant financial relationships to disclose.