Background: Adjuvant chemotherapy for colorectal carcinoma was found to improve survival of patients with American Joint Committee on Cancer/International Union Against Cancer Stage III disease. The usefulness of chemotherapy in patients with Stage II disease continues to be debated, and it is likely that only those patients with a poor prognosis should receive adjuvant chemotherapy. Biologic prognostic factors may allow further insight into the optimal treatment strategy for patients with Stage II or earlier disease. In this study the prognostic role of S-phase fraction (SPF) determined by flow cytometry was assessed in patients with Stage I-II colorectal carcinoma.
Methods: Specimens of surgically resected colorectal carcinoma were examined for SPF by flow cytometric DNA analysis. Consecutive patients referred to the study institution were considered eligible for this study. The main inclusion criteria were a Stage I-II tumor together with sufficient tumor material and adequate follow-up information. For each stage of disease, SPF data were associated with the recurrence rate and the disease free survival (DFS).
Results: Analysis was performed on 167 patients (65 with Stage I disease and 102 with Stage II disease). Among Stage I patients, SPF was high in 20 patients and low in 45 patients. In Stage II patients, there were 36 patients with low SPF and 66 patients with high SPF. In both stages, the recurrence rate and DFS were significantly worse for the subgroups of patients with high SPF.
Conclusions: SPF has revealed prognostic differences among patients with surgically resected Stage I-II colorectal carcinoma. These data should be considered for planning future trials in the adjuvant setting because patients with high SPF may benefit from adjuvant chemotherapy.