Prognostic Significance of Tumor Regression in Locally Advanced Rectal Cancer after Preoperative Radiochemotherapy

Background: The majority of rectal cancers are discovered in locally advanced forms (UICC stage II, III). Treatment consists of preoperative radiochemotherapy, followed by surgery 6-8 weeks later and finally by postoperative chemotherapy. The aim of this study was to find out if tumor regression affected long-term survival in patients with localy advanced rectal cancer, treated with neoadjuvant radiochemotherapy.

Patients and methods: Patients with rectal cancer stage II or III, treated between 2006 and 2010, were included in a retrospective study. Clinical and pathohistologic data were acquired from computer databases and information about survival from Cancer Registry. Survival was estimated according to Kaplan-Meier method. Significance of prognostic factors was evaluated in univariate analysis; comparison was carried out with log-rank test. The multivariate analysis was performed according to the Cox regression model; statistically significant variables from univariate analysis were included.

Results: Two hundred and two patients met inclusion criteria. Median follow-up was 53.2 months. Stage ypT0N0 (pathologic complete response, pCR) was observed in 14.8% of patients. Pathohistologic stage had statistically significant impact on survival (p = 0.001). 5-year survival in patients with pCR was>90%. Postoperative T and N status were also found to be statistically significant (p = 0.011 for ypT and p < 0.001 for ypN). According to multivariate analysis, tumor response to neoadjuvant therapy was the only independent prognostic factor (p = 0.003).

Conclusions: Pathologic response of tumor to preoperative radiochemotherapy is an important prognostic factor for prediction of long-term survival of patients with locally advanced rectal cancer.