Postoperative radiotherapy in rectal cancer: long-term results of 290 patients

To evaluate treatment results and to identify prognostic factors affecting local-relapse-free (LRFS), disease-free (DFS) and overall survival (OS) in patients treated with postoperative radiotherapy (RT) for rectal cancer.

A retrospective review was performed in 290 patients treated between January 1990 and December 2005. Median RT dose was 54 Gy. A total of 220 (75.8%) patients also received 5-fluorouracil based chemotherapy.

During a median follow-up of 56 months (range 9-216 months), 68 patients (23.4%) developed local recurrence and 96 patients (33.1%) developed distant metastases. Five-year LRFS, DFS, and OS rates were 74.6%, 52.6%, and 53.7%, respectively. On multivariate analysis, significant prognostic factors for LRFS were age, pathologic T stage (pT), and distance from anal verge; for DFS were pT stage, and positive surgical margin; for OS were pT and pathologic N (pN) stages. One hundred and fifty-two node-positive patients whose number of retrieved and metastatic nodes are known were evaluated according to the lymph node ratio (LNR). OS and DFS rates significantly decreased with increasing LNR (p = 0.005, and p = 0.023 respectively). RT related Grade 3-4 late morbidity rate was 3.1%. A second primary malignancy developed in 4.8% of patients.

Among several prognostic factors, pT stage significantly predicted for LRFS, DFS and OS on multivariate analysis, while pN stage was significant for all three only on univariate analysis. LNR which affected DFS and OS could be an important tool for prognostic prediction for node-positive patients.