Failure patterns correlate with the tumor response after preoperative chemoradiotherapy for locally advanced rectal cancer.

BACKGROUND AND OBJECTIVES

To determine whether the patterns of failure are correlated with the degree of response to preoperative chemoradiotherapy (CRT) and to evaluate outcomes after recurrence in rectal cancer patients who underwent CRT followed by resection.

METHODS

Response to CRT was evaluated according to tumor regression grade (TRG), with 581 patients categorized into two groups, a good response (GR, TRG 3/4, n = 224) and a poor response (PR, TRG 1/2, n = 357) group.

RESULTS

At a mean follow-up of 61 months, the 5-year overall (88.2% vs. 71.3%, P < 0.001) and disease-free (86.7% vs. 63.6%, P < 0.001) survival rates were higher in the GR group. In patients with recurrence, time to recurrence was shorter (13.5 months vs. 18.7 months, P = 0.01), and the cumulative 2-year recurrence rates (92.9% vs. 73.4%, P = 0.024) was higher in the GR group. Rates of local (1.3% vs. 9.5% P < 0.001) and systemic (11.6% vs. 27.2%, P < 0.001) recurrence were significantly lower in the GR group, as were rates of pulmonary (3.6% vs. 15.1%, P < 0.001) and systemic lymph node (1.3% vs. 5.9%, P = 0.009) recurrences. The 5-year overall survival rates after recurrence were similar (GR: 23.7% vs. PR: 16.0%, P = 0.911).

CONCLUSIONS

More than one-third of patients with locally advanced rectal cancer showed good response to CRT, with improved local and systemic recurrence rates, especially low rates of pulmonary and systemic lymph node recurrence. Recurrence occurred earlier in the GR than the PR group, and oncologic outcomes after recurrence did not differ between the two groups.