Response to chemotherapy in patients with recurrent rectal cancer in previously irradiated area

Tumor lesions in previously irradiated area may have a less favorable response to chemotherapy compared to tumor sites outside the radiation field. The aim of the present study was to evaluate the response to chemotherapy of locally recurrent rectal cancer (LRRC) within the previous radiation field compared to the response of distant metastases outside the radiation field.

All patients with LRRC referred between 2000 and 2012 to our tertiary university hospital were reviewed. The response to chemotherapy of LRRC within previously irradiated area was compared to the response of synchronous distant metastases outside the radiation field according to the Response Evaluation Criteria in Solid Tumors (RECIST).

Out of 363 cases with LRRC, 29 previously irradiated patients with distant metastases were treated with chemotherapy and eligible for analysis. Twenty-six patients (89 %) suffered a first recurrence and three patients (11 %) a second recurrence. These patients were followed with a median of 22 months (IQR, 9-40 months) and had a median survival of 33 months (IQR, 14-42). In 23 patients (79 %), the local recurrence showed stable disease, but the overall response rate of the local recurrences in the previously irradiated area was significantly lower than the response rate of distant metastases outside the radiation field (10 vs. 41 %,p = 0.034).

Previously irradiated patients with LRRC have a lower response rate to chemotherapy of the local recurrence within the radiation field compared to the response rate of distant metastases outside the radiation field. This suggests that chemotherapy for local palliation may not have the desired effect.