Long-term results of preoperative radiation therapy alone for stage T3 and T4 rectal cancer

There has been a resurgence of interest in the use of preoperative radiation therapy, with or without chemotherapy, for locally advanced rectal cancer. The purpose of this study was to analyse the time course and pattern of failure for 74 patients with clinical stage T3 or T4 (cT3-4) rectal cancer treated with preoperative radiation therapy for whom long-term follow-up was available.

Seventy-four patients with cT3-4 rectal cancer received a median of 45.0 Gy radiation alone followed by surgery 4-8 weeks later. Median follow-up was 90 months; two-thirds of patients were followed for at least 60 months.

Following radiation therapy the pathological stage was 4 per cent pT0, 26 per cent pT1-2 and 70 per cent pT3-4. Thirty-two per cent had involved lymph nodes. The actuarial 5-year rates of local control, freedom from distant metastasis and disease-specific survival were 80, 64 and 73 per cent respectively. The corresponding 10-year rates were 73, 51 and 50 per cent. Median times to detection of local and distant recurrence were 34 and 24 months respectively. Eighty per cent of local recurrences were detected within 54 months; 80 per cent of distant recurrences were detected within 57 months.

In this analysis, the time to detection of both local and distant recurrences following preoperative radiation therapy for advanced rectal cancer was surprisingly long. Almost 5 years (57 months) of follow-up were required to detect 80 per cent of all failures. The 5-year local control rate of 80 per cent compares favourably with that achieved by more aggressive chemoradiation regimens for fixed cancers; however, the high distant failure rate with radiation therapy alone suggests that adjuvant systemic therapy should be investigated.