What is the optimal length of neo-adjuvant therapy? — ASN Events

What is the optimal length of neo-adjuvant therapy? (#110)

Sam Ngan 1
  1. Peter MacCallum Cancer Centre, East Melbourne, VIC, Australia

Adding radiotherapy to surgery has been shown conclusively to improve local control for rectal cancer. Short course preoperative radiotherapy of 25Gy in 5 consecutive days has been shown to be very effective in tumor control by the Swedish and the Dutch rectal cancer trials. Long course preoperative chemoradiation of 50.4Gy in 5 weeks and 3 days with concurrent chemotherapy has been widely practiced in the last 15 years. In the German rectal cancer trial, its superiority, in terms of local control, was demonstrated when compared with postoperative chemoradiation. Although both short course preoperative radiotherapy and long course preoperative chemoradiation have been practiced in parallel for over 15 years, it has not been clear which form of preoperative radiotherapy provides better tumor control. The Australian and New Zealand study (TROG 01.04) was performed to compare short course (SC) radiotherapy with long course (LC) chemoradiation. It demonstrated a small difference in local recurrence rate at three years, 3.1%, favoring LC (P = 0.24). The 95% CI for the difference (SC-LC: -2.1% to +8.3%) includes differences of 8% or more in favor of LC (e.g. 10% versus 2%) so the trial has not excluded there being a clinically important difference in 3-year LR rates. The data are consistent with either no difference or an important clinical difference in favor of LC. There was a large observed difference for distal tumour favoring LC (6 of 48 SC versus 1 of 31 LC patients recurred locally) but it was not statistically significant. At this stage of knowledge it may be reasonable to suggest a policy that distal or bulky tumors be treated with long course and that where convenience is an important consideration short course be used.