Postoperative radiotherapy following mastectomy for high-risk breast cancer. A randomised trial.

Grade III, node-positive breast cancer carries a high risk of loco-regional relapse after simple mastectomy. A randomised trial was conducted to assess whether this would be significantly reduced by postoperative radiotherapy. Between 1985 and 1991, 76 patients who had undergone a simple mastectomy and axillary sampling, and whose tumours had been found to be grade III and node-positive, were randomised to receive postoperative radiotherapy to the chest wall and axilla or no further loco-regional treatment. Radiotherapy was delivered with 8 MV X-rays to the axilla and supraclavicular fossa and with 8 MeV electrons to the chest wall, to a dose of 45 Gy in 15 fractions over 3 weeks. All patients have been followed-up until death, or for a minimum of 10 years. All loco-regional recurrences occurred within the first 4 years after mastectomy. There were 26 such events in the 40 patients randomised to the 'watch' policy (65%), as opposed to 9 out of 36 (25%) who received radiotherapy (P<0.01). Ten-year survival was 39% in the radiotherapy arm as opposed to 25% in the no radiotherapy arm. Recruitment to the trial was closed in 1991, when a preliminary safety analysis revealed the size of the effect of radiotherapy, and from then on all node-positive patients with grade III tumours have routinely been given this treatment. Further follow-up has confirmed this finding, as borne out by these 10-year results, which shows that radiotherapy has a significant impact on reducing loco-regional recurrence in patients at high risk after mastectomy. There is an apparent survival benefit although, because of the small numbers in this trial, this has not reached statistical significance.