We did a randomised phase III trial comparing external irradiation alone and external irradiation combined with an analogue of luteinising-hormone releasing hormone (LHRH) to investigate the added value of long-term androgen suppression in locally advanced prostate cancer.

Between 1987 and 1995, 415 patients were randomly assigned radiotherapy alone or radiotherapy plus immediate androgen suppression. Eligible patients had T1–2 tumours of WHO grade 3 or T3–4 N0–1 M0 tumours; the median age of participants was 71 years (range 51–80). In both treatment groups, 50 Gy radiation was delivered to the pelvis over 5 weeks, and 20 Gy over 2 weeks as a prostatic boost. Goserelin (3·6 mg subcutaneously every 4 weeks) was started on the first day of irradiation and continued for 3 years; cyproterone acetate (150 mg orally) was given for 1 month starting 1 week before the first goserelin injection. The primary endpoint was clinical disease-free survival. Analyses were by intention to treat.

412 patients had evaluable data, with median follow-up of 66 months (range 1–126). 5-year clinical disease-free survival was 40% (95% CI 32–48) in the radiotherapy-alone group and 74% (67–81) in the combined-treatment group (p=0·0001). 5-year overall survival was 62% (52–72) and 78% (72–84), respectively (p=0·0002) and 5-year specific survival 79% (72–86) and 94% (90–98).

Immediate androgen suppression with an LHRH analogue given during and for 3 years after external irradiation improves disease-free and overall survival of patients with locally advanced prostate cancer.