High energy neutron treatment for pelvic cancers: study stopped because of increased mortality.

OBJECTIVE To compare high energy fast neutron treatment with conventional megavoltage x ray treatment in the management of locally advanced pelvic carcinomas (of the cervix, bladder, prostate, and rectum). DESIGN Randomised study from February 1986; randomisation to neutron treatment or photon treatment was unstratified and in the ratio of 3 to 1 until January 1988, when randomisation was in the ratio 1 to 1 and stratified by site of tumour. SETTING Mersey regional radiotherapy centre at Clatterbridge Hospital, Wirral. PATIENTS 151 patients with locally advanced, non-metastatic pelvic cancer (27 cervical, 69 of the bladder, seven prostatic, and 48 of the rectum). INTERVENTION Randomisation to neutron treatment was stopped in February 1990. MAIN OUTCOME MEASURES Patient survival and causes of death in relation to the development of metastatic disease and treatment related morbidity. RESULTS In the first phase of the trial 42 patients were randomised to neutron treatment and 14 to photon treatment, and in the second phase 48 to neutron treatment and 47 to photon treatment. The relative risk of mortality for photons compared with neutrons was 0.66 (95% confidence interval 0.40 to 1.10) after adjustment for site of tumour and other important prognostic factors. Short term and long term complications were similar in both groups. CONCLUSIONS The trial was stopped because of the increased mortality in patients with cancer of the cervix, bladder, or rectum treated with neutrons.