Re-irradiation of locally recurrent tumors with fast neutrons.

Forty-six patients with locally recurrent disease were re-irradiated with fast neutrons at Fermilab. All had received prior radical radiation therapy either with or without surgery. Six were palliative. Forty patients treated with curative intent were analyzed for local response, survival, and complications. The overall response rate was 78% (31/40); 50% (20/40) had a complete local response. Ten of 16 patients (63%) with non-epidermoid carcinomas in the head and neck regions had complete response, whereas only nine of twenty patients (45%) with epidermoid carcinomas were complete responders. In a subset of 12 patients with salivary gland type tumors, 10 had a complete response (83%). Two of these 10 patients are alive beyond 5 years. Observed median survival for the forty patients was 9.3 months, and for complete responders 14.4 months. Observed median survival for partial responders was only 7.5 months. Four of six patients treated for palliation had significant subjective improvement. Significant morbidity, Grade III or greater (EORTC/RTOG scale), was seen in only 10 patients (25%), and this was found to depend directly on the total dose delivered. We conclude that neutron beam therapy can be used as a therapeutic modality for patients with recurrent tumors with an acceptable degree of morbidity.