The Role of Fast Neutrons in the Treatment of Squamous Cell Carcinomas of the Head and Neck: The European Experience

After the first European stet on neutron therapy of head and neck cancer, published by Catterall and Bewley, revealed significant advantages of neutrons over photons in 134 randomized patients, the subsequent phase II and phase III studies led to controversial results. Figures for local tumor control varied from 26–76% after 2 years to 19% after 10 years and for survival from 16–46% after 2 years to 14% after 10 years. Results of all studies were consistent in showing an increased incidence of severe late effects. Eligibility criteria with regard to the tumor stage, histology, and previous therapies of relapses varied from study to study. Also, physical treatment parameters, such as neutron energy, LET and OER, neutron and photon doses for one fraction and for the total radiotherapy were rather different. The benefit of neutron therapy in comparison with photons was low or non-existent when smaller tumor stages, such as primaries T 2 or lymph nodes N 1 were included into the trial. It increased when only T 4 tumors, recurrences or tumors persisting after conventional radiotherapy were treated and when the percentage of fixed lymph nodes increased. There was only one European study in which patients suffering from lymph node metastases of the neck had, in contrast to American data (Griffin et al. 1978), a worse prognosis after neutrons than after photon therapy (Duncan et al. 1987b). In our own phase II study on reactor neutron therapy of 100 patients suffering from relapses and persistent tumors, not yet published, 3-year survival of 21% and 3-year local control of 32% were obtained. Although this was not a randomized study, during this period all patients with equivalent tumors treated by photon therapy alone died within 2 years. In conclusion, there is no general indication for neutron therapy in squamous cell carcinoma of the head and neck, but there is a benefit of neutrons in palliative treatment of recurrences, necrotic and hypoxic primaries and lymph nodes.