The role of fast neutron radiation therapy in the management of advanced salivary gland malignant neoplasms.

Fifty-three patients with locally advanced salivary gland malignant neoplasm were treated with fast neutron radiation therapy. All patients received treatment for gross inoperable, residual unresectable, or recurrent disease--clinical situations in which results using photon irradiation were suboptimal. With a median follow-up of 42 months and a minimum follow-up of 1 year, locoregional tumor control in the treatment field was achieved in 92% (48 of 52) of patients. An additional eight patients had regional failures outside the treatment field, resulting in an overall locoregional tumor control rate of 77% (40 of 52). The 5-year actuarial locoregional control rates were 65% overall and 75% in patients with node-positive disease. Grouping patients according to prior treatment status, actuarial 5-year locoregional control rates were 92% for patients treated definitively (without a prior surgical procedure), 63% for those treated postoperatively for gross residual disease, and 51% for those treated for recurrent disease after a surgical procedure. The P values associated with these differences were 0.12 and 0.01, respectively. There were no instances of radiation-induced facial nerve damage. This study suggests that neutron irradiation alone should be the therapy of choice in the treatment of advanced-stage salivary gland tumors and that surgery should be limited to those patients in whom disease-free margins can be obtained. The potential morbidity of a debulking surgical procedure before neutron irradiation is not warranted by an improvement in loco-regional control over that achievable with neutron therapy alone.