The regression of tumors of the head and neck treated with neutrons.

Measurements were made of the exponential regression of cervical nodes from 44 patients with squamous carcinoma of the head and neck and of 20 salivary gland tumors treated with neutrons (7.5 MeV). In 80% of patients, the tumor regressed exponentially from the first day of treatment; in 20% of patients there was an initial shoulder followed by exponential regression. The volume-halving times were calculated and found to vary widely for each histological type. There was no correlation of the volume-halving time either with the differentiation of the squamous carcinomas or with the initial tumor volume. The mean volume-halving time for squamous carcinoma of the head and neck was 20.8 days; for malignant pleomorphic adenomas of the parotid gland the mean volume-halving time was 122.6 days.