Radiation therapy for stage I and II laryngeal cancer using 10 MV X-rays or cobalt-60 gamma-rays

From 1970 to 1985, 117 patients with stage I and stage II carcinoma of the larynx (98 with glottic, 15 with supraglottic, and 4 with subglottic cancer) received radiation therapy. The patients were treated with (1) a 60Co machine equipped with 45-degree wedge filters, at a total dose of 6,000-7,000 cGy, 300 cGy per fraction, 3 days a week in the period from 1970-1974; (2) 10 MeV linear accelerator X-rays from 1975-1980, and (3) 10 MeV linear accelerator X-rays and/or the 60Co machine in the period from 1981-1985, at a total dose of 6,000-7,000 cGy, 5 days a week by parallel opposing portals without wedge filters. The 5-year local control rates by radiotherapy alone were 66%, 78%, and 83%, respectively, in the three periods, and the 5-year survival rates were 77%, 97%, and 96% following salvage surgery for recurrent disease. In the 1970-1974 period, four patients developed severe laryngeal edema, and two patients had total laryngectomy without local residual tumor. In the 1975-1985 period, 16 patients had local recurrence in five years, and in five of them the tumor exhibited verrucous-like histopathological findings. In the 1975-1980 period, local recurrence was considered to result from underdosing of lesions with 10 MV X-ray beams and split-course irradiation. In the last five years of the period, the 5-year local control rate for stage I and II carcinoma of the glottis, excluding verrucous-like carcinoma, reached 90% with 10 MV X-rays combined with 60Co gamma-rays.