Radiation therapy of glottic carcinoma stage I

Results of radiation therapy in early glottic carcinoma (T1, T2 N0)

Glottic carcinoma is curable by either surgery or radiotherapy. A total of 60 patients were treated by radiation alone at the Northern Israel Oncology Center, Rambam Medical Center, Haifa, between 1970 and 1980. Twenty-nine (48%) were classified as T1 N0 and 31 (52%) as T2 N0. All patients received radiotherapy primarily with curative intent, with surgery reserved for recurrences. The 5-year actuarial survival for all patients was 90% and actuarial disease-free survival was 95%. In ten patients (17%) there was local failure, and five of them were salvaged by surgery. There were no significant acute or long-term complications of radiation. Factors influencing treatment outcome (anterior commissures involvement, degree of differentiation, treatment volume, and technique of irradiation) and the occurrence of second primary malignancies are discussed.

Iso-effect tables and therapeutic ratios for epidermoid cancer and normal tissue stroma

Available literature on radiation injury to normal tissue stroma and ablation of epidermoid carcinoma was surveyed. Computer programs (RAD3 and RAD1) were then used to derive cell kinetic parameters and generate iso-effect tables for the relevant tissues. The two tables provide a set of limiting doses for tolerance of normal connective tissue (16% risk of injury) and for ablation of epidermoid cancer (16% risk of recurrence) covering a wide range of treatment schedules. Calculating the ratios of normal tissue tolerance to tumor control doses for each treatment scheme provides an array of therapeutic ratios, from which appropriate treatment schemes can be selected.

Local control of T1 vocal cord cancer with radiation therapy: the importance of tumor character vs. treatment parameters

Ninety-one patients with T1 vocal cord carcinoma received primary irradiation treatment. The 5- and 10-year determinate disease-free survival was 80%; the 5- and 10-year determinate survival including surgical salvage was 92%. Tumors involving more than one-half of a vocal cord or involving the anterior commissure or exhibiting an exophytic growth pattern had numerically, but not statistically, higher local failure rates than tumors without these characteristics. Precise radiation treatment technique appears more important for local control (LC) than tumor character. The crucial treatment factors for high LC with few radiation complications are reproducible daily patient positioning, use of contour-compensating devices (wedges), field size of 5 X 5 cm, and a radiation prescription with a time-dose fractionation value of 101 to 106.