Radiation therapy in early glottic cancer. Analysis of 177 consecutive cases

Early vocal cord carcinomas (TiS or T1) in a consecutive series of 177 patients treated by primary radiotherapy over a 10-year period 1970-79 at the Department of General Oncology, Radiumhemmet, Karolinska Sjukhuset, were analysed regarding treatment results. In 137 cases the tumours were invasive (T1N0M0) and in 40 cases carcinoma of in situ type (TiS). Patient were treated with cobalt 60 gamma irradiation in fractions of 2 Gy up to a total dose of 64 Gy delivered as split course (CRE=17.8). Minimum follow-up time was 5 years. Tumour recurred in 21 cases (12%). All but 4 patients were rescued by subsequent surgery, giving 98% total survival. Treatment failures after primary radiotherapy were analysed in detail. Failures could not be attributed to treatment irregularities. No difference in pretreatment tumour size was detected when cured patients were compared with patients who relapsed. Biological factors that cause a relative radioresistance are considered to be the main reason for radiotherapy failures in early glottic cancer.