Concomitant boost radiotherapy schedules in the treatment of carcinoma of the oropharynx and nasopharynx

Abstract

Concomitant boost schedules are characterized by delivering the boost (10-12 fractions) as second daily treatments during rather than following the basic wide field irradiations. This results in shortening the overall time to administer 69-72 Gy from 7 1/2-8 weeks to 6 weeks, which we hoped would improve the tumor control rate by reducing the opportunity for tumor clonogens to regenerate during treatment. From August 1985 to August 1988, 79 patients with T2-4 carcinomas of the oropharynx (72 patients) or nasopharynx (7 patients) were treated according to 1 of the 3 variants of the concomitant boost technique. The median age of patients was 60 years (range: 19-84 years) and the male-to-female ratio was 2.6. The overall 2-year actuarial primary and nodal control rates by radiotherapy alone were 74% and 76%, respectively. The ultimate 2-year control rates after surgical salvage were 82% and 84%, respectively. If the boost given during the last 2-2 1/2 weeks of basic treatment, a slightly better primary control rate (p = 0.11) resulted than if the boost was delivered during the first 2-2 1/2 weeks or twice a week throughout the basic treatment. The 2-year actuarial primary control rate of the 13 patients receiving induction chemotherapy prior to radiotherapy was significantly lower than that of patients treated with radiation only (81% vs 34%, p = 0.01), but this could be partly attributed to a more advanced stage in the chemotherapy group. The acute mucosal reactions were, as expected, more severe than those observed with conventional fractionation. Fifty patients developed confluent mucositis covering more than half of the boost area. Such reactions lasted for more than 6 weeks in seven patients. Late complications, however, so far observed, have been few. Three patients experienced chronic mucosal tenderness, 1 chronic mucosal ulceration, 2 transient bone exposure, and 1 carotid rupture following salvage surgery. The results so far appear to be better than the outcome of conventional radiotherapy. Its real value will be determined in a prospective randomized study.