LOCAL-CONTROL IN MEDICALLY INOPERABLE LUNG-CANCER - AN ANALYSIS OF ITS IMPORTANCE IN OUTCOME AND FACTORS DETERMINING THE PROBABILITY OF TUMOR-ERADICATION

Purpose: For patients who are medically unable to tolerate a surgical resection for technically resectable non-small-cell lung carcinoma, ra diation therapy is an acceptable alternative. We report on the effect of achieving local control of the primary tumor on survival end-points , and analyze factors that may influence local control. Methods and Ma terials: We reviewed the records of 152 patients with medically inoper able non-small-cell lung carcinoma treated at our institutions. All pa tients had technically resectable lesions and no evidence of metastati c disease. Treatment was delivered using megavoltage irradiation to do ses ranging from 45 to 75 Gy. Results: For patients with tumors 3 cm o r less, locally controlling the tumor significantly improved survival (p = .0371). Patients with Tl tumors had a higher probability of survi val and disease-free-survival than patients with larger tumors if the primary tumor was locally controlled, but this survival advantage disa ppeared if the tumor was not controlled. Overall, patients with smalle r tumors had a lower incidence of distant spread, but this association was maintained only when the primary tumor was controlled (36 month r isk of 10%, 23%, and 57% for tumors < 3 cm, 3-4.9 cm, 5 cm or greater, respectively, p = .0027). For patients whose tumors were not controll ed, there was no significant difference in the risk of distant dissemi nation by tumor size. Higher radiation doses influenced local control and metastatic spread. We observed no influence of the initial field s ize in the risk of local control and in the probability of survival. C onclusion: Radical radiation therapy is an effective treatment for sma ll (T1 or < 3 cm) tumors when treated to doses of 65 Gy or more, and s hould be offered as an alternative to surgery in elderly or infirm pat ients. New therapeutic strategies to improve the local control rate sh ould be considered for larger tumors, through the use of hyperfraction ated treatment, endobronchial ''boost'' irradiation, and sensitizing c hemotherapy agents.