Evaluation of Hypothyroidism Incidence After Breast Cancer Supraclavicular Irradiation

Prospective, multicentric, comparative, non randomised, in current care. Primary objective: * To evaluate the incidence of hypothyroidism in breast cancer patients treated by radiotherapy including the supra-clavicular area over a period of 5 years (60 months). Secondary objectives : * To calculate the dose of irradiation received by thyroid gland during the treatment. * To compare the rate of incidence of hypothyroidism in women who received a supra-clavicular irradiation (group 1)and in those who did not (group 2). * To estimate and compare the rate of incidence of chronic thyroid lesions in the 2 groups. * To look for predictive factors of hypothyroidism de novo in group 1 women particularly regarding the dose-volume parameters. * To propose recommendations for the thyroid follow-up after supra-clavicular irradiation.