CB. Breast masses in women treated for childhood cancer: incidence and screening guidelines. Cancer 1998;82:784-792. Background: The authors' aims were to define the frequency, characteristics, and methods of detection of breast masses in young women treated for childhood cancer and to develop screening guidelines for the growing population of long term survivors. Methods: The authors reviewed medical records of all female patients treated for malignancy at a childhood cancer center over a 34-year period to identify those who developed a breast mass and to determine the cumulative incidence of breast cancer as a second primary cancer. Results: A breast mass was identified in 66 patients who had been diagnosed with a malignancy at a median age of 13.8 years (range, 0.4-24.4 years). Masses were initially detected by breast self-detection in 32 and clinical examination in 28; the method of detection was unknown in 6 cases. Breast lesions were