In all National Surgical Adjuvant Breast and Bowel Project (NSABP) breast cancer trials in which patients are treated with lumpectomy and postoperative breast irradiation, the quality assurance requirements dictate submission of a completed radiotherapy data form with the stated administered doses, the volumes treated, treatment prescription and daily treatment record sheets, dosimetry and calculation sheets, isodose distributions on the breast contour, photos of the patient in the treatment position, and portal or simulation films. A review of radiotherapy data on 1,982 patients who had lumpectomies accrued to seven recent NSABP breast cancer studies revealed only 2 patients who were judged to have inadequate fields. In both cases, a very small portion of the breast tissue was not included in the irradiated volume as demonstrated by the submitted films. On this basis, it was argued that submission of portal or simulation films for patients receiving postlumpectomy breast irradiation is not necessary. However, there was concern as to the incidence of patients with a possible excess amount of lung tissue included in the irradiated volume. To address this concern, the amount of irradiated lung was determined for the first 208 patients who had lumpectomies, with submitted data entered into the recent NSABP pathologic node-positive protocol B-28. Current NSABP radiation therapy guidelines suggest limiting the thickness of the irradiated lung in the portal beams to < or =3 cm. Only two patients (<1%) were found to have >3 cm of irradiated lung tissue in the treatment volume. Portal film submission is a considerable inconvenience to the individual institutions and is costly in terms of shipping, handling, and storage. These results indicate that submission of portal films is not a necessary part of quality assurance in NSABP breast cancer protocols. The NSABP has therefore eliminated the requirement for routine submission of portal films in protocols for which radiotherapy is not part of the test question.