IORT: A broad consensus was expressed by physicians about clinical indications of IORT: it may be an alternative to whole-breast adjuvant radiotherapy (WBRT) for postmenopausal women over 55 years of age, with nonspecific, ductal, grade 1 or 2 carcinomas, unifocal tumors of good prognosis and size <20 mm, no lymph node involvement, hormone receptor positive, and HER2 not overexpressed. If the cancer is “in situ”, it must not be expansive. Unifocal character of the tumor must be confirmed by angiomammography and MRI before treatment can be proposed. However, according to participants, other criteria may be taken into consideration to offer this treatment: geographical remoteness of the patient, very old age and lower life expectancy, other more serious cancer (allows treatment of everything at the same time) and previous radiotherapy (P15), technical contraindication or impossibility of WBRT (impossibility to lift the arms for example) (P1), and associated comorbidities or severe disease making external radiotherapy of little benefit compared to IORT (P11). Most physicians also considered that there are fewer side effects and sequelae with IORT than with WBRT: less fatigue, less breast sequelae (less fibrosis, burns, pain), better cosmetic result (less breast deformity), and less long-term toxicity to peripheral organs (lung and heart).

Radiation omission: In the case of breast-conserving surgery, withholding radiotherapy was not considered a treatment option by the physicians interviewed, mainly because it is not currently an option validated by the French health authorities, and it is associated with an increased risk or at least uncertainty about long-term risk of cancer relapse. As a result, radiation omission was exceptional and was only described in very old patients with poor general conditions, major co-morbidities, or short-term vital prognosis or when it was technically impossible to carry out radiotherapy. According to the interviewed physicians, radiation omission could only be an option in conjunction with radical mastectomy. Some doctors regretted that women were not well informed about this treatment option, as some might choose total mastectomy, which avoids radiotherapy while ensuring optimal local control. The physicians interviewed were rarely confronted with patients refusing radiotherapy. Refusal may be related to fear of radiation in women who have a breast prosthesis or in the oldest patients who do not invest much in the future and are afraid of all the treatments. It may also follow a history of very negative family radiotherapy experience or may be part of a broader context of overall refusal of conventional care in patients who turn to alternative medicine.