The position and current status of radiation therapy after primary systemic therapy in breast cancer: a national survey-based expert consensus statement.

Background: Primary systemic therapy (PST) is changing the role of radiation therapy (RT) in breast cancer. Without randomized studies, the optimal indications for RT after PST and surgery are not clear. The present study provides consensus-based recommendations to clarify the role of RT.

Methods: Radiation oncologists (n = 82; 77 % response rate) in Spain were surveyed to determine their recommendations for locoregional RT following PST and surgery.

Results: Most (98 %) specialists support whole breast irradiation after breast-conserving surgery (BCS), regardless of pathologic response to PST. In T1-T2 and T3-T4 tumours with sentinel node biopsy (SNB) prior to PST, 91 and 56 % of respondents, respectively, recommend irradiating the supraclavicular (level IV) and axillary level III nodes when nodal involvement is detected (9 and 44 % of respondents recommend irradiating these areas by independent of nodal status). If SNB is not available, 57 and 30 % of specialists agreed that the aforementioned nodal regions should be irradiated (33 and 65 % of respondents recommend irradiating these areas by independent of nodal status). Between 58 and 76 % of specialists agreed that nodal levels I and II should be irradiated in cases of insufficient lymphadenectomy or when >75 % of the resected nodes are involved.

Conclusion: Agreement is strong regarding the indications for local RT after PST and surgery, but less so for nodal irradiation. All patients who undergo BCS should receive RT, even with complete pathologic response. After mastectomy, RT is recommended in all node-positive stage III cases. Prospective studies will clarify indications for RT in this patient population.