Postmastectomy Radiation Therapy: An ASTRO/ASCO/SSO Clinical Practice Guideline

Postmastectomy radiation therapy (PMRT) has emerged as a cornerstone in the comprehensive management of breast cancer, particularly for patients at high risk of locoregional recurrence. The updated clinical guideline jointly issued by ASTRO, ASCO, and SSO provides an evidence-based framework addressing indications, treatment volumes, dose-fractionation regimens, and technical approaches. The guideline underscores that PMRT significantly reduces recurrence and breast cancer–related mortality, with the greatest benefit observed in women with nodal involvement, T3–T4 disease, or positive surgical margins.

The recommendations advocate for individualized care: in patients with low nodal burden or those achieving a pathological complete response after neoadjuvant systemic therapy, PMRT may be selectively considered. Moderate hypofractionation is encouraged as the preferred regimen, given its equivalent oncologic outcomes and lower toxicity, while conventional schedules remain acceptable in selected complex scenarios. On the technical side, CT-based volumetric planning is recommended, with IMRT or VMAT advised when three-dimensional conformal radiotherapy is insufficient to meet dosimetric goals. Deep inspiration breath hold (DIBH) is also highlighted as an effective strategy to spare cardiac and pulmonary exposure.

The consensus emphasizes balancing benefits and risks, integrating biological features, age, comorbidities, and pathological characteristics. It further stresses the importance of equitable access to advanced techniques, recognizing existing disparities across healthcare systems.

For Costa Rica: Adoption of these guidelines could directly improve national clinical practice. In a setting marked by waiting lists and limited technological capacity, embracing hypofractionation and modern planning techniques would help optimize scarce resources and expand patient access. Embedding these recommendations into local protocols would foster safer, more standardized, and evidence-driven treatments, ultimately enhancing equity and improving outcomes for Costa Rican women facing breast cancer.

Jimenez RB, Abdou Y, Anderson P, Barry P, Bradfield L, Bradley JA, Heras LD, Khan A, Matsen C, Rabinovitch R, Reyna C, Salerno KE, Schellhorn SE, Schofield D, Taparra K, Washington I, Wright JL, Zeidan YH, Zellars RC, Horst KC. Postmastectomy Radiation Therapy: An ASTRO/ASCO/SSO Clinical Practice Guideline. Ann Surg Oncol. 2025 Sep 16. doi: 10.1245/s10434-025-18057-3. Epub ahead of print. PMID: 40956531.