Update on ASTRO/ASCO/SSO Postmastectomy Radiation Therapy Guideline: A Case-Based Discussion

Breast cancer is the most commonly diagnosed cancer among women. For patients who undergo mastectomy and have adverse risk factors, postmastectomy radiation (PMRT) is routinely advised to decrease the risk of local regional recurrence and improve breast cancer specific survival. It is imperative for radiation oncologists to keep pace with advances in practice that inform which patients are most likely to benefit from PMRT, as well as which treatment regimens and techniques should be utilized to optimize the therapeutic ratio. This activity is a case-based presentation of the updated ASTRO guidelines on post-mastectomy radiation, focusing on which cohorts of patients should receive PMRT and describing the radiotherapy regimens and treatment techniques that are recommended when delivering PMRT.

This module presents the key recommendations from the Postmastectomy Radiation Therapy (PMRT) guideline (being finalized by late Summer 2026), using a case-based format and Audience Response System to illustrate different clinical scenarios. Specifically, the activity, drawing on a diverse set of speakers, discusses updated recommendations for PMRT both in the upfront surgical setting and after neoadjuvant systemic therapy. It also provides guidance on appropriate target volumes, dosing and treatment techniques and polls the audience about current practices.

Topics:

  1. Introduction to Current Guidelines
    Kathleen C. Horst, MD, FASTRO
    Rachel B. Jimenez, MD, FASTRO
  2. Case 1: PMRT in the Upfront Surgical Setting
    Rachel Abrams Rabinovitch, MD, FASTRO
  3. Case 2: PMRT in the Neoadjuvant Systemic Therapy Setting
    Youssef Zeidan, MD, PhD
  4. Case 3: Options for Dose/Fractionation
    Parul Barry, MD
  5. Case 4: Utilization of IGRT/SGRT
    Case 5: Utilization of Bolus
    Iman Washington, MD
  6. Q and A
    Kathleen C. Horst, MD, FASTRO – Moderator
    Full Panel

This activity is available from July 7, 2026, through 11:59 p.m. Eastern time on July 6, 2028. 

The content was originally presented and recorded at the 2025 ASTRO Annual Meeting.

Target Audience

The activity is designed to meet the interests of medical oncologists, radiation oncologists, surgeons, nurses, diagnostic radiologists, radiation therapists and residents.

Learning Objectives

Upon completion of this activity, participants should be able to:

  • Report on the evolving evidence base that supports changes to the utilization of, and consideration for, postmastectomy radiation. 
  • Identify which patients with breast cancer who have undergone mastectomy can safely forgo postmastectomy radiation. 
  • Implement change in clinical practice with regard to radiation dose/fractionation and technique for patients that require postmastectomy radiation.  
Course summary
Available credit: 
  • 1.25 AMA PRA Category 1 Credit™

    The American Society for Radiation Oncology (ASTRO) is accredited by the Accreditation Council for Continuing Medical Education for physicians. ASTRO designates this Enduring material for a maximum of 1.25 AMA PRA Category 1 Credit™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

  • 1.25 Certificate of Attendance
    This activity was designated for 1.25 AMA PRA Category 1 Credit™.
Course opens: 
07/07/2026
Course expires: 
07/06/2028
Cost:
$149.00
Rating: 
0

Moderators:  

  • Rachel B. Jimenez, MD, FASTRO, is employed by Massachusetts General Hospital. Dr. Jimenez has no relevant financial relationship with ineligible companies to disclose.  
  • Kathleen C. Horst, MD, FASTRO, is employed by Stanford University School of Medicine. Dr. Horst has no relevant financial relationship with ineligible companies to disclose.  

Speakers:

  • Rachel Abrams Rabinovitch, MD, FASTRO, is employed by University of Colorado. Dr. Rabinovitch serves an uncompensated role on the advisory board with Prelude. Dr. Rabinovitch owns stock in Abbott Laboratories, Bristol-Myers Squibb, Intuitive Surgical, Pfizer and Zimmer Biomet. 
  • Youssef Zeidan, MD, PhD, is employed by Lynn Cancer Institute, Baptist Health South Florida. Dr. Zeidan has no relevant financial relationship with ineligible companies to disclose.  
  • Parul Barry, MD, is employed by University of Pittsburgh. Dr. Barry has no relevant financial relationship with ineligible companies to disclose.  
  • Iman Washington, MD, is employed by H. Lee Moffitt Cancer Center and Research Institute. Dr. Washington has no relevant financial relationship with ineligible companies to disclose.  

Planners:

  • Malcolm Mattes, MD, is employed at Rutgers Cancer Institute. Dr. Mattes received research/grant funding from Gilead Sciences (relationship ended 8/30/2025). Dr. Mattes has no relevant financial relationship with ineligible companies. 
  • Parul Barry, MD, is employed by the University of Pittsburgh Medical Center. Dr. Barry has no relevant financial relationship with ineligible companies. 
  • Michael Haddock, MD, is employed by Mayo Clinic and has no relevant financial relationship with ineligible companies to disclose.
  • Manisha Palta, MD, is employed by Duke Cancer Center and Duke University Hospital. Dr. Palta receives grant/research funding from Merck and Varian Medical Systems. 
  • Salma Jabbour, MD, is employed by Rutgers Cancer Institute. Dr. Jabbour receives grant/research funding from Merck & Co., Inc. and Beigene. Dr. Jabbour receives compensation/payment as a consultant with Radialogica and IMX Medical. 
     

All relevant financial relationships have been mitigated.

The American Society for Radiation Oncology (ASTRO) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Available Credit

  • 1.25 AMA PRA Category 1 Credit™

    The American Society for Radiation Oncology (ASTRO) is accredited by the Accreditation Council for Continuing Medical Education for physicians. ASTRO designates this Enduring material for a maximum of 1.25 AMA PRA Category 1 Credit™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

  • 1.25 Certificate of Attendance
    This activity was designated for 1.25 AMA PRA Category 1 Credit™.

Price

Cost:
$149.00
Please login or register to take this course.

Course Fees:
ASTRO members must log in to the ASTRO website to view and receive the member rate.

  • Nonmember: $149
  • Member: $99
  • Member-in-Training: $49
  • Student/Graduate Student/PGY-1 Member: $49
  • Postdoctoral Fellow Member: $49

If you are an ASTRO member from a low or lower-middle income country, as identified by the World Bank, you can receive a 50% discount off your corresponding registration for this activity. Please email [email protected] to inquire about the discount.

Policies:
No refunds, extensions, or substitutions will be made for those participants who, for any reason, have not completed the activity by the expiration date. 

Participants using ASTRO Academy activities to satisfy the requirement of a Continuing Certification (MOC) program should verify the credit number and type and availability dates of any activity before making a purchase. No refunds, extensions, or substitutions will be made for participants who have purchased activities that do not align with their MOC requirement.

The activity and its materials will only be available on the ASTRO website until July 6, 2028, regardless of purchase date. At the expiration of the activity, participants will no longer have access to the activity or its materials. ASTRO reserves the right to remove an activity before its expiration date. 

Required Hardware/software

One of the two latest versions of Google Chrome, Mozilla Firefox, Internet Explorer or Safari.