The American Society for Radiation Oncology (ASTRO) issued recommendations for patient-centered strategies for performing partial-breast irradiation in patients with early-stage invasive breast cancer or ductal carcinoma in situ (DCIS). The new clinical guidelines were published by Shaitelman et al in Practical Radiation Oncology.
Background
Breast cancer—the leading cause of cancer incidence across the world—is the most common malignancy treated with radiation therapy in the United States. Patients diagnosed with early-stage breast cancer are often eligible for breast-conserving therapy, which combines surgery to remove the tumor with radiation therapy to reduce the likelihood of cancer recurrence. With partial-breast irradiation, the radiation dose is delivered just to the part of the breast where the tumor was removed, offering a more localized alternative to whole-breast irradiation that may be associated with lower out-of-pocket costs and less time away from work.
Since ASTRO last issued recommendations for partial-breast irradiation in 2017, several studies have compared the clinical outcomes between partial-breast irradiation and whole-breast irradiation, and found no significant differences in recurrence in the same breast, overall survival, and cancer-free survival as well as similar or improved side effects with the partial-breast treatment.
“There have been more than 10,000 [patients] included in these randomized controlled trials, with 10 years of follow-up showing equivalency in tumor control between partial-breast and whole-breast irradiation for appropriately selected patients,” highlighted lead guideline author Simona F. Shaitelman, MD, EdM, Professor of Breast Radiation Oncology at The University of Texas MD Anderson Cancer Center and Vice Chair of the guideline task force. “These data should be driving a change in practice, and partial-breast irradiation should be a larger part of the dialogue when we consult with patients on decisions about how best to treat their early-stage breast cancer,” she continued.
Study Methods and Findings
In a new systematic literature review and comparative effectiveness evidence review, a multidisciplinary team of investigators from the Agency for Healthcare Research and Quality—comprising academic and community-based radiation, medical, and surgical oncologists; medical physicists; and patient representatives—compiled evidence from several recent, large-scale, randomized clinical trials published through June 2022 to provide guidance on which patients may benefit from partial-breast irradiation as well as techniques and best practices to deliver effective treatment to patients with early-stage invasive breast cancer or DCIS.
Among the new guidelines were:
- Partial-breast irradiation is strongly recommended as an alternative to whole-breast radiation for patients with early-stage, node-negative invasive breast cancer who have favorable clinical features and tumor characteristics: grade 1 to 2 disease, estrogen receptor–positive status, age 40 or older, and small tumor size. It is conditionally recommended if the patients have indicators of higher recurrence risk such as grade 3 disease, estrogen receptor–negative histology, or larger tumor size. It is not recommended for patients with positive lymph nodes, positive surgical margins or germline BRCA1/2 mutations, or those who are younger than 40. The treatment is conditionally not recommended for those with less favorable risk features like lymphovascular invasion or lobular histology, because of the lack of robust data on these patient subsets in published randomized trials.
- Partial-breast irradiation is strongly recommended as an alternative for patients with DCIS who have favorable clinical and tumor features outlined in the guidelines and is conditionally recommended for those with higher grade disease or larger tumors. However, the treatment is not recommended for patients with positive surgical margins, BRCA mutations, or younger than 40 years of age.
- Three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, and multicatheter interstitial brachytherapy are recommended techniques for partial-breast irradiation based on published research showing similar long-term rates of ipsilateral breast recurrence compared with whole-breast irradiation. Single-entry catheter brachytherapy is conditionally recommended. Intraoperative radiation therapy techniques, including electron intraoperative radiation therapy and photon intraoperative radiation therapy without whole-breast irradiation, are not recommended unless as part of a clinical trial or multi-institutional registry.
The investigators also provided the optimal dose-fractionation regimens, target volume delineation, and treatment planning parameters for different partial-breast irradiation techniques—with particular attention focused on clinical and cosmetic side effects. A daily or every-other-day course of partial-breast irradiation was recommended over twice-daily regimens.
Conclusions
“We hope that by laying out the evidence from these major trials and providing guidance on how to administer partial-breast irradiation, the guidelines can help more oncologists feel comfortable offering this option to their patients as an alternative to whole-breast irradiation,” emphasized senior guideline author Janice A. Lyons, MD, Professor of Radiation Oncology at the University Hospitals Seidman Cancer Center and Chair of the guideline task force. “For example, we discuss data linking certain fractionation schedules with better cosmetic outcomes to help providers achieve positive results for their patients,” she underscored.
ASTRO concluded that its new clinical guidelines were intended to be utilized as tools to promote appropriately individualized, shared decision-making between physicians and patients. None of the guidelines should be construed as strict or superseding the appropriately informed and considered judgments of individual physicians and patients.
Disclosure: For full disclosures of the study authors, visit practicalradonc.org.
