ASCO/ASTRO/SSO Develop Focused Guideline Update on Postmastectomy Radiotherapy
As reported by Recht et al in the Journal of Clinical Oncology, a joint ASCO, American Society for Radiation Oncology (ASTRO), and Society of Surgical Oncology (SSO) panel has developed a focused guideline update of the ASCO guideline on postmastectomy radiotherapy. A recent Cancer Care Ontario systematic literature review provided the primary evidentiary basis for the update. In addition, the joint panel reviewed targeted literature searches to identify new data that might contribute to practice change.
The clinical questions posed in review of data and the key associated recommendations are reproduced/summarized below. The type of recommendation, quality of evidence, and strength of recommendation are shown in brackets.
Clinical Question 1: Is postmastectomy radiotherapy indicated in patients with T1–2 tumors with one to three positive axillary lymph nodes who undergo axillary lymph node dissection?
Recommendations
- 1a. The panel unanimously agreed that the available evidence shows that postmastectomy radiotherapy reduces the risks of locoregional failure, any recurrence, and breast cancer mortality for patients with T1–2 breast cancer and one to three positive lymph nodes. However, some subsets of these patients are likely to have such a low risk of locoregional failure that the absolute benefit of postmastectomy radiotherapy is outweighed by its potential toxicities. In addition, the acceptable ratio of benefit to toxicity varies among patients and physicians. Thus, the decision to recommend postmastectomy radiotherapy or not requires a great deal of clinical judgment. The panel agreed clinicians making such recommendations for individual patients should consider factors that may decrease the risk of locoregional failure, attenuate the benefit of reduced breast cancer–specific mortality, and/or increase the risk of complications resulting from postmastectomy radiotherapy. These factors include patient characteristics (age > 40–45 years, limited life expectancy because of older age or comorbidities, or coexisting conditions that might increase the risk of complications), pathologic findings associated with a lower tumor burden (eg, T1 tumor size, absence of lymphovascular invasion, presence of only a single positive node and/or small size of nodal metastases, or substantial response to neoadjuvant systemic therapy), and biologic characteristics of the cancer associated with better outcomes and survival and/or greater effectiveness of systemic therapy (eg, low tumor grade or strong hormonal sensitivity). [Recommendation type = informal consensus; evidence quality = intermediate; strength of recommendation = moderate]
There are several risk-adaptive models that physicians may find useful in explaining the benefits of postmastectomy radiotherapy during shared decision-making with patients. However, the panel found insufficient evidence to endorse any specific model or to unambiguously define specific patient subgroups to which postmastectomy radiotherapy should not be administered. [Recommendation type = no recommendation; evidence quality = low; strength of recommendation = weak] Further research is needed on how to accurately estimate individuals’ risk of locoregional failure and hence their potential reductions in locoregional failure and breast cancer mortality.
- 1b. The decision to use postmastectomy radiotherapy should be made in a multidisciplinary fashion through discussion among providers from all treating disciplines early in a patient’s treatment course (soon after surgery or before or soon after the initiation of systemic therapy), either in the context of a formal tumor board or by referral. [Recommendation type = informal consensus; evidence quality = insufficient; strength of recommendation = strong]
- 1c. Decision-making must fully involve the patient, whose values as to what constitutes sufficient benefit and how to weigh the risk of complications against this in light of the best information the treating physicians can provide regarding postmastectomy radiotherapy in her situation must be respected and incorporated into the final treatment choice. [Recommendation type = informal consensus; evidence quality = insufficient; strength of recommendation = strong]
Clinical Question 2: Is postmastectomy radiotherapy indicated in patients with T1–2 tumors and a positive sentinel node biopsy who do not undergo completion axillary lymph node dissection?
Recommendation
- For patients with clinical T1–2 tumors with clinically negative nodes, sentinel node biopsy is now generally performed at the time of mastectomy, with omission of axillary lymph node dissection if the nodes are negative. Axillary lymph node dissection has generally been performed if the nodes are positive, but there is increasing controversy about whether this is always necessary, especially if there is limited disease in the affected nodes. The panel recognizes that some clinicians omit axillary dissection with one or two positive sentinel nodes in patients treated with mastectomy. This practice is primarily based on extrapolation of data from randomized trials of patients treated exclusively or predominantly with breast-conserving surgery and whole-breast irradiation or breast plus axillary irradiation. In such cases where clinicians and patients elect to omit axillary dissection, the panel recommends these patients receive postmastectomy radiotherapy only if there is already sufficient information to justify its use without needing to know that additional axillary nodes are involved. [Recommendation type = informal consensus; evidence quality = weak; strength of recommendation = moderate]
Clinical Question 3: Is postmastectomy radiotherapy indicated in patients presenting with clinical stage I or II cancers who have received neoadjuvant systemic therapy?
Recommendation
- Patients with axillary nodal involvement that persists after neoadjuvant systemic therapy (eg, less than a complete pathologic response) should receive postmastectomy radiotherapy. Observational data suggest a low risk of locoregional recurrence for patients who have clinically negative nodes and receive neoadjuvant systemic therapy or who have a complete pathologic response in the lymph nodes with neoadjuvant systemic therapy. However, there is currently insufficient evidence to recommend whether postmastectomy radiotherapy should be administered or can be routinely omitted in these groups. The panel recommends entering eligible patients in clinical trials that examine this question. [Recommendation type = informal consensus; evidence quality = low; strength of recommendation = weak]
Clinical Question 4: Should regional nodal irradiation include both the internal mammary nodes and supraclavicular-axillary apical nodes when postmastectomy radiotherapy is used in patients with T1–2 tumors with one to three positive axillary nodes?
Recommendation
- The panel recommends treatment generally be administered to both the internal mammary nodes and the supraclavicular-axillary apical nodes in addition to the chest wall or reconstructed breast when postmastectomy radiotherapy is used for patients with positive axillary lymph nodes. There may be subgroups that will experience limited, if any, benefits from treating both these nodal areas compared with treating only one or perhaps treating only the chest wall or reconstructed breast. There is insufficient evidence at this time to define such subgroups in detail. Additional research is needed to identify them. [Recommendation type = informal consensus; evidence quality = intermediate; strength of recommendation = moderate]
Mark R. Somerfield, PhD, of ASCO, is the corresponding author of the Journal of Clinical Oncology article.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
