2013 San Antonio Breast Cancer Symposium (SABCS)
Radiation in the treatment of the axilla in neoadjuvant chemotherapy for breast cancer
Dr Barbara Fowble - University of California, San Francisco, USA
The discussion today revolved around the axillary nodes and how they should be addressed either before or after neoadjuvant chemotherapy. In general there are two approaches, one where surgery is done before chemotherapy and the other where surgery is done after chemotherapy. The advantage of before chemotherapy is that you know the precise pathologic status of the axillary nodes and that helps you make decisions regarding local regional treatment options whereas if you do surgery after neoadjuvant chemotherapy the patient is offered the possibility of avoiding an axillary dissection and only having a sentinel node biopsy.
My presentation revolved around the situation where surgery is done after neoadjuvant chemotherapy and some of the complexities of doing sentinel node biopsy and whether that should be followed with axillary dissection. We reviewed two of the recent trials in women who have positive axillary nodes before chemotherapy, demonstrated either by imaging studies or fine needle aspirate or core biopsy who then following chemotherapy have a negative sentinel node biopsy. What those two studies have demonstrated is that you need at least three sentinel nodes for the assessment to be accurate and to avoid missing a positive lymph gland. The question then arises if you don’t have three sentinel nodes do you have to commit to an axillary dissection or can you use radiation as a substitute for the axillary dissection? This question is being addressed in two randomised trials in the United States; the first will look at women who have a positive axillary node, either by fine needle aspirate or core biopsy. They have chemotherapy, they are felt to have negative nodes, they have surgery and they’ll be randomised to an axillary dissection or axillary dissection and radiation.
The second trial will look at women who have positive axillary nodes, either by fine needle aspirate or core biopsy before chemotherapy and then at the time of their surgery are found to have a positive sentinel node. Again these patients will be randomised to regional node irradiation or axillary dissection plus regional node irradiation.
How does micrometastasis work within the node?
That’s a good question because the issue is if you demonstrate that you have a positive node before chemotherapy, either by fine needle aspirate or core biopsy, how much disease do you have in the node afterwards that would prompt a recommendation either for radiation or for axillary dissection, and that’s an unanswered question.
What about leaving and watching in terms of micrometastasis?
It depends on what you mean by leaving and watching because if a patient has breast conserving surgery and radiation, generally the breast radiation will include a portion of the axilla so it’s not no intervention in the axilla, it would be radiation but it wouldn’t be radiation to the entire axillary region. If you talk about mastectomy then the question would be would that finding prompt a recommendation for post-mastectomy radiation? There are a few small studies, one from Sloan-Kettering in New York where they had patients with a micrometastasis sentinel node only, underwent mastectomy and did not receive post-operative radiation. There the regional node recurrence rate was about 2%. None of those patients had neoadjuvant chemotherapy so this is more in the adjuvant setting but there are surgeons who are translating what was seen in the adjuvant setting in a Z11 trial perhaps to the neoadjuvant setting with only having a micrometastasis.
Where are we with treatment as of today?
Today it is a huge conundrum with tremendous variations in practice. They range from trying to diminish the extent of surgery in the axilla with or without evidence to support that to continuing to do axillary dissection to trying to define the role of radiation in the absence of information related to the axillary dissection.
I think that practices vary, not only within the United States but geographically between Europe and the United States. Right now I’m not sure that any one approach is favoured over the other and hopefully as we get more information we can better define the roles of systemic therapy, surgery and radiation.