Post-Chemotherapy Sentinel Node Biopsy Value Questioned

Lymphatics of the axillary region
Lymphatics of the axillary region (Photo credit: Wikipedia)

Today’s post is directed at those of you with a special interest in breast cancer, as it is quite technical. For the rest of you, hold on, we’ll get a more general one out soon! Thanks for stopping by the blog.

Background: Historically, the number of axillary (underarm) nodes involved with cancer has been the most important prognositc factor for survival (at least, for patients with no distant spread of cancer). Today, the most common way to check the lymph nodes for cancer is a sentinel node biopsy. A radioactive substance (called a tracer) and/or a blue dye is injected into the breast near the tumor. The surgeon then locates the sentinel node(s) by looking for the node(s) that has absorbed the blue dye or using a special device, the tracer. The surgeon usually removes one to three sentinel nodes. In certain cases, the surgeon may also remove one or two additional non-sentinel nodes. The pathologist checks the node(s) for cancer cells. Sentinel node biopsy is a good way to assess lymph node status (that has abetter side effect profile compared to a lymph node dissection).

A meta-analysis that combined the results of 69 studies showed sentinel node biopsy correctly predicted lymph node status in 96 percent of women with breast cancer. And, the chance of missing a positive lymph node (false positive rate) was low (about seven percent). So what about patients who have chemotherapy first (and then surgery)? Can we find the sentinel node, and is its status and accurate prognosticator

Bottom line results: The SENTINA trial (from Germany and Austria) demonstrates that sentinel lymph node biopsy can be performed routinely in patients who undergo neoadjuvant chemotherapy, with results that are similar to patients who have surgery as their first intervention. However, the trial confirmed that doing a SLNB twice (before neoadjuvant  chemoterhapy and then again after) is not reliable. The SENTINA trial also confimed that the number of nodes removed is inversely proportional to the false negative rate. The NSABP B32 trial in the USA had already shown this: One noe removed led to a FN rate of 18%; 2 nodes removed 10%, and 3 nodes removed 7%. In the current study, the use of BOTH blue dye and radioactive material increased the ability to find the sentinel node by about 10%.

My take: SLNB can be performed routinely in patients who undergo neoadjuvant chemotherapy. The ACOSOG Z11 trial taught us that a completion lymph node dissection is not associated with an improvement in overall or long-term disease-free survival for patients with low-volume nodal metastases. Now, we need to prove that the same holds for those who undergo neoadjuvant therapy, with trials addressing this issue opening soon. I’m Dr. Michael Hunter.

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minuteable now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

References:; Lancet Oncology (2013;14:609-618, PMD 23683750).

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Harvard AB Yale MD UPenn Radiation Oncology Radiation Oncologist, Seattle area

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