JAMA ONCOLOGY PATIENT PAGE Lymphatic Mapping and Sentinel Lymph Node Biopsy for Breast Cancer

Sentinel lymph nodes provide valuable information to guide breast cancer treatment.

The Lymphatic System and Lymph Nodes Lymph nodes are kidney bean–shaped structures found through- Sentinel lymph node biopsy for breast cancer out the body that are an important part of the immune system. For- Sentinel lymph nodes are the first nodes eign particles such as bacteria or tumor cells can travel in lymphatic to which cancer cells may spread from a tumor. In breast cancer, the sentinel lymph channels toward lymph nodes, which act as a filter. Some breast can- nodes are in the axilla (armpit) and can be cer cells have the ability to travel through the lymphatic channels in evaluated by a sentinel lymph node biopsy. the breast toward the lymph nodes in the axilla (the underarm area).

What Is a Sentinel Node? 1 Colored dye and/or radioactive tracer is There are usually between 20 and 40 lymph nodes in each axilla, and injected into breast tissue theseareconnectedwitheachotherandwiththebreast.Ingeneral,lym- surrounding the tumor. Axillary lymph nodes phaticchannelsfromthebreastmergeastheytraveltowardthelymph Primary tumor nodes,initiallydraininginto1orseveralnodesbeforemovingontoreach other nodes. This first point of drainage, whether into 1 lymph node or 2 The injected substance drains into the sentinel several,isconsideredthesentinel,or“guarding”lymphnodeornodes. lymph nodes and identifies them for surgical removal. How Are Sentinel Nodes Identified? Sentinel lymph nodes The sentinel nodes are identified through a mapping procedure. Be- cause cancer cells are too small to be easily traced as they travel, a tracking substance is injected into the lymphatic channels near the 3 Sentinel lymph nodes are cancer to define the potential path that cancer cells might take and surgically removed and to identify the sentinel node(s) where those cells might end up. The examined for cancer cells. most commonly used tracking substances are a radioactive tracer (isotope) called technetium 99 and a blue dye called isosulfan blue. They follow the same route that cancer cells would through the lym- phatic channels and allow the sentinel node to be identified at the time of surgery because the sentinel nodes will contain the dye or Information about cancer cells found in the isotope. Although cancer might not yet have spread to this area, if sentinel lymph nodes is used for prognosis and it has spread, it will be found first in the sentinel node or nodes. to make decisions about breast cancer treatment.

How Will the Information Be Used? Atthetimeofsurgery,thesentinelnodeornodeswillbeidentifiedand presentthere.Everyonehasauniquenumberofsentinellymphnodes; removed. They will be analyzed to determine whether the cancer has you may have 1 or more. Todetermine if there is cancer present in the reached them, and this information can be used to refine the patient’s sentinel node, it must be removed and carefully evaluated. prognosis. The information is often used to make decisions about fur- ther treatment, if surgery is performed prior to any other treatment. If the surgical procedure is performed after chemotherapy,the senti- nel node procedure will indicate whether the treatment has affected FOR MORE INFORMATION anycancerthatmighthavebeeninthelymphnodesbeforetreatment. • Sentinel Lymph Node Biopsy for Early-Stage Breast Cancer http://www.cancer.net/research-and-advocacy/asco-care Important Concepts -and-treatment-recommendations-patients Everyone has sentinel lymph nodes; conducting the mapping pro- /sentinel-lymph-node-biopsy-early-stage-breast-cancer cedure to discover the sentinel nodes does not mean that cancer is

Author: Alexandra S. Heerdt, MD, MPH The JAMA Oncology Patient Page is a public service of JAMA Oncology. The information Published Online: November 22, 2017. doi:10.1001/jamaoncol.2017.4000 and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your Conflict of Interest Disclosures: None reported. personal medical condition, JAMA Oncology suggests that you consult your physician. Section Editor: Howard (Jack) West, MD. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, call (312) 464-0776.

jamaoncology.com (Reprinted) JAMA Oncology March 2018 Volume 4, Number 3 431

© 2017 American Medical Association. All rights reserved.

Downloaded From: https://jamanetwork.com/ on 09/26/2021