Sentinel node biopsy is done during surgery to remove early-stage breast cancer. This biopsy is done to see if cancer has spread to the lymph node closest to the breast cancer (called the sentinel node). This information can help your doctor decide whether or not the lymph nodes under the arm need to be removed. Removing all or most of the under-arm lymph nodes is called axillary lymph node dissection.
A very large study found that a number of non-medical factors seem to make it more likely that the under-arm lymph nodes will be removed without a sentinel node biopsy being done first. These factors are:
- being older than 72
- being a minority
- having Medicaid insurance or no medical insurance
- not having a high school diploma
- having a lower than average household income
During surgery to remove breast cancer, surgeons can use their hands to find the sentinel node. To identify the sentinel node more accurately, they often inject a dye or radioactive material where the cancer is and then follow the path of the dye or radioactive material to the sentinel node. Once it's identified, the sentinel node is removed and evaluated by a pathologist, who determines if cancer is in the node.
If cancer has spread to the sentinel node, a surgeon can be more confident that removing the lymph nodes under the arm is necessary. When the sentinel node has no cancer, a surgeon can be more confident that the lymph nodes under the arm don't need to be removed. Not removing the lymph nodes under the arm usually minimizes risks and complications after breast cancer surgery, including the risk of arm swelling (lymphedema).
Deciding whether or not to do sentinel node biopsy should be determined by medical factors. The study reviewed here found this doesn't seem to be happening all of the time. The researchers don't say why the non-medical factors appear to influence the sentinel node biopsy decision. It's possible that there are medical factors associated with the non-medical factors that may explain some of it, but the researchers didn't find this. Unfortunately, it's also likely that age, social, and economic factors might be distorting doctors' opinions about who would or would not benefit from sentinel node biopsy.
If you're going to have surgery to remove early-stage breast cancer, ask your surgeon about how it will be decided whether the cancer has spread to your lymph nodes. Ask whether a sentinel node biopsy will be done. If your surgeon plans on doing an axillary node dissection without doing a sentinel node biopsy first, ask why, and make sure the explanation makes sense to you. If you're uncomfortable with the surgeon's answer or recommendations, seek out a second opinion.
Visit the breastcancer.org Sentinel Lymph Node Dissection page to learn more about sentinel node biopsy, who can benefit from this technique, and how it is performed.
Editor's note: To make sure that women have the appropriate lymph node surgery, the American Society for Clinical Oncology released guidelines on sentinel lymph node biopsy for people diagnosed with early-stage breast cancer. The guidelines say sentinel lymph node biopsy SHOULD be offered under these circumstances:
- breast cancer in which there is more than one tumor, all of which have formed separately from one another (doctors call these multicentric tumors); these types of breast cancers are rare
- DCIS treated with mastectomy
- women who have previously had breast cancer surgery or axillary lymph node surgery
- women who have been treated before with chemotherapy or another systemic treatment (treatment before surgery is called neoadjuvant treatment)
Sentinel node biopsy SHOULD NOT be offered under these circumstances:
- the cancer is 5 cm or larger or locally advanced (the cancer has spread extensively in the breast or to the nearby lymph nodes)
- the cancer is inflammatory breast cancer
- DCIS treated with lumpectomy
- the woman is pregnant
The guidelines also say:
- Women with negative sentinel node biopsies shouldn’t have axillary node surgery.
- Women with one or two positive sentinel nodes who plan to have lumpectomy plus radiation also don’t need axillary node surgery.
- Women who have one or more positive sentinel nodes and plan to have mastectomy with no radiation should be offered axillary node surgery.