Summary: A relatively new procedure to see if breast cancer has spread to the lymph nodes may spare women some troublesome side effects of surgery. A study published in the Journal of Clinical Oncology found that sentinel lymph node biopsy caused fewer problems than the older surgery that routinely removed all the lymph nodes from under the arm (a procedure called axillary lymph node dissection).

Why it's important: Breast cancer will be diagnosed in nearly 213,000 women in the US this year, and most of them will have surgery to treat it. Usually, that surgery includes axillary lymph node dissection. In a typical procedure, anywhere from 15 to 40 lymph nodes are removed from the underarm on the same side as the cancer. Although axillary lymph node dissection helps doctors learn whether the cancer has spread, afterward, many women have side effects such as arm swelling, numbness in the arm, and trouble moving the arm. Preventing these side effects will help women get back to their normal routines quicker after breast cancer treatment.

What's already known: In the last few years, a technique called sentinel lymph node biopsy has been developed. Surgeons inject a blue dye and a radioactive tracer into the breast cancer before removing it. These tracers travel to the lymph node where the cancer is most likely to spread first -- the sentinel node. Previous research has shown that if the sentinel node doesn’t contain cancer neither will the rest of the lymph nodes. The surgeon finds the sentinel node (it either turns blue, or becomes radioactive, or both) and removes it to examine it for cancer. The rest of the underarm lymph nodes only have to be removed if cancer is detected in the sentinel node. If there is none, the rest of the lymph nodes do not have to be removed. This procedure is generally reserved for women who do not have enlarged lymph nodes under that arm, which could indicate that the cancer has spread.

How this study was done: The study was performed on 298 women undergoing surgery for breast cancer. The women had very small tumors that did not appear to have spread to the lymph nodes. Approximately half received the usual axillary node procedure where all the lymph nodes were surgically removed. The other half underwent the sentinel node procedure and had all the lymph nodes removed only if cancer was found in the sentinel node. This happened in about one-third of the women. Afterward, they were followed for 1 year to look for side effects of the surgeries.

What was found: Women who had sentinel lymph node biopsy had fewer side effects. Those who did not need to have more than the sentinel lymph node removed had arm swelling (known as lymphedema) at about one-fifth the rate of the women who had axillary lymph node dissection.

Arm numbness was only half as likely to develop in the women who had the sentinel node procedure. Arm motion was also better preserved in these women early on, although by the end of the year, both groups had fairly normal arm motion. The same was true of the women's quality of life. The women with the full axillary surgery had lower vitality and physical functioning right after surgery, but after a year, these had returned to the level of the women who had the sentinel node procedure.

The bottom line: Sentinel lymph node biopsy can spare many women the side effects of the full axillary lymph node surgery. If a woman does not have enlarged lymph nodes under her arm (in which case the surgeon would take them all out) she may be eligible for sentinel lymph node biopsy and should ask about the procedure. It is important that the surgeon be experienced in performing this type of surgery.

Citation: "Morbidity After Sentinel Lymph Node Biopsy in Primary Breast Cancer: Results from a Randomized Controlled Trial." Published in the Journal of Clinical Oncology (Vol. 23, No. 19: 4312-4321). First author Anand David Purushotham of Cambridge University Hospitals, United Kingdom.