Fewer Side Effects with Sentinel Lymph Node Removal

R.E. Mansel et al.

San Antonio Breast Cancer Symposium, December 2004, Abstracts #15, 18

Background and importance of study:

When a woman is diagnosed with breast cancer, it's important to know whether breast cancer cells have spread to the underarm (axillary) lymph nodes near the affected breast. Fluid from the breast drains into the armpit, and the lymph nodes filter it. If cancer cells are found in one or more lymph nodes, there's a higher risk of the cancer coming back in other parts of the body. So the information that comes from lymph node removal helps you and your doctor decide on the best treatment for you.

The standard way to remove lymph nodes (called axillary lymph node dissection) is to remove a pad of fat along the bundle of blood vessels and nerves from the armpit. The removed fat contains about a dozen lymph nodes. A pathologist looks carefully at the nodes under the microscope.

A newer way to detect cancer cells in the lymph nodes, called sentinel lymph node removal, may be done in women who have no lymph node enlargement of concern that can be felt by physical examination before surgery. The "sentinel" node, the one closest to the breast, is the "watchdog" node that's responsible for filtering out cancer cells that may be trying to go beyond the armpit. Your surgeon wants to be sure to remove this lymph node because it's the most likely lymph node for the cancer to travel to.

In this procedure, the surgeon injects a blue dye, a radioactive substance (tracer), or both into the area around the cancer or behind the nipple. The dye or tracer follows the path that the cancer cells would most likely take from the breast area to the lymph nodes. The surgeon then removes just the sentinel node (or sometimes the first few nodes)—the one that first takes up the dye or tracer. Nodes that are clear of dye or tracer but near the sentinel node may also be removed.

The lymph nodes are examined under a microscope. If they contain cancer cells, then your surgeon might recommend doing a standard lymph node removal to check for additional areas of cancer. If there are a significant number of cancer cells in the lymph nodes, additional lymph nodes are usually removed. If only a few cancer cells are seen, your doctor may advise against more surgery.

But if the sentinel node is free of cancer cells, no more nodes are removed.

The standard lymph node procedure removes more tissue and requires more work around the blood vessels and nerve bundles than sentinel lymph node removal. Because of this, many experts think the standard procedure is more likely to cause side effects. These can include numbness, sensitivity, and swelling in the area where the lymph nodes were removed.

The study from the United Kingdom reported here looked at whether women who have the sentinel node procedure actually do have fewer side effects than women who have standard lymph node removal.

Study design:

This clinical trial randomly divided 1,031 women with early-stage invasive breast cancer into one of two groups:

• One group had sentinel node removal.
• The other group had standard lymph node removal.

The researchers then compared the side effects and complications of the two groups at one, three, six, and 12 months after their lymph nodes were removed. This information was collected through various measurements at follow-up visits.

Cancer cells were found in the sentinel nodes of 120 women (24.8% of the women who had sentinel node removal). Those women then had either standard lymph node removal or axillary radiation therapy (radiation therapy to the rest of the lymph nodes under the arm).

In gathering results, this study compared women who did not have cancer in their nodes—whether in the sentinel node, for women in that group, or in all the nodes removed, for women in the standard lymph node removal group. (Therefore, all 120 women in the sentinel node group with cancer were excluded.)

Study results:

Compared to the women who had sentinel lymph node dissection, the women who underwent the standard lymph node removal had:

• Significantly more swelling and numbness one, three, and six months after their surgery. Numbness did improve in 12 months. Although the women who had sentinel node removal surgery also had some numbness, it improved after six months.
• Significantly more difficulty in moving their arms and shoulders one month after surgery (but not three, six, or 12 months after).
• Significantly longer hospital stays, operation times, and a need for drainage tubes.
• Significantly more time until they returned to their normal activities.
• Significantly more infections.

Conclusions:

This study found that sentinel node removal caused fewer side effects, including:

• numbness,
• swelling,
• infection, and
• less ability to move the affected arm and shoulder.

Women who had the sentinel node removal surgery also had shorter hospital stays and returned to their normal activities more quickly than those who had the standard surgery.

Take-home message:

In this study, sentinel lymph node removal caused fewer side effects than standard lymph node removal. However, the sentinel node procedure is not appropriate for everyone. It has its own limitations and must be done by a surgeon who has significant experience with the technique.

Also, keep in mind that the approach to your treatment may change over time. For example, if your lymph nodes felt normal before surgery, sentinel lymph node removal may have been recommended. But if the surgeon and pathologist find a significant amount of cancer in the sentinel lymph node, then removal of additional lymph nodes might be advised.

If you have some lymph nodes that feel abnormal or are enlarged (and it's unclear what's making them enlarged), your surgeon may still recommend using the sentinel lymph node approach. The enlarged nodes will be removed, and your surgeon may use the tracer and dye to identify additional lymph nodes in the area that might also need to be removed.

Just because a new procedure seems to have fewer side effects than an older one doesn't mean that the new procedure can completely replace the old one. The new procedure has to prove itself in other important ways, including:

• Accuracy: How well does the sentinel lymph node predict what's happening in the other lymph nodes left in place? If the sentinel lymph node is cancer-free, does that mean that all the others are also clear? Or if the sentinel lymph node contains cancer cells, does that mean that the others might also contain cancer? A study by South Korean researchers presented at the Primary Therapy of Early Breast Cancer Conference in St. Gallen, Switzerland, in January 2005 found that removing both the first AND second lymph nodes that took up the most dye or radioactive tracer was more accurate than just removing one node. An earlier study showed similar results.
• Risk assessment: What is the risk of requiring a standard lymph node removal after an initial sentinel lymph node removal finds significant cancer in the sentinel node? Whenever possible, it's best to avoid two surgical procedures (each requiring general anesthesia) in the underarm lymph node area. This study does not address the side effects of doing a sentinel lymph node removal followed later by a standard lymph node dissection. There are probably more side effects when both procedures are done than when the standard approach is used up front. To avoid this situation, clearly it's very important to offer the sentinel lymph node approach only to women who have no clear signs of lymph node involvement, such as hard enlarged lymph nodes that feel abnormal or abnormal lymph nodes seen on mammogram, ultrasound, MRI, PET, or other radiology studies. By working with an experienced team of breast cancer doctors, you're more likely to make the best choice of procedures and treatments.
• Recurrence: When only one lymph node is removed, the rest are left behind. What about the risk of cancer recurrence in the lymph nodes that were not removed?. This study followed women for only one year, and only looked at side effects. Studies are needed that carefully evaluate any lymph node recurrences and that follow women for a longer time.

Talk to your doctor about the pros and cons of sentinel lymph node removal and decide which treatment is best for you. And stay tuned to breastcancer.org for the results of more studies in this area.

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