By James W. Jakub, MD

Individuals afflicted with breast cancer are concerned about the threat of the disease traveling to other parts of their bodies. In breast cancer patients, the presence of cancer cells in the lymph nodes remains the strongest prognostic factor for the spread of the disease. But new procedures are making it less intrusive to harvest these lymph nodes and to evaluate them with the utmost precision once they have been removed.

Up until now, the standard of care has been a complete axillary lymph node dissection, which removes all lymph nodes in the armpit below the axillary vein. Unfortunately, a complete lymph node dissection is associated with risks, the most significant of which is swelling of the arm (lymphadema), not to mention the inconvenience of a drain from the wound after the procedure.

Questions arose as to why a patient needed to have all of her lymph nodes removed when many of them may not contain cancer. Is it possible to accurately test the lymph nodes by only removing a few of them? The answer is yes, with the development of the sentinel lymph node biopsy procedure, which is fast becoming the standard for doctors treating breast cancer.

The sentinel lymph nodes (SLN) are the first few lymph nodes that drain from the breast cancer. The lymphatics draining from the breast cancer do so in an orderly fashion. If cancer cells have not spread to the SLNs, the remainder of the lymph nodes should also be negative.

Likewise, if the SLN is positive, the risk exists that other nodes may also contain metastatic disease. This theory has since been proven by numerous studies.

A patient typically has one to three SLNs, though rarely, even up to ten can be found. The number of SLNs cannot be predicted prior to surgery, so all SLNs must be removed to accurately stage the patient.

Kathryn Scarborough, a 73-year-old patient of mine, was receiving chemotherapy for her surgically resected colon cancer. To find out in the middle of her treatment that she also had breast cancer was obviously difficult news to bear.

One of Kathryn’s major concerns was the idea of having all the lymph nodes under her arm removed. She knows people who had the more invasive procedure and they found the severe swelling that sometimes followed the operation quite disabling. Kathryn was thrilled to find that only between one and three of her lymph nodes had to be removed, with a much smaller incision.

She had a lumpectomy and SLN biopsy performed as an outpatient procedure. The two SLNs removed were negative and as a result she did not need further chemotherapy for her breast cancer. Kathryn is one of the lucky ones.

Statistics show that by the time they are diagnosed with breast cancer, approximately 30% of patients already have had the disease spread to the lymph nodes. The risk of cancer spreading to the lymph nodes is directly proportional to the size of the breast cancer. As breast cancers increase in size they are more likely to spread to the lymph nodes.

But since the lymph nodes can test positive for cancer in women with even the smallest breast tumors, a SLN biopsy should be considered by all breast cancer patients without known metastatic disease. The procedure is less invasive than a complete lymph node dissection, it is also less expensive, does not require a hospital stay, and allows for quicker recovery.

Most importantly, a SLN procedure allows for a much more precise pathological evaluation. Therefore it is a win-win situation for the patient and physician, a safer and more accurate procedure than a complete lymph node dissection.

Following a complete axillary lymph node dissection, the pathologist evaluates the specimen for any metastatic spread to the lymph nodes. By having to investigate 10-30 lymph nodes in a specimen, it is impossible for the pathologist to know which lymph node is most important. By performing a SLN biopsy, however, the pathologist has only 1-3 lymph nodes on which to focus. This allows the critical lymph node(s) to be more thoroughly evaluated.

The simplifying of this procedure has lead to the development of new more sensitive methods to evaluate the lymph nodes. These new techniques involve special stains being added to slides, which allow the cancer cells to be seen much more easily under magnification.

Routine pathology samples about one percent of the lymph node and can identify one cancer cell in a background of 10,000 lymphocytes (lymphocytes are the cells in the lymph nodes). With the help of these new special stains, one breast cancer cell in a background of a 100,000 lymphocytes can be seen.

An even newer experimental technique called reverse transcriptase-polymerase chain reaction (RT-PCR) is 10 times as sensitive and can detect one cancer cell in the background of one million normal lymphocytes. These small number of cancer cells in the past could not be identified.

Despite these advancements, many questions persist. Is it necessary to remove all the remaining lymph nodes if the SLN is positive, or is chemotherapy a sufficient treatment? Researchers are now trying to answer this and other questions.

Another issue: does a patient’s prognosis change if small numbers of cancer are detected in the lymph nodes that weren’t detectable before? Is finding one cancer cell in a background of 100,000 lymphocytes relevant, considering that this lymph node was already surgically removed at the time of the SLN biopsy?

At this point we do not know the answer to all these questions. But what we do know is that the SLN biopsy, in experienced hands, is at least as accurate as a complete node dissection, with fewer potential risks. It is a procedure that should be seriously considered by all women who have recently been diagnosed with breast cancer.

James W. Jakub, MD is the Director of Gastrointestional Oncology, Director of Clinical Trials, and Assistant Director of the Breast Oncology Program at the Lakeland Regional Cancer Center in Lakeland, Florida.