Traditionally, when a woman had a mastectomy, all or almost all of the tissue in the axilla was removed along with the breast. This tissue
consists mainly of fat, lymph nodes, lymph and blood vessels. Removal of this tissue as part of a mastectomy or through a separate incision in the axilla is called an axillary dissection. During the last 20 years, we
have come to look upon the axilla as a prognostic indicator or predictor, rather than the "gateway " to and through the axilla - - meaning that removing lymph nodes gives us vital information on the prognosis and
treatment of breast cancer but that removing the lymph nodes does not, in fact, prevent the cancer from spreading to other sites in the body. At about this same time, we learned that survival rates are equivalent if
breast cancer is treated with breast conservation (lumpectomy or partial mastectomy) or if the entire breast is removed (mastectomy), for the majority of early cancers. Women undergoing lumpectomy have an additional
incision made under the arm- - in or just below the hair-bearing area of the armpit. This incision allows the surgeon to remove lymph nodes.
The majority of women with early breast cancer will not benefit from
removing axillary nodes (although the incidence of lymph node positivity increases with increasing tumor size). A large study conducted by the National Surgical Breast and Bowel Project revealed that survival was not
compromised if women did not have axillary nodes removed compared with those women who did have their nodes removed. This study has shown these results to be consistent over more than 15 years of follow-up.
So breast
cancer specialists are asking the question, " Why remove lymph nodes if it does not help the majority of women?" Furthermore, removing lymph nodes can cause serious problems in some women: chronic pain, soreness,
tingling, numbness, and the most devastating complication of all - - lymphedema ( a chronic and debilitating condition of arm and /or hand swelling).
The status of the lymph nodes still remains the most important
prognostic factor for breast cancer, we use it to stage the cancer and to determine whether other therapies are necessary following surgery. Often, the number of nodes involved with cancer is also important because
treatment may change if a woman has many nodes involved with metastases. And in protocols or trials looking at the benefits of certain chemotherapy drugs over others, it is required that a minimum number of lymph nodes
be removed and tested. Nowadays, women with node-negative tumors that are over 1cm, are being recommended to take chemotherapy or hormonal treatments (i.e. anti-estrogens- - tamoxifen). So in these cases, the lymph node
status is less important because it did not determine follow-up treatment. Women with intraductal cancer (DCIS) and very small invasive cancers (under 1cm) probably do not benefit from a node dissection, because the
chance of finding any cancer cells is less than 1 in 10. If all this sounds confusing and controversial, it is.
We now have a procedure which is accurate and reproducible and carries with it negligible complications,
as seen with axillary node dissection, and this new procedure, called sentinel node biopsy, is included in surgery for breast cancer. The sentinel node procedure helps to untangle this controversy. The sentinel node
refers to the "node on watch,"", or the"guarding" node. This is the first node to receive drainage from the tumor, and if this node is negative (there are no cancer cells), then the remaining nodes are negative 99
out of 100 times (cancer cells rarely "skip" and go to higher nodes). If the sentinel node is positive and cancer cells are seen under the microscope, in the lymph node, then other lymph nodes must be removed to
determine whether they too are involved. Most women have negative nodes, consequently, most women are spared an axillary dissection where and the risks of this procedure!
The way it works is that a physician (your
surgeon, radiologist or nuclear medicine physician) injects a minute amount of radioactivity labeled tracer substance (similar to the substance used for a bone scan or liver scan) around the tumor. After 45 minutes to 8
hours (depending on the protocol your physician follows), you are brought to the operating room, where the surgeon then injects a small amount of blue dye, and after waiting about 5 minutes, a small incision is made in
the axilla, and the node(s) which are blue and "hot" - - registering high ""counts"" using a Geiger-counter type probe (called the gamma counter), are identified and removed. The lymph node(s) is then
carefully and meticulously examined under the microscope by the pathologist. They used to look at 10 to 20 lymph nodes, or even more. Lymph nodes can be about the size of peas or beans, and sometimes very tiny, such as
the size of a grain of rice. Because of technical difficulties in finding cancer cells in lymph nodes, the pathologist would not be able to find cancer cells in lymph nodes 10 to 20% of the time. The sentinel node
procedure therefore has the added advantage of being more accurate and telling the oncologist even more clearly, the status of the axillary nodes.
What are the side effects of the sentinel node biopsy? The blue dye
will turn the urine green for about 24 hours and may temporarily cause a slight bluish discoloration of the breast skin. The radioactive tracer is used in tiny amounts (less than a bone scan) and it disappears from your
system in 24 to 48 hours.
An axillary node dissection, which removes many of the lymph nodes under the arm is still considered the "standard" approach. Many centers however are using the sentinel node technique for
women with early breast cancers because it offers a reasonable alternative to aggressive and unnecessary surgery much as removing a breast tumor alone (lumpectomy) has become an attractive alternative to removing the
entire breast (mastectomy).
With adaptation from Salick Health, Inc.
