Clinical Impact of False-Negative Sentinel Node Biopsy for Breast Cancer is Low
According to a recent article in the British Journal of Surgery, the clinical impact of a false-negative sentinel node biopsy reading in early breast cancer appears to be minimal.
The practice of sentinel lymph node biopsies is becoming more common in women with early-stage breast cancer. For over 30 years, the standard of practice for breast cancer staging has included the removal of axillary (under the arm) lymph nodes to aid in determining the spread of cancer in the body. If cancer spreads from its site of origin, it is thought to spread first to the lymph nodes that initially collect the excess lymph fluid from that area (sentinel lymph nodes). With current standard staging procedures, axillary lymph nodes are removed during surgery and are tested to determine if they contain breast cancer cells. The presence or absence of cancer cells in axillary lymph nodes is an essential factor in defining optimal treatment strategies following surgery. Women who have cancer cells present in their axillary lymph nodes are thought to have cancer that has spread and therefore require adjuvant systemic (full-body) therapy. Conversely, women without cancer cells in their axillary lymph nodes are thought to have only localized breast cancer and may require less aggressive adjuvant therapy and observation.
Unfortunately, the removal of axillary lymph nodes (approximately 25 nodes) is associated with chronic side effects including pain, infection, limited shoulder motion, numbness and lymphedema (swelling of the arm due to an accumulation of lymph fluid). Since these complications can become debilitating, the strategy of sentinel lymph node dissection is becoming common among patients with early breast cancer and is still being evaluated and refined. This strategy incorporates the removal of only the sentinel lymph node(s) for biopsy (SNB) to determine the extent of cancer spread. Because the sentinel lymph node(s) (SLN) receives initial drainage from the cancer, it has the highest probability of containing cancer cells if the cancer has spread. Therefore, the removal of other axillary lymph nodes may be unnecessary if the SNB is negative. If accurate, this practice could eliminate the need for axillary node dissection and its complications.
The precision in correctly identifying the SLN is imperative in order for this procedure to provide accurate results. Currently, there are two methods that are commonly used together: 1) injections of blue dye in the area immediately encompassing the cancer, 2) injections of a radioactive substance in the area immediately encompassing the cancer. The injections are administered prior to surgery. During surgery, the surgeon identifies the node(s) containing either the blue dye (through direct visualization) or the radioactive substance (through a hand-held probe that detects radioactivity), indicating the collection of drainage from the cancer. The node(s) that collects the injected substances is determined to be the SLN and is subsequently removed for a SNB.
Patients and physicians, however, worry about the inaccuracy of a SLN in correctly determining if a woman has spread of cancer to the axillary lymph nodes. A false-negative reading refers to biopsy results that do not detect the presence of cancer cells in axillary lymph nodes when, in fact, the cancer has spread to these node(s). A false-negative reading could result in the under-treatment of patients, as physicians would assume the cancer was contained to the site of origin and may not offer patients subsequent appropriate therapy to reduce the risk of a cancer recurrence.
Recently, researchers from Australia evaluated the impact a false-negative SLN reading would have in women with early-stage breast cancer. The researchers evaluated 328 women with early-stage breast cancer who underwent a SNB immediately followed by axillary node dissection. The SLN was identified in 285 women and 101 patients had spread of cancer to their axillary nodes. Of these 101 patients, 8 (7.9%) had a false-negative SLB. Based on disease characteristics determined by laboratory processes and clinical features of the cancer, physicians would have recommended chemotherapy to 6 of these patients. Only 2 patients (.7%) of 285 women in this study would have had their treatment regimen altered due to a false-negative SLB.
These researchers concluded that false-negative results of SNB appear to have minimal impact on the treatment course offered to patients with early-stage breast cancer, particularly because physicians include disease characteristics in the determination of optimal therapeutic regimens. It is important that patients with early-stage breast cancer who are considering a SNB, undergo this procedure with a physician who has been trained in this procedure and performs numerous SNBs annually. In addition, these patients may wish to speak with their physician about the risks and benefits of SNB or the participation in a clinical trial further evaluating this issue. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. ECancerTrials.com also provides personalized clinical trial searches on behalf of patients.
Reference: Nano M, Kollias J, Farshid G, et al. Clinical impact of false-negative sentinel node biopsy in primary breast cancer.
British Journal of Surgery. 2002;89:1430-1434.
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