Hormone Sentinel Node Biopsy
as Effective with Fewer Side Effects as Axillary Dissection
in Breast Cancer
According to results published in The New England Journal
of Medicine, the largest analysis to date indicates a sentinel node biopsy is just as effective as
standard axillary node dissection, with fewer associated side
effects, in patients with early-stage breast cancer.
The presence or absence of cancer cells in axillary (under
the arm) 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.
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). Standard staging procedures had included the removal
of axillary lymph nodes during surgery, referred to as axillary
dissection. These nodes were then tested in the laboratory
to determine if they contained breast cancer cells. Although
axillary node dissection is still commonly used today, a different
strategy to test for the presence of cancer cells in axillary
lymph nodes, called sentinel node biopsy, is gaining momentum
in the clinical setting as results from more clinical trials
are indicating that sentinel node biopsy is effective.
The removal of axillary lymph nodes (approximately 10-25
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 continues to be refined
and evaluated. This strategy incorporates the removal of only
the sentinel lymph node(s) for biopsy (SNB) to determine the
extent of cancer spread. The sentinel lymph node(s) (SLN)
receives initial drainage from the cancer, and thus 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 standard 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 can be used individually or 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. Furthermore, the accuracy
in identifying a SLN depends largely on the skills of the
physician, with more practiced physicians resulting in improved
accuracy.
Researchers from Italy recently conducted a clinical trial
to further evaluate the effectiveness of sentinel-node biopsy
in patients with early breast cancer. This trial involved
516 patients with breast cancer that was no greater than 2
centimeters in diameter. The patients were divided into two
groups: one group received SNB followed by axillary node dissection
(axillary dissection group), and the other group received
SNB followed by axillary node dissection only if cancer cells
were present in the sentinel node (sentinel node group). In
the axillary dissection group, the overall accuracy of SNB
was nearly 97%. The number of sentinel nodes identified in
each group were similar, as well as the number of patients
identified with positive sentinel nodes (33% in each group).
Nearly 4 years following therapy, cancer recurrences, spread
of cancer or a possible second breast cancer occurred in 10
patients in the sentinel node group, compared with 15 patients
in the axillary dissection group. No patients who were treated
only with SNB have developed cancer spread to the axillary
lymph nodes as determined by physical examination. Patients
receiving SNB only, suffered from less pain, numbness, arm
swelling and had greater arm movement than those undergoing
axillary node dissection.
The researchers concluded that SNB appears just as effective
in determining cancer spread to axillary lymph nodes as axillary
dissection, and results in fewer side effects in patients
with breast cancer that is 2 cm or smaller in diameter. Patients
with early breast cancer may wish to speak with their physician
about the risks and benefits of SNB compared to axillary dissection.
If SNB is considered, patients should inquire as to the number
of SNB procedures performed at their institution.
Reference: Veronesi U, Paganelli G, Viale G, et al. A randomized
comparison of sentinel-node biopsy with routine axillary dissection
in breast cancer. The New England Journal of Medicine. 2003;349:546-553.
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