Judy C. Boughey, M.D., Kelly K. Hunt, M.D.,
and colleagues for the Alliance for Clinical Trials in Oncology
conducted a study to determine the false-negative rate of sentinel lymph
node surgery in patients with node-positive breast cancer receiving chemotherapy
before surgery. A false-negative is occurrence of negative test results
in subjects known to have a disease for which an individual is being
tested. The study, published by JAMA, is being released early
online to coincide with its presentation at the American College of
Surgeons 2013 Annual Clinical Congress.
Axillary (the armpit region) lymph node status is an important
prognostic factor in breast cancer and is used to guide local, regional,
and systemic treatment decisions. Accurate determination of axillary
involvement after chemotherapy is important; however, removing all
axillary nodes to assess for residual nodal disease exposes many
patients to the potential side effects of surgery and, potentially, only
a subset will benefit. To avoid the complications associated with
axillary lymph node dissection (ALND), it is preferable to identify
nodal disease with the less invasive sentinel lymph node (SLN) surgical
procedure, which results in fewer side effects, according to background
information in the article.
The American College of Surgeons Oncology Group (ACOSOG) Z1071 trial
enrolled women from 136 institutions from July 2009 to June 2011 who had
various stages of breast cancer and received neoadjuvant (before
surgery) chemotherapy. Following chemotherapy, patients underwent both
SLN surgery and ALND. The primary end point for the study was the
false-negative rate of SLN surgery after chemotherapy in women who
presented with cN1 disease (disease in movable axillary lymph nodes).
The researchers evaluated the likelihood that the false-negative rate in
patients with 2 or more SLNs examined was greater than 10 percent, the
rate expected for women undergoing SLN surgery who present with clinical
node-negative (cNO) disease.
Seven hundred fifty-six women were enrolled in the study. Of 663
evaluable patients with cN1 disease, 649 underwent chemotherapy followed
by both SLN surgery and ALND. The researchers found that the
false-negative rate was 12.6 percent with SLN surgery and exceeded the
prespecified threshold of 10 percent. "Given this [10 percent]
threshold, changes in approach and patient selection that result in
greater sensitivity would be necessary to support the use of SLN surgery
as an alternative to ALND in this patient population."
Editorial: Sentinel Node Biopsy After Neoadjuvant Chemotherapy
"Decisions about using systemic therapy after neoadjuvant therapy are not dependent upon identifying residual cancer
in lymph nodes when all the planned chemotherapy is given
preoperatively to maximize the cancer response," write Monica Morrow,
M.D., and Chau T. Dang, M.D., of Memorial Sloan-Kettering Cancer Center,
New York, in an accompanying editorial.
"However, accurate detection of residual lymph node cancer may be
important in prospective trials of novel agents in which post -
neoadjuvant treatment decisions, including possible research protocol
participation, may hinge on the detection of residual disease. When
considering how much information can be extrapolated from an initial SLN
biopsy, it is important to recognize that patients with residual cancer
following neoadjuvant therapy have some level of resistance to systemic
therapy. These patients might require more aggressive local therapy
such as complete ALND or radiation therapy to the axilla. Because there
is no information regarding long-term local cancer control or survival
for patients initially presenting with clinically node-positive disease
who receive neoadjuvant therapy but have a 20 percent to 30 percent rate
of residual cancer in the axilla following SLN biopsy, we do not
believe that SLN biopsy, regardless of the number of SLNs removed, can
be considered standard management for these patients."
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