GREENVILLE, NCPatient age and surgeon experience appear to play
the biggest role in failure of sentinel lymph node biopsy for
detection of breast cancer, according to a large multicenter clinical
trial presented at the San Antonio Symposium.
In a multivariate analysis of potential factors associated with
biopsy failure, only patient age of 50 years or greater and a
procedural experience of 10 or fewer cases correlated significantly
with failure, said Peter Ng, MD, of East Carolina University.
Our data also suggest that medial tumor location correlates
with a higher false-negative rate, though the correlation was not
statistically significant in our series, Dr. Ng said.
Dr. Ng reported findings from the first prospective, randomized,
multicenter trial that used both radiolabeled sulfur colloid and
isosulfan blue dye to identify sentinel nodes. The study involved 485
patients and 41 surgeons. Three fourths of the patients had
infiltrating ductal carcinoma, and 90% of the tumors were smaller
than 5 cm. All sentinel node findings were confirmed by axillary node dissection.
Participating surgeons were not required to have any prior
experience with sentinel node biopsy outside of an initial training
course, Dr. Ng said. No surgeon had participated in a
learning trial of sentinel node biopsy prior to joining the study.
The surgeons successfully identified the sentinel node in 420 of the
485 patients for an 87% success rate. In addition to the 65 patients
with no sentinel node identified, there were 18 false-negative
sentinel node biopsies (13%). A false-negative finding was defined as
identification of a sentinel node that proved to be pathologically
negative with a positive nonsentinel node identified by axillary dissection.
Correlation analysis of factors associated with biopsy success and
failure included surgeon experience, probe type, primary tumor
location, tumor size, method of tumor diagnosis (fine needle
aspiration, core biopsy, previous lumpectomy, or previous biopsy),
patient age, vascular lymphatic invasion, and dye injection interval.
Only patient age and surgeon experience proved to be significant
independent predictors of sentinel node biopsy outcome. Mapping
failure occurred in 5.1% of patients younger than 50, compared with
15.4% in patients 50 and older. Surgeons who performed more than 10
cases had a failure rate of 8.2%, compared with 17.9% for surgeons
who had performed 10 or fewer cases.
Medial tumor location was a statistically significant predictor of
biopsy success in a univariate analysis, but not in the multivariate analysis.
On the basis of our results, we recommend that surgeons not
abandon complete axillary node dissection without adequate sentinel
node experience, Dr. Ng concluded, and that surgeons show
discretion in applying this technique to older patients and those who
have medial tumors.
A Decrease in Lymphatics?
In answer to a question, Dr. Ng hypothesized that the failure rate in
older women is due to anatomical changes that develop with age and
fatty changes in the breast. Theres probably a decrease
in the lymphatics that in some way contributes to the increased
failure rate, he said.
When asked how many procedures are generally required to achieve an
adequate success rate, Dr. Ng said he agreed with the consensus
statement of the American College of Surgeons, which recommends 30
cases, with a success rate of greater than 85% and a false-negative
rate of less than 5%.