NEW YORK (Reuters Health) Apr 18 - Sentinel lymph node biopsy (SLNB) doesn't reliably predict axillary lymph node status in breast cancer patients who have already undergone neoadjuvant chemotherapy, and should not be used in these patients, the authors of the largest-yet single-site study of the practice have concluded.
"Dramatic changes" in the anatomy of the breast and axilla, such as lymph node blockage, that can occur after neoadjuvant chemotherapy may influence the accuracy of SLNB, Dr. Dusan Kolarik of the Teaching Hospital Bulovka in Prague, Czech Republic, and colleagues note in a March 22 online publication in the journal Cancer.
To investigate success rates of SLNB after neoadjuvant chemotherapy, as well as false negatives associated with the procedure, Dr. Kolarik and colleagues reviewed medical records for 343 patients treated between 2005 and 2009. All were diagnosed with primary breast cancer, treated with neoadjuvant chemotherapy, and underwent lymphatic mapping to identify sentinel nodes.
The researchers note that they have used lymphatic mapping in their institution since 2001, and have achieved a 98.1% identification rate and a 2.4% false-negative rate in early breast cancer.
Patients in the study underwent SLNB 20 to 26 hours before axillary dissection surgery. They received a single injection of radionuclide, followed by lymphoscintigraphy 30 minutes later.
SLNB identified at least one sentinel node in 277 patients, confirmed as being cancerous during surgery, for an overall success rate of 80.8%. In the remaining 66 patients, 54 had no sentinel node identified before or during surgery; nine had at least one SLN identified preoperatively, but no "hot spots" confirmed during surgery; and three had no SNL identified preoperatively, but did have at least one active lymph node identified and removed during surgery.
The success rate of SLNB was significantly higher in patients with negative lymph nodes, the researchers found. Other factors that influenced success rate included patient age (it was higher in patients under 50), estrogen receptor positivity, lower proliferation index and absent lymphovascular space invasion.
The false negativity rate was 19.5%, and was marginally higher in patients who did not have lymphatic or vascular invasion within the tumor.
The overall accuracy of SLNB (defined as positive SLNs and true negative SLNs divided by the number of patients with at least one SLN) was 91.5%. Sensitivity was 80.5% and negative predictive value was 86.9%.
"To our knowledge, in the field of SLNB after preoperative chemotherapy, this series is among the largest studies performed and is the largest single-institution study ever published," Dr. Kolarik and colleagues note.
"About one third of originally lymph node-positive patients will benefit from sterilization of axillary nodes..., but this advantage is counteracted by hypothetically altered axillary anatomy decreasing the reliability of sentinel biopsy," they add.
Possible reasons for the low detection rate and high false-negative rate in their study could include "infrequent use of blue dye for lymphatic mapping, low number of resected SLN, and absence of any selection among the patients included in the study," they say.
The researchers conclude: "With the present technique, SLNB cannot be recommended as a reliable predictor of axillary lymph node status or when performed at our institution after neoadjuvant chemotherapy."
SOURCE: http://bit.ly/fJ1HY9
Cancer 2011.
"Dramatic changes" in the anatomy of the breast and axilla, such as lymph node blockage, that can occur after neoadjuvant chemotherapy may influence the accuracy of SLNB, Dr. Dusan Kolarik of the Teaching Hospital Bulovka in Prague, Czech Republic, and colleagues note in a March 22 online publication in the journal Cancer.
To investigate success rates of SLNB after neoadjuvant chemotherapy, as well as false negatives associated with the procedure, Dr. Kolarik and colleagues reviewed medical records for 343 patients treated between 2005 and 2009. All were diagnosed with primary breast cancer, treated with neoadjuvant chemotherapy, and underwent lymphatic mapping to identify sentinel nodes.
The researchers note that they have used lymphatic mapping in their institution since 2001, and have achieved a 98.1% identification rate and a 2.4% false-negative rate in early breast cancer.
Patients in the study underwent SLNB 20 to 26 hours before axillary dissection surgery. They received a single injection of radionuclide, followed by lymphoscintigraphy 30 minutes later.
SLNB identified at least one sentinel node in 277 patients, confirmed as being cancerous during surgery, for an overall success rate of 80.8%. In the remaining 66 patients, 54 had no sentinel node identified before or during surgery; nine had at least one SLN identified preoperatively, but no "hot spots" confirmed during surgery; and three had no SNL identified preoperatively, but did have at least one active lymph node identified and removed during surgery.
The success rate of SLNB was significantly higher in patients with negative lymph nodes, the researchers found. Other factors that influenced success rate included patient age (it was higher in patients under 50), estrogen receptor positivity, lower proliferation index and absent lymphovascular space invasion.
The false negativity rate was 19.5%, and was marginally higher in patients who did not have lymphatic or vascular invasion within the tumor.
The overall accuracy of SLNB (defined as positive SLNs and true negative SLNs divided by the number of patients with at least one SLN) was 91.5%. Sensitivity was 80.5% and negative predictive value was 86.9%.
"To our knowledge, in the field of SLNB after preoperative chemotherapy, this series is among the largest studies performed and is the largest single-institution study ever published," Dr. Kolarik and colleagues note.
"About one third of originally lymph node-positive patients will benefit from sterilization of axillary nodes..., but this advantage is counteracted by hypothetically altered axillary anatomy decreasing the reliability of sentinel biopsy," they add.
Possible reasons for the low detection rate and high false-negative rate in their study could include "infrequent use of blue dye for lymphatic mapping, low number of resected SLN, and absence of any selection among the patients included in the study," they say.
The researchers conclude: "With the present technique, SLNB cannot be recommended as a reliable predictor of axillary lymph node status or when performed at our institution after neoadjuvant chemotherapy."
SOURCE: http://bit.ly/fJ1HY9
Cancer 2011.
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