Sentinel Lymph Node Biopsy Successful After Neoadjuvant Chemotherapy for Breast Cancer

WASHINGTON—Sentinel lymph node (SLN) biopsy, which is "evolving as a possible alternative" to complete axillary node dissection in breast cancer, can be performed as successfully in patients who have received neoadjuvant chemotherapy as in patients who have not, said Eleftherios Mamounas, MD, of Aultman Cancer Center, Canton, Ohio, and the National Surgical Adjuvant Breast and Bowel Project (NSABP).

Neoadjuvant chemotherapy is often used before surgery to downstage breast cancers to permit lumpectomy rather than mastectomy, Dr. Mamounas said in his presentation at the 54th Annual Cancer Symposium of the Society of Surgical Oncology (plenary session III).

Although randomized comparisons of the two methods of axillary staging are currently underway, little was known about the usefulness of SLN biopsy after neoadjuvant chemotherapy. A number of small studies have yielded varying success rates and false-negative rates.

It was not known, for example, whether neoadjuvant chemotherapy affects lymphatic drainage and thus makes SLN biopsy more difficult, Dr. Mamounas commented.

He reported an analysis of data from NSABP B-27 that explored these questions. Patients in this trial received neoadjuvant chemotherapy before either lumpectomy and axillary lymph node dissection or modified radical mastectomy.

During the trial, some participating surgeons also performed SLN biopsy before doing axillary node dissection. This afforded an opportunity to study SLN biopsy in conjunction with neoadjuvant chemotherapy.

Of the 1,936 patients randomized from 1996 through 1999, 1,832 had complete surgical information available, and 325 of these patients had lymphatic mapping with an attempt at SLN biopsy before axillary node dissection.

The surgeons had not followed any set protocol for SLN biopsy. Some used radioisotope, some used blue dye, and some used both together. A sentinel node was found and removed in 83% of the cases when it was attempted. Isotope used alone or combined with blue dye proved more successful than blue dye alone.

"The success rate in finding sentinel nodes did not differ by year of surgery, patient age, or tumor size," Dr. Mamounas said.

The sentinel node truly predicted the status of the axilla in 94% of all cases. In 6% of all cases (or 11% of all node-positive cases), the sentinel node was falsely negative, although Dr. Mamounas believes that the false-negative rate would be lower if surgeons had followed a set protocol.

Giving Patients Options

This study’s success rate and false-negative rate, which were similar to those found in patients who had not received systemic therapy, suggests that the "sentinel node concept may also be applicable to patients who have received neoadjuvant therapy," Dr. Mamounas said.

In the future, this might give more patients the option to undergo neoadjuvant chemotherapy followed by SLN biopsy and avoid axillary lymph node dissection if the sentinel node is negative, he said.