Because sentinel node biopsy is very reliable when done before chemotherapy is given to reduce tumor volume, even women with large breast cancer tumors can benefit from use of lymphatic mapping and sentinel node biopsy, according to an article in the September issue of the American Journal of Surgery.

Until the current study, the surgical technique had not been used widely for women with large breast tumors because of a lack of data proving its reliability. David W. Ollila, lead author, said that the data suggest that sentinel node biopsy is an option that might benefit all women with breast cancers: “Our study indicates that women with large breast cancers can derive a benefit from the sentinel node technology just like women with small breast cancers.”

Subjects in the American study were 21 breast cancer patients with tumors large enough in relation to the size of the breast that neoadjuvant chemotherapy was required to make lumpectomy an option. Before neoadjuvant chemotherapy was given, the researchers performed sentinel node biopsy, modifying the technique slightly for larger cancers by using a larger volume of dye and more injections.

If the procedure showed disease in the sentinel node or if the tumor was larger than five centimeters, all axillary nodes were removed and the patient received chemotherapy and surgery. If the biopsy showed tumor-free sentinel nodes and the tumor was less than five centimeters in diameter, no further lymph nodes were removed and the patient received chemotherapy and surgery.

In an average of 36 months of follow-up, no patients showed progression of cancer in the lymph nodes. The sentinel node biopsy accurately predicted node involvement, with a false negative rate of 0 percent.

Some surgeons advocate performing sentinel node biopsy in women with large tumors only after chemotherapy to discover how much tumor remains. However, these results show that performing the procedure before treatment provides a more accurate picture of lymph node involvement, Ollila said: “If sentinel node biopsy is done after chemotherapy, the false negative rate skyrockets.”

Published studies show false negative rates as high as 33 percent when the procedure is performed only after chemotherapy. False negatives may result, for example, when chemotherapy kills cancer cells in the sentinel node but not in other nodes.

“We’re looking at a way in which the patient has definitive breast cancer and nodal staging before she ever undergoes chemotherapy, so we know exactly where she starts,” Ollila said. “Performing this procedure before neoadjuvant chemotherapy makes it easier for the medical oncologist and the radiation oncologist to know exactly what they need to do.”