Less invasive biopsy for large tumors

USA Today (Society for the Advancement of Education), Oct, 2005

New breast cancer research shows for the first time that even women with large breast tumors can benefit from a less invasive biopsy method that has been reserved until now for those with smaller lumps. Lymphatic mapping and sentinel node biopsy, when used to determine how far the cancer has progressed into the lymph nodes, can help some patients avoid the pain and discomfort of full armpit node removal, which often causes swelling, numbness, and infection.

"The study suggests that sentinel node biopsy is an option that might benefit all women with breast cancer," contends David W. Ollila, an associate professor of surgery and a member of the Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill. "I think any woman diagnosed with breast cancer should ask her physician what role this technique might play in her overall treatment."

Lymphatic mapping and sentinel lymphadenectomy before chemotherapy is the standard of care for patients with small breast cancers. Yet, its use on larger tumors has been controversial because of lack of reliability.

In sentinel node biopsy, a surgeon injects the area near the tumor with a blue dye, which follows the path that tumor cells most likely would take to the lymph nodes. The surgeon removes only the nodes that initially absorb the dye. These are thought to be the "sentinel" nodes, those to which cancer cells are more likely to travel. If the biopsy finds no cancer in the sentinel nodes, then no further nodes are removed.

Subjects in the study had tumors large enough that the breast could not be preserved. Such patients typically received neoadjuvant chemotherapy to shrink the tumor before surgery--thus decreasing the possibility of recurrence and, for a small number of women, making it feasible to have a lumpectomy rather than a mastectomy.

Before neoadjuvant chemotherapy, the researchers performed sentinel node biopsy, modifying the technique slightly for larger cancers by using a greater volume of dye and more injections. If the procedure showed disease in the sentinel node or if the tumor was more than five centimeters, all the axillary nodes were removed, and the patient underwent chemotherapy and surgery. If the biopsy showed tumor-free sentinel nodes, and the tumor was less than five centimeters, no further lymph nodes were removed and the patient received chemotherapy and tumor removal.

In an average of 36 months of post-treatment follow-up, none of the patients showed progression of cancer in the lymph nodes. The sentinel node biopsy accurately predicted node involvement, with a false negative rate of zero percent.

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

"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. 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"