Study examines effect of “hidden” cancer cells in early-stage breast cancer survival rates

USF Health surgical oncologist a co-author on Journal of American Medical Association paper

A new study shows that removing lymph nodes due to the presence of occult, or microscopic, cancer cells found in the sentinel lymph node – the one directly linked to the tumor — has no impact on survival outcomes of women with early-stage breast cancer. However, the presence of occult cancer cells found in bone marrow was significantly associated with decreased survival.

The latest study, conducted by the American College of Surgeons Oncology Group (ACOSOG) and supported by the National Cancer Institute, was published in the July 27, 2011 issue of the Journal of the American Medical Association (JAMA).

Dr. Douglas Reintgen, now a surgical oncologist at USF Health, was one of the investigators for ACOSOG study and a co-author of the JAMA paper. The ACOSOG trial involved 5,210 patients at 126 sites nationwide, including 100 enrolled at Lakeland Regional Medical Center who continue to be followed at USF. All the patients underwent breast conserving surgery and sentinel lymph node dissection; about 67 percent underwent bone marrow biopsies.

Dr. Douglas Reintgen was a local principal investigator for
the American College of Surgeons Oncology Group study

Previous groundbreaking research by Dr. Armando E. Giuliano of Cedars-Sinai Medical Center showed that survival outcomes were no different between women undergoing total lymph node removal and those only having the sentinel lymph node removed. This finding dramatically changed the surgical approach for early-stage breast cancer patients. Women now can be spared the pain and side effects of comprehensive lymph node removal.

In this new ACOSOG study, principal investigator Dr. Giuliano and colleagues sought to determine whether there is an association between patient survival rates and the presence of microscopic cancer cells that have spread from an early-stage tumor to nearby lymph nodes.

Occult metastases usually cannot be seen in routine pathological or clinical examination. The tiny cells were detected with immunochemical staining of sentinel lymph nodes and bone marrow specimens from patients with early-stage breast cancer.

The researchers determined that the presence of tiny sentinel lymph node metastases had no bearing on survival outcomes, but microscopic metastases in bone marrow, though rare, did.

“This study identifies another important staging parameter for women with breast cancer – that is, whether there is any evidence of bone marrow spread,” Dr. Reintgen said. “These results may be equally important as the current standard staging procedure – that of sampling the axillary, or nearby, lymph nodes.”

The researchers did not recommend incorporating bone marrow biopsy into routine practice for patients with the earlier stages of breast cancer, because the incidence of bone marrow metastases in the ACOSOG trial was too low. However, they added that “improved techniques for isolating and detecting occult tumor cells may make their assessment in the bone marrow more efficient and feasible.”