A lymph node-sparing test hailed as revolutionary for its conservative approach does not lead to longer survival times for women undergoing lumpectomies whose early-stage breast cancer has spread microscopically, a large, new study suggests.
Examining the medical records of more than 5,200 patients who underwent breast-conserving surgery for early, invasive breast cancer, researchers found that tiny cancer cells in the sentinel lymph node - the first node to which malignant cells are likely to spread from a primary tumour - detected with a diagnostic procedure called immunohistochemical (IHC) staining had no effect on overall survival.
The biopsy procedure known as sentinel lymph node (SLN) dissection has been praised for averting the removal of large numbers of armpit lymph nodes during breast cancer surgery, which can lead to a painful buildup of fluid called lymphedema.
"I think I'd have to say it was highly controversial whether these occult [hidden] metastases would be clinically relevant," said study author Dr Armando Giuliano, chief of surgical oncology at Cedars-Sinai Medical Center in Los Angeles. "If it's not going to affect mortality, it shouldn't affect treatment."
The study is published in the issue of the Journal of the American Medical Association.
What the study found
The observational study included data from women included in the American College of Surgeons Oncology Group trial at 126 sites from May 1999 to May 2003, and all patients were followed until April 2010. Results were blinded to treating physicians to avoid the bias of over-treatment, Giuliano said.
At a midpoint follow-up of 6.3 years, 435 women had died and 376 experienced recurrence of their cancer. Based on IHC staining, five-year overall survival rates of those whose samples tested positive for node involvement were 95.1%, compared to 95.7% for those whose SLN biopsies tested negative. Corresponding five-year rates of disease-free survival were 90.4% and 92.2%, respectively.
Giuliano said the research, when adopted clinically, can save patients several hundred dollars or more in unnecessary tests. Women with microscopic metastases in their SLNs can also be spared from certain more aggressive treatments that were thought to increase their survival rates, he said.
Dr. Lora Weiselberg, chief of breast cancer service at the Monter Cancer Center of North Shore-LIJ Health System in Lake Success, NY, said many physicians have questioned the significance of the SLN biopsies evaluated in the study.
"In certain cases . . . we would want to do them anyway, but otherwise I think this is very strong evidence," Weiselberg said. "I think more and more pathology laboratories are going to go in that direction [of fewer tests] because adding another costly test, if it's not going to help the patient, is unnecessary."
The U.S. National Cancer Institute has more on sentinel lymph node biopsies.
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