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(Updates with treatments in fifth paragraph.)
Jan. 31 (Bloomberg) -- The number of repeat surgeries in women who had a breast tumor removed varies dramatically based on their individual surgeons and medical centers, without any clear reason for the discrepancies, a study found.
Almost one in four women who get breast-conserving “lumpectomy” surgery undergo another operation to ensure no malignant cells remain, according to a report in the Journal of the American Medical Association. Nearly half of those women had no conclusive evidence of lingering cancer, the data showed.
“There continues to be considerable variation in how we deliver health care based on individual opinion rather than strong evidence,” said lead researcher Laurence McCahill, director of surgical oncology at the Lacks Cancer Center in Grand Rapids, Michigan, in a telephone interview. “In an ideal world, there would be a greater degree of logic or evidence as to why someone would undergo a second operation.”
The investigators tracked 2,206 women with invasive breast cancer who elected to undergo a lumpectomy, a surgical removal of the tumor that leaves the healthy breast intact and has been shown in studies to be as effective as a full mastectomy, with similar survival rates.
The need for additional surgery after a lumpectomy can extract a financial and psychological cost, the researchers said. Of those women who got a repeat operation, one-third had a mastectomy, which entails complete removal of the breast.
Surgeons walk a fine line between trying to cut out all of the cancer and leaving enough of the breast for cosmetic appearances. While some didn’t do any repeat surgeries on women whose tests were inconclusive, others brought back 70 percent of patients, the research found.
The inconsistency is a challenge, said Shawna Willey, director of the Betty Lou Ourisman Breast Health Center at Georgetown University Hospital in Washington, who wasn’t involved in the study. Willey said she tells patients that as many as 40 percent of women may need a second surgery.
One problem for doctors is determining if the surgeon removed all the cancer, Willey said in a telephone interview. Currently, physicians put six different colors of ink around the extracted tumor, then study it under a microscope to see how close the malignant cells are to the edge.
While some are satisfied if there are no signs of cancer on the rim, called a clear or negative margin, others want a bigger zone of safety, she said.
“What’s the definition of a clear margin? We have whole conferences discussing that,” she said. “It would be nice if all practitioners in the breast cancer field could arrive at a consensus of what a negative margin is. That’s one reason we see so much variability among surgeons.”
Fourteen percent of women with cancer at the edge of the extracted tissue didn’t undergo a repeat operation, known as a re-excision, the researchers said.
While previous work found positive margins increase the risk that the cancer will return, no studies have shown how large a cancer-free rim is needed to reduce the risk. Removing additional tissue in women with no remaining signs of cancer hasn’t been shown to influence recurrence rates, they said.
The findings show why tissue margins shouldn’t be used to evaluate the quality of surgical care for breast cancer, said Monica Morrow, from Memorial Sloan-Kettering Cancer Center’s department of surgery in New York and Steven J. Katz, from the University of Michigan’s department of health management and policy in Ann Arbor.
The research didn’t take into account the reasons for returning to the operating room, Morrow and Katz wrote in an editorial. Some physicians may have low rates because they offer breast-conserving surgery only to patients with tiny tumors that are easiest to remove, leaving others to get an unnecessary mastectomy. It can also be avoided by removing large amounts of normal breast tissue, with a poor cosmetic result, they said.
“Uncertainty about the link between process and patient health outcomes underscores the challenge of determining ‘which rate is right,’” they wrote. Providing retreatment rates for individual doctors “may result in greater use of mastectomy as surgeons restrict breast-conserving surgery to patients for whom negative margins are easily achieved.”
The researchers used electronic medical records for patients treated from 2003 to 2008 at the University of Vermont, Kaiser Permanente in Colorado, Group Health in western Washington and the Marshfield Clinic in Wisconsin to conduct the study. It was funded by the U.S. National Institutes of Health.
--Editors: Andrew Pollack, Angela Zimm
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