Experts: Breast Cancer Not Spread by Biopsy
Still Unexplained: Why Lymph-Node Spread More Likely After Needle Biopsy
June 28, 2004 -- It's a puzzling finding: Women whose breast cancers have spread to their lymph nodes are more likely to have had their cancer diagnosed by needle biopsy.
What the finding means isn't at all clear. But what it doesn't mean is very clear indeed, says Nora M. Hansen, MD, assistant director of the Joyce Eisenberg Keefer Breast Center at the John Wayne Cancer Institute in Santa Monica, Calif.
"This study does not link biopsy with spread [of breast cancer]," Hansen tells WebMD via email. "We have not changed our practice and do not plan to. We still prefer to perform a needle biopsy to confirm the diagnosis of cancer and then will proceed at another time to definitive surgical management."
Hansen and colleague Armando Giuliano, MD, developed the sentinel lymph node biopsy technique now used worldwide to help diagnose breast cancer. This technique uses dye to find the lymph node most likely to have cancer cells in a woman with a solid breast cancer mass. If this lymph node shows no sign of cancer, it's almost certain that the cancer has not spread beyond the breast.
But some researchers have wondered whether the kind of biopsy a woman has might affect how well the sentinel-node technique predicts how far a breast cancer has spread.
More Options for Women
Not long ago, there was only one way to biopsy a suspicious lump in the breast: by cutting it out. This is called an excision biopsy. If the lesion turned out to be a tumor, the surgeon proceeded to remove the breast.
Nowadays, doctors often use a two-step approach. First they use a needle to get a sample of the suspicious breast tissue. If the tissue tests positive for cancer, the woman may in many cases be able to choose to have a lumpectomy instead of a full mastectomy.
Hansen's team looked at 663 women whose suspicious lumps turned out to be breast cancer. They looked at these women's sentinel lymph nodes to see whether they harbored cancer cells, small tumors (less than 2 mm in diameter), or larger tumors (larger than 2 mm in diameter).
Women whose breast cancers had been diagnosed by needle biopsy were about 50% more likely to have their lymph nodes test positive for cancer than those who underwent excision biopsies. Most of this difference was due to the presence of larger tumors.
The findings appear in the June issue of the Archives of Surgery.
An Odd but Interesting Finding
The lymph node tumors were detected only two weeks after the needle biopsies. It seems very unlikely that tiny tumor cells dislodged by biopsy could have grown so large so fast, says Mehra Golshan, MD, associate surgeon at Boston's Brigham and Women's Hospital.
"I cannot imagine that needle biopsy could cause tumor deposits greater than 2 mm in these patients," Golshan tells WebMD. "These [tumors] took months or years to grow, not days or hours after a needle core biopsy."
Golshan says the study findings will spur more research. But he is sure they will not affect clinical practice.
"I will not be more apt to tell my wife or anyone else to get an excision biopsy because of worry about a higher rate of metastases from needle biopsies," he says.