According to a new study, early breast cancer patients may not need multiple lymph nodes removed, a common practice used to prevent the spread of tumors.

The research, published in The Journal of the American Medical Association Feb. 9, found that the procedure does not increase survival rates of women with early stages of the cancer.

During the painful treatment that can lead to swelling, discomfort and numbness, physicians cut out cancerous lymph node tissues from the armpit. Medical researchers say the underarm is the first place invasive cancer spreads.

Lymph node removal has been commonplace for 100 years, ever since doctors began performing mastectomies. Yet, the new study’s 10 researchers concluded it might be more detrimental than beneficial because of risks associated with the surgery, and the minimal variation in survival rates between women who have the procedure and those that do not.

For a little over six years, the researchers followed 891 early breast cancer patients receiving treatment in 115 different medical centers.

The women were subjected to lumpectomies and radiation or chemotherapy to treat their tumors and had biopsies that revealed one or two cancerous lymph nodes. Some were randomly selected to have 10 or more additional nodes removed; for others, the nodes were not removed. Six years later, the cancer recurrence and survival rates for both groups were almost the same, the researchers said. .

Researchers say this means that for women with very small tumors in the early stage of the disease–about 20 per cent or 40,000 patients a year–need no more than one or two lymph nodes removed for quick evaluations.

“This is such a radical change in thought that it’s been hard for many people to get their heads around it,” Dr. Monica Morrow, one of the study’s authors, told The New York Times.

Nonetheless, some medical centers are already rethinking the procedure based on the findings. A spokeswoman said oncologists at Johns Hopkins Hospital called a meeting soon after learning the study’s conclusions back in September.

Spokeswoman Vanessa Wasta said Hopkins physicians now allow breast cancer patients to opt out of lymph node removal if they met the qualifications.

“This can significantly improve the clinical outcome of patients by reducing the complications associated with complete nodal dissection without a negative effect on survival or local recurrence,” Dr. Mehran Habibi, assistant professor of surgery at Johns Hopkins said in a Hopkins blogpost.

It is still unclear if the findings can apply to other forms of cancer or if lymph node removal is still necessary for patients who have not undergone chemotherapy or radiation.