Women with early breast cancer may not need to have surgery to remove cancerous lymph nodes under the armpit, U.S. researchers said on Tuesday.

The finding may spare many women the pain and years of side effects related to this long-standing procedure.

Certain women with breast cancer who had only their sentinel lymph node removed — the lymph node closest to the cancer — survived just as long as women who had more extensive surgery to remove lymph nodes in the armpit, known as axillary lymph node dissection or ALND, the researchers found.

For the study, published on Tuesday in the Journal of the American Medical Association, Armando Giuliano of Saint John's Health Center in Santa Monica, California, and colleagues analyzed the two procedures in women with invasive breast cancer who had their tumors removed and underwent radiation and chemotherapy.

Overall survival rates after five years were about the same in both groups. Removing cancerous lymph nodes in these women may not be necessary because the radiation and chemotherapy attacks cancers in the lymph nodes before they have time to spread, the team said.

They noted that removing lymph nodes from the armpit "carries an indisputable and often unacceptable risk of complications," including infection and chronic and painful swelling of the arm.

The findings, when combined with other research, are strong enough to change the way certain women with breast cancer are treated.

"Implementation of this practice change would improve clinical outcomes in thousands of women each year by reducing the complications associated with ALND and improving quality of life with no diminution in survival," the team wrote.

Breast cancer is the second-leading cause of cancer death among U.S. women, after lung cancer. It kills 500,000 people globally each year and is diagnosed in close to 1.3 million people around the world.