Two studies set to be published Thursday in the New England Journal of Medicine suggest that radiation therapy may reduce the rate of breast cancer recurrence. The research illustrates that targeting the therapy to lymph nodes as well as the breast, where the cancer begins, can prevent the disease from spreading.

Radiation therapy, which uses high-energy X-rays to destroy cancer cells while limiting damage to healthy cells, is usually done after a lumpectomy and sometimes following a mastectomy to help prevent the local recurrence of breast cancer, according to the Cleveland Clinic. In breast cancer treatment, radiation is applied to cancerous cells in the breast and sometimes in the lymph nodes under the arm or at the collarbone.

In the studies— the first involving over 1,800 women at the Juravinski Cancer Center at Hamilton Health Services in Canada, and the second more than 4,000 women at Radboud University Medical Center in the Netherlands— delivering radiation to the lymph nodes didn’t prevent survival rates of breast cancer patients, but it did reduce recurrence rates.

“By treating a larger area to include the lymph nodes, it not only prevented recurrences from happening locally in the area of the breast and the lymph nodes but also prevented breast cancer from showing up elsewhere in the body,”  Dr. Rahul Tendulkar, a breast cancer specialist at Cleveland Clinic, said in a news release.

For both studies all of the participants had a lumpectomy or a mastectomy. Study authors then analyzed how radiation therapy used in patients’ lymph nodes affected the spread of breast cancer compared to radiation therapy delivered only to the affected breast. Each of the studies showed that radiation therapy in the lymph nodes helped prevent recurrence of the disease.

Tendulkar pointed out that the findings suggest a greater need for more personalized care in breast cancer treatment.

“There are many different varieties of breast cancer and a lot of different factors that must be taken into consideration when coming up with a treatment plan for each individual,” he said.