Correction: An earlier version of this article incorrectly stated that lumpectomies are always coupled with radiation. The procedure is almost always coupled with radiation. The article has been updated.

A majority of young women who have breast cancer opt to have a mastectomy rather than a more modest, but in many cases equally effective, procedure that spares much of the breast, according to new research to be presented Monday.

The study, to be presented at the American Society of Clinical Oncology’s annual meeting in Chicago, found that 62 percent of women with breast cancer under age 40 chose to have their breasts removed despite previous research showing that women who have more targeted procedures coupled with radiation have similar survival rates.

The study is likely to fuel concerns that women are increasingly undergoing medically unnecessary mastectomies. The issue gained renewed attention recently after actress Angelina Jolie disclosed that she underwent a double mastectomy as a preventive measure against cancer.

Jolie, 37, carries a gene that predisposes her to an aggressive form of breast cancer. Her disclosure was widely praised for highlighting the difficult choices faced by women at risk for the disease. But it also renewed fears that women might choose a more radical approach to dealing with that risk when less invasive methods are available and provide similar results.

The new study, jointly penned by researchers at the Dana- Farber Cancer Institute and the Harvard School of Public Health, examined 277 women who had been diagnosed with Stage 1, 2 or 3 breast cancer. It centered on women who were given a choice between a mastectomy and a lumpectomy, the targeted removal of cancerous tissue and some healthy tissue around it. It excluded women with conditions requiring the breasts to be removed.

The study did not closely scrutinize the reasons for the women’s choices. Shoshana M. Rosenberg, the lead researcher, said the findings highlighted the need to study whether outsize anxiety about recurrence or death plays a part and whether women are getting adequate information.

“We’re not saying this is a good or bad decision,” Rosenberg said. “We want to make sure that women are making informed decisions and that they themselves weigh the risks and benefits. For some women, mastectomy may be the right decision.”

According to the Susan G. Komen Foundation, which funds breast cancer research and partially funded the study, the procedures have equal survival rates and incidences of the cancer spreading to other organs. However, women who undergo lumpectomies have a slightly higher rate of the cancer returning to the breast.

The main benefits of a mastectomy over a lumpectomy is that radiation therapy may not be needed and that the procedure may offer greater peace of mind, according to Komen. Lumpectomies are almost always coupled with radiation, but the advantages are that more of the original shape and tissue of the breast are preserved, and it is a less invasive procedure. A mastectomy typically requires an overnight hospital stay and a longer recovery.