Call it the Angelina Effect. More women are choosing to have double mastectomies.

Some, like the actress and director Angelina Jolie, don’t have cancer at all but have both breasts removed as a preventive measure. Others are diagnosed with cancer in one breast but have both breasts removed for prevention. Many celebrities have gone that route—Sharon Osbourne, Wanda Sykes, and more recently, Amy Robach and Sandra Lee.

Nor is it only celebrities. Between 1998 and 2011, the rates of women with breast cancer having a double mastectomy for single-breast disease zoomed from less than 2% to more than 11%, according to a recent study published in JAMA Surgery.

Here’s the catch: Some women are choosing to remove healthy breasts even when doing so isn’t likely to help them avoid cancer…or live longer.

What’s a good reason to have a healthy breast removed? What’s a bad reason? To help women faced with this difficult decision, we spoke with Deborah Axelrod, MD, surgical oncologist at NYU Langone Medical Center and coauthor of Bosom Buddies, a guide for women with breast cancer.

REASONS TO REMOVE A HEALTHY BREAST—OR NOT

“There are indeed many reasons why you may want to remove the ‘other’ breast…and they’re not all purely medical,” said Dr. Axelrod. “But you shouldn’t be pressured. It’s important to understand that most women overestimate their risk for breast cancer returning or getting a cancer in the other breast.”

In her practice, when Dr. Axelrod asks patients what they are thinking about their condition and treatment options, she hears a number of reasons for choosing a double mastectomy. Here are the four reasons she hears most often—and the science that supports or negates them…

REASON #1: “I NEVER WANT TO HAVE WORRY ABOUT BREAST CANCER AGAIN.”

“This is possibly the worst reason to choose a double mastectomy,” said Dr. Axelrod. That’s true whether you are newly diagnosed with cancer in one breast…or have already gone through treatment. Why? “Removing the second breast won’t have any effect on the cancer that you have been diagnosed and treated for,” said Dr. Axelrod. “A bevy of credible research has found no meaningful survival benefit in women who have had cancer in one breast and elect to undergo a double mastectomy. Women who die of breast cancer most likely die of cancer that has spread outside the breast and the lymph nodes. If your breast cancer is going to recur, it will happen locally in the same breast—we can never remove all of the tissue—or systemically, meaning it traveled from the lymph nodes to another part of your body, most typically the bones, liver, lungs and brain. Removing the other, healthy breast is not going to prevent either type of recurrence from happening.”

REASON #2: “I’VE GOT THE BREAST CANCER GENE.”

As a carrier of the BRCA1 gene mutation, Angelina Jolie had an 87% lifetime risk of developing breast cancer and a 50% lifetime risk of developing ovarian cancer. Her diagnosis hit close to home, too—her mother died of ovarian cancer at the age of 56. Angelina Jolie eventually had not only both her breasts but also her ovaries removed as a preventive measure. Said Dr. Axelrod, “Carriers of the well-publicized BRCA1 or BRCA2 genes, as well as a number of other genes that have been discovered more recently, including TP53 (Li-Fraumeni syndrome), pTEN (Cowden’s disease), CDH1, and PALB2 have a significantly higher risk. And as in Jolie’s case, removing the breasts and ovaries even when there is no cancer present will greatly reduce the odds of both forms of the disease and bring peace of mind.

“Still, you don’t have to go to this extreme—with your breasts anyway. Ovarian cancer is harder to diagnose in the early stages, so there is a good argument for having your ovaries removed.” With your breasts, however, it’s a more complicated decision. You can chose to be closely monitored for very early signs of breast cancer, which is 98% curable if caught in Stage 0 or 1. “However, women who are BRCA1 carriers have a higher rate of small aggressive cancers,” she said, “and preventive mastectomy substantially reduces that risk.”

REASON #3: “I HAVE A FAMILY HISTORY OF BREAST CANCER.”

“Many women have close relatives—mothers, sisters, grandmothers—who have been diagnosed with breast cancer, yet testing has not revealed any genetic link.” That’s actually the case most of the time, since only 5% to 10% of women who get breast cancer have known genetic risk factors. “That doesn’t rule out a genetic predisposition,” she said. “It could well mean that we haven’t yet discovered the particular gene mutation that you have yet. But it’s not a good argument for removing a healthy breast. You can avoid unnecessary surgery with close monitoring.”

REASON #4: “I WANT BOTH MY BREASTS TO LOOK THE SAME.”

“While this is not a medical reason, it is a valid personal reason why one may choose to remove a healthy breast along with a diseased one,” Dr. Axelrod said. “Breast reconstruction has come a long way, but there is still a big difference between a natural breast and a reconstructed one, and if you’re going to have both reconstructed, better symmetry can be achieved if you choose to have them done at the same time. In addition, if you choose to have a TRAM (transverse rectus abdominis) flap (in which some of the abdominal muscle is used to create the new breast) or a DIEP flap (which uses abdominal skin and tissue but no muscle), it can be performed only once, so choosing to have both breasts done makes sense to many women. Bear in mind, however, that the length of time you will spend on the operating table for this procedure is at least double that of traditional reconstruction with implants, and your recovery time will be longer because you’re also having abdominal surgery, which also increases the risk for complications. You’ll likely be in the hospital for five days as opposed to two or three. And not every woman is a candidate for this procedure: If you’re thin, you likely won’t have enough belly tissue. Women who have had multiple cesarean deliveries or other abdominal surgeries also may not be candidates.”

All of this adds up to a very personal decision in which you must consider your comfort, convenience, recovery, appearance, family history and fears. “Take your time and consider all the options,” said Dr. Axelrod. No doctor should tell you that you need to be on the operating table ASAP, nor should any doctor casually say, ‘how about taking off the other breast?’ Both kinds of comments are warning signs that you need another opinion.” To learn much more about breast cancer prevention, detection and recovery, see Bottom Line’s guide.