For more than a decade, growing numbers of women diagnosed with cancer in one breast have been opting to get both removed.
Experts have been trying to discourage this radical approach, because for most women, it adds to surgical risks and medical costs without improving survival. It also defies decades of advances, such as lumpectomy, that have made surgery less aggressive.
Now, the first study to look at the double mastectomy trend state by state finds wide geographic variation, with startlingly high rates among younger women.
In 2012, the percentage of patients under age 45 who got both breasts removed ranged from 16 percent in Hawaii to 49 percent – almost half – in South Dakota.
South Dakota and four neighboring Midwest states — Nebraska, Missouri, Colorado, and Iowa — were pacesetters, with more than 40 percent of younger patients choosing double mastectomy.
In Pennsylvania, the comparable rate was 30 percent – close to the national average of 33 percent – while New Jersey's was 25 percent.
"We don't know," said American Cancer Society epidemiologist Ahmedin Jemal, senior author of the study published Wednesday in JAMA Surgery.
Lisa Newman, director of breast oncology at the Henry Ford Health System in Detroit, offered a guess: That region of the nation could be a harbinger.
"The Midwest is … home of the so-called bellwether states whose voting patterns have consistently predicted the outcome for national elections," Newman wrote in a commentary in the journal. If political patterns can be generalized to cancer-treatment patterns, "then the study … indicates we have not yet seen a peak in the rising rates" of double mastectomy.
The new analysis, co-led by Emory University researchers, used cancer registry records for 1.2 million women diagnosed with early-stage breast cancer between 2004 and 2012.
Like previous studies, the new one found a steady increase in double mastectomies. The rates rose over the study period from about 4 percent to 10 percent among women 45 and older. Among younger women, in whom breast cancer is relatively uncommon, rates rose from 10 percent to 33 percent.
The researchers didn't have data to tease out how many women were at high risk of breast cancer because of genetic defects or family history. Such women are in a minority but for them, preventive surgery can be beneficial and should be considered, expert guidelines agree.
The study did have data on breast reconstruction. Surveys have found many women are concerned that removing and reconstructing one breast will leave them with "asymmetry" – an unattractive mismatch. But although the rate of reconstruction went up in most states, it didn't keep pace with the increase in double mastectomies, the researchers found.
The study also looked at women's insurance status. Thirteen percent of privately insured women, 9 percent on Medicaid (the government program for the poor), and 4 percent on Medicare (the government program for seniors and the disabled) underwent double mastectomies.
So did 1,569 women with no insurance, suggesting that some hospitals provided the surgery as charity care.
Jemal, the senior author, said he doesn't know why insurers apparently aren't denying coverage of procedures that may not be medically necessary.
But experts who have studied this trend in breast surgeries say insurers generally have been loath to infringe on a woman's right to decide what is best for her body and life, given the complex emotional and personal nature of the decision. So have surgeons.
The American Society of Breast Surgeons last year issued a consensus statement that double mastectomy should be discouraged for average-risk women, "but the patient's values, goals and preferences" should be included in the discussion of benefits and harms.
The lead author of that statement, Mayo Clinic breast surgeon Judy C. Boughey, said the discussion can be challenging. Many patients don't understand that although removing a healthy breast averts cancer that might arise there, it does nothing to ensure the initial breast tumor has not spread to other organs or to bones — which is the real threat to survival.
Boughey explains to patients that double mastectomy "is not going to improve your survival. It's not going to improve your outcome from this index [original] cancer. You can't breastfeed after having this done. There will be body image changes, sex life changes," she said, referring to the fact that a reconstructed breast may look fine, but sensation changes.
"But at the end of the day, the final decision is the woman's," she said.
Susan E. Clare, a breast surgeon and researcher at Northwestern University's Feinberg School of Medicine in Chicago, conducted a survey that found women who choose double mastectomy are strongly influenced, and heavily reinforced, by their social networks, especially family and friends. Curtailing the double mastectomy trend, Clare believes, will take a sophisticated, multimedia educational campaign that "interviews women who are pleased with their outcomes, and women who aren't."
She added that her own attitude has changed. "When I was younger, I was uncomfortable taking off something that was healthy. But then I evolved into saying maybe it was necessary for the patient's peace of mind."
It was for Melissa Marks, 42, of Oklahoma City.
A marathon runner and Pilates instructor, Marks had no genetic factors that put her at high risk of breast cancer when she was diagnosed almost two years ago. She did, however, have a history of painful cysts in her breasts – a problem she believes was linked to her cancer even though medical studies discount that idea.
When a large tumor was found in her left breast, it had an overactive protein, called HER2, that is a sign of aggressiveness. Even with targeted drug treatment, having HER2 put her at higher risk of recurrence. She decided on a double mastectomy. Afterward, tissue analysis revealed the cancer had spread to a single lymph node that had been removed.
"I was pretty insistent on doing it my way. When you go through something so traumatic, you go into fight-or-flight mode," Marks said. "It's hard to hear those words, 'You have cancer.' You get a lot of things thrown at you. But you start researching. You become a novice in the medical field."
Marks, a Federal Aviation Administration engineering manager, is now a "young advocate" with Bala Cynwyd-based Living Beyond Breast Cancer. Although she still faces reconstructive surgery, she believes she made the right choice.