Updated

More U.S. women, particularly young women, who have cancer in only one breast are getting both breasts removed, according to research that found the trend more than doubled in just six years.

It is still a rare option: Most breast cancer in the U.S. is treated by lumpectomy, removing just the tumor while saving the breast.

But the new study suggests 4.5 percent of breast cancer surgery in 2003 involved women getting cancerous and healthy breasts simultaneously removed, a 150 percent increase from 1998 — with no sign that the trend was slowing.

Young women are most likely to choose the aggressive operation, researchers report Monday in the Journal of Clinical Oncology.

The concern is whether they are choosing in the heat of the moment — breast cancer surgery often is within two weeks of diagnosis — or with good understanding of its pros and cons.

"Are these realistic decisions or not?" asks Dr. Todd Tuttle, cancer surgery chief at the University of Minnesota, who led the study after more women sought the option in his own hospital.

"I'm afraid that women believe having their opposite breast removed is somehow going to improve their breast cancer survival. In fact, it probably will not affect their survival," he said.

The initial tumor already may have sent out seeds of spread to key organs, Tuttle explained.

But removing the remaining healthy breast does greatly lower, although not eliminate, chances of a new cancer developing on the opposite side.

Do not underestimate the peace of mind that brings, said Trisha Stotler Meyer of Vienna, Virginia, who had her breasts removed three weeks ago.

"Doctors are not up at night crying" in fear of their next mammogram, said Meyer, 37, who went back for a double mastectomy after her initial cancer surgery. "I don't want to have to deal with the stress."

Meyer is far from alone.

In a single day last week, Dr. Shawna Willey of Georgetown University's Lombardi Cancer Center had two patients seek the operation.

One needed her entire cancerous breast removed, and immediately asked to have the healthy one removed, too. Another woman had recently undergone a lumpectomy and was sick from chemotherapy — and returned to ask that both breasts be fully removed.

"Her perception is, 'If I have my breasts taken off, I never have to do this again,"' said Willey, who asked the woman to see a counselor and finish chemo before deciding.

"I can understand that point of view," she added. "But I always tell them, it's not a guarantee."

The American Cancer Society estimates 178,480 U.S. women will be diagnosed with breast cancer this year. About 40,460 will die of it.

Some women at high risk, because of notorious breast cancer genes or family history, choose preventive mastectomies before cancer ever strikes.

Tuttle's study is the first national look at how many women choose to remove both a diseased and healthy breast together.

He used a government cancer registry that covers 16 regions, a representative sample of the U.S. population, to track more than 150,000 breast cancer surgeries between 1998 and 2003.

Tuttle calculated that lumpectomies accounted for almost 60 percent of those surgeries in 2003. Lumpectomies have gradually increased since they were proven just as effective as breast removal for early cancer in 1991.

The surprise: Single mastectomies remain the No. 2 option but are dropping — while double mastectomies, although uncommon, were on the rise for every stage of cancer. Even women who qualify for anti-hormone drugs that greatly protect the remaining breast were as likely to choose removal as women with harder-to-treat tumors.

Why? Tuttle is planning a new study to tell, and to see if candidates are warned about such risks as infection that increase with the bigger surgery.

Meyer, the Virginia woman, had time to fully consider the option. She was diagnosed with cancer in January 2005, shortly after her son's birth. At first, she was content with a lumpectomy, followed by chemotherapy and radiation. But she did not qualify for protective anti-hormone drugs. And then in March, Meyer found a lump in her healthy breast. It was not cancer but a cyst that would wax and wane, making for tense checkups.

"It really freaked me out," Meyer said. "It was at that moment that my breasts became like tonsils. I don't need them anymore. They're gone."

Georgetown's Willey says better reconstructive surgery is partly spurring the trend. Still, she often encourages women to wait to remove the second breast, as lining up reconstruction sometimes dangerously delays treating the cancer.

"When I was younger ... I really tried to argue with patients and talk them out of it," Willey said. Now, if they have weighed the options, she does not.

"I can't recall a single patient who tells me they regret that decision."