A new review of a decade's worth of U.S. cancer statistics finds that women who got breast-conserving surgery and radiation to treat early-stage cancer were less likely to die from breast cancer during the next 10 years than those who had their breasts removed.

Researchers found that 94 percent of women who had lumpectomy and radiation between 1998 and 2008 had not died of breast cancer after 10 years, compared to about 90 percent of the women who had mastectomy, with or without radiation.

"We can see what's happening in modern-day practice," Dr. Shailesh Agarwal said. "Patients who are undergoing breast conservation therapy - versus patients who are undergoing mastectomy - are having better survival."

Agarwal, an associate professor of plastic and reconstructive surgery at the University of Utah School of Medicine in Salt Lake City, is the study's lead author.

His team's report, published in the journal JAMA Surgery, is not the first to point out that women who have lumpectomy and radiation for breast cancer appear to live longer than others.

But research looking into whether women who have breast-conserving therapy have a higher risk of their cancer returning or spreading has yielded mixed results.

In January 2013, a study published in the journal Cancer found that Californian women who had lumpectomy were also more likely to survive longer than those who had their breasts removed.

But older randomized controlled trials, considered the "gold standard" of medical research, have found that survival is about equal between women who undergo lumpectomy with radiation and those who have their breasts removed.

For the new study, the researchers used data on more than 130,000 U.S. women between the ages of 18 and 80 years old who were treated for early-stage breast cancer. That meant the tumor size was less than 4 centimeters and three or fewer lymph nodes showed signs of cancer cells having spread.

Overall, about 70 percent of the women underwent lumpectomy with radiation, about 27 percent had mastectomy and about 3 percent had mastectomy with radiation.

After five years, about 97 percent of women who had lumpectomy with radiation had not died of breast cancer. That compared to about 94 percent of women who had mastectomy and about 90 percent of women who had mastectomy and radiation.

After 10 years, about 94 percent of women who had lumpectomy with radiation had not died of breast cancer. That compared to about 90 percent of women who had mastectomy and about 83 percent of women who had mastectomy and radiation.

The researchers acknowledge in their report that they can't explain why people who have breast conservation therapy are less likely to die of breast cancer, compared to those who have their breasts removed.

It could be, they write, that there are differences in the other therapies they received, such as chemotherapy, or the aggressiveness of a woman's tumor, that were not reflected in the data.

There could also be differences between the women who chose one therapy over another, including unrelated health problems, lifestyle, family history and other variables.

When researchers compared women with similarly-sized tumors and similar lymph node involvement, for example, race appeared to play a role in survival, with African American women nearly twice as likely to die from the cancer.

Women who had mastectomy and radiation were also typically younger with more advanced breast cancer, which may partially explain why they were most likely to die of breast cancer over 10 years, Agarwal and his colleagues write.

But when women with similar tumors and other variables were compared, overall, the women who had lumpectomy with radiation still had a lower chance of dying than those who had mastectomy.

Dr. Shelley Hwang, who led the 2013 study, said the new study validates her team's findings.

"I think it's really going to help women make decisions about which one to choose and show women that lumpectomy is not a less and worse treatment," she said.

Hwang was not involved in the new study but is chief of breast surgery at Duke University Hospital in Durham, North Carolina.

She emphasized that the findings only apply to people who have early-stage breast cancer without other complications.

"This is not for the special cases of women who have a (genetic) mutation or that sort of thing," Hwang said.

Agarwal said that it's also important for women to have frank discussions with their doctors about treatments.

"Despite this being a large database study and a large number of patients, breast cancer treatment is highly individualized," he said.

"I think the main thing is to have good discussion with your breast surgeon and even the multi-disciplinary (treatment) team so that you have the best chance of getting the optimal treatment."