Pregnant women who develop breast cancer do not have worse odds of death or of cancer returning than other young breast cancer patients, a new study has found.

The study is one of the largest to look at whether breast cancer hits pregnant and recently pregnant women harder than other women. It contradicts some smaller, earlier studies that suggested maternity made things worse.

"If we can get them early, we can treat them aggressively and have good and promising outcomes for both woman and child," said the study's lead author, Dr. Beth Beadle of the University of Texas M.D. Anderson Cancer Center.

The Houston hospital has the world's largest registry of pregnant breast cancer patients and their children.

Frightening for any woman, a breast cancer diagnosis is particularly terrifying for a pregnant woman. It presents complicated decisions about how to treat the mother and not harm the fetus. Some doctors recommend abortion so they can focus on treating the mother.

In the new study, being published Monday in the journal Cancer, researchers analyzed data from 652 women ages 35 and younger who were treated for breast cancer at M.D. Anderson from 1973 through 2006.

The study group included 104 women with pregnancy-associated cancers — 51 who had breast cancer during pregnancy, and 53 who developed the illness within a year after.

The rates of cancer recurrence, cancer spread and survival were about the same for the women with pregnancy-associated breast cancers as they were for the other women, the researchers found. The researchers calculated the rates for 10 years after the cancer diagnosis.

The women who were pregnant had tumours at a more advanced stage, probably because women and their doctors may have discounted breast changes, attributing them to breast feeding or pregnancy, the researchers believe.

Generally, breast cancers are more aggressive in younger women, and survival rates are significantly lower. While age may be a factor, it's not clear that pregnancy is: There was no evidence in the new study that tumours were faster growing in the pregnant women, said Beadle, a radiation oncologist.

Treatment complicated

Radiation — dangerous to a fetus — is commonly used in mammography and breast cancer treatment. But ultrasound can be used to look for breast tumours instead. And surgery and certain kinds of chemotherapy can treat the cancer without poisoning the womb.

However, it remains a complicated medical situation that can depend on the severity of the cancer and how far into the pregnancy the mother is, said Dr. Ruth O'Regan, an associate professor at Emory University's Winship Cancer Institute in Atlanta.

"It's quite complicated, but all of us have been able to treat pregnant women successfully," O'Regan said.

The study did not present data on how well the children did. Other research at M.D. Anderson has not found developmental problems in those children, Beadle said.

One success story was Emily Behrend, 35, who gave birth to a healthy baby girl last spring.

Behrend was diagnosed roughly four months into her pregnancy. On New Year's Day last year, she felt a lump at the top of her right breast. "It didn't feel like your typical swollen gland," said Behrend, a tax auditor from Tomball, Texas.

Doctors diagnosed cancer. She talked to several physicians about what to do, including one who suggested an abortion. "That was never an option for me," said Behrend, noting this was going to be her first child.

She went to M.D. Anderson, where surgeons removed the lump. She also had three chemotherapy treatments before she gave birth in May. Her daughter, Julia Grace, was healthy with a full head of blonde hair.

"I looked for that right away," said Behrend, who had lost her hair during the chemotherapy.

Behrend underwent additional chemo after the birth and her cancer is in remission. She called the whole experience "a blessing."

Her advice to other pregnant women: Don't be shy about signs you think might be related to breast cancer. "I would definitely ask your doctor," she said.