FRIDAY, June 23 (HealthDay News) — Some 3,000 pregnant women in the United States are diagnosed with breast cancer each year, and many worry about the effects cancer treatment could have on the fetus.

But a new study finds that, in most cases, those fears may be unfounded.

“Treating women who have breast cancer diagnosed while pregnant can result in happy mothers and the expected outcome of a healthy baby,” said Dr. Richard Theriault, a professor of medicine at the University of Texas M.D. Anderson Cancer Center, Houston.

Theriault and his colleagues have been tracking the health of 57 pregnant women diagnosed with breast cancer. He presented the findings to reporters Thursday at an American Medical Association news briefing in New York City. The study is expected to be published soon by a major cancer journal, Theriault said.

In companies the past, cancer treatment during pregnancy meant a grim dilemma: not treating the cancer and risking the life of the mother, or treating the cancer and risking the health of the baby, Theriault said.

“The attitude we hear most often is, ‘we can’t treat the cancer because of the pregnancy,’ ” Theriault said. Doctors then offered patients one of two options: “Delay the treatment, or terminate the pregnancy, so we can treat it. But terminating the pregnancy doesn’t improve the mother’s outcome. It does, however, obviate the concern about fetal outcomes.”

Things have gotten better for both mother and child, however, Theriault said.

“Breast cancer during pregnancy can be treated successfully,” Theriault said. “So, there is hope. The delivery of healthy babies is an expected outcome. [In the study] we have 64 consecutive live births with no stillborns. The outcomes are not different from other high-risk groups.”

Among the 57 patients, deliveries occurred between 37 weeks and 42 weeks of gestation, and mean birth weight of the babies was 6.4 pounds. Fifty-seven percent of the women had a vaginal delivery, Theriault said. Thirty-nine percent had a Caesarian delivery, he said.

Sixty-three percent of the infants had no neonatal complications, the Houston doctor said. One child was born with Down’s syndrome and another with a clubfoot, neither related to chemotherapy.

“Among the mothers, 75 percent are alive without breast cancer recurrence,” Theriault said. In addition, there appeared to be no difference in outcome among women with breast cancer who were pregnant compared with those who were not pregnant, he said.

The bottom line, according to Theriault: “Termination of pregnancy is not required to provide treatment and has no benefit in the perspective of the cancer.”

That doesn’t mean that a woman’s pregnancy has no impact on her breast cancer treatment, however. Theriault said radiation therapy remains the one intervention that can’t be used, since it can adversely affect the fetus. Mastectomy is the most common breast cancer treatment for pregnant patients, because most pregnant women are diagnosed in an advanced stage of the disease. Breast-conserving “lumpectomy” surgery is also possible for some women, Theriault added.

Radiation, if needed in addition to surgery, can be postponed until after the baby is born, the Houston expert said. And women can receive chemotherapy during pregnancy, but, “we usually try to time our chemotherapy, so the last cycle will end three weeks before delivery,” Theriault said. “We try to avoid the potential for low white-blood-cell count, low platelet counts or anemia,” he added.

“This is a very important paper,” said Dr. Carolyn D. Runowicz, president of the American Cancer Society and director of the Carole and Ray Neag Comprehensive Cancer Center, University of Connecticut Health Center.

Runowicz noted that newer, highly-targeted cancer ther