A routine mammogram at age 39 alerted doctors that Tracy Grant had breast cancer.

Now 46, Grant said she started her mammograms when she was 30 because of a family history with the disease. She said her mother, grandmother and three aunts are all survivors.

"Early awareness and detection made a huge difference" in her case, said Grant, a filmmaker and artist. "I would never have waited until I was 50 with this history."

Nearly a year ago, the U.S. Preventive Services Task Force announced that it would no longer recommend that women between the ages of 40 and 49 get mammograms, a change from earlier guidelines that recommended women start getting the procedure at 40. The new guidelines instead recommended women start mammograms at age 50.

The American Cancer Society said, "No population-based data have yet been published regarding mammography use since the change."

But the change has had little impact on the recommendations made by the nation's largest breast cancer organizations -- such as the American Cancer Society and Susan G. Komen for the Cure. Both have not changed their guidelines and still recommend that women start getting their mammograms at age 40.

"We haven't changed our stance," said John Hammarley, a spokesman for Susan G. Komen for the Cure. "Women of average risk for breast cancer should begin receiving regular annual screening mammograms starting at the age of 40."

Dr. Otis Brawley, the chief medical officer for the American Cancer Society, said before a U.S. House committee last December that breast cancer mortality has been declining in the United States since mammography became the standard for most women.

In 2009 alone, he said, "about 15,000 breast cancer deaths were avoided that would have occurred had rates not begun to drop due in part to greater access to mammography."

Breast cancer is the leading cause of cancer death among women worldwide, according to the American Cancer Society. It is diagnosed in 1.4 million women and kills nearly 500,000 every year, according to the International Agency for Research on Cancer.

By adjusting the age for mammograms to 50, researchers hoped to delay some women's exposure to radiation and reduce the anxiety and costs of the tests.

In documents on its website, the U.S. Preventive Services Task Force said the harms that result from screening too early for breast cancer include "psychological harms, unnecessary imaging tests and biopsies in women without cancer and inconvenience due to false-positive screening results."

The task force said false-positive results are more common for women aged 40 to 49 years.

Overdiagnosis can also happen, the task force said.

But the drawbacks aren't enough for others in the field to follow the recommendations.

"Each year, more than 25,000 women in the U.S. under the age of 45 are diagnosed with breast cancer, and almost 3,000 women under the age of 45 will die of the disease," said Hammarley with Susan G. Komen, which still recommends that women get mammograms starting at age 40.

Grant, who has made a documentary on how the disease has affected her, said the choice to get routine mammograms earlier was easy for her, but may not be for other women.

"I think the choice is up to the individual," she said.