Breast Cancer Risk for Women Rises to 1 in 9

The average American woman runs a one in nine risk of developing breast cancer during her lifetime, an increase over the previous estimate, the American Cancer Society said Thursday.

The increase reflects rising breast cancer rates and the fact that women are living longer, the society said.

About 175,000 American women will get breast cancer this year, and 44,500 women will die from the disease, the society said in releasing its annual projections.

“Every American woman should consider herself at risk,” Dr. Clark Heath, the society’s vice president for epidemiology and statistics, said in a statement.

The society had projected a one in 10 risk since 1987, based on data from the early 1980s. The new estimate is based on federal figures for 1987, the latest available, cancer society statistician Catherine Boring said.

Edward Sondik, the National Cancer Institute’s deputy director of the division of cancer prevention and control, noted that the change means going from a risk of 10% to one of 11%.

The difference is “not that great,” he said, but “the bottom line is that there’s no question that it’s going up.”

Sondik said that increased mammography appears to account for a large percentage of the reported increase in breast cancer rates.

But, apart from that, “there is a genuine, relatively small, slow increase that’s been going on” of about 0.5% a year over the last 30 to 40 years, he said. “We really don’t know what that’s due to.”

Possible explanations include changes in diet, which is being investigated, and increases in women who delay childbearing, Boring said. Women who have not produced a live birth before age 30 face an increased breast cancer risk, she said.

Boring said that another contributor to the increase in individual risk is simply that women are living longer. The risk of breast cancer rises with age.