Researchers Improve Breast Cancer Risk Assessment Model

A significant increase in breast cancer development was found among a specific subset of women.

A new method to measure breast cancer risk may lead to improved screening practices and risk reduction, a recent study indicates.

Published in the Journal of Clinical Oncology, the study refined the national risk model that measures the chance of developing breast cancer for improved accuracy. Based on data from more than 1 million women with breast cancer, researchers found a 300% increase in a subset of women with a 5-year risk estimated at 3% or higher.

The previous version of the Breast Cancer Surveillance Consortium risk model included density categories, which are significant in determining the potential for disease development. The new model now incorporates benign biopsy results, after the old model failed to account for non-malignant proliferative conditions diagnosed through a biopsy.

The updated model includes atypical ductal hyperplasia, which increases the risk 3.5 to 5 times higher than in women without the condition. The model also includes lobular carcinoma in situ, which increases the risk 7 to 11 times higher, the study noted.

Investigators evaluated data from 1.1 million racially diverse women, aged from 35 to 74 years, who received a mammography and had no history of breast cancer. With a follow-up average of 6.9 years, nearly 18,000 women were diagnosed with invasive breast cancer, which was defined as malignancy that spread outside the lobules or milk ducts and invaded healthy tissue.

Among women with proliferative findings, the number with a breast cancer risk 3% or more jumped from 9.3% under the old model to 27.8% in the updated model.

"This revised model enables us to more accurately identify those women whose risk may merit use of chemoprevention,” said lead researcher Jeffrey Tice, MD, of UC San Francisco. “For these women, the benefits of medications that prevent breast cancer generally outweigh the harms.”

Chemoprevention involves using selective estrogen receptor modulators, including tamoxifen and raloxifene, to block the hormone vital to tumor growth in some breast cancers. These drugs may decrease breast cancer risk by more than one-third.

The new data categories enhances the benefits from the previous model, which also measures risk by age, ethnicity, family history of breast cancer, and breast density.

"This new information will enable women to work with their physicians to implement an optimal screening and risk reduction plan to reduce their chances of breast cancer," Dr. Tice added.