In a recent study from The University of Texas MD Anderson Cancer, researchers find that breast cancer patients with dense breast tissue have higher risk of developing disease in the contralateral breast.
The study is published in the journal Cancer.
It is among the first studies to find the association between breast density (BD) and contralateral breast cancer (CBC).
According to the researchers, a big challenge in the management of this patient population, especially as they are making surgical decisions, is trying to counsel women appropriately on their risk of developing breast cancer in the other breast.
The estimated 10-year risk for women with breast cancer developing CBC can be as low as 2%, and as high 40%, said Bedrosian.
The dramatic range is due in large part to the variability of risk factors across the patient population, she explained.
For the study, the researchers identified 680 stage I, II and III breast cancer patients, all treated at MD Anderson between 1997 and 2012.
BRCA patients were excluded from the study because of their known increased risk of CBC.
Women with an additional diagnosis of metachronous CBC — defined as BC in the opposite breast diagnosed more than six months after the initial diagnosis — were the “cases,” and patients who had not developed CBC were the “controls.”
Cases and controls were matched on a 1:2 ratio based on a number of factors, including age, year of diagnosis and hormone receptor status.
Of the selected patients, 229 were cases and 451 were controls.
The MD Anderson researchers categorized each patient’s breast density by mammogram reading, assessed at the time of first diagnosis, as “nondense” or “dense,” using the categorizations from the American College of Radiology.
Among the cases, 39.3%were classified as having nondense breast tissue and 60.7% as having dense breast tissue, compared to 48.3% and 51.7%, respectively, in the controls.
After adjusting for known breast cancer risk factors, the researchers found almost a two-fold increased risk of developing CBC in breast cancer survivors with dense breasts.
In the long-term, the researchers hope to use this tool to counsel patients on their personal risk and their options for treatment and surveillance, if their risk is sufficiently high.