Sep 08, 2015
Among the various breast cancer risk assessment tools currently available, the Breast Cancer Surveillance Consortium (BCSC) is the only one to include breast density as a risk factor (click here to see the online risk calculator). However, the BCSC has not included benign breast disease (BBD) as one of its risk factors. BBD, along with breast density, is a strong, independent risk factor for developing breast cancer and includes proliferative diagnoses (both with and without atypia) such as ductal hyperplasia and non-proliferative diagnoses such as cysts and calcifications.
A new study in the Journal of Clinical Oncology (JCO), published online, ahead of print, August 17, asked: Would incorporating the risk factor of BBD into the BCSC increase the model’s power to predict which women are at risk of developing breast cancer?
The study, “Breast Density and Benign Breast Disease: Risk Assessment to Identify Women at High Risk of Breast Cancer” found that among women with proliferative disease, adding BBD to the BCSC model increased the percentage of women found to have a three percent or higher risk of developing breast cancer in the next five years from 9.3% to 27.8%. Among women with a known biopsy result, the model significantly improved risk prediction (in this group, the percentage of women with a three percent or higher risk of developing breast cancer in the next five years went from 7% to 14%, a significant increase). The model slightly underestimated breast cancer rates among younger women (ages 35-39) and among Asian and Hispanic women.
A better understanding of risk might encourage preventive medicine
According to the study’s first author, Jeffrey Tice, MD, who was involved in developing the initial BCSC model, including BBD in the BCSC risk model allows doctors to potentially identify more women at high risk of developing breast cancer, and to speak with these patients about preventive care.
“Many, many women have breast biopsies every year—the most common cited number is 1.6 million,” said Dr. Tice. “And even though most biopsies are benign, the results are still quite concerning to patients. Adding in the benign breast cancer diagnoses to our model allows physicians to estimate a woman’s risk from future breast cancer, which may prompt the physicians to inform patients about things they can do to lower their risk. For women in the highest risk categories, such as those who have lobular carcinoma in situ, most breast cancer specialists would recommend that they strongly consider medicine like tamoxifen or raloxifene and behavioral changes in alcohol consumption and diet.”
Finely-tuning and updating the BCSC risk assessment model
To calculate the independent hazard ratio for BBD and other risk factors in their model, the researchers gathered data on breast cancer incidence for 1,135,977 women from the BCSC. This incidence data was then combined with data breast cancer incidence from the 2000-2010 Surveillance Epidemiology and End Results (SEER) database and mortality data from 2010 vital statistics. This hazard ratio for BBD was then entered into the BCSC model as an additional risk factor.
The BCSC data also allowed the researchers to update the existing BCSC by calculating updated hazard ratios for the other risk factors in the model: race/ethnicity, family history of breast cancer, history of breast biopsy, and breast density.
“We had a larger data set than the first time we calculated risk for the BCSC so we were able to more carefully use statistical techniques to estimate risks,” said Dr. Tice. “For example, we identified risk factors according to age—some risk factors, such as breast density, are much stronger when women are younger than when they are older and so as women age, the relative risk goes down.”
Dr. Tice also noted that the updated BCSC model calculates both five- and ten-year risk, whereas the previous version included five-year risk only.
Jeffrey Tice, MD, is a general internist at the University of California, San Francisco.
Abstract of the original JCO article.
PDF of the original JCO article.
Tice JA, MD; Miglioretti DL, Li CS, et al. Breast density and benign breast disease: risk assessment to identify women at high risk of breast cancer. J Clin Oncol. Epub 2015 August 17.
The Exclusive Coverage series on ASCO.org highlights selected research from JCO and JOP with additional perspective provided by the lead or corresponding author.
@ 2014 American Society of Clinical Oncology