Do breast density laws affect racial disparities in supplementary screenings?

A new study has found that rates of supplemental screening among black women with dense breasts increased after the passage of statewide mandatory breast density notification laws, according to research published Oct. 18 in the Journal of the American College of Radiology.  

Though supplemental screening can help women with increased breast cancer risk, breast density notification laws may encourage additional screening that is incompatible with non-high-risk women, explained lead author Mark Manning, PhD, of the Karmanos Cancer Institute in Detroit, and colleagues.  

“The variability and lack of consensus regarding supplemental screening for non-high-risk women with dense breasts presents challenges for physicians’ follow-up recommendations—the introduction of breast density notification legislation compounds these challenges,” Manning et al. wrote. “Breast density likely informed decision making about supplemental screening before adoption of breast density laws; however, we expect that its role was amplified after adoption of notification legislation.”  

Manning and colleagues examined supplemental breast screenings (MRI, ultrasound or tomosynthesis within six months of screening mammogram) from a sample of 2,764 black women and 691 white women in Detroit. All had returned for at least one screening mammogram after the state of Michigan adopted a breast density notification law in July 2015. The women also had findings that were negative or benign at each screening mammogram. 

The researchers found an increase from 14 percent to 70 percent in supplemental breast screenings of women who originally had negative results after the passage of the law.

The increase, they noted, was driven greatly by an increase in supplemental screening knowledge among black women. The researchers suspected this was because physicians were less likely to discuss breast density and associated risks or to refer black women with dense breast for supplemental screening before the notification law.  

“Subgroup analyses (n = 250) indicated that whereas five-year breast cancer risk was positively associated with supplemental screening before the law and negatively associated after the law for white women, five-year risk was not associated with supplemental screening either before or after passage of the law for black women,” the researchers wrote. 

Overall, breast density was more strongly related to supplemental screening after the passage of the law and, according to the researchers, explained race-differences in supplemental screening and the distribution of breast cancer risks factors. Study findings suggest that the passage of breast density notification laws lessened the consideration of breast cancer risk in supplemental screening decision-making.  

“Future studies ought to examine how supplemental screening rates continue to evolve as women and their physicians gain more familiarity with breast density and breast cancer risk and whether more supplemental screening yields more breast cancer tumor detection,” the researchers wrote.