More than 75 percent of breast tumors showing posterior enhancement on ultrasound imaging were grade III, and approximately one-third were triple negative, whereas posterior shadowing was strongly associated with an estrogen receptor (ER)-negative and low-grade tumor, researchers reported in a study published in the February issue of American Journal of Roentgenology.
Although many studies have focused on breast cancer subgroups, including ER, progesterone receptor (PR) and human epidermal growth factor receptor 2 (ERRB2) or triple-negative breast cancers, few studies have examined links between imaging features and the biologic nature of breast tumors.
Abid Irshad, MD, from the Medical University of South Carolina in Charleston, S.C., and colleagues conducted a retrospective review to examine the correlation between sonographic tumor features and prognostic factors.
Two radiologists retrospectively reviewed static images and cine clips for 160 ultrasound-guided breast biopsies performed between January 2010 and June 2011. They divided acoustic features into four categories: posterior attenuation or shadowing, posterior enhancement, mixed pattern and no change. Tumor margins were categorized as spiculated, angular, indistinct, microlobulated or lobulated and circumscribed. Individual features were correlated with histologic tumor grade and hormone receptor status.
Of the 160 women, 102 were ER-positive/PR-positive, 32 were ER-positive/PR-negative and 26 were triple negative.
Logistic regression models showed 96.8 percent of tumors with posterior shadowing were ER-positive and 91.8 percent were low-grade tumors. These tumors had greater than nine times the odds of ER positivity and greater than 13 times the odds of a grade I or II vs. III tumor than those without posterior shadowing.
“[T]he presence of posterior shadowing was found to be a very strong predictor of a receptor (ER)-positive, which in turn almost rules out a triple-negative tumor,” wrote Irshad and colleagues.
A total of 36.4 percent of tumors showing posterior enhancement were ER-negative/PR-negative and 76.4 percent were grade III. These tumors had a significantly greater probability of having ER-negative/PR-negative status than those without enhancement.
The researchers observed a similar but weaker correlation between spiculated or angular margins and low tumor grade. In contrast, triple-negative tumors tend to be cellular and rapidly growing, leading to relatively circumscribed margins, according to the authors.
These findings may help physicians with limited access to sophisticated laboratory testing stratify their patients on the basis of the biological aggressiveness of their tumors and manage them within the boundaries of available resources, according to the researchers.
The study was limited by it small sample size, and the researchers suggested larger studies with more observers to test these results. They concluded, “[C]ertain tumor features on ultrasound show strong correlation with tumor grade and receptor status of breast cancer. These findings may help to expand the scope of ultrasound in predicting with confidence certain biologic tumor characteristics that are currently beyond the scope of ultrasound BI-RADS.”