Breast cancer in nonpalpable lesions: can mammographic parenchymal pattern improve the predictive value of biopsy?

The increasing number of women referred for surgical biopsy of nonpalpable breast lesions detected by screening mammography led to a retrospective review of all such cases from October 1, 1986 to September 30, 1990. There were 165 consecutive, wire-localized, excisional biopsies of radiographic lesions performed on 158 patients during this 4-year period. A positive (i.e., malignant) result was found in 16 patients (10%); all but one of these 16 patients had stage I disease at subsequent treatment. Examination of historical factors (age, family history, prior biopsy, breast symptoms) and mammographic factors (mass, microcalcification, irregular borders, new lesion, parenchymal pattern of increased fibroglandular density) revealed that no patient with a diffuse parenchymal pattern of increased fibroglandular density had a malignant diagnosis. This finding was statistically significant (P = 0.002) by chi-square analysis. This negative relationship of radiographic parenchymal pattern to early cancer in nonpalpable lesions is contrary to what one would expect, based on several reports in the radiology literature. Over one-third (36%) of the author's patients had the increased fibroglandular x-ray pattern, making this finding potentially important for surgeons evaluating the patient with a nonpalpable lesion detected by mammography.