Enhancement of true-positive rates for nonpalpable carcinoma of the breast through mammographic selection.

A retrospective review of 332 needle localization biopsies for nonpalpable mammographic abnormalities was performed. Twenty-one invasive and 12 noninvasive carcinomas were identified in this population, for a true positive biopsy rate of 10 percent. A review of all needle localization mammograms performed on these patients by a radiologist specializing in mammography identified 225 mammograms with a low probability of malignancy. In this group, there were four in situ and six invasive carcinomas (true positive biopsy rate of 4 percent). In the remaining 107 mammograms with a high probability of malignancy, there were eight in situ and 15 invasive carcinomas (true positive biopsy rate of 21.4 percent). In the low probability group, fine needle aspiration or excisional biopsy were recommended for six of the ten neoplasms and follow-up mammograms at three to six months for the remaining four (two in situ and two invasive carcinomas). Using selectivity, 225 biopsies could have been avoided at a savings of $97,368 (Canadian dollars) in fees for physicians alone while still identifying 29 of 33 neoplasms (87 percent of all neoplasms) and possibly delaying diagnosis for three to six months or longer in four of 33 neoplasms (13 percent, two in situ and two invasive) for which follow-up mammograms were recommended.