SCINTIMAMMOGRAPHIC ANALYSIS OF NONPALPABLE BREAST-LESIONS PREVIOUSLY IDENTIFIED BY CONVENTIONAL MAMMOGRAPHY

Background: In randomized trials, screening mammography has led to dec reased mortality from breast cancer. However, the low positive predict ive value of mammography (i.e., the proportion of patients with a posi tive test result who actually have breast cancer) results in a large n umber of unnecessary biopsies, We determined whether scintimammography with technetium-99m-sestamibi is a useful supplemental diagnostic too l for women with nonpalpable breast abnormalities identified by conven tional mammography. Methods: Scintimammography was performed preoperat ively on 70 women who were 31-66 years of age (mean age and median age = 51 years), These women had nonpalpable breast abnormalities identif ied by conventional mammography; subsequently, a needle-localization e xcisional biopsy of each suspicious lesion was performed. Scintimammog raphic images were interpreted independently by two nuclear medicine p hysicians who were blinded to all clinical and pathologic data, and an interobserver variation analysis was performed, Results: Interobserve r variation analysis of the scintimammographic findings showed an agre ement for breast diagnosis of 97% and a kappa coefficient of 0.90. Com parison of scintimammographic findings and histopathologic results rev ealed that the sensitivity (proportion of patients with breast cancer who had a positive test result), the specificity (proportion of patien ts without breast cancer who had a negative test result), the positive predictive value and the negative predictive value (proportion of pat ients with a negative test result who actually did not have breast can cer) of scintimammography were 56% (95% confidence interval [CI] = 23% -85%), 87% (95% CI = 75%-94%), 38% (95% CI = 15%-68%), and 93% (95% CI = 82%-98%), respectively. Four of nine breast cancers were not detect ed by scintimammography. Conclusion: Because of excellent interobserve r agreement, scintimammography provides an objective way of detecting primary breast carcinoma. In view of its low sensitivity and positive predictive value, however, scintimammography is not currently recommen ded as a screening test in patients with nonpalpable positive mammogra phic findings.