Multivariate analysis of roentgenologic characteristics and risk factors for nonpalpable carcinoma of the breast.

Screening mammography improves carcinoma of the breast survival through early detection and treatment of nonpalpable, often noninvasive, carcinomas. Consideration of the roentgenologic characteristics of mammographic masses and calcifications in combination with risk factors of patients may improve the yield of spot localization breast biopsy. Risk factors solicited by questionnaire were correlated with the roentgenologic appearance and histopathologic factors of 482 specimens from spot localization breast biopsies (39 percent malignant). Masses with irregular contour (p < 0.001) and high density (p < 0.005) were associated with malignant tumors. Packed, coarse and round calcifications were associated with benignity (p < 0.001), whereas scattered, fine and mixed calcifications were associated with malignant tumors (p < 0.05). Malignant masses with smooth contour were significantly more likely to be associated with noninvasive histology. Patients found to have malignant tumors were significantly older than patients with benign lesions (58 versus 52 years, p < 0.001). Stepwise logistic regression was used to evaluate the relative usefulness of demographics and roentgenologic features in predicting benign and malignant pathology among masses and calcifications. Age and irregular contour were independent significant predictors of malignancy for masses. Age, round, coarse, packed or scattered calcifications were significant independent predictors of benignity among calcifications. The radiologist correctly predicted malignant pathology in 60 percent of the patients and benign pathology in 78 percent. Parity, age at menarche, age at first pregnancy, age at menopause, history of benign breast disease, history of carcinoma of the breast, family history of carcinoma of the breast, birth control pill exposure and smoking were not significantly associated with the diagnosis of malignant tumor. These results suggest that risk factors for carcinoma of the breast are insignificant for nonpalpable lesions because patients referred for needle localization are already selected for high risk. Roentgenologic patterns of masses are useful for predicting which lesions are invasive.