Accuracy of short-interval follow-up mammograms by patient and radiologist characteristics

The purpose of our study was to examine the accuracy of short-interval follow-up mammograms and evaluate patient and radiologist characteristics associated with accuracy.

We evaluated 45,007 initial short-interval follow-up mammograms from the Breast Cancer Surveillance Consortium interpreted 3-9 months after a probably benign assessment on a screening or diagnostic examination between 1994 and 2004. We linked these mammograms with patient characteristics and breast cancer diagnoses within 12 months. A subset of short-interval follow-up examinations (n = 13,907) was merged with radiologist characteristics collected from survey data from 130 interpreting radiologists. Using logistic regression, we fit generalized estimating equations to model sensitivity and specificity of short-interval follow-up mammograms by patient and radiologist characteristics.

For every 1,000 women, 8.0 women (0.8%) were diagnosed with breast cancer within 6 months and 11.3 (1.1%) within 12 months. Sensitivity was 83.3% (95% CI, 79.4-87.3%) for cancers diagnosed within 6 months and 60.5% (56.2-64.7%) for those diagnosed within 12 months. Specificity was 97.2% (96.9-97.6%) at 6 months and 97.3% (96.9-97.6%) at 12 months. Sensitivity at 12 months increased among women with unilateral short-interval follow-up mammograms (odds ratio, 1.56 [95% CI, 1.06-2.29]) and when the interpreting radiologist spent more than 10 hours a week in breast imaging (odds ratio, 3.25 [1.00-10.52]).

Initial short-interval follow-up mammography examinations had a lower sensitivity for detecting breast cancer within 12 months than other diagnostic mammograms (61% for short-interval follow-up vs 80% for diagnostic mammograms reported in the literature). However, sensitivity within the 6-month interval that is usually recommended for subsequent follow-up was 83%. Accuracy of short-interval follow-up mammograms was influenced by few patient and radiologist characteristics.