Missed breast carcinoma; why and how to avoid?

Introduction : Despite the advances in mammography techniques, it still has a number of limitations. It is estimated that about 10 to 25% of lesions are overlooked in mammograms out of which about two thirds are detected retrospectively by radiologists and oncologists. Causes of missed breast cancer on mammography can be secondary to many factors including those related to the patient (whether inherent or acquired), the nature of the malignant mass itself, poor mammographic techniques, provider factors or interpretive skills of radiologists and oncologists (including perception and interpretation errors). Aim of Work : The aim of this study is to investigate the aforementioned factors hindering early breast cancer detection and in turn lowering mammographic sensitivity and to outline the major guidelines to overcome these factors aiming to an optimum mammographic examination and interpretation by radiologists and oncologists. Subject and Methods : We conducted this multicenter study over a two-year interval. We included 152 histopathologicaly proven breast carcinomas that were initially missed on mammography. The cases were subjected to mammography, complementary US, MRI and digital mammography in some cases and all cases were histopathologically proven either by FNAB, CNB or open biopsy. Results : Revision of the pathological specimens of these 152 cases revealed 121 infiltrating ductal carcinomas, 2 lobular, 4 mucinous, 14 inflammatory carcinomas, 6 carcinomas in situ (3 of which were intracystic), 2 intraductal papillary carcinomas and 3 cases with Paget's disease of the nipple. In analyzing the causes responsible for misdiagnosis of these carcinomas we classified them into 4 causative factors; patient, tumor, technical or provider factors. Tumor factors were the most commonly encountered, accounting for 44.1%, while provider factors were the least commonly encountered in 14.5 %. Carcinomas were detected using several individual or combined complementary techniques. These techniques mainly included double reading, additional mammography views, ultrasound and MRI examinations. Forty four carcinomas were detected on double and re-reading by more experienced radiologists. Additional mammographic views were recommended in 35 (23%) cases. Complementary ultrasound examination was performed for all 152 cases (100%) and showed a higher sensitivity than mammography in carcinoma detection. It was diagnostic in 138 (90.8%) cases only. In the remaining 14 cases, further MRI and biopsy were performed. Conclusion : Why can breast carcinoma be missed? Four main factors are responsible for missing a carcinoma: (1) Patient factors (Inherently dense breasts or acquired dense breasts). (2) Tumor factors (subtle carcinoma, masked carcinoma, multifocal carcinoma and multicentric carcinoma). (3) Technical factors (bad exposure factors, malpositioned breasts and bad processing quality). (4) Provider factors (bad perception and misinterpretation). How to avoid missing a breast carcinoma? Review clinical data and use US and other adjunct techniques as MRI and biopsy to assess a palpable or mammographically detected mass. Be strict about positioning and technical factors. Try to optimize image quality. Be alert to subtle features of breast cancers. Always consider the well defined carcinoma. Compare current images with multiple prior studies to look for subtle increases in lesion size. Look for other lesions when one abnormality is seen. Judge a lesion by its most malignant features. Double reading and the use of computer aided diagnosis (CAD) and finally FFDM (Full Field Digital Mammography). Close cooperation between the oncologist, radiologist and pathologist is essential to avoid missing any case of breast carcinoma. Key Words : Missed breast carcinoma -Mammography - Ultrasonography -MRI.