Mammography after breast-conserving surgery and radiation therapy is an important tool for followup. Early diagnosis of local recurrence enables prompt treatment decisions, which may affect patient prognosis. For complicated post-treatment changes, radiologists sometimes have difficulties in interpreting follow-up mammography. Fat necrosis, dystrophic calcifications, suture calcification features, breast edema, seroma and distorted breast are benign changes related to treatment. These findings may mimic or hide tumor recurrence making it difficult to diagnose recurrences or prevent inappropriate biopsies. Recurrent tumors in follow-up mammography show several typical findings such as increasing asymmetric density, enlarging mass, reappearance of breast edema, and micro-calcifications. The purpose of this pictorial review is to demonstrate and discuss mammographic findings of recurrent tumors and important post-treatment changes that may mimic benign or malignant lesions, also using breast ultrasound images or breast magnetic resonance images. Recognizing post-treatment changes may help radiologists to more effectively identify candidates for suspected local recurrences.
Keywords: breast cancer; breast-conserving surgery; digital mammography; radiation therapy; recurrence.