Sizing It Up: Concordance between Breast Imaging and Pathologically Determined Tumor Measurement.

BACKGROUND

Accurate preoperative imaging of breast tumor size is essential, as small measurement differences can influence the treatment strategy. This study evaluates the accuracy of tumor size estimation by mammography, ultrasound, and magnetic resonance imaging (MRI) compared with pathology and examines factors influencing imaging performance.

PATIENTS AND METHODS

We retrospectively analyzed patients with breast cancer treated from 2019 to 2024. Measurements were considered concordant if they fell within ±20% of the pathological size. Statistical analyses performed include paired t-tests, chi-squared tests, Lin's concordance correlation coefficient (CCC), and logistic regression. Python-based framework was used to identify the most accurate weighted formula.

RESULTS

We included 460 patients with a median age of 57 (26-90) years. MRI had the highest concordance (62%), outperforming mammography (57%) and ultrasound (53%) (p = 0.004). Our alternative weighted average formula (0.66 × MRI size + 0.35 × US size) yielded the highest concordance rate (65.2%, CCC = 0.785). Average tumor size on pathology was 17.31 mm. MRI slightly overestimated the size (18.38 mm, p = 0.482), while mammography (14.8 mm, p = 0.06) and ultrasound (14.31 mm, p = 0.019) underestimated. MRI demonstrated the highest accuracy in T-stage classification (89%). Concordance was highest for masses without non-mass enhancement (NME) (CCC = 0.834) and declined with NME (CCC = 0.635). MRI accuracy improved in tumors > 15 mm (OR 2.47) and high-grade tumors (OR 1.75) but declined in extremely dense breasts (OR 0.42) and lobular histology (OR 0.46).

CONCLUSIONS

MRI demonstrated the highest concordance with tumor size and T stage. Its accuracy improved in larger and high-grade tumors but decreased with dense breasts, NME, and lobular histology. A combined imaging approach using MRI and ultrasound may enhance preoperative size estimation.