Preoperative Measurement of Breast Cancer Overestimates Tumor Size Compared to Pathological Measurement

BACKGROUND Tumor size is one of the most important factors in making clinical and pathological assessment of breast cancer. In the present study, we aimed to determine whether the preoperative measurement of tumor size, by imaging modalities, deviate from the postoperative pathological measurement in breast cancer. PATIENTS AND METHODS 1296 patients diagnosed with invasive ductal breast carcinoma (IDC) during 2007 and 2009 were involved. Pre- and postoperative measurements of tumor size were compared using paired t-test and Chi-square test. RESULTS The mean maximum diameters of tumors by imaging modalities and pathology were 27.9 mm and 22.4 mm, respectively. There was a statistically significant difference of 5.5 mm (95% CI: 4.7-6.2, p<0.001) between them. The discordance between pre- and post-surgical measurements of tumor size had significant effect on choosing surgery type, causing less application of breast conserving therapy (p<0.0001). CONCLUSION Compared to pathological size, preoperative measurement by imaging modalities tends to overestimate tumor size. These differences could have implications in the treatment of patients with breast cancer.