['Patients seeking a second opinion or continuation of care at our hospital will routinely have their pathology reviewed prior to initiating treatment. To assess the relevance of this review in patients with breast cancer, we compared original pathology reports submitted during the referral with second-review reports issued at our institution. We also assessed compliance with College of American Pathologists (CAP) requirements regarding inclusion of scientifically validated data elements (SVDE) in these pathology reports.', 'We retrospectively studied all 1,970 breast pathology referral cases reviewed during one calendar year. The variables studied were histologic classification; tumor grade, necrosis, size, margin status, lymphatic/vascular invasion, dermal involvement, and biomarker profile (ER, PR, and Her-2). Each variable was rated as "agree," "disagree," "missing information," or "not applicable."', 'A significant discrepancy, defined as a disagreement that affected patient care, was found in 226 cases (11.47%). Additionally, in 418 resection cases (31.6%), some CAP-checklist specific required information was missing. The most common areas of significant discrepancy were histologic category (66 cases; 33%) and biomarker reporting (50 cases; 25%). The most problematic diagnostic categories were intraductal lesions, lobular carcinoma, metaplastic carcinomas, and phyllodes tumors. Most disagreements in the biomarker-profile category were interpretive, but in 20% of discrepant cases, findings were supported by repeat immunohistochemical analysis.'] Does breast pathology second review identify clinically significant discrepancies in over 10 % of patients?