Background: Periodic auditing of histopathology report (HPR) of breast cancer, monitors compliance and increases the standards of reporting. This study was done to audit the completeness of breast cancer HPR in accordance with the CAP protocol and to analyse the amendments in tumour summaries. Methods: Retrospective review of HPR of invasive breast carcinoma resections from 2016-2020. Core (CE) and non-core elements (NCE) evaluated using CAP protocols. Outcome measures analyzed: (i) overall report completeness for CE (ii) element specific completeness for all reports. Amendments were reviewed. Results: Breast cancer reports included 246 resections. Most common histological variant was ductal type, NOS. Overall completeness was seen in 87%. Biomarker status was available in 83.1%. Reporting format was synoptic-like structured format. CAP protocol underwent five revisions between 2016-2019 with shifting of parameters between CE and NCE. Adequately represented CE: procedure, tumour size & type, Nottingham score, grade, stage, DCIS, margin status, lymph nodes and lymphovascular invasion. Less commonly reported CE: laterality, extent of involvement, size of largest metastatic deposit and extranodal extension. Frequently reported NCE: LVI, architecture/grade of DCIS, findings in adjacent breast. Biomarker reporting and treatment effect was complete in all reports. Amended reports were 4.8%. Majority were transcriptional errors. Conclusion: Common CE were satisfactorily represented in majority. Reasons for deficiencies were frequent change in CAP protocols and flexibility in synoptic-like structured format over synoptic format. The study underscores the need for periodic auditing of breast cancer summaries to monitor gaps in CE reporting. Synoptic reporting with additional free text field will improve compliance and overcome deficiencies.