Abstract 5927: Assessing the impact of improved pre-analytic tissue handling on immunohistochemistry and breast cancer subtypes in Ghana

Abstract Background: The prevalence of triple negative breast cancer (TNBC) in sub-Saharan Africa has been inconsistently reported, with some studies in Ghana citing rates as high as 80%. The discrepancies in TNBC prevalence have been partly attributed to poor tissue handling during the pre- analytic phase, and the lack of 10% neutral buffered formalin for proper fixation. With a higher proportion of TNBCs being reported, many women are not candidates for targeted therapy. This study evaluates the impact of improved pre-analytic tissue handling on the diagnostic outcome of 4000 breast biopsies in Ghana, focusing on molecular subtypes, including TNBC Methods: A multi-center approach was employed by Precision Medicine for Aggressive Breast Cancer (PMABC) across Ghana to refine pre-analytic tissue handling. Interventions included: (1) training providers on core needle biopsy techniques and supplying them with biopsy needles, (2) providing and training centers on the preparation and use of 10% neutral buffered formalin and (3) conducting workshops and hands-on training on proper tissue handling. Histopathology and immunohistochemistry were performed on 4000 cases at a partner pathology center (Pathologists without Borders) using Ventana BenchMark GX and CAP reporting protocols Results: Among the 4000 cases analyzed, the mean age was 52.77 +/- 13.45 years (range: 14-101 years), with male breast cancer accounting for 1.6% of cases. Molecular subtype analysis revealed the following prevalence: Luminal A (12.1%) Luminal B (40.7%), HER2-enriched (12.6%), TNBC (29.7%). About 4.9% of cases which were classified as Other, comprised of HER2 equivocal. A comparative analysis of age group and molecular subtype revealed Luminal A is more predominant in the age group 50-69 years, Luminal B, HER2-enriched and TNBC are most prevalent in age group 40-59 year. TNBC was most prevalent in patients younger than 40 years, particularly those under 30. A statistically significant association was observed between age and molecular subtype (p<0.001). Conclusion: The prevalence of TNBC in Ghana was revised to 29.7% (excluding HER equivocal cases) following improved tissue handling practices, contrasting with earlier inflated estimates. TNBC remains the most common subtype in younger patients, underscoring the need for tailored diagnostic and treatment strategies. Notably, molecular subtype varied significantly with age, showing a strong association between age group and subtype (p<0.001). This study highlights the importance of ensuring quality pre-analytic practices to ensure correct molecular sub-typing for accurate treatment stratification of breast cancer patients in sub-Saharan Africa to improve outcome. Citation Format: Patrick Akakpo, Sylvester Antwi, Kwabena Agbedinu, Emmanuel G. Imbeah, Foster Amponsah, Veneranda Nyarko, Harriet Larrious-Lartey, Samuel Mensah, Josephine Nsaful, Valerie Ofori Aboah, Moses Dokurugu, Michael Nortey, Mohammed Sheriff, Nelson Affram, Jessica Bensenhaver, Haythem Ali, Ghassan Allo, Eleanor Walker, Evelyn M. Jiagge. Assessing the impact of improved pre-analytic tissue handling on immunohistochemistry and breast cancer subtypes in Ghana [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5927.