Molecular Classification of Breast Cancers using Immunohistochemical Surrogates; The Sri Lankan Experience

[摘要] Background: Breast cancer diagnosis hasevolved over the past decades. Today, it is vitalto classify breast cancers according to geneticexpression. Immunohistochemical surrogateshave been identified as a cost-effective routinemethod to address the genetic diversity ofbreast cancers.Aim: To describe the survival pattern of acohort of breast cancer patients in the SriLankan setting, according to the molecularclassification using IHC surrogates.Method: Breast cancer (BC) patientsinvestigated in our laboratory from 2006-2015were included. Tissue microarrays wereconstructed using their archived BC tissue.Immunohistochemical assessment of hormonereceptors, Her2, Ki67, CK5/6 and EGFR weredone. The Pearson chi-square test, KaplanMeier model and Cox-regression model wereused for analysis.Results: The study cohort comprised 1122patients. The complete molecular classificationcould be performed only for 939 patients with27.7% -Luminal - A, 10.5% - luminal - B (Her2-),9.1%-luminal -B (Her2+), 14.6% - Her2enriched, 9.9% - triple negative and 8.2% -basal-like BC.Molecular subtypes had a significantassociation with age (p=0.045), tumour size(p=0.001), Nottingham grade (p<0.000), lymphnode stage (p=0.001) and prevalence oflympho-vascular invasion (p=0.003). Five-yearBC specific survival (BCSS) of the study cohortwas 75.5% (92.3% in luminal-A, 54.2% in Her2-enriched, 72.2% in triple-negative and 64.4% inbasal-like groups; p<0.001). The molecularsubtype (p<0.000, p=0.003) and lymph nodestage (p<0.001) had an independent effect onthe BCSS and RFS respectively.Conclusion: The molecular classification usingimmunohistochemical surrogates, classifybreast cancers into clinically useful groups withdistinctively different survival rates.

[学科分类] 生理学与病理学

[关键词] breast cancer;molecular classification;immunohistochemical surrogates