Introduction: Immunohistochemical detection of HER-2/neu expression in breast carcinoma is a required test, yet expensive. Only 10-30% of breast cancers over-express HER-2/neu. Therefore it is important to evaluate the pathological parameters which predict HER-2/neu expression in order to select patients for HER-2/neu assessment in a poor resource setting.
Objective: To determine the positive and negative predictive values of Nottingham Grade, Nottingham Prognostic Index (NPI) and estrogen and progesterone receptor (ER and PR) status in predicting the HER-2/neu status of breast carcinoma.
Method: Seventy five consecutive invasive breast carcinomas were assessed for HER-2/neu status at the Diagnostic Immunohistochemistry Laboratory, Department of Pathology, Faculty of Medicine, Galle. Predictive values of the aforementioned four histological parameters were assessed in predicting the HER-2/neu status of breast carcinoma.
Results: Out of the 75 breast carcinomas 18 (24%) strongly expressed HER-2/neu. A Quick Score of 0 or 2 for ER gave a positive predictive value of 37% and a negative predictive value of 91% in predicting HER-2/neu status. The positive and negative predictive values of a Quick Score of 0 or 2 for PR were 32% and 86% respectively. The Nottingham grade being 2 or 3 had a positive predictive value of 26% and a negative predictive value of 91%. NPI of >3.4 had a positive predictive value of 26% and a negative predictive value 93.2%.
Conclusion: Nottingham Grade of 2 or 3, NPI of >3.4 and a Quick Score of 0 or 2 for ER and PR have a good negative predictive value in predicting the HER-2/neu status of breast carcinoma. NPI is the best parameter in this respect.
Keywords: Breast carcinoma; HER2; ER; PR; NPI; Nottingham grade.