Abstract P5-01-14: Discrepancy between routine and expert pathologists in histological assessment of early stage non palpable breast cancer and its impact on loco regional and systemic treatment

Abstract

Abstract Background: Histopathological parameters are essential for deciding on further adjuvant treatment in patients with breast cancer after surgery. Here, we assessed the impact of inter observer variability on further treatment strategy in patients with clinically node negative, non palpable breast carcinomas. Methods: Clinical and histopathological data of 314 patients with clinically node negative non palpable invasive breast cancer were analysed. Histological assessment of the primary tumour and sentinel nodes was first performed in a routine setting, subsequently central review took place. In cases of discordance between local en central assessment, we determined the impact on locoregional and systemic treatment strategy. Results: Discordance between local and central review was seen in 13% of the patients (kappa 0.60 95% CI 0.50–0.71) for type, in 12% (k = 0.796 95% CI 0.73–0.86) for grade, in 1% for ER status (k = 0.898 95% CI 0.80–1.0), in 2% for PR status(0.940 95% CI 0.89–0.99). Discrepancy in the assessment of the sentinel node(s) was seen in 2% of the patients. (k = 0.954 95% CI 0.92–0.98). Practising current Dutch Guidelines, loco regional treatment would be affected in 2% (7/310), systemic treatment in 5% (16/310) and both in 1% (2/310) of the patients. For patients in whom central review would have led to additional systemic treatment (3%), the 10 years mortality and recurrence rate would decrease with a median of 4.6% and 15% respectively. Conclusion: Inter observer variation in the histopathological assessment of non-palpable breast carcinoma specimens and sentinel nodes results in a different loco regional or systemic treatment advice in 8% of the patients. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-01-14.