Biomarkers in breast cancer: Quantifying discordance with best practice when hormone receptor status is an extravagance

Background: In Zimbabwe, the hormone receptor status is not always available when patients with breast cancer are started on treatment. Aim: This study evaluated the discordance of treatment approach in such patients, with National Comprehensive Cancer Network (NCCN) guideline recommendations as the reference standard when these results are eventually available. Setting: Female patients who presented to the Parirenyatwa Central Hospital Radiotherapy and Oncology Centre with a histological diagnosis of breast cancer, managed between 1 January 2014 and 31 December 2016. Methods: Patients with breast cancer having unknown receptor status at diagnosis, and the hormone receptor status were subsequently available either clinically or the tissues were available for study-specific analysis, were eligible for the study. The level of agreement between treatments received and the NCCN recommendations if the receptor status was known was tested using Kappa statistic. Results: Patients in stage I–III received treatment that were in strong agreement with the use of chemotherapy, and endocrine treatments with agreement scores of 1 (95% CI 0.91–1) and 0.81 (95% CI 0.65–0.95), respectively; but moderate agreement with regard to the choice of chemotherapy regimen, with a score of 0.5 (95% CI 0.32–0.68). There was a median delay of 8 (range 3–27) months for the availability of receptor status. Of the 38 stage IV patients, 33 (87%) were recommended chemotherapy. Of the 38 patients, 25 (66%) had hormone driven disease. There was somewhat agreement for use of chemotherapy, choice of chemotherapy regimen and use of endocrine treatments as initial choice with agreement scores of 0.53 (95% CI 0.36,0.69), 0.18 (95% CI 0.07, 0.35) and 0.68 (95% CI 0.51,0.82) respectively. Conclusion: Treatment approaches were largely in agreement with the NCCN guidelines for patients in stage I–III. Discordance was noted in stage IV patients with under-utilisation of hormone therapy as the initial treatment when the receptor status was unknown.