Variations of the ER, PR, and HER2 expression status according to operation day in breast cancer patients.

Abstract

e11009 Background: Estrogen receptor (ER), progesteron receptor (PR) and HER-2 are prognostic and predictive markers in the management of breast cancer treatment. Delay in fixation of the specimens may reduce the ability to detect breast cancer biomarkers and resulting in false negative immunhistochemical results. Handling of specimens from operation rooms to pathology laboratories may delay sometimes, especially Fridays. We hypothesized that ER, PR and HER-2 expression status may change according to the day of surgical procedure. Methods: Patients who operated between 2005 and 2010 for breast cancer in our Hospital were analyzed retrospectively. Consecutive 462 patients who had breast conserving surgery and modified radical mastectomy were included into the study. Patient’s demographics data and tumor characteristics and surgical procedure day were obtained from medical charts. Results: The mean age of the study population was 50±11 years. There were not differences between the T, N, M stage and age of patients according to operation day. ER, PR, HER-2 expressions were similar in Monday, Tuesday, Wednesday and Thursday. So we grouped the patients operated on Friday and others. Among the patients, 121 (26%) were operated on Friday. ER and PR negativity was higher on Friday procedures than the other weekdays (40% vs 23.2%; p=0.008 and 35.7% vs 27.9%; p=0.08, respectively). HER-2 positivity on Friday was significantly higher than the other weekdays (41.9% versus 23.4%; P=0.005). Conclusions: Cold ischemic time is the interval between removal of the tissue and placement in the tissue fixative. ER and PR are thermolabile proteins whose levels of expression are altered by prolonged cold ischemic time. Studies have shown delays in handling of breast cancer tissues affect biomarkers positivity and some tumors were classified falsely as negative. Specimens obtained on Friday may have more delaying for handling; therefore may have more hormon receptor negative results. In our study we have shown that ER negativity and HER-2 positivity are significantly higher on patients who were operated on Friday. Our study showed that handling of the specimen to the pathology laboratories is crucial and affect the treatment decisions.