[232] Delay to Formalin Fixation Effect on Breast Carcinoma Biomarkers.

Melike Pekmezci, Alia Salhadar, Prabha Rajan, Cagatay Ersahin. Loyola University Medical Center, Maywood, IL

Background: ASCO/CAP guidelines recommend that estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status be determined on all invasive breast cancers, and the time to fixation should be kept ≤1 hour to comply with these recommendations. In this study we investigated the effect of delay to fixation on breast biomarkers in our institution.
Design: Breast tumors with preceding core biopsy that were surgically resected (lumpectomy or mastectomy) at our institution between 2004 and 2009, and had biomarker tests performed on both specimens were included in the study. According to our institutional protocols, core biopsy specimens were immediately placed in 10% neutral buffered formalin (≤1hour). However, the excision specimens from the same patients placed in formalin within 1 to 5 hours. Fixation times for both specimens were between 6 to 48 hours. Tumor architecture, nuclear or Nottingham grade and ER, PR and HER2 status were retrospectively collected. ER, PR and HER2 results were classified as positive and negative.
Results: Of 35 cases included in the study 30 were invasive tumors (ductal-19; lobular-8; papillary-3) and 5 were ductal carcinoma in-situ. Tumor morphologies (architecture and nuclear or Nottingham grade) were identical in biopsies and excisions in all cases. ER, PR and HER2 results on biopsy and excision specimens were presented in table1.

Breast Biomarkers in Breast Biopsy and Excisions

			Discrepancy
	Biopsy* (positive/tested)	Excision** (positive/tested)	Biopsy(+); Excision(-)	Biopsy(-); Excision(+)
ER	24/35	22/35	2	0
PR	22/35	20/35	4	2
HER2	2/29	2/29	0	0

*: Time to fixation ≤1hour; **: Time to fixation: 1-5 hours

Of 24 cases with ER-positive biopsies, 2 were ER-negative in the subsequent excision specimen. Similarly, 4 PR-negative excisions had previous PR-positive biopsies. Majority of these biopsies were weak positive for hormone receptors (Allred score 3). There were 2 biopsies with false-negative PR results where subsequent excision specimens were PR-positive. HER2 results were consistent between biopsies and excisions in all cases tested.
Conclusions: Our results show that delay to fixation has a negative effect on ER and PR testing. These results are consistent with the studies leading to ASCO/CAP guideline recommendations. HER2 results, however, were not affected by the delay to fixation in our limited number of patients. Previous studies have shown that PR may give false negative results because of wide heterogeneity of staining in tissue. This might explain false negative PR results in two biopsies.
Category: Breast

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 28, Monday Morning