Delay to Formalin Fixation Effect on Estrogen and Progesterone Receptors in Breast Cancer: A Study of Three Different Clones
J Qiu, S Kulkarni, R Chandrasekhar, M Rees, K Hyde, G Wilding, D Tan, T Khoury. Roswell Park Cancer Institute, Buffalo, NY; Leica Microsystems, Bannockburn, IL; Ventana, Tucson, AZ; MD-Anderson Cancer Center, Houston, TX
Background: We have previously reported that delay to formalin fixation (DFF) is a factor that can negatively affect estrogen receptor (ER, clone 1D5) and progesterone receptor (PR, clone PgR636). Here, we further investigated the effect of DFF on ER (clones 6F11 and SP1) and PR (clones 16 and 1E2).
Design: Ten palpable invasive breast cancers were resected and underwent immediate gross evaluation. For each case, the procured tumor was divided into 8 parts and consecutively fixed after 0, 10, 30 minutes, 1, 2, 4, and 8 hours; one section was kept in saline and stored overnight at 4C°. Two tissue microarray (TMA) blocks were constructed. Three consecutive slides were stained with anti ER antibodies, clones 1D5, 6F11 and SP1 and 3 more consecutive slides were stained with anti PR antibodies, clones PgR636, 16 and 1E2 from DAKO, Leica and Ventana venders respectively. Q score was carried out recording both percentage of positive cells and staining intensity. Statistical analyses for pairwise comparison of groups were performed using the non-parametric sign test. A cumulative logist model was used to assess if the scores differed with the clone.
Results: All ten cases were invasive ductal carcinomas. There were 6 cases positive for ER and 4 cases positive for PR. For ER, mean Q score started to decline at 2 to 4 hour mark for clones 1D5 and 6F11 and 1 hr mark for SP1. Comparing each 2 clones, there was no statistically significant difference between them at each time mark, except between clones1D5 and SP1 at 8 hr mark. SP1 was superior to 1D5 at this hour mark (p=0.03). For PR, Q score started to decline at 1 hr mark for clones PgR636 and 16 and at 4 hr to 8 mark for 1E2. However, the difference was not statistically significant.
Conclusions: Regardless of antibodies clones, DFF has negative effect on hormonal receptors. Therefore, we recommend that specimens should not be delayed to formalin fixation for more than 1 hour and definitely not to be stored overnight.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 22, Tuesday Afternoon