Loss of antigenicity with tissue age in breast cancer

Abstract

Archived tumor specimens, particularly those collected by large cooperative groups and trials, provide a wealth of material for post hoc clinical investigation. As these tissues are rigorously collected and preserved for many decades, subsequent use of the specimens to answer clinical questions must rely on the assumption that expression and detection of target biomarkers are not degraded with time. To test this assumption, we measured the expression of estrogen receptor (ER), human epidermal growth receptor 2 (HER2), and Ki67 in human breast carcinoma using quantitative immunofluorescence (QIF) in a series of formalin-fixed paraffin-embedded (FFPE) tissues from 1295 individual patients preserved for 7 to 53 years in four cohorts on tissue microarrays. Protein expression was measured using the automated quantitative analysis method for QIF. Change in quantitative protein expression over time was estimated in positive cases using both Pearson's correlation and a polynomial regression analysis with a random effects model. The average signal decreased with preservation time for all biomarkers measured. For ER and HER2, there was an average of 10% signal loss after 9.9 years and 8.5 years, respectively, compared with the most recent tissue. Detection of Ki67 expression was lost more rapidly, with 10% signal loss in just 4.5 years. Overall, these results demonstrate the need for adjustment of tissue age when studying FFPE biospecimens. The rate of antigenicity loss is biomarker specific and should be considered as an important variable for studies using archived tissues.

Estrogen receptor quantitative measures and breast cancer survival

“…In SEER data collected since implementation of the ASCO/CAP guidelines recommending the 1% threshold [21] (diagnosis years 2011–2013), 84% of invasive tumors in white women are classified as ER positive [22], thus our percent positive appears representative. Absolute proportion of tumor marker staining by IHC can decline with elapsed time in FFPE tissue [23,24], and such was also noted in our study. Adjustment for years elapsed since diagnosis did not alter our results.…”

Stability of oestrogen and progesterone receptor antigenicity in formalin‐fixed paraffin‐embedded breast cancer tissue over time

“…Combs et al. , on the other hand, found a decrease in ER expression in older FFPE samples using quantitative immunofluorescence, with a 10% signal loss after 10 years. Although categorization into ER‐positive/ER‐negative groups, as in our study, may make smaller decreases in antigenicity harder to detect, such a large decrease in antigenicity would indeed have been detected in our material with up to 40‐year‐old samples.…”

“…Moreover, new analysis of FFPE tissue from the primary breast cancer (BC) can be important in clinical management of late disease relapse as a new biopsy is not always possible to retrieve. However, few studies have investigated the validity of using archival FFPE tissue for immunohistochemical (IHC) analysis years after these samples were initially collected .…”

“…may vary between antigens . Although loss of immunoreactivity in tissue slides after sectioning has repeatedly been shown , there are only a few studies investigating IHC antigenicity in archival FFPE tumour tissue from different decades of the 20th century . The studies by Dowsett et al.…”

“…suggested that FFPE blocks were generally well preserved for up to 70 years , while Combs et al. showed a loss of antigenicity with time using quantitative immunofluorescence. The conclusions from these studies are, however, limited due to the lack of comparison with antigen analysis at the time of diagnosis or clinical outcome.…”