Routine assessment of prognostic factors in breast cancer using a multicore tissue microarray procedure

Tissue microarrays in clinical oncology

Tissue microarray (TMA) is a recently implemented, high-throughput technology for the analysis of molecular markers in oncology. This research tool permits the rapid assessment of a biomarker in thousands of tumor samples, using commonly available laboratory assays such as immunohistochemistry and in situ hybridization. Although introduced less than a decade ago, TMA has proven to be invaluable in the study of tumor biology, the development of diagnostic tests, and the investigation of oncologic biomarkers. This review describes the impact of TMA-based research in clinical oncology and its potential future applications. Technical aspects of TMA construction and the advantages and disadvantages inherent to this technology are also discussed.

Pleomorphism of the nuclear envelope in breast cancer: a new approach to an old problem

In routine practice, nuclear pleomorphism of tumours is assessed by haematoxylin staining of the membrane-bound heterochromatin. However, decoration of the nuclear envelope (NE) through the immunofluorescence staining of NE proteins such as lamin B and emerin can provide a more objective appreciation of the nuclear shape. In breast cancer, nuclear pleomorphism is one of the least reproducible parameters to score histological grade, thus we sought to use NE proteins to improve the reproducibility of nuclear grading. First, immuno-fluorescence staining of NE as well as confocal microscopy and three-dimensional reconstruction of nuclei in cultured cells showed a smooth and uniform NE of normal breast epithelium in contrast to an irregular foldings of the membrane and the presence of deep invaginations leading to the formation of an intranuclear scaffold of NE-bound tubules in breast cancer cells. Following the above methods and criteria, we recorded the degree of NE pleomorphism (NEP) in a series of 273 invasive breast cancers tested by immunofluorescence. A uniform nuclear shape with few irregularities (low NEP) was observed in 135 cases or, alternatively, marked folds of the NE and an intranuclear tubular scaffold (high NEP cases) were observed in 138 cases. The latter features were significantly correlated (P-value <0.002) with lymph node metastases in 54 histological grade 1 and in 173 cancers with low mitotic count. Decoration of the NE might thus be regarded as a novel diagnostic parameter to define the grade of malignancy, which parallels and enhances that provided by routine histological procedures.

Patients with advanced stage breast carcinoma immunoreactive to biotinylated Herceptin are most likely to benefit from trastuzumab-based therapy: an hypothesis-generating study

BACKGROUND

Biotin-labeled trastuzumab (BiotHER) can be used to test for HER2 by immunohistochemistry. We previously showed that BiotHER immunoreactivity is highly correlated with HER2 amplification and indicated that it could be associated with better clinical outcome in advanced breast cancer patients receiving trastuzumab.

PATIENTS AND METHODS

Tumor specimens and clinical information from 234 patients who received trastuzumab-based treatments were collected from 10 institutions. HER2 amplification and BiotHER immunoreactivity were assessed centrally. The effect of BiotHER positivity on response rate (RR), time to progression and survival were studied by univariate and multivariate analysis in patients presenting HER2-amplified breast cancer. The pathologic reviews of the assays were blinded to patient outcomes.

RESULTS

BiotHER was positive in 109/194 (56%) HER2-amplified breast cancers and in one not amplified tumor. RRs were 74% [95% (confidence interval) CI 64%-81%] and 47% (95% CI 36%-58%) in BiotHER-positive and -negative tumors, respectively (P < 0.001). BiotHER immunoreactivity was independently associated with increased probability of tumor response (odds ratio 3.848; 95% CI 1.952-7.582), with reduced risk of disease progression [hazard ratio (HR) 0.438; 95% CI 0.303-0.633] and with reduced risk of death (HR 0.566; 95% CI 0.368-0.870) by multivariate analysis.

CONCLUSION

The results support a role for BiotHER testing in better tailoring trastuzumab-based treatments in patients with advanced HER2-amplified breast cancers.

Predicting gefitinib responsiveness in lung cancer by fluorescence in situ hybridization/chromogenic in situ hybridization analysis of EGFR and HER2 in biopsy and cytology specimens

In non-small cell lung cancer (NSCLC), epidermal growth factor receptor (EGFR) mutational analysis is an excellent predictor of responsiveness to treatment with tyrosine kinase inhibitors, such as gefitinib. In up to 80% of NSCLCs, cytologic samples or endoscopic biopsies are the only specimens available for molecular analysis, but PCR amplification of DNA from small fixed and paraffin-embedded samples may create artifactual mutations. Fluorescence in situ hybridization (FISH) of EGFR and HER2 has been proposed as an alternative method of analysis. This project aimed to determine the optimal scoring method for FISH or chromogenic in situ hybridization (CISH) assays when analyzing small NSCLC samples to predict response. FISH or CISH analysis of EGFR and HER2 genes was done on 42 small samples derived from NSCLC patients treated with gefitinib. EGFR mutational analysis was done after quantity and quality controls of DNA. In seven of seven cases, a balanced increase in EGFR gene and chromosome 7 number was found to correlate with the presence of specific EGFR mutations. In addition, seven of seven cases with balanced EGFR/HER2 polysomy and two of three cases with balanced EGFR/HER2 trisomy responded to gefitinib (75% of responders). Instead, the EGFR mutations predicted only 7 of 12 (58%) of gefitinib-responsive patients. When only endoscopic biopsies or cytologic specimens are available, we propose using FISH/CISH for EGFR and HER2 as the test of choice for selecting patients for treatment with gefitinib and to consider as negative predictive factor the absence of EGFR/HER2 gene gain.

Tissue microarray technology in breast cancer HER2 diagnostics

Tissue microarrays (TMAs) as current medical research tools significantly lower the costs of immunohistochemical examinations (IHC) and fluorescence in situ hybridization (FISH) while enabling high levels of standardization and reliability. Taking HER2 testing of breast cancer into consideration, we assessed the routine applicability of TMAs. A hundred and seventy-four consecutive samples of invasive breast cancer cases were selected. TMAs were constructed in order to conduct double HER2 immunohistochemical analysis and FISH abreast using the conventional slide by slide method. Comparing the immunohistochemical data obtained from TMAs with the routinely processed large sections, we found a 94.5%/92.7%, 85.7%/88.9% and 91.2%/90% concordance at immunohistochemically HER2-negative, HER2 2+ and 3+ cases using the CB11/HercepTest, respectively. FISH performed on TMAs helped to determine Herceptin therapy suitability in all cases, and when discordance was found, we controlled FISH on "large sections". Being able to conduct FISH examinations at a reasonable price with or without prior immunohistochemical analysis, departments confronted with a certain frequency of breast cancer cases might extensively use the type of TMAs applied in our study. This is a relieve not only with regard to diagnostic work using microarrays, but this also allows to take new directions in research by shedding light on certain unusual cases.