Real time RT-PCR approach for the evaluation of ERBB2 overexpression in breast cancer archival samples: a comparative study with FISH, SISH, and immunohistochemistry.

We tested the reliability of real time reverse transcription polymerase chain reactions as an alternative method for the assessment of ERBB2 status in paraffin-embedded tissues of 83 patients with breast cancer and 20 non-neoplastic controls. PCR was also compared with the immunohistochemical (IHC) HercepTest score and with fluorescence (FISH) and silver (SISH) in-situ hybridization, in 42 selected cases. ERBB2 mRNA was overexpressed in 26/83 (31%) breast cancer samples, using a cutoff calculated as the mean value of the controls plus 3 SD or with the receiver operating curve. The PCR test showed a 96% sensitivity and a 100% specificity when compared with FISH, with an area under the receiver operating curve of 98.4%. Overexpression of ERBB2 at PCR was also significantly correlated with amplification in FISH (P<0.001, Mann-Whitney test) and in SISH (P<0.001, Mann-Whitney test), and with the IHC HercepTest scores 2 or 3 (P<0.001, Spearman rank correlation). FISH, SISH, and IHC were also compared with each other. ERBB2 amplification in FISH significantly correlated with that in SISH (P=0.002, chi test with a concordance of the 87%), but not with IHC HercepTest scores (P=0.214, chi test). Real time PCR is a reliable and cost-effective method for the assessment of ERBB2 status in archival breast cancer samples, compared with FISH. Its introduction in routine diagnostic pathology practice is feasible even if it requires amendments to the current clinical oncology protocols.

Thorough intraoperative analysis of breast sentinel lymph node biopsies: histologic and immunohistochemical findings.

BACKGROUND: We report the use of a thorough intraoperative sentinel lymph node (SLN) biopsy screening procedure for patients with small N0 breast tumors. METHODS: Sixty-eight consecutive female patients with monofocal stage I or "small" stage II (ie, 2.1-3.0 cm) N0 tumors received intraoperative SLN screening according to a procedure on the basis of comprehensive histologic analysis and cytokeratin immunohistochemical determination (CkID) of adjacent frozen sections of the SLN taken at 50-microm cutting levels. RESULTS: The maximum duration of intraoperative analysis including CkID was 40 minutes. Positive SLN were found in 15/68 (22%) patients (always in a single node); they included 5 instances of micrometastasis and 3 of carcinomatous lymphangitis. In the 14 patients who underwent axillary lymph node dissection, no further metastasis was found at histologic analysis or CkID. SLN positivity correlated with histologic type (P=.044), intratumoral or peritumoral vascular invasion (P<.001) and Mib1 score (P=.042). CONCLUSIONS: It is possible for an experienced team to perform intraoperative SLN screening for T1 or small T2 N0 breast tumors with frozen sections taken at 50-microm cutting levels. This procedure facilitates identification of micrometastasis, as well as of carcinomatous lymphangitis to help understand the biologic implications of these small lesions in the long term. SLN positivity appears to correlate with histologic type, intratumoral/peritumoral vascular invasion and Mib1 score.