Do prognostic marker studies on core needle biopsy specimens of breast carcinoma accurately reflect the marker status of the tumor?

Core needle biopsies (CNB) are often used for the diagnosis of breast lesions. In some breast cancer patients, e.g., those treated with preoperative chemotherapy, the CNB specimen might be the only pretreatment tissue sample available for studies of prognostic and predictive markers. Our purpose was to evaluate whether marker studies performed on CNB specimens accurately reflect the marker status of the tumor. Immunostaining for five commonly used prognostic and predictive markers was performed on both CNB and subsequent excision specimens from 56 consecutive patients who had a CNB with carcinoma followed by excision of the tumor. None of the patients received radiotherapy or chemotherapy between the CNB and the excision. Paraffin sections of the CNB and excision specimens were immunostained for bcl-2, estrogen receptor (ER), c-erbB-2, and p53. These markers were scored as positive or negative. Microvessel density (MVD) was scored as a continuous variable on sections immunostained for Factor VIII-related antigen by calculating the average number of microvessels in three 224x fields of highest tumor vascularity ("hot spots"). Immunostaining results for bcl-2, ER, c-erbB-2, and p53 on the CNB and the corresponding excision specimens were 100% concordant. Although there was significant correlation between MVD on the CNB specimens and the corresponding excisions (r = 0.507, P = 0.0002), the mean MVD on the CNB and corresponding excision specimens differed by more than 10% in 85.7% of cases, with differences ranging from 4.3 to 233.3%. MVD was higher in the CNB than in the excision specimens in 30 (61.2%) of 49 cases. In conclusion, in all of the cases studied, accurate results for the dichotomously scored markers bcl-2, ER, c-erbB-2, and p53 were obtained on CNB specimens. In contrast, in most cases, MVD, which was scored as a continuous variable, could not be reliably assessed on the CNB specimen.

Loss of tumor marker-immunostaining intensity on stored paraffin slides of breast cancer

BACKGROUND

We previously observed decreased p53 immunostaining over time in paraffin-embedded sections of ductal carcinoma in situ of the breast of women; these sections had been stored on slides at room temperature. This observation suggests that slide storage adversely affects p53-immuno-staining intensity and could result in spurious negative staining for p53 in patient samples.

PURPOSE

The goals of this study were to determine the time course and factors influencing loss of p53 immunoreactivity and to investigate whether a similar loss of reactivity occurs with other antigens commonly used to study breast cancer.

METHODS

Serial sections cut from 12 formalin-fixed, paraffin-embedded, p53-positive invasive ductal carcinomas of the breast were stored on slides at room temperature or at 4 degrees C, with or without an additional paraffin coating, for 2, 4, 8, or 12 weeks. For each case, freshly cut slides from the same block (day 0) and stored slides were simultaneously stained for p53 by use of an automated immunostainer. Slides cut from formalin-fixed, paraffin-embedded breast carcinomas and stored for 12 weeks were also stained for factor VIII-related antigen (n = 12), estrogen receptor (ER) (n = 9), and Bcl-2 protein (n = 9). The staining intensity of all slides was assessed by visual microscopic examination and was also quantified by image analysis. Quantitative results were expressed as a percentage (mean +/- standard error) of the staining intensity on day 0. Data were analyzed by the Friedman Repeated Measures Analysis of Variance on Ranks, with statistical significance set at two-sided P < .05.

RESULTS

The intensity of p53 staining decreased over time in nine (75%) of the 12 cases studied. In three (or 25% of all cases studied) of the nine cases that showed decreased p53 staining, slides stored for 12 weeks were scored as p53 negative. Antigen loss on slides stored at 4 degrees C was significantly less than that on slides stored at room temperature at all time points (all P < .05). At 12 weeks, the average staining intensity of slides stored at 4 degrees C was 33.2% +/- 9% of that on day 0 compared with 8.4% +/- 3% of that on day 0 for slides stored at room temperature (P < .001). Paraffin coating of the sections did not significantly diminish antigen loss at either room temperature or 4 degrees C, except for slides stored at room temperature for 12 weeks. The intensity of factor VIII staining decreased in nine of 12 cases (average staining intensity, 37.3% +/- 6% of that on day 0 at 12 weeks; P = .0001). The intensity of ER and Bcl-2 staining decreased in all nine cases studied at 12 weeks (average staining intensity, 14.0% +/- 6% and 21.0% +/- 4% of that on day 0, respectively; P = .0001 for each).

CONCLUSIONS AND IMPLICATIONS

Slide storage, particularly at room temperature, results in substantial loss of p53 reactivity, with some p53-positive cases becoming p53 negative after 12 weeks of storage. Substantial loss of immunoreactivity for factor VIII, ER, and Bcl-2 occurs on slides stored at room temperature for 12 weeks. Storage of unstained slides for up to 12 weeks may lead to false-negative immunostaining for p53 and other antigens.

bcl-2 expression in the spectrum of preinvasive breast lesions

BACKGROUND

The bcl-2 gene encodes for a protein that blocks apoptosis. Although the bcl-2 protein has been identified in some invasive breast cancers, its expression in preinvasive breast lesions has not been well characterized.

METHODS

We studied bcl-2 expression using immunohistochemistry in cases of normal breast tissue (n = 10), ductal hyperplasia (n = 18), atypical ductal hyperplasia (ADH) (n = 10), atypical lobular hyperplasia/lobular carcinoma in situ (lobular neoplasia, LN) (n = 10), and ductal carcinoma in situ (DCIS) (n = 42). We also related bcl-2 expression to p53 expression in these lesions because the p53 gene is altered in many invasive breast cancers and is also involved in the regulation of apoptosis.

RESULTS

bcl-2 was consistently expressed in the epithelial cells in all normal breast tissue, ductal hyperplasia, ADH, and LN lesions. In contrast, bcl-2 expression was present in 76% of the DCIS cases and was related to the histologic grade of DCIS. Staining for bcl-2 was observed in 100% of the well differentiated DCIS cases, 90% of intermediately differentiated cases, and 33% of poorly differentiated cases (P < 0.001). No immunoreactivity for the p53 protein was seen in any of the cases of normal breast tissue, ductal hyperplasia, ADH, or LN lesions. However, 24% of the DCIS cases were p53 positive. The bcl-2+/p53- phenotype, as seen in all cases of normal breast tissue, ductal hyperplasia, ADH, and LN was also observed in 67% of the DCIS cases. In contrast, the remaining 33% of DCIS cases showed combinations of bcl-2 and p53 expression that differed from that of normal breast epithelium and the other pathologic lesions studied. Most lesions with altered bcl-2/p53 phenotypes, including all bcl-2-/p53+ cases, represented examples of poorly differentiated DCIS.

CONCLUSIONS

The bcl-2 protein is consistently expressed in normal breast epithelium, ductal hyperplasia, ADH, and LN. bcl-2 expression is variable in DCIS. Among DCIS cases, bcl-2 is most common in well differentiated and intermediately differentiated lesions. Most DCIS lesions are bcl-2+ and p53-, similar to normal epithelium, benign proliferative lesions, and LN. However, a minority of DCIS lesions show combinations of bcl-2 and p53 expression that differ from normal breast epithelium and from the other pathologic lesions studied. It is possible that such lesions may represent a subset of DCIS in which the regulation of apoptosis is no longer under normal control mechanisms, resulting in enhanced tumor cell survival and tumor growth.