Comparison of chromosome 1 aneusomy detected by interphase cytogenetics and DNA ploidy in carcinoma of the breast

Interphase cytogenetic analysis of lung adenocarcinomas with bronchioloalveolar pattern

Aneuploidy has been suggested as a marker for stratification of many neoplasms but its potential usefulness in adenocarcinoma (ADC) with bronchioloalveolar (BAC) pattern has not been well defined. We examined paraffin-embedded tissue sections from 28 cases of ADC with BAC pattern as well as 7 benign lung lesions and 9 normal lung tissue samples for chromosomal aneuploidy by in situ hybridization using digoxigenin-labelled probes for chromosomes 1 and X. Of the 28 ADC with BAC pattern, 17 (61%) were diploid and 11 (39%) were aneuploid. Of the 17 diploid cases, 7 (41%) were male and 10 (59%) were female and of the 11 aneuploid cases, 2 (18%) were male, 9 (82%) were female. Regarding the cell type, 24 (86%) were adenocarcinomas in situ (AIS) so called BAC and minimally invasive ADC (MIA), and 4 cases (14%) were invasive ADC. Of the 12 cases each of AIS and MIA, 9 (75%) and 8 (67%) had diploid pattern respectively. Of the 4 invasive ADC cases, all had aneuploid pattern. Seventeen cases (71%) with T1 tumor size (> 0 mm ≤30 mm), had diploid and 4 cases (100%) with T2 tumor size (> 30 mm ≤70 mm) had aneuploid pattern. Statistical analyses showed that nuclear diploidy was significantly correlated with AIS and MIA tumor types while aneuploidy correlated with invasive ADC type (P=0.025). Also a significant correlation was found between ploidy and tumor size (P=0.033). In conclusion, these findings suggest that DNA ploidy analysis provides useful information for the assessment of cellular kinetics and reflect histopathological subtypes in ADC with BAC pattern that are destined to behave aggressively.

Correlation of cytologic findings and chromosomal instability detected by fluorescence in situ hybridization in breast fine-needle aspiration specimens from women at high risk for breast cancer

Cytologic evaluation of ductal lavage or random periareolar fine-needle aspiration (FNA) specimens has been proposed to improve risk stratification of women at high risk for breast cancer. However, cytologic assessment of morphologic changes is subjective. To assess the utility of fluorescence in situ hybridization (FISH) in the categorization of breast lesions, we prospectively evaluated 32 random periareolar FNA specimens from 27 women at high risk for breast cancer. Cytologic specimens were prepared using the thin preparation technique, and diagnoses were made on the basis of previously published criteria. Specimens were also evaluated by FISH for chromosomes 1, 8, 11, and 17. Monosomy was defined as the loss of one signal or both signals in >20% of cells, and polysomy was defined as the presence of > or = 3 signals in >6% of cells. Cytologic smears from seven invasive ductal carcinomas and nine benign breast specimens from women at low risk for breast cancer were included for comparison. In the high-risk group, cytologic findings were nonproliferative epithelium (NPE) in 16 cases and hyperplasia in 16 cases. Chromosomal aberrations were detected in 11 (69%) of 16 NPE cases, 14 (89%) of 16 hyperplasia cases, seven (100%) of seven carcinoma cases, and none of the low-risk cases. High-risk cases had significantly more monosomy of chromosomes 1, 11, and 17 and polysomy of chromosome 8 compared to low-risk cases and significantly less polysomy of chromosomes 1, 8, 11, and 17 compared to patients with cancer. There were no significant differences in monosomy or polysomy of individual chromosomes or a combination of chromosomes between the NPE and hyperplasia groups. This study shows that aberrations of chromosome number are common in high-risk women irrespective of cytologic findings. Studies evaluating the association between specific patterns of chromosomal polysomy and progression to malignancy may be warranted.

Numerical aberrations of chromosomes 1 and 7 by fluorescent in situ hybridization and DNA ploidy analysis in breast cancer

The goals of this study were to detect the numerical alterations of chromosomes 1 and 7 in breast cancer and to correlate the findings with DNA ploidy status as well as with parameters of prognostic significance. Fluorescence in situ hybridization (FISH) with centromeric probes for chromosomes 1 and 7 and cellular DNA content measurement by image analysis-based cytophotometry were applied on interface nuclei from fresh tissue imprints of 59 breast ductal carcinomas. Immunohistochemical stainings for estrogen receptor (ER), progesterone receptor (PR), HER-2, p53, and Ki67 were performed on paraffin tumor sections. The correlation between DNA ploidy and chromosomal aberrations revealed a significant association between aneuploidy and aneusomy for both chromosomes 1 (p=0.002) and 7 (p=0.00001), however, a number of diploid tumors were found to be aneusomic, especially for chromosome 1. Chromosome 7 polysomy was significantly associated with a higher incidence of axillary lymph node metastasis (p=0.05), poorly differentiated (grade III) tumors (p=0.03), negative ER and PR status (p=0.02 and 0.001, respectively), as well as p53 protein expression (p=0.05) and a higher Ki67 labeling index (p=0.004). Chromosome 1 aneusomy was only related with HER-2 protein overexpression (p=0.05). No association between chromosome alterations and tumor size was detected. In conclusion, the results of our study indicate that the detection of numerical aberrations of chromosomes 1 and 7 by FISH seems to be more sensitive than DNA ploidy status for the evaluation of abnormal cellular DNA and chromosome 7 aneusomy characterizes tumors with aggressive features and therefore might be a useful predictor of unfavorable biological behavior in breast cancer.

Prognostic value of chromosome 1 and 8 copy number in invasive ductal breast carcinoma among Iranian women: an interphase FISH analysis

Breast cancer is amongst the leading causes of death in women worldwide and the most common cancer amongst Iranian women. Unfortunately, the current clinical and histological criteria can only help 60 percent of women with breast cancer in diagnosis and long-term treatment. Therefore, genetic markers both at single gene and chromosomal level can play an important role in improving the diagnosis and prognosis of breast cancer patients. The aim of this retrospective study was to investigate the role of chromosome 1 and 8 copy number assessed by interphase fluorescence in situ hybridization (FISH), as prognostic parameters in 50 Iranian women, aged 35 to 64 years, with sporadic invasive ductal breast carcinoma. Chromosome 1 and 8 copy numbers were evaluated in relation to established clinicopathological parameters, the immunohistochemical markers ER, PR, P53 and cathepsin D, DNA index by flow cytometry, age and survival status of the patients. FISH using centromeric probes for chromosomes 1 and 8 was applied to interphase cell suspensions prepared from archived, Carnoyfixed tumor cells and selected paraffin-embedded tumor sections. Aneusomy for chromosomes 1 and 8 was present in all 50 patients to different levels. The total abnormality rate for chromosome 1 was 33.92 percent (4.24 percent monosomy and 29.68 percent polysomy), whereas for chromosome 8 this rate was 28.30 percent (6.48 percent monosomy and 21.82 percent polysomy). Statistically significant association (p<0.05) was demonstrated between monosomy 1 and patients' age below 50 years, and between monosomy 1 and poor survival, respectively. Disomy 8 was significantly associated with P53 expression. A borderline significant correlation was demonstrated between polysomy 8 and diploid DNA content, as well as between disomy 1 and disease-free status of the patients. Chromosome 1 and 8 copy numbers may be considered as useful prognostic markers in invasive ductal carcinoma of the breast.

Incidence of chromosomes 1 and 17 aneusomy in breast cancer and adjacent tissue: an interphase cytogenetic study

BACKGROUND

Characterization of the biopathologic events underlying the early steps of breast carcinogenesis may have a dramatic impact on reducing breast cancer mortality. Genes involved in breast tumorigenesis are localized on chromosomes 1 and 17, and numeric aberrations of these chromosomes have been correlated with breast cancer tumorigenesis and progression. According to the field cancerization hypothesis, specific chromosome aberrations may be present in breast cancer and in normal-appearing adjacent tissue. The latter changes reflect the genomic damage that follows longterm carcinogenic exposure and precede the morphologically detectable neoplastic transformation. We hypothesize that detection of these aberrations in benign breast epithelium may provide a tool for molecular risk assessment.

STUDY DESIGN

Using fluorescence in situ hybridization with centromere-specific probes, we determined the status of chromosomes 1 and 17 in fresh imprints of 28 samples of primary tumors and 54 samples of their surrounding uninvolved parenchyma taken from patients undergoing operations for breast carcinoma. Ten contralateral breast biopsy specimens collected from patients with previous breast carcinoma were also evaluated as a surrogate of a high-risk group to rule out the hypothesis that chromosomal aneusomy in tumor-adjacent tissue could be related to a paracrine effect of the primary tumor. Ten samples of benign breast tissue taken from patients at low risk were used as controls to define tolerance limits for aneusomy definition.

RESULTS

Using threshold values of 40% of signal loss and 13% of signal gain to define chromosome aneusomy (ie, mean + 3 SDs of the control group signals), we found the following: 1) almost all primary breast tumors were aneusomic for chromosomes 1 and 17; 2) primary breast tumor and adjacent uninvolved parenchyma shared the same pattern of chromosomes 1 and 17 aneusomy in 66.7% of patients; and 3) chromosomes 1 and 17 aneusomies in contralateral benign breast samples from high-risk patients were not different from those in primary breast tumor or adjacent tissue samples.

CONCLUSIONS

These results suggest that chromosomes 1 and 17 aneusomy may represent an intermediate biomarker of breast tumorigenesis potentially useful to detect patients at high risk of breast carcinoma who may benefit from preventive interventions.

Increasing chromosome 1 copy number parallels histological progression in breast carcinogenesis

Chromosome 1 copy number in the benign breast lesions hyperplasia and atypical duct hyperplasia (ADH) was investigated using fluorescence in situ hybridization on paraffin sections. Progression of chromosome 1 changes occurring in parallel with histological progression from normal through hyperplasia and ADH to ductal carcinoma in situ (DCIS) and invasive carcinoma was also assessed, both overall and within individual patients. The mean signal number for normal cells was 1.14, while that for hyperplasia was 1.56 and ADH was 1.5, while values for DCIS of 1.95 and invasive duct carcinoma of 1.79, were higher (P < 0.001). Six of the seven cases also showed a significant trend towards an increasing proportion of cells with greater than 2 signals per nucleus occurring with histological progression (P < 0.001). These results support the concept that benign proliferative breast disease is a biological precursor of in-situ and invasive ductal carcinoma, the early histological changes possibly indicating a field effect with further genetic changes required for the development of a malignant phenotype.

Comparative genomic hybridization of ductal carcinoma in situ of the breast-evidence of multiple genetic pathways

There is strong evidence that ductal carcinoma in situ (DCIS) represents a precursor lesion of invasive breast cancer. In order to analyse specific chromosomal alterations of DCIS, 38 paraffin-embedded specimens of DCIS and six associated invasive carcinomas were examined by means of comparative genomic hybridization (CGH). Losses of 16q material were seen almost exclusively in well- and intermediately-differentiated DCIS. These two subgroups differed in the average number of genetic imbalances, 2.5 and 5.5 respectively. Additionally, a higher frequency of gains of 1q and losses of 11q material was seen in intermediately-differentiated in contrast to well-differentiated DCIS. Poorly-differentiated DCIS displayed a higher frequency of amplifications (17q12, 11q13) and a higher average rate of genetic imbalances (7.1). Analysis of adjacent invasive breast carcinoma revealed a genetic pattern almost identical to the one seen in the DCIS counterpart. These data characterize DCIS as a genetically far-advanced, heterogeneous lesion and as a direct precursor of invasive breast cancer.