Our study has identified key features of the histologic phenotypes of breast cancers in carriers of mutant BRCA1 and BRCA2 genes. This information may improve the classification of breast cancers in individuals with a family history of the disease and may ultimately aid in the clinical management of patients.
Columnar cell lesions (CCLs) of the breast are a spectrum of lesions that have posed difficulties to pathologists for many years, prompting discussion concerning their biologic and clinical significance. We present a study of CCL in context with hyperplasia of usual type (HUT) and the more advanced lesions ductal carcinoma in situ (DCIS) and invasive ductal carcinoma. A total of 81 lesions from 18 patients were subjected to a comprehensive morphologic review based upon a modified version of Schnitt's classification system for CCL, immunophenotypic analysis (estrogen receptor [ER], progesterone receptor [PgR], Her2/neu, cytokeratin 5/6 [CK5/6], cytokeratin 14 [CK14], E-cadherin, p53) and for the first time, a whole genome molecular analysis by comparative genomic hybridization. Multiple CCLs from 3 patients were studied in particular detail, with topographic information and/or showing a morphologic spectrum of CCL within individual terminal duct lobular units. CCLs were ER and PgR positive, CK5/6 and CK14 negative, exhibit low numbers of genetic alterations and recurrent 16q loss, features that are similar to those of low grade in situ and invasive carcinoma. The molecular genetic profiles closely reflect the degree of proliferation and atypia in CCL, indicating some of these lesions represent both a morphologic and molecular continuum. In addition, overlapping chromosomal alterations between CCL and more advanced lesions within individual terminal duct lobular units suggest a commonality in molecular evolution. These data further support the hypothesis that CCLs are a nonobligate, intermediary step in the development of some forms of low grade in situ and invasive carcinoma.
Recently it has been shown that epithelial cell expression of the estrogen receptor (ER) and that of the proliferation-associated marker Ki-67 are almost mutually exclusive in the normal premenopausal human breast but that coexpression frequently occurs in estrogen receptor-positive (ER؉) breast cancers. This coexpression may indicate disordered expression of ER in the cell cycle or failure to suppress division of ER؉ cells and could be important in neoplastic transformation. The purpose of this study was to determine whether in situ proliferations known to be associated with different levels of risk for developing breast cancer contain these coexpressing cells and, if so, the stage at which they occur. We found that ER؉ proliferating cells were rare in premenopausal lobules but increased with age in the normal breast. There was no difference in nonlesional tissue between cancerous and noncancerous breasts. The percentage of dual-expressing cells was significantly increased , however , in all of the in situ proliferations and correlated positively with the level of risk of developing breast cancer. We suggest that development of at least some human breast cancers is associated with increasing failure to down-regulate ER as Estrogen is thought to be important in the pathogenesis of breast cancer and is associated with most of the epidemiological risk factors associated with the disease. 1 Furthermore, the antiestrogen tamoxifen decreases proliferation in breast cancers, 2,3 although its role in preventing the disease is in dispute at present. 4 Estrogen is also associated with epithelial proliferation in the noncancerous breast during the menstrual cycle 5,6 and in pregnancy 7 and acts on cells via the estrogen receptor (ER). Recently Clarke 8 has shown that there is almost mutual exclusion of steroid receptor expression and cell proliferation in normal human breast tissue, judged by the lack of dual immunostaining for ER and the human Ki-67 proliferation-associated nuclear antigen, which is usually demonstrable in the late G1, S, G2, and M phases of the cell cycle. This relationship, however, is lost in some breast cancers, in which a variable percentage of proliferating cells are estrogen receptor positive (ERϩ). This coexpression may therefore indicate disordered control of cell division in ERϩ cells or disordered regulation of ER in dividing cells and could represent an important pathogenetic step in the development of breast cancer. We have previously shown that the percentage of ERϩ cells within precancerous lesions correlates with the risk attributed to them in prospective studies. 9 Furthermore, a fundamental change appears to occur between hyperplasia of usual type (without atypia, HUT) and atypical ductal hyperplasia (ADH). The percentage of ERϩ cells in the former type of lesion increases with age, as it does in the normal breast, whereas in ADH it is high at all ages, as it is in ERϩ ductal carcinoma in situ (DCIS). This suggests that regulation of ER expression or control of numbers of ERϩ cells esca...
As oestrogen is associated with most of the epidemiological risk factors for breast cancer, the number and distribution of oestrogen receptor positive (ER+) cells could have a bearing on the development of the disease. ER+ cells were thus studied in the normal breast and in the spectrum of in situ proliferations which range from non‐atypical hyperplasia to in situ carcinoma and are associated with different levels of risk for developing breast cancer. In the normal pre‐menopausal breast, ER+ cells comprised the minority and were distributed singly, being surrounded by oestrogen receptor negative (ER−) cells. ER+ cells showed a statistically significant increase with age, reaching a plateau after the menopause, and the increase was associated with a tendency for positive cells to become contiguous in patches of variable size. A small proportion of lobules showing involutional change comprised over 90 per cent ER+ cells. The significance of this feature is not clear but no evidence was found that it was pre‐cancerous. The percentage of ER+ cells was slightly increased in hyperplasia of usual type (non‐atypical hyperplasia, HUT) and the relationship to age was maintained. The staining pattern was variable; in some lesions ER+ cells were surrounded by ER− cells whereas in others there were contiguous groups of positive cells sometimes accounting for more than 90 per cent of cells in the lesion. In contrast, all cases of atypical ductal hyperplasia (ADH), lobular in situ neoplasia (LIN) and ductal carcinoma in situ (DCIS) exhibited positivity of contiguous cells accounting for the majority in the lesions. Furthermore, the relationship between ER+ cell numbers and age was lost in these lesions, indicating autonomy of ER expression or of proliferation of cells expressing the receptor. It is hypothesized that this dysregulation of receptor expression or of ER+ cell numbers at the ADH stage may be the precursor of abnormal expression of cyclins and other cell cycle control proteins which have been shown first to appear in DCIS. Copyright © 1999 John Wiley & Sons, Ltd.
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