Johannes L. Peterse

Breast cancer metastasis: markers and models

Breast cancer starts as a local disease, but it can metastasize to the lymph nodes and distant organs. At primary diagnosis, prognostic markers are used to assess whether the transition to systemic disease is likely to have occurred. The prevailing model of metastasis reflects this view — it suggests that metastatic capacity is a late, acquired event in tumorigenesis. Others have proposed the idea that breast cancer is intrinsically a systemic disease. New molecular technologies, such as DNA microarrays, support the idea that metastatic capacity might be an inherent feature of breast tumours. These data have important implications for prognosis predicition and our understanding of metastasis.

Neu-protein overexpression in breast cancer. Association with comedo-type ductal carcinoma in situ and limited prognostic value in stage II breast cancer.

Amplification of the neu proto-oncogene in breast cancer has been reported to correlate with the presence of lymph-node metastases and with a poor prognosis. We describe a method for the immunohistochemical detection of overexpression of neu protein on formalin-fixed paraffin-embedded tissue, with the use of two different monoclonal antibodies. In a group of tumors with a known neu-gene copy number, intense membrane staining of tumor cells was present in all tumors with neu-gene amplification. Of 189 tumors from patients with Stage II breast cancer, 27 (14 percent) had neu-membrane staining. Neu overexpression was associated with larger tumor size (P = 0.006) but not with lymph-node involvement. Neu-protein expression in lymph-node metastases was the same as its expression in primary tumors. Among the patients with neu overexpression (median follow-up, 37 months), disease-free survival was not significantly shorter; overall survival was reduced significantly in these patients (P = 0.042), but this reduction did not remain significant after adjustment for tumor size. Of 45 ductal carcinomas in situ, 19 (42 percent) had neu-membrane staining. These 19 were all of the large-cell, comedo growth type. None of 16 ductal carcinomas in situ of small-cell, papillary, or cribriform growth type had neu overexpression. We conclude that neu overexpression may be an early step in the development of a distinct histologic type of carcinoma of the breast, but we could find no association of overexpression with lymph-node status or tumor recurrence.

Radiotherapy in breast-conserving treatment for ductal carcinoma in situ: first results of the EORTC randomised phase III trial 10853

BACKGROUND Ductal carcinoma in situ (DCIS) of the breast is a disorder that has become more common since it may manifest as microcalcifications that can be detected by screening mammography. Since selected women with invasive cancer can be treated safely with breast conservation therapy it is paradoxical that total mastectomy has remained the standard treatment for DCIS. We did a randomised phase III clinical trial to investigate the role of radiotherapy after complete local excision of DCIS. METHODS Between 1986 and 1996, women with clinically or mammographically detected DCIS measuring less than or equal to 5 cm were treated by complete local excision of the lesion and then randomly assigned to either no further treatment (n=503) or to radiotherapy (n=507; 50 Gy in 5 weeks to the whole breast). The median duration of follow-up was 4.25 years (maximum 12.0 years). All analyses were by intention to treat. FINDINGS 500 patients were followed up in the no further treatment group and 502 in the radiotherapy group. In the no further treatment group 83 women had local recurrence (44 recurrences of DCIS, and 40 invasive breast cancer). In the radiotherapy group 53 women had local recurrences (29 recurrences of DCIS, and 24 invasive breast cancer). The 4-year local relapse-free was 84% in the group treated with local excision alone compared with 91% in the women treated by local excision plus radiotherapy (log rank p=0.005; hazard ratio 0.62). Similar reductions in the risk of invasive (40%, p=0.04) and non-invasive (35%, p=0.06) local recurrence were seen. CONCLUSIONS Radiotherapy after local excision for DCIS, as compared with local excision alone, reduced the overall number of both invasive and non-invasive recurrences in the ipsilateral breast at a median follow-up of 4.25 years.

Risk Factors for Recurrence and Metastasis After Breast-Conserving Therapy for Ductal Carcinoma-In-Situ: Analysis of European Organization for Research and Treatment of Cancer Trial 10853

PURPOSE In view of the increasing number of patients treated with breast-conserving treatment (BCT) for ductal carcinoma-in-situ (DCIS), risk factors for recurrence and metastasis should be identified. PATIENTS AND METHODS Clinical and pathologic characteristics from patients with DCIS in the European Organization for Research and Treatment of Cancer trial 10853 (excision with or without radiotherapy) were related to the risk of recurrence. Pathologic features were derived from a central review of 863 of the 1,010 randomized cases (85%). The median follow-up was 5.4 years. RESULTS Factors associated with an increased risk of local recurrence in the multivariate analysis were young age (< or = 40 years) (hazard ratio, 2.14; P =.02), symptomatic detection of DCIS (hazard ratio, 1.80; P =.008), growth pattern (solid and cribriform) (hazard ratios, 2.67 and 2.69, respectively; P =.012), involved margins (hazard ratio, 2.07; P =.0008), and treatment by local excision alone (hazard ratio, 1.74; P =.009). The risk of invasive recurrence was not related to the histologic type of DCIS (P =.63), but the risk of distant metastasis was significantly higher in poorly differentiated DCIS compared with well-differentiated DCIS (hazard ratio, 6.57; P =.01). CONCLUSION Patients with poorly differentiated DCIS have a high risk of distant metastasis after invasive local recurrence. Margin status is the most important factor in the success of BCT for DCIS; additionally, young age and symptomatic detection of DCIS have negative prognostic value.

Differences in Risk Factors for Local and Distant Recurrence After Breast-Conserving Therapy or Mastectomy for Stage I and II Breast Cancer: Pooled Results of Two Large European Randomized Trials

PURPOSE Risk factors for local and distant recurrence after breast-conserving therapy and mastectomy were compared to define guidelines for the decision making between both treatments. PATIENTS AND METHODS The data of two randomized clinical trials for stage I and II breast cancer patients were pooled. The total number of patients in the study was 1,772, of whom 879 underwent breast conservation, and 893, modified radical mastectomy. Representative slides of the primary tumor were available for histopathologic review in 1,610 cases (91%). RESULTS There were 79 patients with local recurrence after breast-conservation and 80 after mastectomy, the 10-year rates being 10% (95% confidence interval [CI], 8% to 13%) and 9% (95% CI, 7% to 12%), respectively. Age no more than 35 years (compared with age >60: hazard ratio [HR], 9.24; 95% CI, 3.74 to 22.81) and an extensive intraductal component (HR, 2.52; 95% CI, 1.26 to 5.00) were significantly associated with an increased risk of local recurrence after breast-conserving therapy. Vascular invasion was predictive of the risk of local recurrence, irrespective of the type of primary treatment (P <.01). Tumor size, nodal status, high histologic grade, and vascular invasion were all highly significant predictors of distant disease after breast-conserving therapy and mastectomy (P <.01). Age no more than 35 years and microscopic involvement of the excision margin were additional independent predictors of distant disease after breast-conserving therapy (P <.01). CONCLUSION Age no more than 35 years and the presence of an extensive intraductal component are associated with an increased risk of local recurrence after breast-conserving therapy. Vascular invasion causes a higher risk of local recurrence after mastectomy as well as after breast-conserving therapy and should therefore not be used for deciding between the two treatments.

Refinement of breast cancer classification by molecular characterization of histological special types.

Most invasive breast cancers are classified as invasive ductal carcinoma not otherwise specified (IDC NOS), whereas about 25% are defined as histological ‘special types’. These special‐type breast cancers are categorized into at least 17 discrete pathological entities; however, whether these also constitute discrete molecular entities remains to be determined. Current therapy decision‐making is increasingly governed by the molecular classification of breast cancer (luminal, basal‐like, HER2+). The molecular classification is derived from mainly IDC NOS and it is unknown whether this classification applies to all histological subtypes. We aimed to refine the breast cancer classification systems by analysing a series of 11 histological special types [invasive lobular carcinoma (ILC), tubular, mucinous A, mucinous B, neuroendocrine, apocrine, IDC with osteoclastic giant cells, micropapillary, adenoid cystic, metaplastic, and medullary carcinoma] using immunohistochemistry and genome‐wide gene expression profiling. Hierarchical clustering analysis confirmed that some histological special types constitute discrete entities, such as micropapillary carcinoma, but also revealed that others, including tubular and lobular carcinoma, are very similar at the transcriptome level. When classified by expression profiling, IDC NOS and ILC contain all molecular breast cancer types (ie luminal, basal‐like, HER2+), whereas histological special‐type cancers, apart from apocrine carcinoma, are homogeneous and only belong to one molecular subtype. Our analysis also revealed that some special types associated with a good prognosis, such as medullary and adenoid cystic carcinomas, display a poor prognosis basal‐like transcriptome, providing strong circumstantial evidence that basal‐like cancers constitute a heterogeneous group. Taken together, our results imply that the correct classification of breast cancers of special histological type will allow a more accurate prognostication of breast cancer patients and facilitate the identification of optimal therapeutic strategies. Copyright

Gene expression profiles of primary breast tumors maintained in distant metastases

It has been debated for decades how cancer cells acquire metastatic capability. It is unclear whether metastases are derived from distinct subpopulations of tumor cells within the primary site with higher metastatic potential, or whether they originate from a random fraction of tumor cells. Here we show, by gene expression profiling, that human primary breast tumors are strikingly similar to the distant metastases of the same patient. Unsupervised hierarchical clustering, multidimensional scaling, and permutation testing, as well as the comparison of significantly expressed genes within a pair, reveal their genetic similarity. Our findings suggest that metastatic capability in breast cancer is an inherent feature and is not based on clonal selection.

E-cadherin inactivation in lobular carcinoma in situ of the breast: an early event in tumorigenesis

In breast cancer, inactivating point mutations in the E-cadherin gene are frequently found in invasive lobular carcinoma (ILC) but never in invasive ductal carcinoma (IDC). Lobular carcinoma in situ (LCIS) adjacent to ILC has previously been shown to lack E-cadherin expression, but whether LCIS without adjacent invasive carcinoma also lacks E-cadherin expression and whether the gene mutations present in ILC are already present in LCIS is not known. We report here that E-cadherin expression is absent in six cases of LCIS and present in 150 cases of ductal carcinoma in situ (DCIS), both without an adjacent invasive component. Furthermore, using mutation analysis, we could demonstrate the presence of the same truncating mutations and loss of heterozygosity (LOH) of the wild-type E-cadherin in the LCIS component and in the adjacent ILC. Our results indicate that E-cadherin is a very early target gene in lobular breast carcinogenesis and plays a tumour-suppressive role, additional to the previously suggested invasion-suppressive role.

Somatic loss of BRCA1 and p53 in mice induces mammary tumors with features of human BRCA1-mutated basal-like breast cancer

Women carrying germ-line mutations in BRCA1 are strongly predisposed to developing breast cancers with characteristic features also observed in sporadic basal-like breast cancers. They appear as high-grade tumors with high proliferation rates and pushing borders. On the molecular level, they are negative for hormone receptors and ERBB2, display frequent TP53 mutations, and express basal epithelial markers. To study the role of BRCA1 and P53 loss of function in breast cancer development, we generated conditional mouse models with tissue-specific mutation of Brca1 and/or p53 in basal epithelial cells. Somatic loss of both BRCA1 and p53 resulted in the rapid and efficient formation of highly proliferative, poorly differentiated, estrogen receptor-negative mammary carcinomas with pushing borders and increased expression of basal epithelial markers, reminiscent of human basal-like breast cancer. BRCA1- and p53-deficient mouse mammary tumors exhibit dramatic genomic instability, and their molecular signatures resemble those of human BRCA1-mutated breast cancers. Thus, these tumors display important hallmarks of hereditary breast cancers in BRCA1-mutation carriers.

Simultaneous loss of E-cadherin and catenins in invasive lobular breast cancer and lobular carcinoma in situ

Loss of expression of the intercellular adhesion molecule E‐cadherin frequently occurs in invasive lobular breast carcinomas as a result of mutational inactivation. Expression patterns of E‐cadherin and the molecules comprising the cytoplasmic complex of adherens junctions, α‐, β‐ and γ‐catenin, were studied in a series of 38 lobular breast carcinomas with known E‐cadherin mutation status. The effect of loss of E‐cadherin by mutational inactivation (or other mechanisms) on the expression of catenins was investigated. Complete loss of plasma membrane‐associated E‐cadherin expression was observed in 32 out of 38 invasive lobular carcinomas, for which in 21 cases a mutation was found in the extracellular domain of E‐cadherin. In total, 15 frameshift mutations of small deletions or insertions, ranging from 1 to 41 bp, three non‐sense mutations, and three splice mutations were identified. Mutations were scattered over the whole coding region and no hot spots could be detected. In all cases, simultaneous loss of E‐cadherin and α‐ and β‐catenin expression was found; in 50 per cent of these cases, additional loss of γ‐catenin was observed. In six invasive lobular carcinomas, expression of both E‐cadherin and catenins was retained. In none of these carcinomas was an E‐cadherin mutation detected. Lobular carcinoma in situ adjacent to invasive lobular carcinoma showed simultaneous loss of E‐cadherin and catenins in all the cases studied—remarkably, also, in four cases positive for E‐cadherin and catenin expression in the invasive component. These results indicate that simultaneous loss of E‐cadherin and α‐, β‐ and γ‐catenin may be an important step in the formation of lobular carcinoma in situ, as a precursor of invasive lobular breast cancer. Events additional to E‐cadherin inactivation must be involved in the transition of lobular carcinoma in situ to invasive lobular carcinoma.