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Molecular profile of ductal carcinoma in situ of the breast in BRCA1 and BRCA2 germline mutation carriers
  1. P van der Groep1,
  2. P J van Diest1,
  3. F H Menko3,
  4. J Bart4,
  5. E G E de Vries5,
  6. E van der Wall2
  1. 1
    Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
  2. 2
    Department of Internal Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
  3. 3
    Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
  4. 4
    Department of Pathology, University Medical Center Groningen, Groningen, The Netherlands
  5. 5
    Department of Medical Oncology, University Medical Center Groningen, Groningen, The Netherlands
  1. Correspondence to Petra van der Groep, Department of Pathology, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands; p.vandergroep{at}umcutrecht.nl

Abstract

Aims: Ductal carcinoma in situ (DCIS) is an established late precursor of sporadic invasive breast cancer and to a large extent parallels its invasive counterpart with respect to molecular changes and immunophenotype. Invasive breast cancers in germline BRCA1 and BRCA2 mutation carriers have a distinct “basal” and “luminal” immunophenotype, respectively, but the immunophenotype of their precursor lesions has hardly been studied, and this was the aim of this study.

Methods: DCIS lesions of 25 proven BRCA1 and 9 proven BRCA2 germline mutation carriers and their 22 and 6, respectively, accompanying invasive lesions were stained by immunohistochemistry for oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor (HER)2/neu, cytokeratin (CK)5/6, CK14, epidermal growth factor receptor (EGFR) and Ki67.

Results: DCIS lesions in BRCA1 mutation carriers were mostly of the basal molecular type with low ER/PR/HER2 expression, while they frequently expressed CK5/6, CK14 and EGFR, and were mostly grade 3 and highly proliferative. DCIS lesions in BRCA2 mutation carriers were mostly of luminal molecular type with frequent expression of ER/PR, and infrequent expression of CK5/6, CK14 and EGFR, and they were mostly grade 3 and showed low proliferation. In BRCA1 and BRCA2 mutation carriers there was a high concordance between DCIS lesions and their concomitant invasive counterpart with regard to expression of individual markers as well as “molecular” subtype.

Conclusions: Although the number of cases studied was low, DCIS lesions in BRCA1 and BRCA2 mutations carriers are usually of the basal and luminal molecular type, respectively, similar to their accompanying invasive cancers, thereby providing evidence that DCIS is a direct precursor lesion in these hereditary predisposed patients. This also suggests that crucial carcinogenetic events leading to these phenotypes in hereditary predisposed patients occur before the stage of invasion.

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Footnotes

  • Funding Partly supported by an unrestricted educational grant from Aegon, Inc.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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