Maastricht Delphi consensus on event definitions for classification of recurrence in breast cancer research.

Martine Moossdorff, Lori van Roozendaal, Luc Strobbe, Stefan Aebi, David Cameron, J Dixon, Armando Giuliano, Bruce Haffty, Brigid Hickey, Clifford Hudis, V Klimberg, Bogda Koczwara, Thorsten Kühn, Marc Lippman, Anthony Lucci, Martine Piccart, Benjamin Smith, Vivianne Tjan-Heijnen, Cornelis van de Velde, Kimberly Van ZeeJan Vermorken, Giuseppe Viale, Adri Voogd, Irene Wapnir, Julia White, Marjolein Smidt

    Research output: Contribution to journalArticlepeer-review

    81 Citations (Scopus)


    Background In breast cancer studies, many different endpoints are used. Definitions are often not provided or vary between studies. For instance, "local recurrence" may include different components in similar studies. This limits transparency and comparability of results. This project aimed to reach consensus on the definitions of local event, second primary breast cancer, regional and distant event for breast cancer studies. Methods The RAND-UCLA Appropriateness method (modified Delphi method) was used. A Consensus Group of international breast cancer experts was formed, including representatives of all involved clinical disciplines. Consensus was reached in two rounds of online questionnaires and one meeting. Results Twenty-four international breast cancer experts participated. Consensus was reached on 134 items in four categories. Local event is defined as any epithelial breast cancer or ductal carcinoma in situ (DCIS) in the ipsilateral breast, or skin and subcutaneous tissue on the ipsilateral thoracic wall. Second primary breast cancer is defined as epithelial breast cancer in the contralateral breast. Regional events are breast cancer in ipsilateral lymph nodes. A distant event is breast cancer in any other location. Therefore, this includes metastasis in contralateral lymph nodes and breast cancer involving the sternal bone. If feasible, tissue sampling of a first, solitary, lesion suspected for metastasis is highly recommended. Conclusion This project resulted in consensus-based event definitions for classification of recurrence in breast cancer research. Future breast cancer research projects should adopt these definitions to increase transparency. This should facilitate comparison of results and conducting reviews as well as meta-analysis.

    Original languageEnglish
    Article numberdju288
    Pages (from-to)dju288
    JournalJournal of the National Cancer Institute
    Issue number12
    Publication statusPublished - 2014


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