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

Martine Moossdorff, Lori M. Van Roozendaal, Luc J.A. Strobbe, Stefan Aebi, David A. Cameron, J. Michael Dixon, Armando E. Giuliano, Bruce G. Haffty, Brigid E. Hickey, Clifford A. Hudis, V. Suzanne Klimberg, Bogda Koczwara, Thorsten Kühn, Marc E. Lippman, Anthony Lucci, Martine Piccart, Benjamin D. Smith, Vivianne C.G. Tjan-Heijnen, Cornelis J.H. Van De Velde, Kimberly J. Van ZeeJan B. Vermorken, Giuseppe Viale, Adri C. Voogd, Irene L. Wapnir, Julia R. White, Marjolein L. Smidt

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


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 (US)
JournalJournal of the National Cancer Institute
Issue number12
StatePublished - Dec 1 2014
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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