Inflammatory breast cancer defined: proposed common diagnostic criteria to guide treatment and research

PURPOSE: Inflammatory breast cancer is a deadly and aggressive type of breast cancer. A key challenge relates to the need for a more detailed, formal, objective definition of IBC, the lack of which compromises clinical care, hampers the conduct of clinical trials, and hinders the search for IBC-specific biomarkers and treatments because of the heterogeneity of patients considered to have IBC. METHODS: Susan G. Komen, the Inflammatory Breast Cancer Research Foundation, and the Milburn Foundation convened patient advocates, clinicians, and researchers to review the state of IBC and to propose initiatives to advance the field. After literature review of the defining clinical, pathologic, and imaging characteristics of IBC, the experts developed a novel quantitative scoring system for diagnosis. RESULTS: The experts identified through consensus several “defining characteristics” of IBC, including factors related to timing of onset and specific symptoms. These reflect common pathophysiologic changes, sometimes detectable on biopsy in the form of dermal lymphovascular tumor emboli and often reflected in imaging findings. Based on the importance and extent of these characteristics, the experts developed a scoring scale that yields a continuous score from 0 to 48 and proposed cut-points for categorization that can be tested in subsequent validation studies. CONCLUSION: To move beyond subjective ‘clinical diagnosis’ of IBC, we propose a quantitative scoring system to define IBC, based on clinical, pathologic, and imaging features. This system is intended to predict outcome and biology, guide treatment decisions and inclusion in clinical trials, and increase diagnostic accuracy to aid basic research; future validation studies are necessary to evaluate its performance. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10549-021-06434-x.