(a) This chart depicts the 340 different clinical institutions that ASCproject patients reported they received some aspect of their clinical care for AS (x-axis) and the number of patients that reported care at any given institution (y-axis). This information was provided on the medical release forms completed by consented Angiosarcoma Project patients (n = 225 patients). Of the 227 consented ASCproject participants, 2 people did not fill out the medical release form, and are not included in this figure. The majority of the 340 total institutions were listed by only one patient. Ten institutions were listed by five or more AS patients as sites of care (box, upper right). (b) A bar chart showing the patient responses to the intake survey question ‘Please select all of the places in your body that you have ever had angiosarcoma (Please select all that apply).’ Patient intake surveys completed by the 227 patients who consented for the Angiosarcoma Project as of September 30, 2018 were analyzed. Each response of a location is counted separately, such that multiple locations are shown for patients that selected more than one answer to indicate that they have had more than one location for their angiosarcoma lesions. 9 patients selected the provided response option of ‘I don’t know’ (‘Don’t Know’), and 7 patients did not respond to this question (’Not Reported’). The HNFS category depicted above includes patient responses of ‘head, face, neck’ and responses of ‘scalp.’ (c) Patient-reported information regarding other cancer diagnoses prior to angiosarcoma. Patient intake surveys completed by the 227 patients who consented for the Angiosarcoma Project as of September 30, 2018 were analyzed to obtain patient-reported information regarding other cancer diagnoses prior to angiosarcoma. Seventy five patients’ responses indicated they had been diagnosed with another cancer prior to angiosarcoma. These patients were identified based on their responses of “Yes” to the survey question “Were you ever diagnosed with any other kind of cancer(s)?”. Patients also provided specific diagnoses years for AS and other cancer(s), which were used to determine that the AS diagnosis occurred in the same year or after another cancer diagnosis. Of those 75 patients, 55 also responded “Yes” to the survey question “Have you had radiation as a treatment for another cancer(s)?”. Of those 55 patients, 39 also reported “breast” as their only primary AS site and indicated breast cancer as a previous cancer. The majority of these 39 patients are expected to be cases of cutaneous AS of the breast. AS, angiosarcoma; ASCproject, The Angiosarcoma Project; HNFS, head, neck, face, scalp.