Pathologic analysis of advanced adult soft tissue sarcomas, bone sarcomas, and mesotheliomas. The eastern cooperative oncology group (ECOG) experience

A total of 488 tumors entered in the Eastern Cooperative Oncology Group (ECOG) Study EST 3377 were evaluated histologically by a panel of pathologists from member institutions for quality control purposes. The overall agreement rate between the eligible submitting diagnosis and the pathology review panel's diagnosis was 74% (312/424). In 10% (44/424), the case was excluded because it was deemed to be nonsarcoma. In the other 16%, the disagreement concerned the type of sarcoma. The histologic type with the lowest agreement rate was rhabdomyosarcoma (17%), followed by sarcoma not otherwise specified (NOS) (27%), angiosarcoma (33%), and fibrosarcoma (48%). These figures reflect the significant degree of difficulty in the diagnosis of these tumor types. The treatment response rate of soft tissue sarcomas in the randomized study of Adriamycin (Adria Laboratories, Columbus, OH) regimens was slightly higher for those with lower grade sarcomas, i.e., 25% (four of 16) response rate for Grade 1 lesions; 22% (17/77) for Grade 2, and 21% (35/170) for Grade 3. When adjusted for type of sarcoma, there was no noticeable difference between Grade 1–2 versus 3 in response rate. A statistically significant difference in the percentage of complete responders was noted between Group A tumors (synovial sarcoma, hemangiopericytoma, sarcoma NOS, and Ewing's; 12.2%) versus Group B tumors (all other types—mostly spindle cell sarcomas; 3.5%) (P = 0.02).