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Stringent Complete Response (sCR) of Multiple Myeloma or Plasma Cell Leukemia
Stringent complete response (sCR) of multiple myeloma or plasma cell leukemia is characterized by complete response plus: normal free light chain ratio, and absence of clonal cells in the bone marrow by immunohistochemistry or immunofluorescence (confirmation with repeat bone marrow biopsy not needed). (Presence and/or absence of clonal cells is based upon the kappa/lamda ratio. An abnormal kappa/lambda ratio by immunohistochemistry and/or immunofluorescence requires a minimum of 100 plasma cells for analysis. An abnormal ratio reflecting the presence of an abnormal clone is kappa/lambda of > 4:1 or < 1:2.). Stringent complete response requires two consecutive assessments made at any time before the institution of any new therapy, and no known evidence of progressive or new bone lesions if radiographic studies were performed; radiographic studies are not required to satisfy stringent complete response requirements. (NCI Thesaurus)