OA15.06 Differences in Pathologic Assessment by MPR Calculation Methods for Multiple Slides of Tumor Bed in SQUAT Trial (WJOG12119L)

Major pathologic response (MPR), which is defined as a condition of residual viable tumor (RVT) occupying 10% or less of tumor bed, has been used as a surrogate endpoint for long-term prognosis in clinical trials for neoadjuvant therapy. IASLC released a recommendation for procedures of handling resected specimens including gross sectioning, whereas MPR calculation methods varies among the clinical trials. In SQUAT trial (WJOG12119L), we adopted weighted viable tumor (WVT), which is calculated with weighted viable tumor percentages according to the area of tumor bed in each slide.