RECIST 1.1 versus clinico-radiological response assessment for locally advanced cervical cancer: implications on interpreting survival outcomes of future trials.

Objective: To investigate differences in standard clinico-radiological evaluation versus Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 for reporting survival outcomes in patients with locally advanced cervical cancer treated with chemoradiation and brachytherapy.

Methods: Between November 2017 and March 2020, patients recruited in cervical cancer trials were identified. MRI at diagnosis and at least one follow-up imaging was mandatory. Disease-free survival and progression-free survival were determined using standard evaluation (clinical examination and symptom-directed imaging) and RECIST 1.1. Agreement between criteria was estimated using κ value. Sensitivity analysis was done to test the sensitivity, specificity, and accuracy of RECIST 1.1 in detecting response to treatment.

Results: Sixty-nine eligible patients had at least one target lesion. Thirty-three patients (47.8%) had pathological lymph nodes. Of these 33 patients, RECIST 1.1 classified only 18% (6/33) as 'target nodal lesions' and the remaining nodes as 'non-target'. There were 6 (8.7%) and 8 (11.6%) patients with disease events using RECIST 1.1 and standard evaluation, respectively. The disease-free survival at 12, 18, and 24 months using RECIST 1.1 was 94.2%, 91.2%, 91.2%, and with standard evaluation was 94.2%, 89.7%, and 88.2%, respectively (p=0.58). Whereas, progression-free survival at 12, 18, and 24 months using RECIST 1.1 and standard evaluation were same (94.2%, 91.2%, and 91.2%, respectively). The κ value was 0.84, showing strong agreement in assessing disease-free survival, although an absolute difference of 3% between endpoint assessment methodologies. RECIST 1.1 had a sensitivity of 75% (95% CI 34.91% to 96.81%), specificity of 100% (95% CI 94.13% to 100%), and accuracy of 97.1% (95% CI 89.92% to 99.65%).

Conclusions: The study showed 1.5% and 3% difference in disease-free survival at 18 and 24 months and no difference in progression-free survival between RECIST 1.1 and standard evaluation in a patient cohort with low event rate.