The purpose of the present invention is to utilize blood PD-1 concentration as a biomarker for predicting a therapeutic effect of an immune checkpoint inhibitor on cancer, for evaluating cancer progression, or for predicting cancer recurrence. The present invention pertains to an agent for arresting cancer progression, for suppressing cancer recurrence, and/or for cancer treatment, the agent being characterized by containing an immune checkpoint inhibitor as an active ingredient and by being administered to cancer patients having a blood PD-1 concentration level less than a predetermined cutoff value.本發明之目的在於利用血中PD-1濃度作為用於預測免疫檢查點阻礙物質對癌之治療效果、評估癌之進展度、或預測癌之復發風險的生物標記。本發明之癌之進展抑制、復發抑制及/或治療劑之特徵在於：包含免疫檢查點阻礙物質作為有效成分，對血中存在之PD-1之濃度未達預先規定之臨界值之癌患者進行投予。
