mCRPCにおける治療反応性評価の予後に関する比較：PERCIST 1.0、RECIST 1.1、PSA反応性基準

Comparative prognostic implication of treatment response assessments in mCRPC: PERCIST 1.0, RECIST 1.1, and PSA response criteria.

抄録

転移性去勢抵抗性前立腺癌（mCRPC）における治療効果を正確に評価することは、腫瘍の不均一性が顕著であること、また多くの確立された治療法と新規治療法の選択肢があることから、困難である。この単施設前向き試験の目的は、mCRPC患者の全生存期間（OS）予測におけるPERCIST 1.0の予後予測有用性を、RECIST 1.1および前立腺特異抗原（PSA）ベースの治療反応性評価と比較して評価することである。全患者は、治療開始前にベースラインのF-フルオロデオキシグルコース（FDG）PET/CT検査を受け、治療開始4ヵ月後に再度PET/CT検査を受けた。ベースライン時と比較した4ヵ月後の治療に対する患者の反応を、RECIST 1.1、PERCIST 1.0、PSA反応基準で評価した。患者の奏効カテゴリーとOSとの関連を評価した。OSは、ベースラインPET/CT施行日から何らかの原因による死亡までの期間と定義した。奏効ステータスの異なる患者をlogrank検定で比較した。4ヵ月時点でPSA反応判定基準により進行性であった患者は、病勢安定（SD）（44％±19％、p＝0.03）、完全奏効（CR）または部分奏効（PR）（53％±11％、p＝0.03）であった患者に比べ、有意にOSが短かった（24ヵ月OS確率：18％±11％）。RECIST 1.1奏効基準はOSに同様の傾向を示したが、SD/非CR、非PD（54％±13％）、CR/PR（54％±14％）と比較してPD患者（25％±15％）では統計学的に有意な差は認められなかった（p=0.13）。PERCIST1.0基準では、CMR/PMR（56％±12％）はSMD（38％±17％、p＝0.03）、PMD（21％±10％、p＝0.01）と比較して、OSに有意差が認められた。PERICST1.0とPSA反応判定基準の両方で進行性病変を示した患者は、どちらか一方の反応判定基準で進行性病変を示した患者に比べ、OSが有意に不良であった（24ヵ月OS：0％、12ヵ月OS：31％±14％）。PERCIST1.0は、特にPSA治療反応判定基準と組み合わされた場合、全身化学療法を受けるmCRPC患者に重要な予後情報を提供する可能性がある。

Accurate appraisal of treatment response in metastatic castrate-resistant prostate cancer (mCRPC) is challenging in view of remarkable tumor heterogeneity and the available choices among many established and novel therapeutic approaches. The purpose of this single-center prospective study was to evaluate the comparative prognostic utility of PERCIST 1.0 in predicting overall survival (OS) in patients with mCRPC compared to RECIST 1.1 and prostate-specific antigen (PSA)-based treatment response assessments. : Patients with mCRPC were prospectively enrolled if they were beginning systemic medical therapy or transitioning to new systemic therapy after not responding to a prior treatment. All patients underwent a baseline F-fluorodeoxyglucose (FDG) positron emission tomography/ computed tomography (PET/CT) prior to the initiation of treatment and again 4 months after the start of therapy. Patients' responses to treatment at 4 months compared to baseline were evaluated with RECIST 1.1, PERCIST 1.0 and PSA response criteria. The associations between patients' response categories and OS were evaluated. OS was defined as the duration in time between the date of baseline PET/CT to death from any cause. Patients with different response status were compared with logrank tests. Survival probabilities were calculated using the Kaplan-Meier method. : Patients with progressive disease by PSA response criteria at 4 months demonstrated significantly shorter OS (24-month OS probability: 18% ± 11%) compared to patients with stable disease, SD, (44% ± 19%, p=0.03) and complete response, CR, or partial response, PR, (53% ± 11%, p=0.03). RECIST 1.1 response criteria demonstrated a similar trend in OS, however no statistically significant differences were noted between patients with PD (25% ± 15%) compared to SD/non-CR, non-PD (54% ± 13%) and CR/PR (54% ± 14%) (p=0.13). PERCIST 1.0 criteria demonstrated significant differences in OS between responders, CMR/PMR (56% ± 12%), compared to SMD (38% ± 17%, p=0.03) and PMD (21% ± 10%, p=0.01). Patients with progressive disease by both PERICST 1.0 and PSA response criteria demonstrated significantly worse OS (24-month OS: 0%, 12-month OS: 31% ± 14%) compared to patients with progressive disease by either response criteria. : PERCIST 1.0 may provide significant prognostic information for patients with mCRPC undergoing systemic chemotherapy, particularly when incorporated with PSA treatment response criteria.