Metzger Giulia, Bayerl Christian, Rogasch Julian Mm, Furth Christian, Wetz Christoph, Beck Marcus, Mehrhof Felix, Amthauer Holger, Ghadjar Pirus, Neumann Christopher, Pelzer Uwe, Zips Daniel, Hofheinz Frank, Grabowski Jane, Schatka Imke, Zschaeck Sebastian
Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nuclear Medicine, Berlin, Germany.
Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Radiology, Berlin, Germany.
Theranostics. 2024 Jul 8;14(11):4184-4197. doi: 10.7150/thno.95329. eCollection 2024.
Ga-labeled fibroblast activation protein inhibitor (FAPI) is a novel PET tracer with great potential for staging pancreatic cancer. Data on locally advanced or recurrent disease is sparse, especially on tracer uptake before and after high dose chemoradiotherapy (CRT). The aim of this study was to evaluate [Ga]Ga-FAPI-46 PET/CT staging in this setting. Twenty-seven patients with locally recurrent or locally advanced pancreatic adenocarcinoma (LRPAC n = 15, LAPAC n = 12) in stable disease or partial remission after chemotherapy underwent FAPI PET/CT and received consolidation CRT in stage M0 with follow-up FAPI PET/CT every three months until systemic progression. Quantitative PET parameters SUV, SUV, FAPI-derived tumor volume and total lesion FAPI-uptake were measured in baseline and follow-up PET/CT scans. Contrast-enhanced CT (ceCT) and PET/CT data were evaluated blinded and staged according to TNM classification. FAPI PET/CT modified staging compared to ceCT alone in 23 of 27 patients in baseline, resulting in major treatment alterations in 52% of all patients (30%: target volume adjustment due to N downstaging, 15%: switch to palliative systemic chemotherapy only due to diffuse metastases, 7%: abortion of radiotherapy due to other reasons). Regarding follow-up scans, major treatment alterations after performing FAPI PET/CT were noted in eleven of 24 follow-up scans (46%) with switch to systemic chemotherapy or best supportive care due to M upstaging and ablative radiotherapy of distant lymph node and oligometastasis. Unexpectedly, in more than 90 % of the follow-up scans, radiotherapy did not induce local fibrosis related FAPI uptake. During the first follow-up, all quantitative PET metrics decreased, and irradiated lesions showed significantly lower FAPI uptake in locally controlled disease (SUV p = 0.047, SUV p = 0.0092) compared to local failure. Compared to ceCT, FAPI PET/CT led to major therapeutic alterations in patients with LRPAC and LAPAC prior to and after radiotherapy, which might help identify patients benefiting from adjustments in every treatment stage. FAPI PET/CT should be considered a useful diagnostic tool in LRPAC or LAPAC before and after CRT.
镓标记的成纤维细胞活化蛋白抑制剂（FAPI）是一种新型正电子发射断层显像（PET）示踪剂，在胰腺癌分期方面具有巨大潜力。关于局部晚期或复发性疾病的数据稀少，尤其是高剂量放化疗（CRT）前后的示踪剂摄取情况。本研究的目的是评估在此情况下的[镓]镓-FAPI-46 PET/CT分期。27例局部复发或局部晚期胰腺腺癌患者（局部复发胰腺癌15例，局部晚期胰腺癌12例），化疗后病情稳定或部分缓解，接受了FAPI PET/CT检查，并在M0期接受巩固性CRT，每三个月进行一次随访FAPI PET/CT检查，直至出现全身进展。在基线和随访PET/CT扫描中测量PET定量参数SUV、SUV、FAPI衍生肿瘤体积和总病变FAPI摄取量。对对比增强CT（ceCT）和PET/CT数据进行盲法评估，并根据TNM分类进行分期。与单纯ceCT相比，27例患者中有23例在基线时FAPI PET/CT改变了分期，导致所有患者中有52%发生了主要治疗改变（30%：由于N分期降低而调整靶体积，15%：仅由于弥漫性转移而改为姑息性全身化疗，7%：由于其他原因放弃放疗）。关于随访扫描，在24次随访扫描中有11次（46%）在进行FAPI PET/CT后出现了主要治疗改变，由于M分期升高以及对远处淋巴结和寡转移灶进行消融放疗而改为全身化疗或最佳支持治疗。出乎意料的是，在超过90%的随访扫描中，放疗未诱导与局部纤维化相关的FAPI摄取。在首次随访期间，所有PET定量指标均下降，与局部未控疾病相比，局部控制良好的疾病中照射部位的FAPI摄取显著降低（SUV p = 0.047，SUV p = 0.0092）。与ceCT相比，FAPI PET/CT在放疗前后导致局部复发胰腺癌和局部晚期胰腺癌患者的主要治疗改变，这可能有助于确定在每个治疗阶段能从调整中获益的患者。FAPI PET/CT应被视为局部复发胰腺癌或局部晚期胰腺癌放疗前后的一种有用诊断工具。
