Survival benefit of ⁶⁸Ga-FAPI PET/CT staging for prognostic assessment in gastric and colorectal cancer compared with CE-CT and ¹⁸F-FDG PET/CT: a single-center retrospective study

The aim of this retrospective study was to investigate whether gallium-68-labeled fibroblast activation protein inhibitor (⁶⁸Ga-FAPI) positron emission tomography/computed tomography (PET/CT) that provided altered staging and adjusted treatment decisions was more effective for prolonging patient survival compared to that achieved by either contrast-enhanced computed tomography (CE-CT) or fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET/CT.

We analyzed patients diagnosed with untreated gastric or colorectal cancer between March 2021 and March 2023 who were staged using these three imaging diagnostic modes described above. The accuracy of staging, reduction of unnecessary surgery, progression-free survival (PFS), and overall survival (OS) were used as the main comparative indicators. The potential independent risk factors affecting the prognosis of patients with gastric or colorectal cancer were also analyzed.

A total of 270 patients (137 gastric and 133 colorectal cancers) were enrolled, with a median follow-up of 3.02 years (95%CI: 2.7–3.3 years). The baseline characteristics of the patient groups were comparable. For both cancers, patients staged by ⁶⁸Ga-FAPI PET/CT had significantly longer median OS than those staged by either CE-CT or ¹⁸F-FDG PET/CT (colorectal cancer: p = 0.0123; gastric cancer: p = 0.037). ⁶⁸Ga-FAPI PET/CT also improved the accuracy of staging and altered staging in 41%–52% of patients, with a reduction in unnecessary surgeries of 42%–69%. Cox multivariate regression identified CE-CT and ¹⁸F-FDG PET/CT as prognostic risk factors relative to ⁶⁸Ga-FAPI PET/CT.

In patients with gastric or colorectal cancer, those who underwent staging with ⁶⁸Ga‑FAPI PET/CT showed improvements in disease progression and survival outcomes compared with those staged with either CE‑CT or ¹⁸F‑FDG PET/CT. The underlying mechanisms of these improvements may be related to increased staging accuracy and the subsequent selection of less invasive therapeutic strategies. These findings highlight the clinical value of ⁶⁸Ga‑FAPI PET/CT in these patient populations. (Trial registration: ChiCTR ChiCTR2400081233. Registered 27 February 2024)