Published online Mar 15, 2025. doi: 10.4251/wjgo.v17.i3.102804
Revised: December 24, 2024
Accepted: January 15, 2025
Published online: March 15, 2025
Processing time: 107 Days and 5.9 Hours
Gastric neuroendocrine carcinomas (NECs) exhibit aggressive features, such as rapid growth, higher rate of metastasis, and a generally unfavorable prognosis compared to gastric adenocarcinoma. As a result, therapeutic options for NECs remain limited, contributing to the poor prognosis of patients. Immunotherapy has emerged as a promising treatment strategy and demonstrated the potential to partially improve the survival and prognosis of patients with NECs. Nevertheless, the unique clinical response termed pseudoprogression (PsP) has garnered considerable attention in the context of immunotherapy.
Presented here is a case of NEC recurrence five and a half months after radical gastric surgery. The 45-year-old male patient underwent combination treatment involving a PD-1 blocker and tyrosine kinase inhibitors and encountered two instances of PsP during treatment. The patient ultimately achieved a durable treatment response without altering his treatment regimens, resulting in a substantial therapeutic benefit.
This case report aimed to provide the authors’ experience with the diagnosis of PsP and treatment strategies for PsP in ongoing immunotherapy.
Core Tip: Neuroendocrine carcinomas (NECs) are generally considered highly malignant, characterized by rapid growth, a high metastasis rate, and poor prognosis, and their malignancy is much higher than that of gastric adenocarcinoma. Immune checkpoint inhibitors are a new type of immunotherapy drugs used in cancer treatment. However, the differences in clinical response and drug resistance pose significant challenges in immunotherapy. This article aims to report an extremely rare case of NEC, in which two significant pseudoprogression (PsP) occurred during treatment with PD-1 inhibitors combined with tyrosine kinase inhibitors. More rarely, this case had two PsP in the same organ under the same treatment plan. Besides, we mainly introduced the existing research on the possible mechanisms, timepoint, clinical manifestations, biomarkers, and medical imaging techniques associated with PsP.