Spontaneous regression of advanced hepatocellular carcinoma following COVID-19 infection and vaccination: a case report and review of literature.

Background: Spontaneous regression (SR) of cancer remains a rare phenomenon, particularly in hepatocellular carcinoma (HCC), where limited literature exists. This case report emphasizes the significance of SR in advanced HCC, shedding light on the proposed mechanisms and addressing the scarcity of documented cases in current medical literature. Case Description: We present the case of a 67-year-old female with a history of localized HCC who underwent right hepatectomy. Surveillance imaging 4 months later revealed tumor recurrence with tumor thrombus in the main portal vein. Radioembolization was deemed unsuitable, leading to the recommendation of systemic therapy with atezolizumab and bevacizumab. Prior to receiving any treatment, the patient tested positive for coronavirus disease 2019 (COVID-19), having previously received both the messenger RNA (mRNA)-1273 vaccine series and a booster. Surprisingly, subsequent imaging 10 months after initial diagnosis showed SR of the previously identified lesions, suggesting a potential link between viral exposure, vaccination, and the observed regression. The patient eventually received treatment with atezolizumab and bevacizumab and has sustained disease control to date, 12 months after initiating treatment. Conclusions: This unique case highlights SR of advanced HCC following COVID-19 infection, raising intriguing questions about the interplay between viral infections, vaccinations, and cancer outcomes. The patient's response in the absence of systemic therapy further underscores the complexity of HCC management and prompts further investigation into the potential immunomodulatory effects of viral infections and vaccinations on cancer regression. Understanding these interactions could have implications for tailoring treatment approaches and improving outcomes in patients with advanced HCC.