The effect of oral paracetamol on [18F]FDG PET/CT in oncology patients following COVID-19 vaccination

ABSTRACT

Aim/Introduction: [18F]FDG PET/CT plays an important role in diagnosis, staging, response assessment and follow-up care for oncology patients. Since mass Coronavirus Disease 2019 (COVID-19) vaccination program in many countries, vaccineassociated hypermetabolic lymphadenopathy (VAHL) may cause misinterpretation, unnecessary lymph node biopsy and alteration of therapy. Prophylactic use of paracetamol has been shown to alleviate the vaccine side-effects;whether it can also reduce the incidence of VAHL is not well studied. In the present study, we aimed to evaluate whether paracetamol can also reduce the incidence of VAHL in suspected or confirmed lung cancer patients. Material(s) and Method(s) This was a single-centre retrospective study. All consecutive patients with suspected or confirmed cancers who underwent [18F]FDG PET/CT between 1 May 2021 and 30 September 2021 and received at least one dose of COVID-19 vaccine within 6 weeks before were investigated. Demographic and clinical history (including details of COVID-19 vaccination, use of oral paracetamol) were collected, and the occurrence of VAHL was measured. Result(s) Among 96 patients (MF = 4056, mean age 60 +/- 11 years), 43.8% (42/96) demonstrated VAHL with median SUVmax of 3.2 (range, 1.5-13.8), median size of 7 mm (range, 3-17 mm) and median number of 3 (range, 1-15). Patients with oral paracetamol (63 +/- 11 years) and those without oral paracetamol (60 +/- 11 years) showed no statistically significant difference in the incidence (p = 0.751), SUVmax (p = 0.174), size (p = 0.932) and number of VAHL (p = 0.208). In addition, positive uptake at vaccine injection site was seen in 38.5% (37/96) of patients;use of oral paracetamol or not did not result in statistically significant difference in the incidence of positive deltoid uptake (p>0.05). Conclusion(s) This study demonstrated that intake of oral paracetamol may not prevent the occurrence of VAHL on [18F]FDG PET/CT in suspected or confirmed cancer patients following COVID-19 vaccination. On the other hand, paracetamol seems not to affect patients' immune response to the vaccine, which is a desirable attribute for a medication commonly prescribed for mitigation of the adverse effects of the vaccine.