The S-IgG concentrations 1–3 months after the second vaccination of patients with cancer were compared among different ages (< 65 and ≥ 65), sexes, BMI levels (< 18.5, normal range, > 30), smoking histories (never smoked, ex-smoker, current smoker), serum albumin levels (less than 3.0 g/dL, 3.0 g/dL or higher), absolute lymphocyte counts (< 500/μL, ≥ 500/μL), and types of COVID-19 vaccines. Here, ALB is linked to cancer.