Seroprevalence of SARS-CoV-2-specific antibodies in cancer outpatients in Madrid (Spain): A single center, prospective, cohort study and a review of available data

Background: Coronavirus disease in 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has emerged as a global pandemic. Published data suggests that patients with a history of or active malignancy are at increased risk of infection and developing COVID-19 related complications. To date, the published data has analyzed the seroprevalence of COVID-19 infection in the general population, but not in cancer patients. Here we present the results of prevalence of IgG and IgM antibodies against SARS-CoV-2 in cancer patients from the University Hospital of Torrejon (Torrejon de Ardoz, Madrid, Spain). Methods: SARS-CoV-2 IgG and IgM antibodies was assessed using a commercially available rapid test (Testsealabs (R) IgG/IgM Rapid Test Cassette) and collect the result from cancer outpatients who attended the medical oncology consult at University Hospital of Torrejon between June 1st and June 19th, 2020. Findings: We analyzed the serological test results of 229 cancer patients. We estimated an overall seroprevalence (IgG or IgM positive) of 31.4%. The probability of SARS-CoV-2 seropositivity was similar between men and women, type of treatment and cancer stage. The probability of seropositivity was significantly higher in cancer patients with pneumonia compared with cancer patients without pneumonia (Odds Ratio (OR) 7.65 [95% confidence interval (CI) 1,85-31,58]). Interpretation: Our results show a higher rate of SARS-CoV-2 antibodies in cancer patients than in the general population. The role of those antibodies in the immune response against the virus infection is unclear.