Prognostic serum biomarkers in cancer patients with COVID-19: A systematic review

•Albumin, CRP, d-dimer, ferritin, hemoglobin, IL-2R, IL-6, LDH, and PCT were identified as commonly changed biomarkers in three different comparison groups.•Increased levels of CRP, d-dimer, ferritin, IL-2R, IL-6, LDH, and PCT are positively correlated to the COVID-19 severity and cancer surveillance in cancer patients with COVID-19.•High levels of CRP, ferritin, and LDH after immunotherapy for COVID-19 in cancer patients indicate a poor prognosis.•Cancer patients who had lower levels of CRP, ferritin, and LDH exhibit a good prognosis after antivirals/antibiotic treatment for SARS-CoV-2 infection.