Cancer and COVID-19: Why are cancer patients more susceptible to COVID-19?

The COVID-19 pandemic has engulfed the entire world and has claimed more than 3 million lives worldwide. This viral disease is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and mainly characterized by fever, dry cough, fatigue, anosmia, anorexia, and dyspnea. The severity of the disease increases with age and presence of comorbidities, including cancer. Multiple clinical studies have shown that the cancer patients are highly susceptible to the severe form of the viral disease. In this review article, we have summarized the available scientific literature regarding the molecular links between COVID-19 and cancer, which make the cancer patients highly susceptible to COVID-19. Few studies have shown that the angiotensin-converting enzyme 2 (ACE2) receptor, transmembrane protease serine 2 (TMPRSS2), and the immune response and inflammation establish the interconnection between the two diseases. Additionally, we have also discussed whether SARS-CoV-2 can contribute to cancer development in COVID-19 patients. A recent study has suggested that SARS-CoV-2 may create a microenvironment that may support cancer cell proliferation and induce the activation of dormant cancer cells (DCCs). In another study, the blood sera of COVID-19 patients were found to activate epithelial-to-mesenchymal transition (EMT) in cancer cells. Overall, this review article will surely help the scientific community to understand why the cancer patients are so much prone to COVID-19 and will also motivate the researchers to find new therapeutic strategies that may save the lives of many COVID-19-infected cancer patients.