Cancer and COVID-19

Coronavirus is currently the main focus of health systems around the world. For certain specialties in medicine, such as those dealing with diseases of the heart and cancer medicine, the virus is especially harrowing. This article will look at the risk of the 2019 coronavirus (COVID-19) in patients undergoing radiation and chemotherapy as well as those with leukaemia and lymphoma.

Patients with certain cancers and those receiving (or who have received) certain treatments are at a higher risk of severe illness if they contract COVID-19 (Lymphoma Action, 2020). These patients include:

· Cancer patients that are undergoing active chemotherapy

· Cancer patients that are undergoing radiotherapy for a lung metastasis/primary cancer

· Patients with cancers of the blood or bone marrow (includes leukaemia, lymphoma, and myeloma)

· Patients taking immunotherapy or antibody treatments

· Patients on protein kinase inhibitors or PARP inhibitors

· Patients that have had stem cell/ bone marrow transplants in the last 6 months, or who are still taking immunosuppressive drugs (Lymphoma Action, 2020).

The first at risk patient group I will address is the group undergoing chemotherapy. Chemotherapy is a drug treatment that uses chemicals to kill rapidly-dividing cells in the body (Mayo Clinic, 2020). These cells include bone marrow cells, which are the progenitor cells of the immune system (Breastcancer.org, 2020). If chemotherapy were not administered, these cells would develop into red cells, platelets, and importantly in this context, white cells (Breastcancer.org, 2020). The main impact of chemotherapy is destruction of the white blood cells, which constitute the entire immune system, therefore leaving the patient at a much higher risk of infection (Breastcancer.org, 2020).

Radiotherapy is another cause for a weakened immune system. With this treatment, biological material is damaged by the absorption of energy from x-rays or gamma rays, or from charged particles within the atoms that may be ionized or excited (Carvalho and Villar, 2018). This damage can be direct or indirect. The direct mechanism is in the form of DNA damage in the tumour cells, leading to apoptosis, autophagy, or necrosis (Carvalho and Villar, 2018). The indirect mechanism is due to free radical production, whereby the free radicals are released into the body and lead to cell death (Carvalho and Villar, 2018). The effects of radiation on the body is not restricted to the tumour cells, it affects the whole microenvironment around the tumour (Carvalho and Villar, 2018). Looking specifically at the immune system, the most radiosensitive cells are lymphocytes (B, T and natural killer cells) (Carvalho and Villar, 2018). The next-most radiosensitive cells include the monocytes, macrophages, and lastly the dendritic cells (Carvalho and Villar, 2018). Therefore it is the immune system that is hindered when radiotherapy is administered, leading to an increase risk of infections and decreased ability to fight infection once diseased.

The last cancer-related risk for infection that will be addressed in this article is that of cancers of the blood and bone marrow. Leukaemia is a cancer that starts in the bone marrow and leads to overproduction of abnormal white blood cells, which are therefore not able to defend the body against infection (Leukaemia Care, 2020). This leads to more severe disease once a pathogen (bacteria or virus) enters the body. A lymphoma is a cancer of the T or B cells and leads to the uncontrolled proliferation of the white blood cells (WebMD, 2020). The white blood cells may be plentiful, however, they do not function normally and cannot mount an adequate response against a pathogen. This leads to an increased susceptibility to infections as well as a worse prognosis once infected.

Due to the toxic effects of radiotherapy and chemotherapy on the immune system, patients receiving these treatments are at an increased risk of COVID-19 infection and have a worse prognosis if they are infected. Patients with blood cancers are also at increased risk as they have inadequately functioning white cells; therefore they are unable to mount an immune response. It is important that these patients are identified as being at risk and that they are educated in taking the necessary precautions to prevent infection.

References

Breastcancer.org. 2014. How Chemotherapy Affects The Immune System. [online] Available at: <https://www.breastcancer.org/tips/immune/cancer/chemo> [Accessed 30 March 2020].

Breastcancer.org. 2020. Coronavirus (COVID-19): What People With Breast Cancer Need To Know. [online] Available at: <https://www.breastcancer.org/about_us/press_room/news/coronavirus> [Accessed 30 March 2020].

Carvalho, H. and Villar, R., 2018. Radiotherapy And Immune Response: The Systemic Effects Of A Local Treatment. [online] NCBI. Available at: <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6257057/> [Accessed 30 March 2020].

Eyre, T., 2020. Lymphoma And The Immune System. [online] Lymphoma Action. Available at: <https://lymphoma-action.org.uk/about-lymphoma-what-lymphoma-immune-system/lymphoma-and-immune-system> [Accessed 30 March 2020].

Irish Cancer Society. 2020. Coronavirus Advice For People Receiving Or Beginning Cancer Treatment. [online] Available at: <https://www.cancer.ie/cancer-information-and-support/coronavirus-and-cancer-info-for-patients-families-volunteers/coronavirus-advice-for-for-people-receiving-cancer-treatment> [Accessed 30 March 2020].

Leukaemia Care. 2020. Leukaemia. [online] Available at: <https://www.leukaemiacare.org.uk/support-and-information/information-about-blood-cancer/blood-cancer-information/leukaemia/> [Accessed 30 March 2020].

Lymphoma Action. 2020. Faqs About COVID-19 And Cancer. [online] Available at: <https://lymphoma-action.org.uk/about-lymphoma-covid-19-and-lymphoma/faqs-about-covid-19-and-cancer> [Accessed 30 March 2020].

Mayoclinic.org. 2020. Chemotherapy. [online] Available at: <https://www.mayoclinic.org/tests-procedures/chemotherapy/about/pac-20385033> [Accessed 30 March 2020].

WebMD. 2020. Lymphoma: Symptoms, Causes, Diagnosis, Treatment. [online] Available at: <https://www.webmd.com/cancer/lymphoma/lymphoma-cancer#1> [Accessed 30 March 2020].