COVID-19 Risk Factors – Cancer

There are certain factors that put particular groups of people at higher risk of experiencing severe disease if infected by SARS CoV-2. Click here for an overview.

The association between non-communicable disorders (NCDs) and more severe COVID-19 symptoms is consistent worldwide; those with underlying NCDs are more vulnerable to experiencing severe complications following infection with SARS CoV-2. 

Some of the most prevalent NCDs include type 2 diabetes, hypertension, cardiovascular disease, chronic lung conditions, chronic kidney disease, chronic liver disease, and cancer. 

This article covers cancer.

Why does having cancer put you in a high risk category?

There are two reasons why cancer patients may fall into a high risk category: depending on the type of cancer they have, it may directly compromise the ability of their immune system to fight infection; alternatively the treatment they are on might weaken the immune system.

All cancer patients are vulnerable at this time, but some are considered to be particularly so. These include:

• Patients currently undergoing chemotherapy.
• Patients undergoing radical radiotherapy for lung cancer.
• Those with cancers of the blood or bone marrow (at any stage of treatment).
• Patients undergoing immunotherapy.
• Those undergoing targeted cancer treatment that affects the immune system.
• Anyone who has had a bone marrow or stem cell transplant in the past six months and/or is still taking immuno-suppressive medications.  

If you fall into any of the above categories it is particularly important that you self-isolate and reduce your infection risk.

Blood cancers

Blood cancer is caused by a dysfunction in white or red blood cell production from the bone marrow or lymph nodes. Leukaemia, lymphoma, and myeloma are white blood cell cancers. The white blood cells normally fight infections, and if they are dysfunctional, your body is less able to fight infections efficiently.

Polycythemia vera is a rare cancer and a type of red blood cell cancer. The red blood cells help to carry oxygen to the rest of your body. 

Having any cancer of the blood puts you at a higher risk of experiencing severe symptoms once infected with SARS CoV-2.

Other cancers

Cancers that affect the major organs, such as the lungs, kidneys, or liver also place individuals at a higher risk, as those organs are unable to function properly if malignant. The fact that COVID-19 is a respiratory disease means that those with compromised lungs, are more likely to suffer severe symptoms if infected.

Cancer treatment 

One of the most widely used treatments for cancer is chemotherapy. Chemotherapeutic agents work by destroying rapidly growing cells by damaging the DNA and preventing cell division. This mechanism of action means that chemotherapy also attacks healthy cells of the body, particularly those that are rapidly dividing such as the stem cells of the bone marrow. These stem cells are responsible for providing a continuous supply of disease-fighting, white blood cells. During and immediately after chemotherapy, a reduced white blood cell count means that your body is less able to defend itself from infection and illness. 

Patients who undergo stem cell transplants are immunosuppressed. Whilst this is necessary to prevent their bodies from rejecting the transplant, it does make them more susceptible to infection. Even under normal circumstances a transplant recipient will be expected to adhere to fairly stringent physical and social isolation prior to and immediately after their procedure. With the added complication of COVID-19, additional precautionary steps will be implemented. You should self-isolate at home for 14 days before your operation and once in hospital you will be placed in protective isolation to reduce the risk of infection. If you test positive for SARS CoV-2, your transplant will be delayed by at least 14 days and ideally until your lung function has improved. Where possible, planned transplants are deferred; however, this is a treatment often reserved for those who are refractory for other therapies, meaning they have advanced disease and are at higher risk of disease progression and therefore, delaying treatment may not be in the patient’s best interest. 

Compared with other types of cancer treatment, radiotherapy can be relatively safely delivered with fewer effects on the systemic immune system. For this reason, it may become the treatment of choice for some cancer patients during this time, reducing the likelihood of further compromising of the immune system. Your doctor is still likely to want to weigh up the benefit of immediate treatment versus the risk of virus exposure before recommending a course of therapy. Stereotactic radiotherapy might be an option; this involves fewer doses than conventional radiotherapy.  

Some patients may feel anxious about visiting a clinic for treatment during these times. Whilst stringent cleaning and sterilising procedures will be in place, if you are anxious talk to your oncologist. If your disease is stable you may be able to delay treatment until the threat of COVID-19 is reduced. If, however, your disease is progressive, aggressive or metastatic the likely benefits of receiving treatment will almost certainly outweigh the risks of catching COVID-19.

The great unknown

As with most things related to COVID-19, we have a lot more to find out. Small scale studies have found that those with cancer have a higher risk of requiring intensive care following SARS CoV-2 infection. However, the urgency in getting data has meant sample sizes were small and the long-term effects of the association are impossible to measure.

It has been suggested that some cancer therapies may actually exert a protective effect, for example, low dose radiotherapy to the lungs. This is a very preliminary suggestion, but is a topic that warrants further work. 

I have cancer, what should I do?

Those with a current cancer diagnosis are strongly advised to implement stringent social distancing and adopt thorough personal hygiene measures. 

Keep in regular contact with your oncologist and health care team, as they will be able to provide you with the most up-to-date information and guidelines. Keep taking any prescribed medications and if you would rather not leave the house, ask friends and family to collect supplies and essentials for you.