Science Series #11: COVID-19 and Cancer

The COVID-19 pandemic has affected the entire world in a drastic way, leading to over 3 million deaths and 132 million confirmed cases of infection. Unfortunately, some individuals, such as cancer patients, are more susceptible to catching the virus than others and are at a higher risk of severe infection.

(Source: WHO, National Cancer Institute)

What is COVID-19?

COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. The symptoms include respiratory symptoms, fever, cough, fatigue, loss of taste and smell, shortness of breath, and difficulty breathing, usually lasting between 2-14 days. In more severe cases, it may cause pneumonia, severe acute respiratory symptoms, kidney failure, and death. The virus is mainly spread from person-to-person by close contact, through exposure to respiratory droplets produced by coughing or sneezing. These droplets cause infection when they enter the mucous membranes of the suspetable individual present inside the nose or mouth. People who are asymptomatic, meaning showing no symptoms, may also spread the virus. Around 80% of infected people suffer from mild to moderate respiratory symptoms such as a cold and mailgia and don’t require the need of hospital treatment. However, around 15% of individuals who are above the age of 60 or have underlying medical conditions develop severe complications. Currently, genetic variants are emerging across the globe as the virus keeps rapidly mutating.

(Source: World Health Organization, Center for Disease Control and Prevention)

Cancer and the Severity of COVID-19 symptoms

Active cancer patients have an increased risk of severe infection due to their weakened immune system by cancer and its treatments. This is because the certain types of cancer may alter the way the immune system blood cells work, or tumors in mucus membranes may allow the passage of the virus. Cancer treatments such as surgery, chemotherapy, immunotherapy and bone marrow transplants can also influence the way the immune system works as most of them damage the immune system cells and cause immune weakness. Additionally, cancer patients with poor nutrition due to cancer itself-which causes difficulty in digestion- or treatments that cause loss of appetite, may have a weakened immune system, increasing their risk of developing severe complications. The main factors linked to the increased susceptibility of cancer patients include: the male sex, age above 60, a history of smoking, obesity, hypertension, cardiovascular disease, and diabetes.

Preliminary studies suggested that patients with lung and hematological cancers or who have undergone treatment in the past month were at a higher risk of developing severe symptoms. However, some recent studies dispute this according to the Centers for Disease Control and Prevention (CDC), proving that there is no correlation between the type of cancer, time of treatment, and the increased risk of death. Another study that evaluated 22,900 Veterans Affairs patients with a history of cancer found that those who have received recent cancer therapy had a lower prevalence of COVID-19 and had similar death occurrences compared to individuals without cancer. Some studies also have shown that hematologic cancer patients are at a higher risk of prolonged infection compared to solid tumor cancer patients considering the abnormal and depleted immune cells which produce antibodies against the virus. Due to the relatively new nature of the virus and the limited data available, the influence of COVID-19 on cancer patients is currently being extensively studied and information regarding the subject matter is constantly being modified.

The National Cancer Institute is conducting a natural history study on 2,000 patients who are undergoing cancer treatment and have contracted COVID-19, and will follow up with the patients after two years to examine the effects of the virus on cancer.

(Source:  Center for Disease Control and Prevention, National Cancer Institute, American Cancer Society)

COVID-19 impact on cancer incidence

COVID-19 has impacted more than our biological health, causing secondary consequences such as the inability to attain access to cancer treatment facilities. In order to divert healthcare resources to treat COVID-19 patients and to protect cancer patients from possible risk of infection, various organizations such as the American Cancer Society recommended the suspension of non-urgent health care practices such as cancer screenings and treatment. However, this had an adverse effect, as although statistically there was a short-term decrease in cancer diagnoses, this was primarily due to the fact that patients were unable to undergo the testing procedures.

Studies suggest that there was a 52% decline in breast cancer diagnosis values during March 1 and April 18 2020 compared to January 6, 2019 and February 29, 2020. Another study analyzing US healthcare institutions found that more than 28 million people reported that patient encounters regarding new cancer diagnosis decreased by approximately 40-50% in April 2020 compared to April 2019. The effect of the decline in cancer incidence has become a prevalent issue worldwide.

(Source: Center for Disease Control and Prevention)

COVID-19 impact on cancer treatment and mortality

As a result of the lack of screening, there was a sharp increase in late cancer diagnoses and preventable cancer deaths. The inaccessibility to cancer treatment facilities led to the delay in treatment regimen plans and an increase in cancer mortality rates. According to a study conducted by American Cancer Society, 79% of patients in active treatment reported a delay in their care in May of 2020. Additionally, 70% of patients in active treatment reported that their anti-cancer treatments such as chemotherapy and hormone therapy have been affected due to the pandemic. Consequently, the inaccessibility to treatment led to the increase of cancer mortality. The National Cancer Institute predicts a 1% increase in the mortality rates of breast and colorectal cancer patients over the next 10 years, which translates to an increase by 10,000 deaths due to the pandemics impact on screening and treatment. In England, a similar study predicted that cancer diagnosis delays would result in an increase in cancer deaths ranging from 5% for lung cancer patients and 15% for colorectal cancer. Many organizations began adjusting treatment protocols to adhere to the COVID-19 guidelines.

The European Society of Medical Oncology recommended the continuation of treatment for patients with potentially curable cancer according to existing guidelines, such as the use of systemic therapies. For vulnerable patients, they recommended the use of supportive measures for individuals receiving treatments with side effects of high immunosuppression in addition to adjusting chemotherapy regimen to diminish the number of clinical visits. Some cancer patients have transitioned to oral medicines instead of going in for infusions, including bone-strengthening treatments and intravenous iron supplementation.

(Source: Center for Disease Control and Prevention, American Cancer Society, National Cancer Institute, Cancer.Net)  

COVID-19 vaccination and cancer

The CDC and the National Comprehensive Cancer Network (NCCN) recommend that patients with cancer or a history of cancer are a high priority group for vaccination since data proved that they are at a higher risk of developing severe COVID-19 complications. Despite the positive findings of COVID-19 vaccine trials suggesting the safety and efficacy of the vaccine on people with underlying medical conditions, these trials unfortunately did not include cancer patients. There is a possibility that immunosuppressed patients may have a weaker response to the vaccine. Hence, cancer patients undergoing active treatments that suppress the immune system such as chemotherapy, stem cell, and bone marrow transplant are advised to consult their doctors on whether to take the vaccine, as some would suggest waiting for at least three months for immune system recovery. This is due to the data from previous vaccines that suggest the limited efficacy during this time when patients are mostly immunosuppressed.

Prior to taking the COVID-19 vaccine, it is important to consider the type of vaccine, the cancer the patient is diagnosed with or had, if they are undergoing treatment and the proper functioning of the immune system. It is best to consult the doctor or medical expert before getting any vaccine, and it is recommended to not interrupt the treatment in order to get the vaccine, as the vaccine does not affect the cancer treatment. Research is currently being conducted to study the vaccine efficacy in patients who had bone marrow transplants and on groups who have blood cancers in order to determine their responses to the vaccine. It is extremely important for caregivers of those with cancer, prioritize taking the vaccine in order to protect the patient, since it would decrease the caregiver’s risk of developing symptomatic infections that allow the transmission of the virus.

Currently, there is no evidence that recommends a certain vaccine over the other for cancer patients. Generally, live virus vaccines are not recommended for cancer patients, yet the current COVD-19 vaccines do not contain these types of live viruses. Most experts advise cancer patients to take the vaccine once it is available to them after considering the various factors and consulting their doctor. Due to the uncertainty about the development of an immune response against the virus, it is recommended that immunocompromised patients with cancer who have been vaccinated still follow the guidelines and take necessary precautions to protect themselves from the virus exposure.

(Source: National Cancer Institute, American Cancer Society, American Society of Clinical Oncology)

COVID-19 vaccine and breast cancer

Studies suggest that the COVID-19 vaccine may cause temporary swelling of the lymph nodes in the armpits. Due to the fact that this side effect may be mistaken as a sign of breast cancer, oncology specialists recommend that people wait 4-6 weeks after completing the COVID-19 vaccination before undergoing a mammography. Doctors also recommended that patients with breast cancer or a history of breast cancer take the vaccine on the opposite side of the breast cancer.

(Source: American Society of Clinical Oncology, American Cancer Society)

COVID-19 and cancer clinical trails

The pandemic has additionally affected cancer clinical trials, and led to the halting and decentralization of about 60% of cancer research programs that required screening or enrollment in clinical trials. According to, there are currently 1,130 total trials that have been stopped due to COVID-19, Additionally, the research resources became allocated for COVID-19 studies, which have reached a value of 5,090 registered clinical trails in April 2021. The US Federal agencies enacted new regulations to support decentralized clinical trials in the hopes of increasing patient access and participation.

(Source:, Center for Disease Control and Prevention, Cancer Research Institute)

How to protect yourself from catching COVID-19 if you are a cancer patient

Due to the fact that cancer patients are more susceptible to developing severe symptoms and complications, it is necessary to take the proper precautions to protect themselves. Such precautions include: shielding, limited contact with others, practicing social distancing, regular hand washing and sanitation.  

(Source: World Health Organization, Cancer Research UK)

Terms of use          Privacy policy