COVID-19 Testing in Asymptomatic Cancer Patients Receiving Cancer Treatment
Based on the recent announcement from the Ministry of Health, asymptomatic cancer patients on treatment are now eligible to be tested for COVID-19.
The Saskatchewan Cancer Agency will phase in testing for asymptomatic cancer patients on treatment as follows:
• Week 1 (May 19): Testing for asymptomatic patients from “areas of concern”. As per Saskatchewan Health Authority outpatient screening guidelines, this test is required for these patients coming to any outpatient facility.
• Week 2: Malignant hematology
• Week 3: Lung cancer
• Week 4: Pause and review processes and outcomes
• Week 5: Head and neck and CNS
• Week 6: Colorectal
Testing will be done 72 hours prior to each chemotherapy cycle x 6 cycles. This will be re-evaluated over time and may be adjusted given the prevalence of COVID in Saskatchewan.
Testing will also be offered to for each patient in the applicable disease site group starting radiation just prior to their CT simulation
Testing for asymptomatic patients (outside of the “areas of concern”) is not mandatory but is recommended based on the information below. Treatment will not be delayed or withheld if patients decline testing.
Testing will begin with the disease site group phased in approach for patients AFTER a discussion with the MRP/clinical associate just prior to their next cycle of systemic therapy or during the discussion to start a new radiation treatment.
The following is an exerpt from CAPCA (Canadian Association of Provincial Cancer Agencies) on asymptomatic testing based on a document produced by Ontario on asymptomatic testing in certain patient populations.
Identifying COVID-19 infected patients is key to risk stratification for treatment decision-making. As asymptomatic patients are often highly infectious in 2-3 days prior to onset of symptoms (Xi H et al), testing would inform the decision to treat or defer, and this can reduce potential complications in patients and reduce infecting other patients and staff in the department.
Rationale for Recommendations
Increased risk for cancer patients:
Ontario Health (Cancer Care Ontario) recognizes the significant risk that the COVID-19 virus poses to immunocompromised patients, including those receiving cancer treatment, as well as the risk of further transmission to others caring for this patient population. This is supported by several findings to date, including:
• In Wuhan, China, Yu et al. (2020) reported that infection rates in cancer patients were more than double the cumulative incidence of all diagnosed COVID-19 cases.
• In Italy, Onder et al. (2020) reported than an estimated 20.3% of COVID-19-related deaths occurred in patients with active cancer.
• Liang et al. (2020) reported COVID-infected cancer patients were observed to have a higher risk of severe events (admission to ICU requiring invasive ventilation, or death) than patients without cancer
• Williams et al. (2020) developed a simple model to estimate the potential harms in patients undergoing chemotherapy during COVID-19. They estimated that the risk of dying is approximately two-fold within the same ages by decade. For example, the absolute mortality increases from 3.3% to 7.9% in the age 60-69 year age group, and from 8.5% to 17% in the age 70-79 year age group in COVID-infected cancer patients undergoing chemotherapy.
The purpose of testing asymptomatic cancer patients is to identify patients who are COVID-19 positive prior to starting on immunosuppressive cancer treatment. If a patient tests positive, then treatment will almost certainly be deferred (exception is most Priority A cases) until they are cleared by the local Infection Control staff.
Proceeding with cancer treatment in patients who are COVID-19 positive exposes patients to developing life threatening complications from a COVID-19 infection. In these cases, treatment should not proceed except in very unusual circumstances where the risks of delay in initiating treatment outweighs the risk of an overwhelming COVID-19 infection developing while on treatment. It is recognized that testing at a moment in time does not ensure that a patient will not subsequently test positive for COVID-19. However, it will allow the patient and oncologist to make the best decision regarding timing of therapy given the benefits of treatment, balanced with the risks of infection.
The guidelines outline a pragmatic approach to testing and are felt to be appropriate for this point in the pandemic. As the prevalence of COVID-19 decreases in the community this will be revisited, and the approach revised as required.