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Asymptomatic screening for COVID-19 in cancer patients still debated



Asymptomatic screening of cancer patients receiving anticancer therapy detected a very low rate of COVID-19 in a retrospective study.

Of more than 2,000 patients, less than 1% were found to be COVID-19 positive on asymptomatic screening, an investigator reported at the AACR Virtual Meeting: COVID-19 and Cancer (Abstract S09-04).

While several models have been proposed to screen for COVID-19 among cancer patients, the optimal strategy remains unknown, said investigator Justin A. Shaya, MD, of the University of California, San Diego.

The most commonly used approach is symptom/exposure-based screening and testing. However, other models have combined this method with polymerase chain reaction (PCR) testing for asymptomatic high-risk patients (such as those undergoing bone marrow transplant, receiving chemotherapy, or with hematologic malignancies) or with PCR testing for all asymptomatic cancer patients.

Dr. Shaya’s institution implemented a novel COVID-19 screening protocol for cancer patients receiving infusional anticancer therapy in May 2020.

The protocol required SARS-CoV-2 PCR testing for asymptomatic patients 24-96 hours prior to infusion. However, testing was only required before the administration of anticancer therapy. Infusion visits for supportive care interventions did not require previsit testing.

The researchers retrospectively analyzed data from patients with active cancer receiving infusional anticancer therapy who had at least one asymptomatic SARS-CoV-2 PCR test between June 1 and Dec. 1, 2020. The primary outcome was the rate of COVID-19 positivity among asymptomatic patients.


Among 2,202 patients identified, 21 (0.95%) were found to be COVID-19 positive on asymptomatic screening. Most of these patients (90.5%) had solid tumors, but two (9.5%) had hematologic malignancies.

With respect to treatment, 16 patients (76.2%) received cytotoxic chemotherapy, 2 (9.5%) received targeted therapy, 1 (4.7%) received immunotherapy, and 2 (9.5%) were on a clinical trial.

At a median follow-up of 174 days from a positive PCR test (range, 55-223 days), only two patients (9.5%) developed COVID-related symptoms. Both patients had acute leukemia, and one required hospitalization for COVID-related complications.

In the COVID-19–positive cohort, 20 (95.2%) patients had their anticancer therapy delayed or deferred, with a median delay of 21 days (range, 7-77 days).

In the overall cohort, an additional 26 patients (1.2%) developed symptomatic COVID-19 during the study period.

“These results are particularly interesting because they come from a high-quality center that sees a large number of patients,” said Solange Peters, MD, PhD, of the University of Lausanne (Switzerland), who was not involved in this study.

“As they suggest, it is still a debate on how efficient routine screening is, asking the question whether we’re really detecting COVID-19 infection in our patients. Of course, it depends on the time and environment,” Dr. Peters added.

Dr. Shaya acknowledged that the small sample size was a key limitation of the study. Thus, the results may not be generalizable to other regions.

“One of the most striking things is that asymptomatic patients suffer very few consequences of COVID-19 infection, except for patients with hematologic malignancies,” Dr. Shaya said during a live discussion. “The majority of our patients had solid tumors and failed to develop any signs/symptoms of COVID infection.

“Routine screening provides a lot of security, and our institution is big enough to allow for it, and it seems our teams enjoy the fact of knowing the COVID status for each patient,” he continued.

Dr. Shaya and Dr. Peters disclosed no conflicts of interest. No funding sources were reported in the presentation.

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