Are certain cancer patients more vulnerable to severe cases of COVID-19, the disease caused by the coronavirus? And do certain procedures and cancer therapies put people being treated for cancer at higher risk of COVID-19 complications? These are some of the questions oncology clinicians have asked since the start of the COVID-19 pandemic.

Answering these questions will help medical professionals identify and protect the cancer patients who are at greatest risk of COVID-19 complications and death. Data, including international registry data on outcomes among cancer patients with COVID-19, are already emerging, but more information on cancer patient outcomes is needed, experts say.

New York City has had a massive COVID-19 outbreak compared to other cities in the U.S., with a peak of just under 600 deaths per day documented on April 7, 2020, and a total of 210,523 positive coronavirus cases as of June 25, 2020. Clinicians at the Manhattan-based Memorial Sloan Kettering Cancer Center (MSK) saw hundreds of cancer patients infected with the coronavirus during the peak of New York City’s pandemic.

“We were hit very, very hard in late March and early April and were among the first cancer centers in the United States that treated a large number of COVID-infected cancer patients,” says Tobias Hohl, an infectious disease specialist and researcher at MSK. Hohl and his colleagues published a paper June 24 in Nature Medicine describing their experience caring for 423 cancer patients infected with the coronavirus who had COVID-19 symptoms and sought care at MSK between March 10 and April 7.

One hundred and sixty-eight of the 423 patients were hospitalized and 40 (9%) required invasive mechanical ventilation for severe respiratory illness. A total of 51, or 12%, of the patients died, including 24% (41 of 168) of the patients who were admitted to the hospital. Of the 423 patients, 234 were over the age of 60 and seven were pediatric patients. All of the pediatric patients had mild COVID-19 cases without complications, echoing findings from another study of 20 children with cancer and COVID-19 also treated at MSK. The earlier study, published May 13, 2020, in JAMA Oncology, found that just one pediatric patient required noncritical hospital care due to COVID-19 and that children with cancer generally had mild COVID-19 cases.

In the new Nature Medicine paper, the researchers found that patients who were a race other than white, had a blood cancer diagnosis or were treated with an immune checkpoint inhibitor within 90 days of developing COVID-19 symptoms were more likely to be hospitalized. Patients who had some combination of corticosteroid use and chronically depleted white blood cells—a measure of immunosuppression—were also at greater risk of hospitalization. Those who had taken an immune checkpoint inhibitor or who were older than 65 years of age were also more likely to have severe respiratory illness. In contrast, patients who had undergone major surgery or had received chemotherapy within 30 days of their COVID-19 diagnosis were not at higher risk of COVID-19 complications. “These are important data that tell us that, at our center, neither surgery nor chemotherapy puts our patients at higher risk for bad COVID-19 outcomes,” says Hohl.

For Hohl, the link between treatment with a checkpoint inhibitor and more severe COVID-19 seen at MSK is something that should be explored. But because the numbers of patients were relatively few, and also because a U.K. observational study​ did not find the same link, the results are not enough to change practice. “Cancer patients should be treated with the best possible therapy for their cancer as the prognosis of their cancer is significantly worse than the prognosis of their potential COVID-19 disease,” says Hohl.

“The connection of checkpoint inhibitor therapy with COVID-19 severity in this current analysis should be studied further but doesn’t mean​ that cancer patients right now shouldn’t receive that treatment,” says Catherine Liu, an infectious disease specialist and researcher at the Fred Hutchinson Cancer Research Center and Seattle Cancer Care Alliance.

For Kieren Marr, an oncology infectious disease specialist at Johns Hopkins University in Baltimore, the data offer a unique snapshot of the outcomes of coronavirus-infected cancer patients at a center that experienced a surge of COVID-19 cases. “Even with similar types of cancer patients, there are differences in the type of management possible when a cancer center is flooded with COVID cases,” says Marr.

Jeffrey Martin, an epidemiologist at the University of California, San Francisco, cautions that the analysis does not include a direct comparator population of individuals without cancer and excluded cancer patients who tested positive for the coronavirus but who were asymptomatic at the time. “Patients with cancer are older and have more comorbid conditions than those without cancer, so poorer COVID-19 outcomes in patients with cancer may simply be due to older age and greater prevalence of comorbid conditions. Excluding the asymptomatic patients also means that the overall incidence of poor outcomes that the authors estimated is inflated,” says Martin.

According to Martin, this early New York City experience stressed the health care system and COVID-19 treatment options may have been limited during that time and so may not easily generalize to other geographies—although, as the authors of the study note, critical care resources were never in short supply at MSK. “I would hope that this paper does not further persuade anyone to delay any aspect of cancer prevention or treatment,” Martin says.

Hohl says there is much more work to be done to understand what clinical and other factors, including those related to the immune system, might determine who gets severely ill if infected with the coronavirus. “The sooner we understand if a cancer patient is likely to get very sick, the more swiftly we can intervene with treatment that is likely to help,” he says.​ 

Anna Azvolinsky is a science writer living in New York City.​

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