Using data from China, two studies suggest that people with cancer are more likely than the general population to contract COVID-19 and to develop more severe disease or die from it.

Two studies analyzing COVID-19 in patients with cancer reveal that they are more likely than the general population to be infected with the virus—and to suffer severe illness and die.

The novel coronavirus SARS-CoV-2 is often more dangerous for older patients and those with certain medical conditions, including diabetes and cardiovascular disease. For example, one study of cases in the United States found that 78% of patients with COVID-19 who were admitted to the intensive care unit (ICU; 358 of 457) and 71% of patients admitted to the hospital but not the ICU (732 of 1,037) had at least one underlying health condition. In contrast, 27% of patients with the illness who did not require hospitalization had an underlying condition (1,388 of 5,143). Patients with cancer are more susceptible to infections, including respiratory infections, but researchers hadn't determined if that's true for COVID-19.

The two studies investigated whether patients with cancer were more likely to contract the illness and to become sicker when they do. In one study, Conghua Xie, MD, of the Zhongnan Hospital of Wuhan University in China, and colleagues analyzed hospital records from December 30, 2019, to February 17, 2020. Of the 1,524 patients with cancer admitted during that period, 0.79% had COVID-19. During the same period, 0.37% of the population of Wuhan was diagnosed with the disease, suggesting that patients with cancer are about twice as likely to become infected.

One explanation is that the patients have suppressed immune systems because of their treatment. However, the researchers found that only 41.7% of the patients were receiving chemotherapy or radiotherapy at the time of their COVID-19 diagnosis. The researchers suggest that frequent visits to the hospital create more opportunities for viral exposure.

In the second study, Wenhua Liang, MD, and Jianxing He, MD, of The First Affiliated Hospital of Guangzhou Medical University, and colleagues collated data from 575 hospitals throughout China. The overall incidence of cancer in China is 0.29%, but the researchers found that 1% of 1,590 patients with COVID-19 had a history of cancer.

On average, the patients with a history of cancer were 14.4 years older and 3.4 times more likely to have smoked than the patients who had never had cancer. The researchers did not detect any differences in the frequency of underlying medical conditions such as diabetes, hypertension, and heart disease. Patients with cancer had more severe infections, and their condition deteriorated faster—and these differences held even when the researchers controlled for factors such as smoking history and age. Overall, 39% of patients with cancer required ventilation in the intensive care unit or died (seven of 18), whereas only 8% of the patients with no history of cancer did (124 of 1,572).

Liang and He aren't sure why patients with cancer seem more vulnerable to COVID-19 and more likely to develop severe symptoms. “However, I believe the compromised immunity due to cancer per se and cancer treatments is the major reason,” says Liang. Patients may have fewer natural killer cells and T cells to destroy SARS-CoV-2–infected cells, Liang hypothesizes, or these protective cells may be less active.

The researchers suggest several strategies could help patients with cancer reduce their risk of infection. When possible, patients should switch from intravenous to oral drugs to cut down on hospital visits. They could also ask about receiving targeted therapies instead of chemotherapy to curtail immune system suppression. –Mitch Leslie