Chinese doctors have cast doubt on an early COVID-19 study that suggested patients with a history of cancer are more susceptible to the virus than the general population. They posit instead that smoking and interrupted cancer treatment may be confounders.

Findings from the nationwide study of 1590 COVID-19 cases from 500 hospitals in China, published in the Lancet Oncology last month, identified 18 patients with a history of cancer, which “seems to be higher than the incidence of cancer in the overall Chinese population”.

The authors noted that this small subset of patients with cancer were observed to have a higher risk of severe events, including requirement for invasive ventilation and death.

They found that 39% (seven of the 18 patients) experienced these severe outcomes, compared with 8% (124 of 1572 non-cancer patients).