In an analysis from the retrospective OnCovid registry study reported in The Lancet Oncology, David J. Pinato, PhD, and colleagues detailed outcomes of the SARS­–CoV-2 omicron variant outbreak among European patients with cancer.

David J. Pinato, PhD

Study Details

The analysis included 3,473 patients with cancer from sites in the United Kingdom, Italy, Spain, France, Belgium, and Germany diagnosed with COVID-19 between February 27, 2020, and January 31, 2022. Outcomes were assessed in phases consisting of:

• Prevaccination phase (from February 27 to November 30, 2020)
• Alpha-delta variant phase (from December 1, 2020, to December 14, 2021)
• Omicron phase (from December 15, 2021, to January 31, 2022).

Key Findings

Among the 3,473 patients, 2,033 (58.5%) were diagnosed with COVID-19 during the prevaccination phase, 1,075 (31.0%) during the alpha-delta phase, and 365 (10.5%) during the omicron phase. Among patients with known vaccination status diagnosed during the omicron phase, 113 (33.3%) of 339 were fully vaccinated and 165 (48.7%) were boosted. Among those diagnosed during the alpha-delta phase, 152 (16.6%) of 915 were fully vaccinated and 21 (2.3%) were boosted.

Patients diagnosed during the omicron phase had improved 14-day (P < .0001) and 28-day case-fatality rates (P < .0001), as well as reduced COVID-19 hospitalizations (P < .0001) and complications (P < .0001). They also had a reduced need for COVID-19-specific therapy (P < .0001) and oxygen therapy (P < .0001) compared with those diagnosed in the alpha-delta phase and prevaccination phase.

In analysis adjusting for country, sex, age, comorbidities, tumor stage, tumor status, and receipt of systemic anticancer therapy at the time of COVID-19 diagnosis, compared with patients diagnosed during the prevaccination phase, those diagnosed during the omicron phase had a lower case-fatality rate at 14 days (adjusted odds ratio [OR] = 0.32, 95% confidence interval [CI] = 0.19–0.61) and 28 days (adjusted OR = 0.34, 95% CI = 0.16–0.79), lower risks of COVID-19 complications (adjusted OR = 0.26, 95% CI = 0.17–0.46) and hospitalization due to COVID-19 (adjusted OR = 0.17, 95% CI = 0.09–0.32), and reduced requirement for COVID-19–specific therapy (adjusted OR = 0.22, 95% CI =  0.15–0.34) and oxygen therapy (adjusted OR = 0.24, 95% CI = 0.14–0.43).  

By comparison, adjusted odds ratios for patients diagnosed during the alpha-delta phase vs the prevaccination phase were 0.49 for case-fatality rate at 14 days and 0.70 for rate at 28 days; 0.76 for COVID-19 complications and 0.56 for hospitalization due to COVID-19; and 0.53 for requirement for COVID-19–specific therapy and 0.64 for oxygen therapy.

Compared with unvaccinated patients diagnosed during the alpha-delta phase, those diagnosed during the omicron phase had similar crude case-fatality rates at 14 days (25% vs 17%) and at 28 days (27% vs 28%) and similar rates of hospitalization due to COVID-19 (43% vs 41%) and complications from COVID-19 (31% vs 36%).

The investigators concluded, “Despite time-dependent improvements in outcomes reported in the omicron phase compared with the earlier phases of the pandemic, patients with cancer remain highly susceptible to SARS–CoV-2 if they are not vaccinated against SARS–CoV-2. Our findings support universal vaccination of patients with cancer as a protective measure against morbidity and mortality from COVID-19.”

Alessio Cortellini, PhD, of the Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, is the corresponding author for The Lancet Oncology article.

Disclosure: The study was funded by the National Institute for Health and Care Research Imperial Biomedical Research Centre and the Cancer Treatment and Research Trust. For full disclosures of the study authors, visit thelancet.com.