(B34) Examining the risk of COVID-19 among cancer patients and comparing it with the Swedish general population: A register-based cohort study within the SCIFI-PEARL project

Publication Number: 645

Background: Cancer patients are considered a high-risk group for severe COVID-19 outcomes due to their underlying medical condition, treatments, and weakened immune systems.

Objectives: We examined the risk of COVID-19 outcomes on cancer patients in terms of COVID-19-related infection as well as hospitalization, intensive care unit (ICU) admission, and cause-specific death using the linked nationwide Swedish register database SCIFI-PEARL (Swedish Covid-19 Investigation for Future Insights – a Population Epidemiology Approach using Register Linkage).

Methods: In this nationwide cohort study, we identified patients with a primary cancer diagnosis between 1 Jan 2015 and 31 Dec 2019 from the National Cancer Register. Follow-up was from 1 Jan 2020 to 31 Dec 2022. Outcome information on positive COVID-19 infection, hospitalization, ICU admission, and COVID-19-related death was obtained from national registers, such as positive SARS-CoV-2 tests from the national infection reporting register, outpatient and hospitalized inpatient specialist care from the National Patient Register, ICU admissions from the Swedish Intensive Care Register and mortality from the Cause of Death register.

Cox regression was used for each outcome to estimate hazard ratios, adjusted (aHR) for prior comorbidities and sociodemographic characteristics, including eg information regarding nursing home residence.

Results: The study population comprised 10,390,479 individuals. Among 594,789 individuals with cancer, 51,120 COVID-19 infections, 12,329 hospitalizations, 1,025 ICU admissions, and 4,388 deaths occurred.

There was an association between cancer overall and increased risk of hospitalization (aHR=1.42, 95%CI 1.36-1.48), ICU admission (1.07, 0.95-1.21), and death (2.16, 1.87-2.5) and decreased risk of COVID-19 infection (0.95, 0.94 - 0.97).
Respiratory cancer patients had the highest risk of hospitalization (2.50, 2.12–2.94) and death (5.36, 3.78–7.59). Conversely, breast and prostate cancer were associated with a lower risk for both outcomes (eg aHR for death 0.57, 0.36-0.91 and 0.48, 0.35-0.69, respectively). No substantial risk increase or decrease was observed for the remaining cancer types.

Conclusions: Our results indicated a moderately decreased risk of COVID-19 infection among cancer patients, potentially due partly to successful shielding of this vulnerable group. Increased risks for severe outcomes, however, indicated that their impaired health status made them vulnerable to severe COVID-19. Higher risk was observed in respiratory cancer, as anticipated. The lower risk in breast and prostate cancer patients was surprising, but may be related to relatively good prognosis for these cancers and reflect that the cancer sites are not target organs of SARS-COV-2.