Patients with cancer who underwent COVID-19 vaccination but did not have SARS-CoV-2 antibody response were at increased risk for breakthrough infection and hospitalization, according to a new study published in JAMA Oncology.
“The results of the National COVID Cancer Antibody Study suggest that COV-S antibody testing can identify patients with cancer who have the lowest level of antibody-derived protection and immunity from SARS-CoV-2 and COVID-19,” the researchers wrote. “Prevention of SARS-CoV-2 infection in these patients should be prioritized to minimize impact on their cancer treatments.”
Researchers in the United Kingdom conducted a population-based cross-sectional study of patients with cancer who had completed SARS-CoV-2 vaccination as part of the National COVID Cancer Antibody Survey. The study included 3555 patients with cancer with 4249 antibody test results. These were compared with antibody tests from 225,272 people without cancer.
Most participants were White (93.72%), and the median age of individuals was in the range of 40-49 years.
Patients with cancer were significantly more likely to have undetectable anti-S antibody responses than the general populations. Among patients with at least two vaccination doses, about 5% of patients with cancer had undetectable responses compared with only 0.13% of those without cancer (P<.001). The lowest antibody titers occurred in patients with leukemia or lymphoma.
A third dose of the vaccination was associated with significantly higher antibody titers as compared with only two doses in the cancer and control groups (P<.001).
Patients with cancer who did not have responses had three times the risk for SARS-CoV-2 breakthrough infection (odds ratio [OR]=3.05; 95% CI, 1.96-4.72; P<.001) and more than six times the risk of SARS-CoV-2-related hospitalization (OR=6.48; 95% CI, 3.31-12.67; P<.001) as compared with those who did have an antibody response to vaccination.
The researchers found that risk for breakthrough infection and hospitalization increased as the antibody titer decreased to below 5,000 U/mL.
“In most countries, SARS-CoV-2 antibody testing is not widely available,” the researchers wrote. “This survey’s results suggest that wider access to antibody testing for individuals with cancer should be evaluated.”