Vaccines did a good job protecting most cancer patients against COVID-19, but those with blood cancers remain at risk for breakthrough infections, new research suggests.
The study analyzed nationwide data on more than 64,000 U.S. cancer patients who were vaccinated against SARS-CoV-2. The researchers looked at types of cancer, key treatments and other risk factors, including age, sex, race, whether patients had other diseases and where they lived.
"This type of analysis is only possible because we have a huge COVID cohort and control cohort," said study leader Jing Su, an assistant professor at Indiana University School of Medicine in Indianapolis.
The U.S. National Institutes of Health COVID database - one of the world's largest - includes more than 12.5 million patients and 4.5 million COVID-19 patients.
The good news: Researchers found that for all types of cancer, patients' risk of breakthrough COVID infection dropped after their second vaccine dose.
But patients with blood cancers - including leukemia, multiple myeloma and lymphoma - were at a higher risk of breakthrough COVID infections than those with solid cancers, the study showed.
And which vaccine patients received mattered.
The Moderna vaccine was more effective than the Pfizer vaccine for patients with blood cancers, especially those with multiple myeloma, the researchers found.
The findings are expected to help guide care of cancer patients who have COVID-19 as well as development of immune-based cancer treatments, Su said. They could predict which patient populations may respond best to certain treatments, including those that rely on a patient's immune capacities.
"In fact, the COVID pandemic provides a unique opportunity for us to screen the immune competence among all cancer patients at a national level," Su said in a university news release. "We could use this to imitate the differential immune capacities among cancer patients. This could guide us to better understand whether cancer patients will have good responses to cancer vaccines and if they are at a higher risk of infection of other viruses, such as the flu."
The investigators, from 10 research institutes across the United States, are now working to answer additional questions about waning immunity and the effectiveness of booster shots.
"With the surging of new variants, especially the BA.2, we don't know whether there will be another wave down the road," Su said. "We are monitoring the situation to see what new variants will mean for cancer patients and how to best protect them through vaccination."
The findings were recently published in the Journal of Clinical Oncology. Other recent research has also focused on vaccine effectiveness in cancer patients.
The U.S. National Cancer Institute has more about COVID vaccines and cancer patients.
SOURCE: Indiana University School of Medicine, news release, April 4, 2022