In the wake of the COVID-19 pandemic, healthcare providers and researchers are working to understand the effects of SARS-CoV-2 and vaccination against the virus. Many studies are examining the impact on particular subgroups of patients with cancer.
At the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, a group of researchers from Japan presented findings from a prospective, observational study that explored the efficacy of vaccination against SARS-CoV-2 variants among patients with breast cancer receiving different types of treatments. They also sought to understand the impact of vaccination on cancer treatment continuation.
The study included 85 eligible patients with a median age of 65 years who were vaccinated between May and November 2021. The researchers grouped patients into 5 cohorts based on treatment:
- Those who were not receiving treatment (n = 5)
- Those who were receiving endocrine therapy (n = 30)
- Those who were receiving a CDK4/6 inhibitor (n = 14)
- Those who were receiving chemotherapy (n = 21)
- Those who were receiving anti-HER2 therapy (n = 15)
The researchers collected serum samples before the first vaccination and after the second to measure immunoglobulin levels, as well as neutralizing antibody titers against particular viral variants.
Overall, the study found a 95.3% seroconversion rate of anti-SARS-CoV-2 immunoglobulin. Seroconversion was lower in patients receiving chemotherapy, at 81.8%. Notably, analyses showed that antibody concentration was positively correlated with lymphocyte count before vaccination. The rates of antibodies were highest against wild-type (90.2%), followed by variants alpha (81.7%), delta (96.3%), and kappa (84.1%). Antibody levels against omicron were very low (8.5%).
Only one patient withdrew or postposed treatment due to vaccination.
“Our data support SARS-CoV-2 vaccination for cancer patients being treated with systemic therapy,” wrote the authors, led by Mitsuo Terada, of the Department of Breast Surgery at Nagoya City University Graduate School of Medical Sciences in Aichi, Japan. However, they added, “A decrease in neutralizing antibody titer was suggested [with] chemotherapy and CDK4/6 inhibitor, raising concerns about the impact on long-term infection prevention. For these patients, infection-preventive behaviors should be recommended even after vaccination. They will also be good candidates for booster vaccinations.”