In an Italian single-center study reported in a letter in The Lancet Oncology, Scoccianti et al found that patients who underwent radiotherapy for cancer within the 6 months prior to receipt of the Moderna mRNA-1273 COVID-19 vaccine did not experience a difference in adverse reactions to the vaccine compared with vaccinated healthy volunteers.
As stated by the investigators, “Because radiotherapy might affect the immune system by both suppressing and enhancing the immune response, the safety of the COVID-19 vaccines might be different in this specific setting…. Therefore, data on the tolerability of COVID-19 vaccines in this population might be of interest to radiation oncologists because there is a paucity of data to help in patient counseling.”
The study included 153 patients with cancer from Santa Maria Annunziata Hospital, Azienda USL Toscana Centro, Florence, and a reference cohort of 185 emergency medical services worker volunteers without cancer from the same institution. Patients were to receive two doses of the vaccine 28 days apart, with volunteers being vaccinated during the same period.
Patients who had received systemic treatment in the prior 6 months were excluded from the study. Radiotherapy was ongoing in 27% of patients and had been completed in the previous 3 and 6 months for 28% and 45%, respectively.
In summary, our data, although based on a small number of patients and limited by the observational nature of the study, showed that the safety profile of the Moderna mRNA-1273 vaccine does not raise any specific concerns in patients with cancer who received radiotherapy in the past 6 months.— Scoccianti et al
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No early adverse events were experienced after the first and second doses in 33% and 38% of the radiotherapy group vs 25% and 25% of the control group.
For early adverse events, grade 1 events after the first and second dose occurred in 58% and 41% of the radiotherapy group vs 72% and 41% of the control group. Grade 2 adverse events occurred in 5% and 26% vs 4% and 42% (P = .46 for first dose, P = 1.00 for second dose). Grade 3 events occurred in 1% and 4% vs 1% and 10% (P = .45, P =.99); the most common were fever (3%) after the second dose in the radiotherapy group and fever (5%) after the second dose in the control group. Grade 4 events (all fever in both groups) occurred in 0% and 4% vs 0% and 5% (P = .73 after second dose).
For late adverse events—defined as those occurring within 28 days after each dose—grade 2 events after the first and second dose occurred in 0% and 1% of the radiotherapy group vs 1% and 2% in the control group (P = .82, P = .72). Grade 3 events occurred in 4% and 0% vs 2% and 1% (P = .17, P = .82). All grade 3 events in the radiotherapy group were injection site reactions; those in the control group consisted of two cases of axillary lymphadenopathy and one case each of injection site reaction and low blood pressure. No grade 4 adverse events were observed.
The investigators concluded, “In summary, our data, although based on a small number of patients and limited by the observational nature of the study, showed that the safety profile of the Moderna mRNA-1273 vaccine does not raise any specific concerns in patients with cancer who received radiotherapy in the past 6 months.”
Silvia Scoccianti, MD, of Santa Maria Annunziata Hospital, Department of Oncology, Azienda USL Toscana Centro, Florence, is the corresponding author for The Lancet Oncology article.
Disclosure: For full disclosures of the study authors, visit thelancet.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.