In Regard to Soyfer et al.

Three cases of radiation recall phenomenon (RRP) after COVID-19 vaccination have been reported in the International Journal of Radiation Oncology, Biology, Physics. All reported cases to date have followed the first or second dose in the vaccination series and have had a 5- to 7-day onset after vaccination. Within our practice, we observed a case of a delayed radiation recall reaction 28 days after the third dose of the Pfizer BioNTech vaccine.

Soyfer et al described 2 patients developing RRP dermatitis after their second dose of Pfizer-BioNTech; 1 patient experienced RRP 5 days after their second vaccination and 66 days after their most recent radiation therapy (RT), and the other experienced RRP 6 days after vaccination and 22 days after RT. Stewart and McDowell described RRP dermatitis after the AstraZeneca vector vaccine, with rapid onset3 hours after the first dose and occurring 6 months after RT. Additional cases have been reported: Afacan et al reported a case of RRP dermatitis 5 days after initial inoculation with Sinovac and 27 months after RT, and Steber et al noted RRP pneumonitis 3 days after initial vaccination with the Moderna mRNA vaccine, approximately 8 months after RT. The SARS-CoV-2 virus itself may induce similar effects: Kurosaki et al, for instance, have reported an RRP pneumonitis coinciding with COVID-19 infection, 3.5 years after initial RT.

Our patient is a 46-year-old female who received 60 Gy (RBE) in 30 fractions of adjuvant proton irradiation (Fig. 1 ) with concurrent cisplatin for American Joint Committee on Cancer 8 pT1N1 p16 tonsillar squamous cell carcinoma, completing treatment June 14, 2021 (Fig. 2 ). She previously received Pfizer-BioNTech vaccination on March 5, 2021, and March 26, 2021, and received her booster vaccine on September 9, 2021. On 3-month follow-up in late September, she exhibited minimal toxicity, with only xerostomia and mild thrush noted. She experienced a dermatitis flare on her neck on October 7 (28 days after dose 3) after 1 day of low-grade fever, nausea, vomiting, and joint pain. Skin cultures were negative, and she was diagnosed with radiation dermatitis (Fig. 1b-f). She was begun on a 2-week oral steroid regimen.

Fig. 1

(a) Radiation treatment plan, 60 Gy (RBE-1.1) in 30 fractions proton radiation, with (b-f) resultant radiation recall phenomenon skin changes noted.

Fig. 2

Patient treatment time course.

Case reports with RRP remain limited, although both dermatitis and pneumonitis have been seen after a range of SARS-CoV-2 vaccinations, timing, and tumor histologies. This case appears to be the first involving RRP after booster vaccination for SARS-CoV-2 and the first report involving proton irradiation, with delayed development of RRP after vaccination.