Long-Term Disease Control from Definitive Radiation Therapy for Inoperable Squamous Cell Carcinoma

Granger EE, Kim EY, Karn EE, Groover MK, Silk AW, Margalit DN, Tishler RB, Schoenfeld JD, Ruiz ES. Definitive radiation therapy for inoperable stage III/IV cutaneous squamous cell carcinoma: A single-institution retrospective cohort study. J Am Acad Dermatol. 2024 Jan;90(1):187-189. doi: 10.1016/j.jaad.2023.09.030. Epub 2023 Sep 19. PMID: 37734666.

Near three quarters of patients who experienced a complete clinical response to radiation remained disease-progression free five years following definitive radiation therapy. 

Clinical Pearls

• This retrospective cohort study looked at 29 patients with cutaneous squamous cell carcinoma in-transit metastasis or American Joint Committee on Cancer (AJCC) Eighth Edition Stage III/IV cutaneous squamous cell carcinoma treated with definitive radiation therapy (DRT) at Brigham and Women’s Hospital/Dana-Farber Cancer Institute.

• The 1-, 3-, and 5-year cumulative incidences of disease progression for patients treated with DRT were 24.1%, 35.1%, and 45.9% respectively.

• Near three quarters of patients who experienced a complete clinical response to radiation remained disease-progression free five years following definitive radiation therapy. 

Discussion:

This research letter by Granger et. al aimed to better understand survival outcomes and progression rates following definitive radiation therapy for patients with inoperable cutaneous squamous cell carcinoma (cSCC). Using a retrospective cohort design for all cases of cSCC with in-transit metastasis or AJCC eighth edition stage III/IV cSCC cases treated with definitive radiation therapy (DRT) at Brigham and Women’s Hospital/Dana-Farber Cancer Institute from 2014 to 2020. Of note, all 29 patients included had underwent multi-disciplinary review and had DRT recommended for inoperable disease.

The median overall survival of all 29 patients included was 21 months. The 1-, 3-, and 5-year cumulative incidences of disease progression for all patients were 24.1%, 35.1%, and 45.9%, respectively. Additionally, the 1-, 3-, and 5- year cumulative incidences of disease specific death were found to be 6.9%, 21.9%, and 33.0%, respectively. Interestingly, of the 23 patients who experienced a complete clinical response to radiation, the cumulative incidence of progression was 13.0% at 1 year and 26.9% at 3 and 5 years. This suggests near 75% of tumors which respond to radiation will not progress within 5 years of treatment. Overall, this study, although limited by its sample size, provides valuable data on the utility of definitive radiation therapy for inoperable cSCC.