ASTRO 2020: Adjuvant Radiation Therapy for Stage I Merkel Cell Carcinoma
Posted: Wednesday, November 18, 2020
Adjuvant radiotherapy to primary tumors less than 1 cm after surgery in patients with stage I Merkel cell carcinoma may improve the overall survival of patients with the disease, according to the findings of a large retrospective analysis. In a study carried out by Benjamin Walker Fischer-Valuck, MD, of Winship Cancer Institute of Emory University, Atlanta, and colleagues, this hypothesis was explored. Their findings were presented at the 2020 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 2015).
“Adjuvant radiotherapy should be strongly considered for all patients, even those with tumors less than 1 cm and without adverse features after surgical resection,” said the authors. “On our propensity-matched analysis, we observed improved overall survival with adjuvant radiation.”
Utilizing the National Cancer Database, the investigators searched for new cases of Merkel cell carcinoma diagnosed from 2004 to 2006 in which patients received more than 45 Gy to the primary tumor; they excluded tumors with M1 pathology, positive lymph-vascular space invasion, and treatments involving chemotherapy or immunotherapy. Additionally, patients who died within 2 months of initial diagnosis were not included in the study.
From a total of 1,128 patients, 619 received adjuvant radiotherapy, and 509 underwent observation. The median dose of radiotherapy was 50 Gy, and unadjusted median overall survival for observed patients and those who received adjuvant radiotherapy was 98.5 months and 124.4 months, respectively. Specific factors such as younger age, treatment of the face or at a nonacademic center, and lower comorbidity score independently attributed to the use of radiotherapy (hazard ratio = 0.73). Specifically, both increasing age and higher comorbidity scores were linked to worse overall survival (P < .01). After the investigators adjusted for sex, age, year of diagnosis, and race, this treatment was associated with an improved overall survival rate. Similar results were obtained in the shoulder/upper-limb subgroup as well.
Disclosure: The study authors reported no conflicts of interest.