# Merkel cell carcinoma: long-term outcomes after radiotherapy treatment

## TL;DR

This study examines the long-term outcomes of Merkel cell carcinoma patients treated with radiotherapy, highlighting high relapse rates and the need for improved monitoring and treatment strategies.

## Contribution

The study provides insights into the effectiveness of radiotherapy and relapse patterns in a rare and aggressive cancer.

## Key findings

- 29% of patients relapsed after a mean follow-up of 44 months.
- Relapses were primarily locoregional and occurred outside the radiotherapy field.
- Early relapse was associated with poor outcomes, suggesting a need for treatment intensification.

## Abstract

Merkel cell carcinoma (MCC) is a rare, aggressive disease with high relapse and fatality rates. Radiotherapy (RT) is essential for local control, but published data on both initial treatment and relapse management remain limited.

We retrospectively analyzed 17 patients treated in a single-center with radical and adjuvant RT.

After a mean follow-up of 44 months, five (29%) patients relapsed (mean time to relapse 5.8 months after RT). Four relapses were locoregional, occurring outside the RT field, and received local salvatge therapy. One relapse was distant. Three patients received up to three consecutive RT courses for locoregional progression without systemic therapy. Five (29%) patients died after a mean time of 35.2 months, four of them with active disease. Two deaths were due to disease progression.

Despite optimal local treatment, relapse remains common and is linked to poor outcomes, such as distant progression and death. Our findings reinforce the need for close postoperative monitoring and early initiation of adjuvant RT. Outcomes after early relapse suggest a potential role for treatment intensification.