Radiotherapy for Merkel Cell Carcinoma of the Skin

We examine the impact of radiotherapy in the treatment of Merkel cell carcinoma (MCC) of the skin. Data at two Canadian institutions (Allan Blair Cancer Centre and London Regional Cancer Program) were collected and charts were retrieved from the registry of 1987 to 2005. A total of 79 patients with definite MCC were studied. All except three had a primary skin lesion. Six patients presented with nodal metastases and three patients with distant metastases. Fourteen patients were referred to the cancer centers at the time of recurrence: 2/14 with local recurrence, 8/14 with nodal recurrence, 2/14 with both local and nodal recurrence, and 2/14 with distant recurrence. The series consisted of 40 males and 39 females with a median age of 80 years (range 48-94). The median follow up was 21 months (range 0.5-150.4). Twenty-two patients (group A) received radiotherapy at the time of presentation,21 being post-operative adjuvant treatment and one being primary treatment without surgery. The 5-year cause-specific survival rate (CSSR) was 42%. The 5-year rates equals the 10-year rate since the CSSR plateaus at a survival of 4.5 years and thereafter, patients died from causes other than MCC. The 5-year overall survival rate (OSR) was 19% for group A. Fifty-seven patients (group B) had surgery alone without post-operative adjuvant radiotherapy. 5-year and 10-year CSSRs were both 63% (P=0.8, using the logrank test when comparing the two groups of patients). The 5-year OSR was 30% and the 10-year OSR was 13% (P=0.6, group A versus group B). Morbidity from radiotherapy was minimal. Only one patient with an ankle lesion did not take the skin graft well and had drainage for one year before healing. One patient had lymphoedema of the arm (which required a pressure garment) after axillary dissection and radiotherapy of 50 Gy in 25 fractions over 35 days. Radiotherapy after surgical excision is well tolerated. It is recommended if there are high risk factors for recurrence and radiotherapy should be started as soon as possible after referral