Radiation Therapy

Because of the aggressive nature of MCC, its apparent radiosensitivity, and the high incidence of local and regional recurrences (including in-transit metastases after surgery alone to the primary tumor bed), some clinicians have recommended adjuvant radiation therapy to the primary site and nodal basin. Nodal basin radiation in contiguity with radiation to the primary site has been considered, especially for patients with larger tumors, locally unresectable tumors, close or positive excision margins that cannot be improved by additional surgery, and those with positive regional lymph nodes, especially after SLND (stage II).[10,11,14,15,25][Level of evidence C2] Several small retrospective series have shown that radiation therapy plus adequate surgery improves local-regional control compared with surgery alone,[2,5,26-29] whereas other series did not show the same results.[4,8][Level of evidence C2]

In the absence of adequately powered, prospective, randomized clinical trials, the following questions remain:[4,8,9,12,21,24,26,30-34][Level of evidence C2]

Because of the small size of these nonrandomized retrospective series, the precise benefit from radiation therapy remains unproven.

When recommended, the radiation dose given has been at least 50 Gy to the surgical bed with margins and to the draining regional lymphatics, delivered in 2 Gy fractions. For patients with unresected tumors or tumors with microscopic evidence of spread beyond resected margins, higher doses of 56 Gy to 65 Gy to the primary site have been recommended.[5,10,11,14,15,27,31,35][Level of evidence C2] These doses have not been studied prospectively in clinical trials.

Local and/or regional control of MCC with radiation therapy alone has been reported in small, highly selected, nonrandomized case series of patients with diverse clinical characteristics.[29,36] Typically, these patients have had inoperable primary tumors and/or nodes or were considered medically inappropriate for surgery.[29,36][Level of evidence C2]

Retrospective Surveillance, Epidemiology, and End Results (SEER) Program data suggest that adding radiation therapy to surgery adds survival value, but the conclusions are complicated by incomplete patient data, no protocol for evaluation and treatment, and potential sampling bias.[32] Prospective randomized clinical trials are required to assess whether combining surgery with radiation therapy affects survival.[33,34][Level of evidence C2]