A single dose of neoadjuvant radiation for Merkel cell carcinoma: Complete pathologic response with minimal morbidity in a rapidly growing lesion of the eye

Merkelcell.org Summary

Merkel cell carcinoma (MCC) is usually treated with surgery, followed by radiation therapy. Traditional radiation is given in small doses over 20–30 visits. Researchers are now studying a newer option called single-fraction radiation therapy, where a higher dose of radiation is given in just one visit. This approach is more convenient and may cause fewer side effects.

This paper describes a patient with a large MCC tumor near his eye. The tumor was growing quickly, and surgery right away could have damaged his eyesight. Doctors never expected one dose of radiation to remove all of the cancer, but they hoped it would shrink the tumor and make surgery safer. So, the patient first received a single dose of radiation.

Two weeks after radiation, the tumor was no longer visible on the skin. Scans were encouraging but still showed a small lump under the skin, so surgery was done as planned. Surprisingly, when doctors examined the tissue removed during surgery under a microscope, they found no living cancer cells left. This was unexpected, as the radiation was meant only to shrink the tumor, not completely eliminate it. After surgery, the patient received one more single dose of radiation to kill any possible remaining cancer cells.
The patient did very well overall and continues to do well today, two years since treatment. He kept his vision, had no major side effects, and his MCC has not returned. This case suggests that for fast-growing tumors or tumors in sensitive areas, such as near the eye, giving a single dose of radiation before surgery may help make treatment safer and more effective. However, radiation given before surgery, especially single-fraction radiation, has not yet been studied in large clinical trials. More research is needed, and patients should carefully discuss their options with MCC specialists.

Abstract

Merkel cell carcinoma (MCC) is a rare skin cancer with an increasing incidence of ∼ 3000 new cases/year in the U.S. and a 40% risk of recurrence. Standard management for locoregional disease is excision and sentinel lymph node biopsy (SLNB), followed by radiotherapy (RT).

Single-fraction radiotherapy (SFRT) has been studied for treatment of painful/large MCC metastases with one 8 gray fraction. SFRT is currently being explored in both adjuvant and palliative settings. To the best of our knowledge, neoadjuvant/preoperative RT has not been described in MCC.

This case demonstrates the potential utility of neoadjuvant SFRT for MCC arising rapidly in a functionally critical location such as near the eye. This patient experienced a complete pathologic response following SFRT, highlighting the remarkable radiosensitivity of MCC, documented by surgical excision of the tumor bed 3 weeks later.