Postoperative Radiation Therapy Is Indicated for “Low-Risk” Pathologic Stage I Merkel Cell Carcinoma of the Head and Neck Region but Not for Other Locations
January 17, 2024
Advances in Radiation Oncology
January 17, 2024
Doctors often differ on whether patients with low-risk MCC should have radiation therapy after surgery. To help find an answer, researchers studied 147 patients with low-risk MCC, meaning their tumor was small, hadn’t spread anywhere else, and they had healthy immune systems. Among them, 79 got radiation after surgery and 68 had only surgery. The researchers focused on finding out if radiation therapy could decrease the chances of cancer coming back in the same area, a ‘local’ recurrence. The study found that having radiation after surgery lowered the risk of the cancer coming back specifically for MCC tumors on the head and neck. But for MCC tumors in other parts of the body, there wasn’t a difference in the risk of the cancer coming back whether radiation therapy was given or not. This study provides valuable insights to doctors, indicating that for low-risk MCC in the head and neck, post-surgery radiation can reduce the risk of local recurrence. However, it is less beneficial for low-risk MCC located in other parts of the body.
The role of postoperative radiation therapy (PORT) in early stage Merkel cell carcinoma (MCC) is controversial. We analyzed the role of PORT in preventing local recurrences (LR) among patients with low-risk, pathologic stage I MCC based on the location of the primary tumors: head/neck (HN) versus non-HN sites.
Methods and Materials
One hundred forty-seven patients with MCC were identified that had “low risk” disease (pathologic T1 primary tumor, negative microscopic margins, negative pathologic node status, no immunosuppression or prior systemic therapy). LR was defined as tumor recurrence within 2 cm of the primary surgical bed, and its frequency was estimated with the cumulative incidence method.
Seventy-nine patients received PORT (30 HN, 49 non-HN) with a median dose of 50 Gy (range, 8-64 Gy) and 68 patients were treated with surgery alone (30 HN, 38 non-HN). Overall, PORT was associated with a decreased risk of LR (5-year rate: 0% vs 9.5%; P = .004) with 6 LRs observed in the surgery alone group. Although the addition of PORT significantly reduced LR rates among patients with HN MCC (0% vs. 21%; P = .034), no LRs were observed in patients with non-HN MCC managed with surgery alone. There was no significant difference in MCC-specific survival comparing HN versus non-HN groups, with or without PORT.
For low-risk, pathologic stage I MCC of the extremities and trunk, excellent local control rates were achieved with surgery, and PORT is not indicated. However, PORT was associated with a significant reduction in LRs among low-risk MCC of the HN.