Postoperative radiation therapy is associated with a reduced risk of local recurrence among low risk Merkel cell carcinomas of the head and neck

Abstract

PurposeMerkel cell carcinoma (MCC) is a rare and often aggressive skin cancer. Typically, surgery is the primary treatment. Postoperative radiation therapy (PORT) is often recommended to improve local control. It is unclear whether PORT is indicated in patients with favorable Stage IA head and neck (HN) MCC.Methods and materialsWe conducted a retrospective analysis of 46 low-risk HN MCC cases treated between 2006 and 2015. Inclusion criteria were defined as a primary tumor size of ≤ 2 cm, negative pathological margins, negative sentinel lymph node biopsy, and no immunosuppression. Local recurrence (LR) was defined as tumor recurrence within 2 cm of the primary surgical bed and estimated with the Kaplan-Meier method.ResultsOmission of PORT was offered to all 46 patients, of which 23 patients received PORT and 23 did not. No patient received adjuvant chemotherapy. There were no significant differences in surgical margins, tumor size, depth, lympho-vascular invasion status, or demographics between the two patient groups. Median follow-up for all patients was 3.7 years. Six of the 23 patients who did not receive PORT developed an LR. Compared to the group that received PORT, there was a significantly higher risk of LR in the group treated without PORT (26% vs. 0%, P = .02). Median time to LR was 11 months. All local failures were effectively salvaged. There was no difference in MCC-specific and overall survival between the 2 groups.ConclusionsFor patients with HN MCC, omission of PORT was associated with a significantly higher risk of local recurrence even among those patients with the lowest-risk tumors (i.e., Stage IA without immune suppression). Thus, it is important to weigh the benefits of PORT against the side effect profile on a case-specific basis for each patient.

Merkel Cell Carcinoma: Therapeutic Update and Emerging Therapies

“…Adjuvant RT to the tumor bed for local control after wide excision may be associated with lower recurrences [ 54 ], although the benefits to overall survival remain controversial. An analysis of 185 patients with localized MCC and margin-negative excision found that adjuvant radiation to the surgical bed did not improve the rate of local control [ 38 ].…”

Management Recommendations for Merkel Cell Carcinoma—A Danish Perspective

“…These include small primary tumors (≤1 cm diameter), negative margin status, no LVI, negative SLNB and no chronic immunosuppression (i.e., lymphoma/leukemia) [18,19,36]. In a small retrospective study on patients with low-risk head-and-neck primary tumors, adjuvant RT was associated with increased local control without a survival benefit [37]. Since all recurrences were salvaged by radiotherapy, adjuvant RT should not routinely be recommended for this patient subgroup but discussed per case.…”

Postoperative, Single-Fraction Radiation Therapy in Merkel Cell Carcinoma of the Head and Neck

“… 1 MCC patients have a high (approximately >30%) risk for locoregional recurrences and distant metastases after resection. 2 , 3 , 4 , 5 , 6 For patients who have localized disease with clinically negative draining lymph nodes (American Joint Committee on Cancer [AJCC] eighth edition stage I-IIIA), initial treatment typically consists of wide excision of the primary tumor and sentinel lymph node biopsy (SLNB). 7 Surgery is then often followed by adjuvant conventionally fractionated postoperative radiation therapy (cPORT) (50 Gy in 25 fractions).…”

“…7 Surgery is then often followed by adjuvant conventionally fractionated postoperative radiation therapy (cPORT) (50 Gy in 25 fractions). 2 , 3 , 4 , 5 , 6 , 8 …”

“…For patients with MCC of the head and neck (H&N), cPORT provides a locoregional control benefit over observation alone, even among the most favorable low-risk cases. 3 , 4 However, acute toxicity in the sensitive regions of the H&N can be substantial (eg, skin erythema and desquamation, painful mucositis, xerostomia, altered taste, anorexia, weight loss). In addition, patients often face logistical challenges in attending a protracted course of radiation therapy (RT) for 5 weeks.…”