Background
Retrospective single-institution series (MD Anderson Cancer Center) of head and neck Merkel cell carcinoma (MCC). MCC of the H&N accounts for ~40–50% of all MCC and carries distinct management considerations (parotid/cervical drainage, proximity to critical structures). Analysis of local control, regional control, and survival in a large institutional cohort treated with surgery ± RT.
Interventions and follow up
Arm A: Surgery ± adjuvant RT to primary site and regional lymph node
Arm B: N/A — retrospective single-arm serie
Primary endpoint: Local control, regional control, disease-specific survival
mFollow up: Not specified
Arm B: N/A — retrospective single-arm serie
Primary endpoint: Local control, regional control, disease-specific survival
mFollow up: Not specified
Results
Local Control (with adjuvant RT): >90%
Regional Control: Improved with adjuvant nodal RT vs. surgery alone
Disease-Specific Survival: Stage-dependent; H&N MCC outcomes comparable to overall MCC data
Parotid involvement: High-risk feature; RT to parotid basin + cervical nodes recommended
Regional Control: Improved with adjuvant nodal RT vs. surgery alone
Disease-Specific Survival: Stage-dependent; H&N MCC outcomes comparable to overall MCC data
Parotid involvement: High-risk feature; RT to parotid basin + cervical nodes recommended
Adverse events
Main adverse events: H&N RT: mucositis, xerostomia, skin desquamation; neck fibrosis; potential for lymphedema in treated cervical basins. IMRT reduces salivary gland dose for parotid-region targets. Acceptable toxicity in this institutional series.
Conclusions
Adjuvant RT achieves excellent local and regional control in H&N MCC. Comprehensive nodal irradiation (parotid + cervical levels) is recommended for H&N MCC given the proximity of parotid drainage and multiple at-risk nodal basins. Results support routine adjuvant RT for H&N MCC after surgery.
Key Limitations
Key Limitations: Retrospective; heterogeneous treatment approaches over long accrual; predates avelumab/pembrolizumab systemic options; small cohort limits subgroup analysis; no standardized RT volumes across treating physicians.
Clinical Context
H&N MCC has distinct anatomic drainage patterns (parotid, facial, occipital nodes) requiring comprehensive nodal planning. Current NCCN guidelines recommend adjuvant RT for all MCC, with RT to the primary site and regional nodes. The emergence of avelumab (anti-PD-L1) for metastatic MCC has opened questions about combining immunotherapy with RT in the adjuvant setting.
References