Sentinel Lymph Node Biopsy Associated With Survival Advantage in Merkel Cell Carcinoma
In patients with Merkel cell carcinoma, sentinel lymph node biopsy was shown to be associated with improved survival, according to the results of a retrospective study reported by Kachare et al in the Annals of Surgical Oncology. Thus, sentinel lymph node biopsy offers prognostic information that may be of value in selecting appropriate adjuvant therapy.
Study Details
Sentinel lymph node biopsy has been suggested by some clinicians for staging patients with Merkel cell carcinoma. To determine the prognostic value of sentinel lymph node biopsy in patients with Merkel cell carcinoma, the investigators analyzed the medical records of 1,193 patients from the Surveillance, Epidemiology, and End Results registry. Patients were assigned to one of two cohorts: those who received wide local excision with sentinel lymph node biopsy (n = 474) and those who underwent wide local excision with nodal observation (n = 719).
Eligible patients had stage I or stage II Merkel cell carcinoma. Most patients were white, male, and had received radiation therapy. The mean age of patients was 78 years. There was no significant difference in gender (P = .44) or race (P = .78) between the two cohorts.
Patients with unknown stage of Merkel cell carcinoma and patients with metastatic disease were excluded from the study, as were patients who received an immediate lymphadenectomy or had unknown nodal treatment.
The median follow-up of the sentinel node biopsy patient population was 21 months, compared with 24 months for the observation patient population. In addition, patients were analyzed for tumor stage and prior treatment interventions, such as radiation therapy and completion lymph node dissection. In total, 35% of the patients who had a positive sentinel lymph node biopsy had previously received radiation therapy and a completion lymph node dissection.
Better Survival Rate With Sentinel Lymph Node Biopsy
Translated over a 5-year period, patients in the sentinel lymph node group had a significantly better survival rate (79.2%) than did patients in the observation group (73.8%; P = .004). Patients in the sentinel lymph node group had a nodal positivity rate of 24.3%; the majority (64.4%) of patients in this group had just one involved node.
Subgroup analysis indicated that survival rates among female patients were higher than in male patients (83.2% vs 70.4%; P = .0004). In addition, improved survival was noted in patients with stage I tumors (81%) compared with patients with stage II tumors (62.8%; P < .0001). As for associated mortality, patients in the observation group had a higher mortality rate than did patients in the sentinel lymph node group.
Clinical Implications
The investigators concluded that sentinel lymph node biopsy is associated with a significant improvement in Merkel cell carcinoma–specific survival compared with wide local excision alone. This improvement in survival associated with sentinel lymph node biopsy may be due to interventions such as completion lymph node dissection and/or nodal irradiation.
Based on these study results, they suggested that patients with Merkel cell carcinoma, except for those with nodal metastases, be considered for sentinel lymph node biopsy. This intervention may be of value in determining appropriate adjuvant therapy.
The investigators remarked, “To the best of our knowledge, this is the first study to demonstrate that the early diagnosis of clinically occult nodal disease by sentinel node biopsy may be associated with a therapeutic advantage in Merkel cell carcinoma–specific survival.”
Timothy L. Fitzgerald, MD, of the Division of Surgical Oncology, East Carolina University, Greenville, North Carolina, is the corresponding author of the article in the Annals of Surgical Oncology.
The authors disclosed no potential conflicts of interest.
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