Outcomes of patients with metastatic cutaneous squamous cell carcinoma to the axilla: a multicentre cohort study.

Background: Metastatic cutaneous squamous cell carcinoma to the axilla is uncommon, with limited data to guide management. We sought to assess the outcomes of patients with this condition after surgery and radiotherapy.

Methods: A retrospective cohort study of patients treated at two Australian hospitals from 1994 through 2016 was performed.

Results: A total of 74 patients were identified, including 48 treated curatively with surgery-plus-radiotherapy and 15 with surgery alone. Compared with patients treated with surgery alone, a higher proportion of patients treated with surgery-plus-radiotherapy had lymph nodes larger than 6 cm (53% versus 8%, P = 0.012) and multiple adverse histopathological features (75% versus 47%, P = 0.04). The groups had similar 5-year disease-free survival (45% versus 46%) and overall survival (51% versus 48%). Presence of multiple positive lymph nodes was associated with reduced disease-free survival (hazard ratio 4.57, P = 0.01) and overall survival (hazard ratio 3.53, P = 0.02). Regional recurrence was higher in patients treated with surgery alone (38% versus 22%, P = 0.22) and patients with lymph nodes larger than 6 cm (34% versus 10%, P = 0.03). All recurrences occurred within 2 years following treatment.

Conclusion: Combined-modality therapy for metastatic cutaneous squamous cell carcinoma to the axilla is recommended for high-risk patients, although outcomes remain modest. The key period for recurrence is within 2 years following treatment.