Systematic review of survival following liver or lung metastasectomy for metastatic anal squamous cell carcinoma

Introduction: Metastatic anal squamous cell carcinoma (SCC) carries a poor prognosis and the evidence base for surgical resection of metastases remains limited. The aim of this study was to establish the survival outcomes for patients undergoing metastasectomy for anal SCC.

Methods: A systematic review was performed using the MEDLINE^®, Embase^®, Cochrane and PubMed^® databases. Studies were considered for inclusion in the review if they involved patients aged >18 years with a diagnosis of stage IV anal SCC who underwent metastasectomy for liver and/or lung metastases. The primary outcome measure was overall survival. Secondary outcome measures were disease free survival, early morbidity according to the Clavien-Dindo classification and quality of life, measured using a validated scoring tool. Risk of bias was assessed with the ROBINS-I (Risk Of Bias In Non-randomised Studies - of Interventions) tool.

Results: There were 10 studies with a total of 98 patients. There was heterogeneity in results reporting, with recurrence free survival the most reported outcome. For all studies reporting on liver metastasectomy, the one-year overall survival rate was 87%. In studies with adequate follow-up reported, the three and five-year overall survival rates were 53% and 38% respectively. Only one study reported on lung metastasectomy patients; the overall median survival was 24 months. None of the studies reported on quality of life measures. The ROBINS-I tool identified a critical risk of bias in six studies, a serious risk in one study and a moderate risk in three studies.

Conclusions: The evidence base for metastasectomy in metastatic anal SCC is limited. Further information is required to inform future treatment methods and use of a standardised outcomes reporting method is needed to support this.