Management of oligometastatic anal cancer-a literature review and a proposed treatment algorithm

Oligometastatic squamous-cell carcinoma of the anus (omSCCA) is a very rare condition. The literature is sparse, and treatment guidelines are lacking. The aim of the present work was to carry out a literature review and to propose an algorithm for intensified treatment of patients with omSCCA. A PubMed search was carried out, which resulted in 15 relevant publications that included any type of definitive metastasis-directed therapy of mSCCA. All of the studies were retrospective. The local treatments were mostly surgical resections of liver metastases, but also radiofrequency ablation and radiotherapy were used, for metastases located in the liver, lungs, or other organs. The reported median overall survival across the studies ranged from 22 to 53 months. Three of the studies described extended-field chemoradiation of para-aortic lymph node metastases (M1 disease), suggesting long-term survival in up to half of the patients. Taken together, these results indicate that a subset of patients with omSCCA may benefit from a multimodal approach, including definitive metastasis-directed therapy given with curative intent. Based on the literature review and clinical experience, we propose a treatment algorithm, including metastasis-directed treatment as well as chemoradiation and induction chemotherapy. The choice of treatment and sequencing depends on the location and extent of the metastases and whether the metastases are synchronous or metachronous. In the absence of strong evidence, the proposed algorithm should be regarded as a starting point for discussions rather than detailed guidelines. Further studies and international collaborations are needed to optimize the treatment of omSCCA.