Role of metastasectomy for liver metastasis in stage IV anal cancer

There is a paucity of data on the role of metastasectomy for metastatic anal cancer on survival outcomes. We aim to define the role of metastasectomy in stage IV anal cancer.

National Cancer Database (NCDB) from 2004 to 2014 was accessed to include patients with metastatic anal cancer, excluding adenocarcinoma, neuroendocrine, and 'other' histologies. We compared patients undergoing metastasectomy (n = 165) to those who did not have metastasectomy (n = 2093) by age, sex, cancer grade, and site of metastasis, including metastasis to bone, liver, and lung, using chi-square analysis. The primary outcome was overall survival.

Patients had equal distribution of metastatic sites between those who underwent metastasectomy versus no metastasectomy: bone (7.64% vs 4.85%, p = 0.22), brain (0.24% vs 0%, p = 1.0), liver (23.22% vs 29.70%, p = 0.07), and lung (11.85% vs 9.09%, p = 0.38). Survival following metastasectomy was increased at one year (71% vs. 61%, p = 0.016), two years (50% vs. 38%, p = 0.014), and five years (30% vs. 19%, p = 0.025). Median overall survival was increased (23 months vs. 16 months; p = 0.015) for patients with metastasectomy. Survival increases were demonstrated only in the group with liver metastasis undergoing metastasectomy. When stratifying for liver metastases only, median overall survival time was further increased (34 months vs. 16 months; p < 0.0001) following metastasectomy.

These results demonstrate a survival benefit for hepatic metastasectomy in stage IV anal cancer. Our findings demonstrate a potential survival benefit in highly select patients with metastatic anal cancer to the liver. These findings support further investigation in a randomized clinical trial to delineate these findings.