A Prospective, Open-Label, Multi-center Comparison of Lymphoseek Identified Lymph Nodes and Clinically Identified Lymph Nodes of Subjects With Known Cancer of the Anus

Inclusion Criteria: * Subject has provided written informed consent with Health Insurance Portability and Accountability Act of 1996 (HIPAA) authorization * Has histologically confirmed squamous cell carcinoma of the anus (anal canal or perianus) * Has a documented clinical stage using the tumor, lymph node, metastasis staging (TNM) classification system that was established by at least physical exam with manual palpation, digital anorectal examination, high-resolution anoscopy and PET/CT imaging evaluation of the bilateral inguinal area * Is at least 18 years of age at the time of consent * Has an Eastern Cooperative Oncology Group (ECOG) performance status of Grade 0 to 3 * If of childbearing potential, the subject has a negative pregnancy test within 48 hours before administration of Lymphoseek, has been surgically sterilized, or has been postmenopausal for at least 1 year Exclusion Criteria: * The subject has had radiation therapy, chemotherapy or immunotherapy within the 30 days prior to Lymphoseek administration * Has had previous surgery or node dissection (exclusive of fine needle aspiration) or radiation to node basins that would be involved in the intraoperative lymphatic mapping procedure * Has a known allergy to dextran * Is breast-feeding or pregnant * Before the administration of Lymphoseek, has received any radiopharmaceutical within 7 radioactive half-lives of that radiopharmaceutical * Has received an investigational product within the 30 days prior to Lymphoseek administration