<prompt> Most common cancer of anus:AdenocarcinomaSquamous cell CABasal cell CAMelanoma  <response>: Ans. b Squamous cell CARef: Sabiston 19th ed. 1405-06B CARCINOMA ANAL CANAL Carcinomas arising proximal to the dentate line pectinate line are known as basaloid,cuboidal, or cloacogenic tumors; about one-third of anal cancers have this histologic pattern. Malignancies arising distal to the pectinate line have squamous histology, ulcerate more frequently, and constitute 55 of anal cancer MC type of CA anal canal: squamous cell CA BCC Melanoma Median age at diagnosis: 60 years MC symptom: Bleeding PR MC site of metastasis: Lung MC site of LN metastasis: Inguinal LNsClinical Features of anal Canal CA Most patients present with rectal bleeding and pain Patients are frequently misdiagnosed as having a benign anorectal condition such as hemorrhoids. Additional symptoms: Incontinence, change in bowel habits, pelvic pain, and rectovaginal or rectovesical fistulas are ominous.Diagnosis: IOC for diagnosis of CA anal canal:Proctoscopy with biopsy.Treatment Nigro regimen: Chemoradiation is the treatment of choice. Chemotherapy regime: 5-FU Mitomycin, Cisplatin More than 80 are cured by chemoradiation. If any residual tumor is left behind after chemoradiation, APR is performed. 