Most common cancer of anus:

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.