What is Anal Cancer (Squamous Cell Carcinoma of the Anus)

The main type of anal cancer is Squamous Cell Carcinoma of the Anus. The anus is a canal that connects the lower part of the large intestine (rectum) to the outside of the body. It allows the faeces to pass from the large intestine during a bowel movement. Faeces are formed in the longest part of the large intestine (colon), stored in the rectum, and pass through the anus. Squamous cell carcinoma of the anus forms from the lining of the anal canal. They are the most common type of anal cancer.

Statistics on Anal Cancer (Squamous Cell Carcinoma of the Anus)

Anal cancer is fairly rare. In young people anal cancer is more common in men. The average age for anal cancer sufferers is 60 years of age.

Risk Factors for Anal Cancer (Squamous Cell Carcinoma of the Anus)

Many people believe anal cancer is caused by the human papillomavirus (HPV). Predisposing factors include:

Progression of Anal Cancer (Squamous Cell Carcinoma of the Anus)

Anal cancer spreads by local invasion initially, and then via the lymphatics – with inguinal, pelvic, para-aortic and iliac nodes being the most common sites of early anal cancer spread.

Symptoms of Anal Cancer (Squamous Cell Carcinoma of the Anus)

Symptoms may include:

  • Bleeding from the anus;
  • Pain in the anal area;
  • Straining during a bowel movement;
  • Anal itching;
  • Change in bowel habits;
  • Change in the diameter of stool;
  • Abnormal discharge; and
  • Swollen lymph node in the anal or groin areas.

Clinical Examination of Anal Cancer (Squamous Cell Carcinoma of the Anus)

A full physical examination is conducted including a digital rectal examination, where a finger is inserted into the anal canal to identify any abnormalities as well as a pelvic examination.

How is Anal Cancer (Squamous Cell Carcinoma of the Anus) Diagnosed?

Signs of anal cancer are checked through routine blood tests for anaemia and infection.

Prognosis of Anal Cancer (Squamous Cell Carcinoma of the Anus)

Anal cancer prognosis depends upon the size of the anal tumour, where the anal tumour is and whether it has spread to the lymph nodes.

How is Anal Cancer (Squamous Cell Carcinoma of the Anus) Treated?

Anal cancer treatment depends upon the stage of the anal cancer and the level of local and extended involvement. Anal surgery is generally conducted, either local resection or an abdominoperineal resection. Radiotherapy and chemotherapy are employed if the cancer is in any of the later stages.

Chemotherapy for anal cancer typically involves:

  • Mitomycin C 10 mg/m2 IV day 1 only
  • 5-Fluorouracil 800 mg/m2/day continuous infusion days 1-4 and 43-46

Radiotherapy for anal cancer typically involves:

  • Initial phase 4 week 36 Gy
  • A 2 week break
  • Second phase 1/2 to 2 weeks (varies) 14.4-18 Gy (Some radiation oncologists do not have the break. In week 5, 5FU is infused)