- Incidence: 2.50 cases per 100,000 person-years
- Peak incidence: 60-70 years
- Sex ratio: more common in females 2:1
- HPV infection causes 80-85% of SSCs of the anus (usually HPV16 or HPV18 subtypes).
- Anal intercourse and a high lifetime number of sexual partners increases the risk of HPV infection.
- Men who have sex with men have a higher risk of anal cancer.
- Those with HIV and those taking immunosuppressive medication for HIV are at a greater risk of anal carcinoma.
- Women with a history of cervical cancer or cervical intraepithelial neoplasia (CIN) are also at greater risk of anal cancer.
- Immunosuppressive drugs used in transplant recipients increase the risk of anal cancer.
- Smoking is also a risk factor.
- Perianal pain, perianal bleeding
- A palpable lesion
- Faecal incontinence
- A neglected tumour in a female may present with a rectovaginal fistula.
Consider a suspected cancer pathway referral (for an appointment within 2 weeks) for anal cancer in people with an unexplained anal mass or unexplained anal ulceration.
- T stage assessment: examination, including a digital rectal examination, anoscopic examination with biopsy, and palpation of the inguinal nodes
- Imaging modalities: CT, MRI, endo-anal ultrasound and PET
- The patient should be tested for relevant infections, including HIV
The following is a T stage system for anal cancer described by the American Joint Committee on Cancer and the International Union Against Cancer:
|TX||primary tumour cannot be assessed|
|T0||no evidence of primary tumour|
|Tis||carcinoma in situ|
|T1||tumour 2 cm or less in greatest dimension|
|T2||tumour more than 2 cm but not more than 5 cm in greatest dimension|
|T3||tumour more than 5 cm in greatest dimension|
|T4||tumour of any size that invades adjacent organ(s) - for example, vagina, urethra, bladder (direct invasion of the rectal wall, perirectal skin, subcutaneous tissue, or the sphincter muscle(s) - is not classified as T4)|