[8] Anal Cancer Flashcards
How common is anal cancer?
Relatively rare - accounts for about 4% of colorectal cancers
What are the types of anal cancer?
Squamous cell carcinomass Adenocarcinomas Melanomas and anal skin cancers
What % of anal cancers are squamous cell carcinomas?
About 80%
Where do squamous cell anal cancers arise?
Below the dentate line
What % of anal cancers are adenocarcinomas?
About 10%
Where do anal adenocarcinomas arise?
From the upper anal canal epithelium and the crypt glands
What may precede the development of invasive squamous anal carcinoma?
Anal intraepithelial neoplasia (AIN)
Where does anal intraepithelial neoplasia affect?
Either the perianal skin or anal canal
What is AIN strongly linked to?
Infection with HPV
What is the grading of AIN dependant on?
The degree of cytological atypia, and hte depth of that atypia in the epidermis
What is considered to be high-grade AIN?
Grade 2 and 3
What is the clinical relevance of high grade AIN?
It is pre-malignant, and may progress to invasive cancer
What are the risk factors for the development of anal cancer?
HPV infection HIV infection Increasing age Smoking Immunosuppressant medication Crohn’s disease
What % of cases of anal cancer are accounted for by HPV infection?
80-90%
Which HPV viruses in particular increase the risk of HPV infection?
HPV-16 and HPV-18
What are the main symptoms of anal cancer?
Pain and rectal bleeding Anal discharge Pruritis Palpable mass
What % of patients with anal cancer have pain and rectal bleeding?
About 50%
What features can be seen in locally invasive anal cancer?
Perianal infection Fistula-in-ano
What feature may be present if the anal sphincters are invaded in anal cancer?
Faecal incontinence Tenesmus
What should be done on examination in suspected anal cancer?
Screen perineum and perianal region for any ulceration or the presence of wart-like lesions
What needs to be done in women with suspected anal cancer?
A vaginal examination is important, to assess for the presence of additional vulval or vaginal lesions
Should a DRE be done in anal cancer?
It should be attempted, however may not always be possible due to pain
What should be done if a mass is palpable on DRE?
You should remember to document the distance from the anal verge where it is fely, and the fraction of the anal circumference which it occupies
Which lymph nodes should be examined when suspecting anal cancer?
Inguinal lymph nodes
Which area drains into the superficial inguinal lymph nodes?
The area below the dentate line
Which lymph nodes to the anal canal and rectum above the dentate line drain into?
The mesorectal, para-aortic, and paravertebral nodes
What can the differential diagnoses for any anal pathology be divided into?
Benign and malignant
What are the benign differentials for anal cancer?
Haemorrhoids Anal fissure Fistula-in-ano Anal warts
What are the malignant differentials for anal cancer?
Low rectal cancer Skin cancer
What initial investigations may be done in suspected anal cancer?
Proctoscopy Examination under anaesthetic Smear test for women HIV testing
What is the purpose of proctoscopy in suspected anal cancer?
To obtain a better initial assessment of the anal canal
What is the purpose of examination under anaesthesia in patients with suspected anal cancer?
It allows for much better assessment for tumour size and invasion of local structures Allows for a biopsy to be taken for histological confirmation
When should a HIV test be considered in suspected anal cancer?
If you suspected immunosuppression on a background of high risk behaviour
Why may a smear test be done in women with suspected anal cancer?
To exclude any cervical intraepithelial neoplasia
What should be done if signs of vulval intraepithelial neoplasia are present?
Further biopsies
What should be done once a biopsy has been taken and anal cancer has been confirmed?
Further staging investigations
What staging investigations are done in anal cancer?
USS-guided Fine Needle Aspiration (FNA) CT thorax-abdomen-pelvis MRI pelvis
What is biopsied using USS-guided FNA in anal cancer?
Any palpable inguinal lymph nodes
What is the purpose of a CT thorax-abdomen-pelvis in anal cancer staging?
Look for distant mets
What is the purpose of a MRI pelvis in anal cancer staging?
To assess the extent of local invasion (T stage)
Who needs to be included in the MDT for the management of anal cancer?
Oncologists General surgeons Radiologists Specialist nurses
What is the first choice treatment of anal cancer?
Chemo-radiotherapy
What chemo-radiotherapy treatment is usually given in anal cancer?
External beam radiotherapy to the anal canal and inguinal lymph nodes, combined with dual-chemotherapy agents,
Give an example of dual-chemotherapy agents used in chemotherapy in anal cancer?
Mitomycin C and 5-flurouracil
What is an exception to chemo-radiotherapy being the treatment of choice in anal cancer?
In early T1N0 carcinomas, where wide local excision may be the preferred treatment
Why might wide local excision be preferred to chemo-radiotherapy in early T1N0 anal cancers?
To avoid the increased morbidity associated with chemo-radiotherapy
When is surgical excision used in anal cancer?
It is usually reserved for management of advanced disease, after failure of chemo-radiotherapy, or in early T1N0 carcinoams
What are the surgical options for management of anal cancer?
Abdominoperineal resection Posterior or total pelvic exenteration
What surgical management option is used for the majority of patients with anal cancer requiring surgical intervention?
Abdominoperineal resection
When do most recurrences of anal cancer occur?
In the first 3 years
What should be done after remission for anal cancer?
Patients should be reviewed every 3-6 months for a period of 2 years, and 6-12 monthly after 5 years
What pattern of relapse tends to occur in anal cancer?
They tend to relapse locally and regionally, rather than metastasise
What is the most common short-term complication of anal cancer treatment?
Chemoradiation-related pelvic toxicity
What symptoms may develop from chemoradiation-related pelvic toxicity?
Dermatitis Diarrhoea Proctitis and cystitis Leucopenia Thrombocytopenia
What longer term complications may result from anal cancer and its treatment?
Fertility issues Faecal incontinence Vaginal dryness Erectile dysfunction Rectovaginal fistula
What is prognosis related to in anal cancer?
The initial staging of the tumour and lymph node spread
