Anal Cancer Flashcards
Epidemiology
Relatively rare
4% of colorectal cancer
1 in 100000
Types of anal cancer
SCC arising from below the dentate line
Rest are adenocarcinomas from upper anal canal epithelium and crypt glands
Rarer than that are melanomas an anal skin cancers
What pre-cancerous condition is related to anal cancer?
Anal intraepithelial neoplasia (AIN) which may precede SCC
Explan AIN
Precancerous condition that affect either the perianal skin or anal canal
Linked to SCC and strongly linked with HPV
Grading of AIN
Dependent of degree of cytological atypia and depth of atypia into the epidermis.
High grade AIN (2 or 3) is considered premalignant and can cause invasive cancer.
Risk factors
HPV infection (HPV-16 and 18) and accounts for 80-90% of cases
HIV infection
Increasing age
Smoking
Immunosuppression
Crohn’s disease
Clinical features
Rectal pain or rectal bleeding
Anal discharge
Pruritus
Palpable mass
Perianal infection and fistula-in-ano can be seen in locally invasive disease as well
Faecal incontinence
Tenesmus
Examination findings
Ulceration
Wart-like lesions
PR examination to see if there is any mass. This should be documented along with its distance from the anal verge and proportion of anal circumference.
Check for lymphadenopathy
What does lymph from below the dentate line drain to?
Superficial inguinal nodes
Where does lymph from above dentate line drain to?
Mesorectal
Para-aortic
Paravertebral
Dx
Haemorrhoids
Anal fissures
Fistula-in-ano
Anal warts
Low rectal cancer
Skin cancer
Initial investigations
Proctoscopy under anaesthetic
Biopsy for histology
In women smear test to exclude CIN ca be done and to see for any signs of vulval intraepithelial neoplasia as well (VIN)
Consider HIV test
Once diagnosis has been confirmed by biopsy what should be done?
Imaging
Imaging
USS-guided Fine needle aspiration of any palpable inguinal lymph nodes
CT chest-abdo-pelvis for metastases
MRI pelvis to assess extent of local invasion (T-stage)
General management
MDT approach with oncologist, general surgeons, radiologist and specialist nurses
What is first choice treatment?
Chemo-radiotherapy via external beam radiotherapy to anal canal and inguinal LN with dual chemo (mitomycin C and 5-fluorouracil)
When is chemoradiation not first line?
T1N0 carcinomas
Wide local excision is used instead
Indications for surgical management
Advanced disease after failure of chemoradiation
T1N0 carcinomas as well
Types of surgical management
Usually done by abdominalperineal resection (APR)
Sometimes posterior or total pelvic exenteration is required instead
Post-op management
Review every 3-6 months for a period of 2 years
Most recurrences occur in the first 3 years following surgery
Relapse usualyl happens locally and regionally
Complications
Chemoradiation-related pelvic toxicity which can present with dermatitis, diarrhoea, proctitis and/or cystitis
Long term -> fertility issues, faecal incontinence, vaginal dryness, ED, rectovaginal fistula.
What is prognosis related to?
Initial staging of the tumour
