Anal Cancer

Question 1

Epidemiology

Answer 1

Relatively rare

4% of colorectal cancer

1 in 100000

Question 2

Types of anal cancer

Answer 2

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

Question 3

What pre-cancerous condition is related to anal cancer?

Answer 3

Anal intraepithelial neoplasia (AIN) which may precede SCC

Question 4

Explan AIN

Answer 4

Precancerous condition that affect either the perianal skin or anal canal

Linked to SCC and strongly linked with HPV

Question 5

Grading of AIN

Answer 5

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.

Question 6

Risk factors

Answer 6

HPV infection (HPV-16 and 18) and accounts for 80-90% of cases

HIV infection

Increasing age

Smoking

Immunosuppression

Crohn’s disease

Question 7

Clinical features

Answer 7

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

Question 8

Examination findings

Answer 8

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

Question 9

What does lymph from below the dentate line drain to?

Answer 9

Superficial inguinal nodes

Question 10

Where does lymph from above dentate line drain to?

Answer 10

Mesorectal

Para-aortic

Paravertebral

Question 11

Dx

Answer 11

Haemorrhoids

Anal fissures

Fistula-in-ano

Anal warts

Low rectal cancer

Skin cancer

Question 12

Initial investigations

Answer 12

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

Question 13

Once diagnosis has been confirmed by biopsy what should be done?

Answer 13

Imaging

Question 14

Imaging

Answer 14

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)

Question 15

General management

Answer 15

MDT approach with oncologist, general surgeons, radiologist and specialist nurses

Question 16

What is first choice treatment?

Answer 16

Chemo-radiotherapy via external beam radiotherapy to anal canal and inguinal LN with dual chemo (mitomycin C and 5-fluorouracil)

Question 17

When is chemoradiation not first line?

Answer 17

T1N0 carcinomas

Wide local excision is used instead

Question 18

Indications for surgical management

Answer 18

Advanced disease after failure of chemoradiation

T1N0 carcinomas as well

Question 19

Types of surgical management

Answer 19

Usually done by abdominalperineal resection (APR)

Sometimes posterior or total pelvic exenteration is required instead

Question 20

Post-op management

Answer 20

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

Question 21

Complications

Answer 21

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.

Question 22

What is prognosis related to?

Answer 22

Initial staging of the tumour