Approach

The most common presenting symptom is rectal bleeding and/or pain, which occurs in 45% of patients. Thirty percent of patients report pain or the sensation of a mass.[3] Anal cancer may also present with itching, discharge, faecal incontinence, fistulae, or a non-healing ulcer.[4] Twenty percent of patients have no rectal symptoms.[3]

Commonly, patients delay consulting their physician, and bleeding is often attributed to haemorrhoids.[3][4] The family physician is usually the first to examine the patient.

History

Key things to ask about in the history include:

  • Anal trauma

  • Haemorrhoids

  • Human papillomavirus (HPV) infection

  • Sexual history, to determine risk of HIV infection

  • A family history of colorectal cancer (although there is no relationship between colorectal cancer and anal cancer, this history is important because rectal bleeding can be related to colorectal cancer).

Physical examination and anoscopy

Given the location of the tumour, physical examination is the most important diagnostic and staging procedure. The physical examination should be focused on the inguinal nodes, a rectal examination, and anoscopy.[4] The superficial inguinal nodes, medial (deep) inguinal nodes, and nodes close to the pubis should be palpated.[4] Most inguinal lymph node metastases are unilateral and ipsilateral to the primary tumour.[18] Female patients should have a gynaecological examination to assess the primary tumour and exclude vaginal invasion or fistula formation.[4] Benign haemorrhoidal bleeding is a diagnosis of exclusion.

The UK National Institute for Health and Care Excellence (NICE) recommends that patients aged 50 years or older, who have unexplained rectal bleeding, should be referred for an urgent (2-week wait) hospital appointment.[31]

Clinicians should consider urgent referral for patients who:[31]

  • Are aged under 50 years and have rectal bleeding with any of the following: abdominal pain, change in bowel habit, weight loss, iron deficiency anaemia

  • Have an unexplained anal mass or anal ulceration

  • Have a rectal mass.

Biopsy

All suspicious anal lesions should be excised or biopsied. Biopsy is essential to confirm the diagnosis.[4]

An incisional biopsy is recommended for diagnosis. Excisional biopsies should be limited to small superficial lesions.

Fine needle aspiration or excisional biopsy of clinically or radiologically enlarged inguinal lymph nodes is recommended.[8] A formal inguinal lymph node dissection is not recommended because of the associated morbidity, its failure to have an impact on outcome, and the high control rates achieved with chemoradiation.[32]

Radiological imaging

High resolution T2-weighted magnetic resonance imaging (MRI) or computed tomography (CT) of the pelvis should be performed to assess the primary tumour and pelvic lymph nodes, and to evaluate whether the tumour involves other organs.[4][8] US guidelines advise using either CT with contrast or MRI with contrast to evaluate the pelvis.[8] European guidelines recommend using MRI pelvis for assessment of the primary tumour and CT pelvis with contrast to screen for metastatic disease.[4] A CT scan of the abdomen and chest should be also performed to screen for metastases.[4][8]

Staging (18F)-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/CT and PET/MRI scans should be considered, in addition to standard diagnostic imaging with CT or MRI.[8] PET/CT has a sensitivity of 99% for the detection of primary disease and a sensitivity of 93% for the detection of inguinal lymph node involvement.[33][34]​​ In one meta-analysis, PET/CT led to a change in nodal staging in 28% of patients.[34]

CT-based simulation is conducted for radiotherapy planning. FDG-PET/CT, FDG-PET/MRI, and MRI pelvis results may also influence planning, in particular dose or field changes.[8][33]

Screening for associated conditions

HIV testing is recommended for patients with anal cancer whose HIV status is unknown, and for people with multifocal or recurrent anal intraepithealial neoplasia.[4][8] Female patients with anal intraepithealial neoplasia or anal cancer should be offered screening for synchronocus cervical epithelial neoplasia, vulvar intraepithealial neoplasia, and vaginal intraepithealial neoplasia, which are also associated with HPV.[4]​​

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