Colorectal cancer is currently the third most common cancer and the fourth most common cause of cancer-related deaths (1).
There are approximately 41,000 new cases of colorectal cancer in the United Kingdom every year (2013-2015).
The National Cancer Institute’s database quotes the five-year relative survival rate for stage I rectal cancer to be 88%,
dropping to 81% for stage IIa disease and 58% for stage IIIc disease.
Trends toward earlier diagnosis due to screening
Bowel screening programmes for colorectal cancer are in place throughout the world.
In England,
bowel screening is currently offered to adults from 60 to 74 years of age using the faecal occult blood test (FOBt) (2), soon to be replaced by the introduction of the faecal immunochemical test (FIT).
High-risk groups excluded from the screening programme include those with a history of colorectal cancer, adenomas,
inflammatory bowel disease,
a strong family history or pre-disposing hereditary conditions. Patients with an abnormal FOBt result are offered either an optical colonoscopy or CT colonography.
Any suspicious lesion is biopsied,
and then referred urgently for management if the biopsy confirms colorectal cancer. Those with a normal screening test are then offered another faecal occult blood test every two years until they reach the maximum age for the screening cohort.
Beyond this age,
patients may be screened every 2 years upon their own request.
It is therefore perhaps unsurprising that although the incidence of colorectal cancer is increasing in the UK,
the mortality is declining (3).
This is almost certainly due to a combination of factors,
including the national bowel screening programme,
the increasing sensitivity of pre-operative imaging,
the development of neoadjuvant chemotherapy,
and improving surgical techniques.
Current T-Staging of Colorectal Cancers: TNM 8 (4)
T Stage
|
Features
|
|
|
TX
|
Primary tumour cannot be assessed
|
T0
|
No evidence of primary tumour
|
Tis
|
Carcinoma in situ
|
T1
|
Tumour invades submucosa
|
T2
|
Tumour invades the muscularis propria
|
T3
|
Tumour invades through muscularis propria into the pericoloretal tissues
|
T4 – T4a
|
Invades through visceral peritoneum
|
- T4b
|
Invades or directly adheres to other adjacent organs or structures
|
N Stage |
Features |
|
|
NX
|
Lymph nodes cannot be assessed
|
N0
|
No regional lymph node metastases
|
N1
|
Metastases in 1 – 3 regional lymph nodes
|
N1a
|
1 lymph node
|
N1b
|
2 – 3 lymph nodes
|
N2
|
Metastases in 4 or more regional lymph nodes
|
N2a
|
4 – 6 lymph nodes
|
N2b
|
7+ lymph nodes
|
M Stage |
Features |
|
|
M0
|
No evidence of metastasis in other sites or organs
– defined by imaging
|
M1
|
Distant metastasis
|
M1a
|
Confined to 1 organ/site without peritoneal metastasis
|
M1b
|
Metastasis to 2 or more sites/organs,
without peritoneal metastasis
|
M1c
|
Metastasis to the peritoneum
|
Surgical Management
Abdominoperioneal (AP) or anterior resection has traditionally been the mainstay of surgical management with curative intent for patients with rectal cancer.
However,
due to earlier diagnosis with the advent of bowel screening,
rectal EUS and improved rectal MRI sensitivity,
there is increasing utilisation of minimally invasive and sphincter preserving surgical techniques including transanal endoscopic operations (TEOs) and transanal total mesenteric excision (taTME) in curative-intent resection of rectal cancer.
Traditional Radical Resection of Rectal Cancer
Abdominoperioneal (AP) resection (including ExtraLevator AP Resection - ELAPE) and anterior resection are forms of radical resection that have traditionally been the mainstay of surgical management with curative intent for patients with rectal cancer.
All radical resections with curative intent also include total mesenteric excision,
involving precise dissection and removal of the entire mesorectum as an intact unit. A brief summary of the indications,
procedure overview and complications are included below:
Abdominoperineal (AP) resection and ELAPE
Indication:
- Low rectal tumours (lower third of rectum)
- Anal carcinoma
Procedure overview:
- Removal of the anus,
rectum,
regional lymph nodes and part of the sigmoid colon
- Formation of an end colostomy.
Complications (5):
- Intra-abdominal or pelvic sepsis: affects up to 32% of patients with early complications (5)
- Perineal wound
- Nerve injury
- Urologic injury (e.g.
if the dissection of Denonvilliers’ fascia is too close to the prostate)
- Sexual dysfunction
Low Anterior Resection
Indication:
- Tumours of the upper two thirds of the rectum
Procedure Overview:
- Anastomosis between the remaining rectum and sigmoid colon
- Preservation of the internal sphincter.
Complications:
- Anastomotic leak
- Abdominal wound infection
- Pelvic abscess
- Haematoma