rectal cancer Flashcards
Hereditary syndromes:
-causes
-types
-cause 10-15% of colorectal cases
-Lynch Syndrome (1 in 300)
APC gene (1 in 7000)
Screening:
why ?
-75% of patients have no apparent risk factors except older age
- 5-yr survival < 60% in most EU countries
screening:aim
Detect localised cancers or pre-malignant adenomas from which 80% of cancers arise
ireland bowel screening programme
-Free
-men and women 60-69
-Home test kit (Faecal Immunochemical Test-FIT )
-every 2 years
Pathology
-Adenocarcinoma (95%)
-Other
§ Squamous Cell Carcinoma
§ Small cell
§ Undifferentiated
§ Lymphoma
§ Carcinoid
Cancer of the rectum is defined as
from the rectosigmoid junction(S3) to anus
Presenting Signs and Symptoms
-abdominal pain
-changes in bowel habits
-bleeding on defaeacation
-unexplained anemia
Rectal Cancer:
Natural History
-Local invasion
◦ Within wall
◦ Through wall
-Lymphatic invasion
-Distance metastases
◦ Rectal cancer: lungs > liver
Goal of staging
-depth of tumour penetration
-lymph node involvement
-extensive mets
Pelvic MRI
indicated
shows relationship of tumour to:
-muscularis propia
-extension of rectal wall
-mesorectal fascia MRF
-involvement of lymph nodes and vessels
CT
indicated
detects metastatic disease in nodes, liver and lungs
Assessment of the Circumferential Resection Margin (CRM)
depth of penetration of tumour thru rectal wall
defined surgically by dissection
how is the assessment carried out
imaging b4 surgery, reported on MRI as distance to mesorectal fascia (MRF)
CRM is a Key prognostic indicator.. why?
+ CRM increases the risk of recurrence by 3.5-fold
and doubles the risk of death from disease
CRM involvement on MRI is normally defined as
distance from tumour to MRF of <1 mm
This indicates that there is a risk that the CRM will be involved after surgery …ie clear margins cannot be achieved
tumour downstaged before surgery if possible because at surgery, MRF is the resection plane and it has to be tumour-free
CRM NEGATIVE
distance between the tumour and MRF > 2mm
Other Workup pt1
-Colonoscopy
-family / medical history
-biospy
Other Workup pt2
-DRE=Most accurate for defining the location of mid and lower rectal tumours
-FBCs= Tumour marker: serum CEA (carcinoembryonic antigen)
…. Preop CEA >5ng/mL have a worse prognosis stage for stage
Traditional Treatment Options:
Neoadjuvant
-CRT
-RT
-none
Traditional Treatment Options:
definitive
surgery
Traditional Treatment Options:
Post-op Adjuvant Therapy
observation
CRT
chemo
Types of Surgery
1.local extension
2.Trans-abdominal resection
a) Sphincter-preserving resection
b) Abdominal perineal resection (APR)
Criteria for surgical option:
◦ Depth of tumour invasion and MRF involvement
◦ Size
◦ Tumour location
◦ Regional lymph node involvement
◦ Invasion of adjacent pelvic organs
Local Excision
-Transanal endoscopic microsurgery (TEM) may be
used
-Minimally invasive
-local excision of rectal cancer between 4cm to ~8cm from the anal verge
-No lymph nodes removed
Criteria for local excision
-Superficial T0 or T1
-<30% circumference of bowel
-Within 8cm of anal verge
-Well to moderate differentiated
- <3cm in size
-N0
2 types of trans-abdominal resection:
A. Sphincter-preserving resection (including TME)
B. Abdominoperineal resection (including TME)
Principles of Resection
◦Invasive cancer cT2-4
◦ Wide resection to achieve negative margins
◦ A total mesorectal excision (TME) and resection of local lymph nodes w A or B
◦ Anorectal sphincter function should be preserved if negative distal margins can be achieved for a
Examples of sphincter-sparing procedure :
◦ Low anterior resection (upper to middle 1/3)
◦ Very low anterior resection (distal rectum)
Criteria for performing sphincter-sparing procedure :
-Invasive beyond the submucosa
- negative distal margin
Criteria for performing: Abdominoperineal resection
-If negative distal margin (1-2cm) of resection cannot be achieved with a
-Salvage procedure for local recurrence or locally advanced rectal cancer
-Includes TME
AKA Permanent colostomy
Total Mesorectal Excision (TME)
-reduces local recurrences and perioperative morbidity
- if resection margin is free of tumour…best surgical treatment
Surgery and Site:Upper Third
Anterior or low anterior resection
middle Third
Very low /Low anterior resection
Lower Third
Very low anterior resection
APR
Why does Low rectal cancer have a higher local recurrence rate ?
-distal tapering of the mesorectal fat tf more easily invades the mesorectal fascia, pelvic wall and surrounding organs
-more difficult to get a tumour free resection
