Colon Tumours Flashcards
what is a colonic poly?
- Protrusion above an epithelial surface – dysplastic epithelial lining
- It is a tumour
what are the different classifications of colonic polyps?
- Benign or malignant
* Epithelial or mesenchymal
what are the macroscopic features of colonic polyps?
pedunculated, sessile, flat, irregular surface, long stalk
what are the different types of benign epithelial polyps?
Neoplastic - Adenoma
Inflammatory – IBD
Hamartomatous - Juvenile polyp and Peutz-Jeghers syndrome
Metaplastic
what are the different types of benign mesenchymal polyps?
Lipoma Lymphangioma Haemangiomas Fibromas Leiomyoma
what are the different types of malignant epithelial polyps?
Polypoid adenocarcinomas
Carcinoid polyps
what are the different types of malignant mesenchymal polyps?
Sarcoma
Lymphomatous polyps
what are examples of other types of colonic polyps?
adenoma, serrated polyp, polypoid carcinoma, other
what are colonic adenoma?
benign tumours, not invasive, do not metastasise, are precursors to adenoma-carcinoma
what are the microscopic features of colonic adenomas?
o Microscopic: Architecture variable – tubullovillous, tubular, villous
o Are all dysplastic
what is the management of colonic adenomas?
need to be removed
when is segmental resection or complete colectomy considered?
- Incomplete excision of malignant polyp
- Malignant sessile polyp
- Malignant pedunculated polyp with submucosal invasion
- Polyps with poorly differentiated carcinoma
- Familial polyposis coli
what is the definition of of low risk colonic polyps?
1 or 2 adenomas less than 1cm
what is the definition of of moderate risk colonic polyps?
3 or 4 small adenomas or 1 adenoma greater than 1cm
what is the definition of of high risk colonic polyps?
More than 5 small adenomas or more than 3 with 1 of them greater than 1cm
what is the follow-up action of low risk colonic polyps?
No follow up or re-colonoscopy at 5 years
what is the follow-up action of moderate risk colonic polyps?
Re-scope at 3 years
what is the follow-up action of high risk colonic polyps?
Re scope at 1 year
what examples if benign colon tumours?
o Adenomatous polyp o Papilloma o Lipoma o Neurofibroma o Haemangioma
what are the clinical features of an adenomatous polyp?
Asymptomatic
Maybe anaemia, slight rectal bleeding
Hypokalaemia – excess mucus secretion
how are adenomatous polyps diagnosed?
screening, occasionally colonoscopy or barium enema
what is the management of adenomatous polyps?
EMR and lifelong surveillance
what are examples of primary malignant colon tumours?
Carcinoma
Lymphoma
Carcinoid tumour
what are the causes of colon tumours?
- FH
- Age
- Diet rich in fat and meat, low in fibre
- IBD
- Diabetes
- Atherosclerotic disease
what cells does colon adenocarcinomas form from?
glandular cells of the mucosal lining of colon
what are common genetic mutations associated with
K-Ras, C-myc, APC, DCC, MCC, C-yes, Bcl-2, P53, 5q + 18q
what are the genetic defects that lead to tumour growth?
o Oncogene activation
o Loss/mutation of tumour suppressor genes
o Loss/suppression of genes involved in DNA repair pathways
what are the macroscopic classifications of colon tumours?
o Papilliferous o Malignant ulcer o Annular o Diffuse infiltrating growth o Mucinous tumour
where are colon tumours located?
o rectal: 40% o sigmoid: 30% o descending colon: 5% o transverse colon: 10% o ascending colon and caecum: 15%
what is the local spread of colon tumours?
encircling the wall of the bowel and invading the coast of the colon, eventually involving adjacent viscera (small intestine, stomach, duodenum, ureter, bladder, uterus, abdominal wall etc)
what is the lymphatic spread of colon tumours?
to the regional lymphnodes, eventually spreading via the thoracic duct, and may involve supraclavicular nodes in late cases
what is the blood spread of colon tumours?
to the liver via the portal vein, and thence to the lung
what are the local effects of colon tumours?
o Change in bowel habit
o Intestinal obstruction due to a constricting neoplasm, commonly left descending
o Perforation of the tumour, either into the general peritoneal cavity or locally with the formation of a pericolic abscess, or occasionally by fistulation into adjuvant viscera
o Left sided lesions are usually constricting, right sided proliferative
what are the clinical features of colon tumours
Iron Deficiency Anaemia, Weight loss, Malaise, Vague abdominal pain, Faecal occult blood loss, Palpable mass, Obstruction, Altered bowel habit, Tenesmus, Rectal bleeding, Anal and perianal pain, Faecal incontinence, Recurrent UTI, Sister Mary Joseph Nodule, Ascites
what are red flag symptoms relating to colon tumours?
- Palpable rectal mass (any age)
- Iron deficiency anaemia in men of any age
- Iron deficiency anaemia in non-menstruating women of any age
- Rectal bleeding and change of bowel habit for more than six weeks in patients over 40
- Rectal bleeding for 6 weeks or more in anybody over 50
- Anybody with a palpable rectal mass
what is the gold standard imaging method for colon tumours?
colonoscopy?
what imaging is used for colon tumours?
Colonoscopy Sigmoidoscopy Double-contrast barium enema CT colonography Carcinoembryonic antigen (CEA) levels
what staging methods are used for colon tumours?
Dukes Scale, TMN
what is the definition of Stage A colon tumours?
the tumour is confined to the mucosa
what is the definition of Stage B colon tumours?
the tumour has spread through all the layers of the mucosa to the serosa. There are no lymph nodes metastasis
what is the definition of Stage C colon tumours?
the same as stage B, but there is lymph node involvement
what are the different types of stage C tumours?
C1 there is local lymph node involvement
C2 there is distant lymph node involvement
what is the definition of Stage D colon tumours?
disease with wide spread metastatic involvement.
what is the management of colonic tumours?
Surgical Resection
Radiotherapy, chemotherapy
what stages of colon tumours is surgery appropriate?
A-C
what are the features of surgery for colon tumour management?
o You should remove 2cm either side of the tumour (5cm in all directions in the rectum)
o Can be a laparotomy or laparoscopy
o Anastomosis is usually, although not always made afterwards
when is radiotherapy and chemotherapy used as adjuvants in colon tumour management?
B-C
when is radiotherapy and chemotherapy used as palliation in colon tumour management?
D
what are the genetic classifications of colon tumour?
sporadic (95%)
Hereditary, non-polyposis colorectal carcinoma (HNPCC)
Familial adenomatous polyposis (FAP<1%)
what is the genetic cause of sporadic colon tumours?
Loss of APC gene
what is the diagnostic criteria for HNPCC?
Occurrence of colon cancer in at least three family members spanning two generations with one before the age of 50
what is the genetic cause of HNPCC?
o MSH2
o MLH1
o Dominantly inherited
what are the features of HNPCC?
o Tumours arise in right colon before age of 50
o Associated with tumours of ovary, uterus and stomach
what is the genetic cause of FAP?
o Adenomatous polyposis coli gene (APC) on chromosome 5
o Autosomal dominant inheritance
what are the features of FAP?
o Polyps appear in adolescence, symptoms of bleeding and diarrhoea start 21, malignant change occurs 20-40
how is FAP diagnosed?
o Hypertrophy of the retinal pigment layer is a useful screening test
o Gardner’s Syndrome - Colonic polyps associated with desmoid tumours and osteromas of the mandible and skill
what is the management of FAP?
total colectomy
