Colonic carcinoma and polyps Flashcards
what is the main form of colorectal cancer?
adenocarcinoma
what are the risk factors for colorectal cancer?
Polyposis syndromes (FAP and HNPCC)
FHx
IBD
diet poor in fruit and veg
what are the clinical features of colorectal cancer based on location?
rectal
- PR bleeding with deep red on stool surface
- change in bowel habit
- difficulty with defecation, painful defecation and tenesmus
- rectal mass
Descending to sigmoid colon
- PR bleed with dark red blood and mucus in stool
- increased frequency
- variable consistency
- bloating and flatulence
Right sided
- presents later
- IDA may be only feature
what InV should be done in colorectal cancer?
FBC
- iron deficiency anaemia
colonoscopy with biopsy
CEA tumour marker
CTAP or PET-CT
- mets
Outline Dukes staging criteria and prognosis
A = confined to mucosa and submucosa - 90% 5YS
B1 = into muscularis - 75-80% B2 = Full thickness into serosa - 60%
C1 = <4 regional lymph nodes C2 = >4 regional lymph nodes - both 25-30%
D = distant Mets (10%)
what is the surgical management of a caecal or ascending colon tumour?
Right Hemicolectomy or Extended Right Hemicolectomy
The surgical approach for caecal tumours or ascending colon tumours, with the extended option performed for any transverse colon tumours. During the procedure the ileocolic, right colic, and right branch of the middle colic vessels (branches of the SMA) are divided and removed with their mesenteries.
what is the surgical management of a descending colon tumour?
Left Hemicolectomy
The surgical approach for descending colon tumours. Similar to the right hemicolectomy, the left branch of the middle colic vessels (branch of SMA/SMV), the inferior mesenteric vein, and the left colic vessels (branches of the IMA/IMV) are divided and removed with their mesenteries.
what is the surgical management of sigmoid tumours ?
Sigmoidcolectomy
The surgical approach for sigmoid colon tumours. In this instance, the IMA is fully dissected out with the tumour in order to ensure adequate margins are obtained.
what is the surgical management of a high rectal tumour?
Anterior Resection
The surgical approach for high rectal tumours, typically if >5cm from the anus. This approach is favoured as leaves the rectal sphincter intact if an anastomosis is performed (unlike AP resections). Often a defunctioning loop ileostomy is performed to protect the anastomosis and reduce complications in the event of an anastomotic leak, which can then be reversed electively four to six months later.
what are the palliative options for colorectal cancer?
Endoluminal stenting can be used to relieve acute bowel obstruction in patients with left-sided tumours
The main side-effects of stents are perforation, migration, and incontinence
Stoma formation can be performed for patients with acute obstruction, usually with either a defunctioning stoma or palliative bypass
Resection of secondaries, not commonly performed but can done with adjuvant chemotherapy for any liver metastases
what are polyps and how can they be grossly described?
they are projections arising from the colonic mucosal surface that may be neoplastic or non-neoplastic
they can be desribed as pedunculated (raised with stalk) or sessile (flat and spreading out over surface of bowel wall)
what are the pathological classifications of polyps?
Juvenile polyps
- mucin filled cystic swelling of the lower rectal mucosa
Hamartomatous polyps
- polyps containing excessive amount of the normal architecture components of the bowel wall, usually isolated
Hyperplastic polyps
- small sessile polyps formed from normal elongated mucosal crypts
- increased risk of cancer
Adenomatous polyps
- true neoplastic polyps formed by excessive growth of colorectal cancer
- precursor of most colorectal CA’s
what are the hereditary polp syndromes?
Familial adenomatous polyposis (FAP)
- defect in APC gene
- Vast number of polyps
- multiple osteomata, fibromata and thyroid inflammation (Gardner’s syndrome)
Hereditary Non-Polyposis Colorectal CA (HNPCC)
- abnormality of MMR genes
- predispose to adenomas
what are the clinical features of polyps?
bleeding - low vol, dark red
mucous discharge - may cause hypokalaemia and hypoproteinaemia
Prolapse - if pedunculated and low in rectum, polyps may prolapse out of the anus
how are polyps investigated and managed?
Most polyps are diagnosed by colonoscopy
Colonoscopic polypectomy is carried out for
pedunculated polyps larger than 1–2mm; others may be removed by endoscopic muscosal resection
Patients with FAP require regular gastroscopy and upper GI surveillance to identify premalignant polyps. FAP is usually treated by proctocolectomy (usually with ileoanal pouch formation) or colectomy and ileorectal anastomosis before early adulthood
Surgical excision is required for polyps that are too large or unsuitable
