Colorectal Cancer Flashcards
(32 cards)
What are colorectal cancers?
Originate from epithelial cells lining the colon or rectum, most commonly adenocarcinoma.
What is the adenoma-carcinoma sequence?
Progression from normal mucosa to colonic adenoma to invasive adenocarcinoma
Which genetic mutations have been implicated in predisposing individuals to colorectal cancer?
Adenomatous polyposis coli (APC) - tumour suppressor gene mutation - leads to growth of adenomatous tissue such as Familial Adenomatous Polyposis (FAP)
Hereditary nonpolyposis colorectal cancer (HNPCC) - DNA mismatch repair gene leads to Lynch syndrome
What are the risk factors for colorectal cancer?
75% sporadic
Increasing age Male FH IBD Low fibre diet Smoking and alcohol High processed meat intake
What are the common clinical features of bowel cancer?
Change in bowel habit Rectal bleeding Weight loss Abdominal pain Symptoms of (iron-deficiency) anaemia
What clinical features may be present for right-sided colon cancer?
Abdominal pain, iron-deficiency anaemia, palpable mass in RIF
Often present late
What are the clinical features of left-sided colon cancers?
Rectal bleeding, change in bowel habit, tenesmus, palpable mass in LIF or on PR exam
What are the NICE guidelines for urgent investigations for bowel cancer?
≥40yrs with unexplained weight loss and abdominal pain
≥50yrs with unexplained rectal bleeding
≥60yrs with iron‑deficiency anaemia or change in bowel habit
Positive occult blood screening test
What are the differential diagnosis for colorectal cancer?
IBD
Haemorrhoids
What is the colorectal cancer screening?
Men and women aged 60-75 years offered a faecal immunochemistry test (FIT) every 2 years
One off screening flexible sigmoidoscopy offer to all people on year of 55th birthday
What investigations bloods should be ordered for suspected colorectal cancer?
FBC - look for microcytic anaemia
LFTS
Clotting
U+Es
CEA - carcinoembryonic antigen - used to monitor disease progression rather then diagnosis
What is the gold standard imaging for diagnosis of colorectal cancer?
Colonoscopy with biopsy
Can tattoo area if think malignant for future laparoscopic surgery
What investigation may be done colonoscopy with biopsy is not suitable for the patient with suspected colorectal cancer?
What are the reasons for not been suitable?
CT colongraphy
Reasons for not being suitable:
Frailty
Co-morbidities
Intolerance
What investigation will be required after the diagnosis of colorectal cancer is made?
CT chest, abdo, pelvis - look for metastases
MRI rectum - for rectal cancers to look for depth of invasion and potential need for pre-op chemo
Endo-anal ultrasound - for early rectal cancer (T1 or T2) to assess suitability for trans-anal resection.
What is done to the biopsy samples in colorectal cancers?
Send for histology - TNM staging, histological sub typing, grading and assessment of lymphatic, perineurial and venous invasion.
Assessed for tumour based markers - e.g. lynch syndrome - optimise potential chemo regimes
What is the staging for colorectal cancer?
Stages cancer according to depth of invasion into the bowel wall (T stage), spread to lymph nodes (N stage) and distant metastasis (M stage).
Dukes classification: not used anymore
Stage A - confined beneath the muscularis propria
Stage B - extension through the muscularis propria
Stage C - involvement of regional lymph nodes
Stage D - distant metastasis
What is the definitive curative option in colorectal cancers?
Surgery although chemotherapy and radiotherapy have important role as neoadjuvant and adjuvant treatments alongside their role in palliation.
What is the general surgery plan for colorectal cancers?
Regional colectomy, to ensure removal of the primary tumour with adequate marigins and lymphatic drainage, followed either by primary anastomosis or formation of a stoma.
What is the surgical options for caecal tumour or ascending colon tumours or transverse colon tumours?
Which vessels are removed?
Right hemicolectomy or extended right hemicolectomy
Ileocolic, right colic and right branch of the middle colic along with their Mesenteries
What is the surgical option for descending colon tumours?
Which vessels are removed?
Left hemicolectomy
Left branch of the middle colic, the inferior mesenteric vein, left colic vessels along with their mesenteries
What is the surgery for sigmoid colon tumours?
Which vessel is removed?
Sigmoidcolectomy
IMA fully dissected in order to remove adequate margins
What is the surgery of choice for high rectal tumours, typically >5cm for anus?
Anterior resection - with anastomosis leaving rectal sphincter intact.
Often defunctioning loop ileostomy is performed to protect anastomosis in case of complications such as a leak. Can be reversed electively 4-6 months later
What is the surgery of choice for low rectal tumours, <5cm from anus?
Abdominoperineal (AP) resection - involves excision of the distal colon, rectum, anal sphincters with permanent colostomy.
What is the advantages of performing elective colectomies laparoscopically?
Faster recovery time
Reduced surgical site infection risk
Reduced post-op pain
