The Big 4 - Colorectal Flashcards
How common is colorectal cancer?
-Comprises 10-15% of all cancers, 4th most common cancer
-41,000 new cases per year, 16,000 deaths
What are the key risk factors for colorectal cancer?
-DIET - rich in animal fat and poor in fibre
-IBD - especially UC
-FAMILY HISTORY - HNPCC (hereditary non-polyposis colon cancer), FAP (familial adenomatous polyposis), Gardner’s syndrome
What are the most common types of colorectal cancers?
-40% = rectum, 20% = sigmoid colon, 6% = caecum, rest in remaining colon
-EPITHELIAL tumours - 90-95% adenocarcinoma
-CARCINOID
-GI STROMAL TUMOUR
-PRIMARY MALIGNANT LYMPHOMA
Through what routes does colorectal cancer normally spread?
-Local invasion
-Lymphatic
-Venous
-Trans-colemic
How does colorectal cancer typically present?
-Altered bowel habit
-Weight loss
-PR bleeding
-Abdo pain
-Iron deficiency anaemia (right-sided tumours)
How would you investigate someone with suspected colorectal cancer?
-DRE
-Sigmoidoscopy / colonoscopy + biopsy
-CT (allows staging)
-CT colonography (can identify synchronous polyps)
-CEA tumour marker blood test
What does T0-4 denote in colorectal cancer staging?
T0 = no evidence of primary tumour
T1 = tumour invades submucosa
T2 = tumour invades muscularis propria
T3 = tumour extends through muscularis propriety into peri-colic tissues
T4 = tumour invades visceral peritoneum or invades adjacent organ structure
What does N0-2 denote in colorectal cancer staging?
N0 = no lymph node involvement
N1 = involvement of 1-3 lymph nodes
N2 = involvement of 4+ lymph nodes
What does M1a-c denote?
M1 = distant mets
M1a = confined to one organ / site but not peritoneum
M1b = 2 or more sites but not peritoneum
M1c = peritoneal spread
What does Dukes’ staging denote?
A = invasion into but not through the bowel wall
B = invasion through bowel wall but not into nodes
C = lymph node involvement
D = distant mets
How would you surgically manage a patient with colorectal cancer?
-Radical resection = standard treatment for primary carcinoma due to risk of unsuspected nodal mets
-Additional resection of liver mets if indicated
-Surgery / colonic stunting may be used palliatively or to prevent obstruction
How is RT used to treat colorectal cancer?
-Mostly used for rectal cancers (risk of toxicity to adjacent organs / mobility of tumours in colon cancers)
-Pre-operative RT is used in high-risk rectal carcinomas before resection
-Local recurrence / metastatic disease may require palliative RT
How is chemotherapy used to treat colorectal cancers?
-Adjuvant (for Dukes’ stage C, 6 months adj chemo may increase survival from 40 to 60%)
-Genetic testing of tumours can influence treatment eg presence of 5-FU has a good response rate
What is the prognosis for colorectal cancer?
Stage A = 80%
Stage B = 50%
Stage C = 15-40%
Stage D = 5%
-Age <40yrs is a poor prognostic factor
What screening is done for colorectal cancers?
-FIT (faecal immunochemical testing) in average-risk populations followed by colonoscopy in positive cases
-Offered to 60-74 year-olds every 2 years
