Colorectal Cancer and Screening Flashcards
Name four heritable conditions that can increase risk of CRC
- Familial risk
- HNPCC
- FAP
- IBD
- Previous adenomatous/colorectal cancer
What are risk factors for sporadic cases?
• Age – incidence increases with age • Male gender • Previous adenoma/CRC • Environmental influences: o Diet – decrease: fibre, fruit and veg, calcium and increase: red meat and alcohol o Obesity o Lack of exercise o Smoking o Diabetes mellitus
What are HNPCC?
Hereditary nonpolyposis colorectal cancer which is autosomal dominant which can cause early onset colorectal cancer right sided
What is FAP?
Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition in which numerous adenomatous polyps form mainly in the epithelium of the large intestine
What is the role of colorectal polyps?
The majority of colorectal cancers arise from pre-existing polyps (adenomas)
What are the three different histological types of adenomas?
Tubular, villous or indeterminate
What are the alarm symptoms of colorectal cancer?
- Rectal bleeding (esp. if mixed with stool)
- Altered bowel opening to loose stools > 4weeks
- Iron deficiency anaemia
- Palpable rectal or right lower abdominal mass
- Acute colonic obstruction if stenosing tumour
- Systemic symptoms of malignancy: weight loss, anorexia (present late)
What is the first investigation for suspected colorectal cancer?
Colonoscopy
• Can take tissue biopsies
• Therapeutic as well as diagnostic
What radiological imaging is used for colorectal cancers?
- Barium enema
* If too unwell for colonoscopy -> CT colonography (must have bowel prep)
What investigations are used to stage cancer?
- CT chest/abdo/pelvis
- MRI for rectal tumour
- PET/rectal endoscopic ultrasound
What criteria is used to sage colorectal cancer?
Duke criteria
Describe Duke’s Criteria
• A: confined to submucosa
• B: invasion through muscularis without lymph involvement
• C: invasion through muscularis with regional lymph node involvement
- C1=1-4 lymph nodes
- C2 = > 4 lymph nodes
• D: presence of distant metastases
What are three strategies of treatment for CRC?
- Surgery
- Chemotherapy
- Radiotherapy
What does Dukes A indicate treatment wise?
Surgery
What does Dukes C indicate treatment wise?
Chemotherapy
When is radiotherapy indicated in CRC?
- Rectal cancer only
* Neoadjuvant +/- chemo to control primary tumour prior to surgery
What is used for palliative care in advanced disease?
- Chemotherapy
* Colonic stenting to prevent colonic obstruction
What is the aim of population screening?
Aim is to detect pre-malignant adenoma/early cancers in the general population
What are five modalities used for screening of CRC?
(• Faecal occult blood test (FOBT)) • Faecal immunochemical test (FIT) • Flexible sigmoidoscopy • Colonoscopy • CT Colonoscopy
What are the indications for the Scottish Bowel Screening Programme?
- Age 50-74yrs
- FIT test every 2 years
- If FIT positive -> colonoscopy
What is the advantage of FIT over FOBT?
- Specific human Hb
- Automate so easier to use
- Quantitative - able to set level of sensitivity to adapt to different populations
- Provides flexibility to alter the cut-off to accommodate risk factors including age and gender which could reduce the interval cancer rate
What steps are taken to reduce risk of CRC in someone with FAP?
- Screening - annual colonoscopy
* Prophylactic proctocolectomy
What is microsatellite instability (MSI)?
HNPCC tumour have MSI characteristic with frequent mutation occurring in short repeated DNA sequences
What other cancers can HPNCC cause other than CRC?
- Endometrial
- Genitourinary
- Stomach
- PANCREAS
What steps are taken to reduce risk of CRC in someone with HNPCC?
Screening from 25yrs -> 2yr colonoscopy
