Pathology

  • 95% cancer in colong and rectum develops from polyps

  • protrusions in mucosal surgace = adenomas

  • polyps

    • common

    • increase in frequency with age

    • 30% >60

    • more common in inherited syndromes

Adenomatous polyps

  • 60-70% of polpys found in colon

  • source vast majority of adenocarcinomas

  • tubular (70-85% adenomatous polyps)

  • tubulovillous

  • villious

Hyperplastic

  • small (\<0.5cm)

  • benign

Submucosal

  • occasionally malignant

  • smooth overlying mucosa

surveillance of asymptomatic

  • mortality increase > 50yo

  • FOBT widley used for screening of colorectalca

  • relative risk reduction 25% with at least 1 round of FOBT

    • mortality 1.25, 5,5 and 17.5 less deaths per 10 0000 aged 40,50,60yo

  • iFOBT = increase sens and spec

  • FOBT not recommended for \< 50yo

    • numver of pfalse positive increases

opitcal colonoscopy

  • recommended investigation following referral for people with positive FOBT

  • small risk of bleedign or colorectal perforation

  • CT colonoscopy = alterantie

    • useful for peopel who had pain, elderly

healthy diet and health lifestyle

  • reduce:

    • red and processed meats

    • high-fat dairy products

    • highly refined grains, starches, sugars

  • exercise

  • healthy BMI

Family history

  • 20% of poepl with colorectal ca have 2 or more first-degree realtvies

sporadic colorectal ca

  • one first-degree family member (parents,siblings, children) increases risk by 2-3 times

  • 2 first degree increase risk 3-6 times

  • 2 second degree (increase risk 2 times)

Inherited colorectal

  • autosomal dominant inheritance
Lynch syndrome

  • hereditary non-polyposis

  • most common

  • females have increase risk of developing endometrial ca

Familial adenomatous polyposis

  • mutation in a tumour suppressor gene

  • multiple >100 adenomatous polyps

  • develop throughout colon in frist year of life

Peuz-Jehghers syndrome

  • gastrointestinal polyps

  • dark patchs (1-5mm) dize

    • mouth, eyes, hands, feet, genitals

  • increase colorectal and breast cancer

Risk

slightly increased

  • one first degree relative @ 55yo

  • healthy lifestyle choices

  • report any bowel symptom to health provider

moderately increased

  • one 1-deg relative 50-55yo or 2 first degree on same side @ any age

  • healthy lifestyle choices

  • colonocscopy every 5 years from age 50 or from 10 years before earliest family diagnosis

potentially high

  • family history of inherited syndrome

  • 1 1deg before 50yo

  • 1 1deg and >2 2deg on same side

  • 1 1deg and >1 2 deg under 55 or mulitple

  • any relative who also had multiple bowel polyps

  • referred to genetic service or the NZ familial gi cancer registry

  • colorectal cancer specialist will then construct serveillance plan

adenomatous polyp

  • low risk - q5yrs

  • intermediate risk - q3yrs

  • high risk - annually

inflammatory bowel disease

  • increase risk of developing colorectal cancer

  • 5-10% after 20yrs

  • 20% after 39yrs

  • surveillance colonoscopy after 8-10yrs after diagnosis

symptoms

  • left side more likely to cause parital / full obstruciton

  • right sided bigger

  • blood mixed in stool

  • change bowel habit (6wks)

  • abdominal pain/bloating

  • weight loss

require referral: (within 2 weeks)

  • palpable rectal mass

  • right-sided abdomin al mass or left sided mass

    • once faecal loading excluded

  • age ≥40yo with rectal bleeding and change in bowel habit lasting longer than 6 weeks

  • age ≥ 60 wiht recal bleeding > 6wks wihtoutut bowel habit hcange and wihtout anal symptoms

  • Age ≥ 60 with change bowel habit for 6 weeks or more without rectal bleeding

  • unexplained iron deficiency anaemia and hb ≤ 110g or ≤ 100g

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