Colorectal cancer (summary)

Last revised by Rania Adel Anan on 19 Dec 2022

Citation, DOI, disclosures and article data

Citation:

Jones J, Anan R, Hacking C, et al. Colorectal cancer (summary). Reference article, Radiopaedia.org (Accessed on 07 Dec 2023) https://doi.org/10.53347/rID-47136

DOI:

https://doi.org/10.53347/rID-47136

Permalink:

https://radiopaedia.org/articles/47136

rID:

47136

Article created:

1 Aug 2016, Jeremy Jones ◉

Disclosures:

At the time the article was created Jeremy Jones had no recorded disclosures.

View Jeremy Jones's current disclosures

Last revised:

19 Dec 2022, Rania Adel Anan ◉

Disclosures:

At the time the article was last revised Rania Adel Anan had no financial relationships to ineligible companies to disclose.

View Rania Adel Anan's current disclosures

Revisions:

9 times, by 4 contributors - see full revision history and disclosures

Systems:

Gastrointestinal, Oncology

Tags:

summary, medical student

This is a basic article for medical students and other non-radiologists

Colorectal cancer, also called colorectal carcinoma (CRC), is the most common cancer of the gastrointestinal tract and the second most frequently diagnosed malignancy in adults. CT and MRI are the modalities most frequently used for staging. Surgical resection may be curative although five-year survival rate is 40-50%.

epidemiology
- common cancer: accounts for 15% of newly diagnosed cancers
- disease of the elderly: median age 60-80 years
- rectal cancers present slightly earlier with a slight male predilection
presentation
- insidious onset with altered bowel habit
- chronic occult blood loss (iron deficiency anemia)
- can present with bowel obstruction, metastases or intussusception
pathophysiology
- 98% are adenocarcinomas
- they may arise from pre-existing adenomas
- occur from the cecum to rectum
  - rectosigmoid: 55%
  - cecum/ascending: 20%
  - transverse: 10%
  - descending: 5%
- staging using the Duke staging system (A-D)
- risk-factor: familial adenomatous polyposis (FAP)
investigation
- CT for diagnosis and staging
- MRI for local staging in rectal carcinoma
- CT colonoscopy for screening
- barium studies no longer used in most centers
treatment
- local surgical control
- adjuvant chemotherapy reserved for Dukes C disease
prognosis
- overall 5-year-survival is 40-50%
- the stage at operation is the key factor affecting survival
  - A: 80-90%
  - B: 70%
  - C: 33%
  - D: 5%

Role of imaging

initial diagnosis
- virtual colonoscopy
- abdominal CT in the acute patient
local staging in rectal carcinoma by MRI
staging by CT CAP (chest, abdomen and pelvis)

Radiographic features

CT

soft-tissue-density masses arising from the bowel wall
- challenging to see small tumors on CT
- low sensitivity for bowel cancer (45-77%)
bowel wall thickening with luminal narrowing
proximal luminal dilatation
ulceration in larger mass
complications, e.g. fistula, obstruction, intussusception, perforation