- Clinical presentation
- Radiographic features
- Treatment and prognosis
- Differential diagnosis
- The Colon and Colon Cancer
Colorectal carcinoma is typical, comprising 15% of recently diagnosed cancers, and is commonly an illness from the seniors, using the median chronilogical age of diagnosis between 60 and 80 years old 2, slightly more youthful for rectal carcinoma. There’s additionally a slight male predilection in rectal cancers, not found for tumours elsewhere within the colon.
Numerous predisposing factors happen to be identified, including:
inflammatory bowel disease (IBD)
Crohn disease (specifically in bypassed loops/in vicinity of chronic fistula)
Recognised hereditary syndromes are noticed in 6% of colorectal carcinomas. Included in this are:
familial adenomatous polyposis syndrome (FAP)
Gardner syndrome variant
Turcot syndrome variant
Clinical presentation is usually insidious, with altered bowel habit or an iron deficiency anaemia from chronic occult bloodstream loss. Bowel problems, intussusception, heavy bleeding and metastatic disease can also be the first manifestation. Positive bloodstream cultures or microbial endocarditis with Streptococcus bovis is strongly an indication of underlying colorectal cancer 6.
Generally, right sided tumours are bigger and offer having a mass, distant disease or an iron deficiency anaemia, whereas left sided tumours present earlier with altered bowel habit.
Colorectal cancers, 98% which are adenocarcinomas, arise in most cases from pre-existing colonic adenomas (neoplastic polyps), which progressively undergo malignant transformation because they accumulate additional mutations 2 (so-known as multi-hit hypothesis).
Morphologically cancers could be:
Rarely the malignant cells will broadly attack the submucosa, similar to linitis plastic from the stomach. These are generally scirrhous adenocarcinomas (signet-ring type).
Metastases might be prevalent in advanced disease, even though the liver is probably the most common site involved.
Colorectal cancers are available between the caecum towards the rectum, within the following distribution 2,5:
- ileocaecal valve: 2%
See: colon cancer staging.
single contrast: 77-94%
Appearances will reflect macroscopic appearance, with lesions viewed as filling defects. These have to be differentiated from residual faecal matter. Typically they seem as exophytic or sessile masses, or might be circumferential (apple core sign). Fistulas to bladder, vagina or bowel can also be shown.
Rarely the stenotic segment is going to be lengthy particularly with scirrhous adenocarcinomas.
CT may be the modality most employed for staging colorectal carcinoma, by having an precision of just between 45-77% 4, in a position to asses nodes and metastases.
It’s frequently in a position to identify tumours even though it is insensitive to small masses. CT colonography is growing in recognition instead of colonoscopy.
Most colorectal carcinomas have soft tissue density that narrow the bowel lumen 4. Ulceration in bigger mass can also be seen. From time to time low-density masses with low-density lymph nodes are noticed in mucinous adenocarcinoma, because of a lot of the tumor made up of extracellular mucin. Psammomatous calcifications in mucinous adenocarcinoma may also be present.
Complications can also be apparent, e.g. fistulae, obstruction, intussusception, perforation 4.
Includes a staging precision of 73% having a 40% sensitivity for lymph node metastases 1. MR is getting an growing role to participate in the staging of rectal cancer.
Treatment and prognosis
Treatment involves local control with resection the. Adjuvant chemotherapy is restricted to stage III disease.
Overall 5 year rate of survival is 40-50%, with stage at operation the best factor affecting prognosis.
Recurrence in keeping:
The tumor marker CEA is routinely employed for discovering publish operative early recurrance and metastatic disease (especially liver disease). It’s also employed for monitoring reponse to management of metastatic disease
Screening recommendations are contentious and vary broadly from nation to nation. A good example could be:
General imaging differential factors on CT include: