Colorectal carcinoma

Contents

Epidemiology

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. 

Risks

Numerous predisposing factors happen to be identified, including:

  • low fibre and fat and protein diet 
  • weight problems (particularly in men)

  • inflammatory bowel disease (IBD)

    • chronic ulcerative colitis

    • Crohn disease (specifically in bypassed loops/in vicinity of chronic fistula)

    • asbestos workers
    • genealogy of benign/malignant colorectal tumours
    • good reputation for endometrial/cancer of the breast

    • pelvic irradiation
    • ureterosigmoidostomy
    • colonic adenoma
    • dysplasia of colon within flat mucosa
    • prominent lymphoid follicular pattern

      • Associations
      Syndromes

      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

        • Peutz-Jeghers syndrome
        • hereditary non-polyposis cancer of the colon syndrome (HNPCC)

          • Clinical presentation

          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.

          Pathology

          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:

          • sessile
          • exophytic
          • circumferential (apple core) 
          • ulcerated 
          • desmoplastic

            • 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.

            Location

            Colorectal cancers are available between the caecum towards the rectum, within the following distribution 2,5:

            • recto-sigmoid: 55%
            • caecum and climbing colon: ~20%
              • ileocaecal valve: 2%
            • transverse colon: ~10%
            • climbing down colon: ~5%

              • Staging

              See: colon cancer staging.

              Radiographic features

              Barium enema

              • sensitivities for polyps >1 cm

                • single contrast:  77-94%

                • double contrast: 82-98%

                • polyps <1 cm: < 50% detection 3

                  • 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

                  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.

                  MRI

                  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.

                  • Duke A: 80-90%
                  • Duke B: 70%
                  • Duke C: 33%
                  • Duke D: 5%

                    • Recurrence in keeping:

                    • local recurrence at type of anastomosis: have a tendency to occur within 2 yrs of diagnosis (80%) 4

                    • distant metastatic recurrence

                      • 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

                      • associated with pension transfer tumor markers it’s inappropriate for screening trained with poor sensitivity and specificity
                      • greater amounts of CEA are connected with:

                        • greater grade tumours
                        • greater stage disease
                        • visceral metastases (especially liver metastases)

                          • Screening recommendations

                          Screening recommendations are contentious and vary broadly from nation to nation. A good example could be:

                          • for persons >50 years old: annual faecal occult-bloodstream make sure sigmoidoscopy/barium enema every three to five years
                          • for first-degree relatives of patients with cancer of the colon: screening should start at 40

                            • Differential diagnosis

                            General imaging differential factors on CT include:

                            • diverticulitis
                            • inflammatory bowel disease
                            • large bowel lymphoma

                              • Resourse: https://radiopaedia.org/articles/

                              The Colon and Colon Cancer


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