Colorectal Cancer (Colon Carcinoma): Diagnostic Tests

In colon carcinoma, a distinction is made between an examination program for early detection (colorectal cancer screening, see Cancer Screening Measure below) and an examination program for confirming the diagnosis. In addition, several examinations are required preoperatively. In the following, the examinations for confirming the diagnosis and preoperatively are discussed in more detail. Mandatory medical device diagnostics.

  • Colonoscopy*, (complete) if necessary with biopsies (tissue samples) of the intestinal mucosa [gold standard] – Indications (areas of application):
    • In HNPCC patients, first examination from the age of 25 years/at the latest 5 years before the youngest age of onset of the disease in the family, examination at one-year intervals.
    • If colon or rectal cancer is suspected.
  • Abdominal sonography* (ultrasound examination of the abdominal organs) – in colon or rectal cancer.
  • X-ray of the thorax* (X-ray thorax / chest), in two planes – in colon or rectal cancer.
  • Rigid rectoscopy (rectoscopy)* – for rectal cancer (rectal cancer).
  • MR (CT) pelvis with indication of the distance of the tumor to the mesorectal fascia* – in rectal cancer (rectal cancer).
  • Rectal endosonography* (internal ultrasound examination) for localized tumor – for rectal cancerNote: Endosonography can be used to reliably determine tumor infiltration (tumor penetration) into the intestinal wall. A decision on whether or not surgery should be performed for rectal cancer is thus possible by an experienced examiner.
  • Computed tomography (CT) of the pelvis (pelvic CT)* .
    • In the case of incomplete colonoscopy due to a stenosing tumor, CT colonography may also be performed preoperatively.
    • To determine local spread (by means of multislice CT (MSCT)).

* Preoperative spread diagnostics.

Optional medical device diagnostics – depending on the results of the history, physical examination, laboratory diagnostics and obligatory medical device diagnostics – for differential diagnostic clarification.

  • Positron emission tomography (PET; nuclear medicine procedure that allows cross-sectional imaging of living organisms by visualizing the distribution patterns of weak radioactive substances); indications:
    • In patients with resectable liver metastases (daughter tumors of the liver) from colorectal carcinoma, with the goal of avoiding unnecessary laparotomy (abdominal incision).
    • For recurrence diagnosis

    Note: PET-CT should not be performed within 4 weeks of administration of systemic chemotherapy or antibody therapy because sensitivity is significantly reduced (Level of Evidence: A).

  • Cystoscopy (urinary bladder examination) – if tumor infiltration is suspected.
  • X-ray contrast enema (KE) – is hardly used anymore.

Obligatory medical device diagnostics for follow-up:

  • Computed tomography (CT) combined with CEA – to detect recurrence; this approach increased the number of recurrences that could be operated on curatively in a randomized trial. However, a significant benefit on colon cancer or all-cause mortality/overall mortality has not been seen.
  • Whole-body MRI – to detect metastases (daughter tumors) According to one study, whole-body MRI in colorectal or lung cancer is superior to standard multimodality examinations in metastasis diagnosis.

Cancer screening measures (KFEM)

  • ≥ 50 years of age: annual test for fecal occult (invisible) blood (immunological FOBT (iFOBT)).
  • ≥ 55 years of age: every 2 years test for occult blood in the stool, alternatively a maximum of 2 colonoscopies at intervals of 10 years.

Note: A 50-year-old man with high genetic risk, an unhealthy lifestyle and no screening colonoscopy has an estimated absolute risk of 13.4% of developing colorectal cancer within the next 30 years. In women with this constellation, the risk is 10.6%.