Treatment Guideline Chart
Colorectal cancer is a carcinoma arising from the luminal surface of the colon.
It is the 2nd most common cancer in women and third most common cancer in male worldwide. It commonly arises from adenomatous polyps.
It is strongly linked to age with 83% occurring in people ≥60 years old.
Rectal cancer is defined as cancerous lesions located within 12 cm of the anal verge.

Colorectal%20cancer Treatment


Unresectable Nonmetastatic Colon Cancer

  • Neoadjuvant RT with concurrent fluoropyrimidine-based chemotherapy may be considered for initially unresectable or medically inoperable non-metastatic T4 colon cancer to aid resectability
  • Intraoperative radiotherapy (IORT) may be considered for patients with T4 tumors, locally unresectable or medically inoperable tumors, or recurrent cancers
  • Recommended dose: 45-50 Gy in 25-28 fractions; additional 10-20 Gy external beam radiation therapy (EBRT) and/or brachytherapy could be considered if IORT is not available

Resectable Nonmetastatic Rectal Cancer

  • Associated with decreased rates of local recurrence for rectal cancer
  • Administration should include the tumor bed with 2 to 5-cm margin, mesorectum, internal iliac nodes and presacral nodes
    • External iliac nodes are included in T4 tumors involving anterior structures 
  • Risks include increased hematologic toxicities, radiation-induced injury

Preoperative versus Postoperative Radiation Therapy (RT)

  • Preoperative RT (along with chemotherapy) is recommended for those with stage II and III rectal cancer
    • Short-course RT may be an option for patients with T3N0 or T1-3N1-2 rectal CA
    • Recommended dose: 45-50 Gy in 25-30 fractions to the pelvis; consider a tumor bed boost of 5.4 Gy in 3 fractions with a 2-cm margin after 45 Gy
  • Advantages of preoperative RT include:
    • Increased rate of sphincter preservation
    • Increased sensitivity to radiation therapy of surgically-naive tissues
    • Avoiding radiation-induced injury that can arise from post-surgical adhesions
    • Increases the likelihood that an anastomosis with a healthy colon can be done
  • Disadvantage of preoperative RT is the possibility of overtreating early-stage tumors that do not require RT
  • Postoperative RT is recommended when stage I rectal cancer has been upstaged to stage II or III after pathologic review of the surgical specimen
    • Recommended dose: 5.4-9.0 Gy in 3-5 fractions

Intraoperative Radiotherapy (IORT)

  • For patients with T4 tumors or recurrent cancers, or if margins are positive or very close
  • Involves direct exposures of tumors to RT intraoperatively while normal structures are removed from the field of treatment
  • Considered as an additional boost to facilitate surgery
  • If unavailable, brachytherapy and/or 10-20 Gy EBRT may be considered soon after resection, prior to adjuvant chemotherapy

Metastatic Colorectal Cancer

Arterial Radioembolization

  • While toxicity is relatively low, evidence supporting its use is still lacking
  • Alternative for highly-selected patients with predominantly hepatic metastases and with chemotherapy-resistant or refractory disease

External Beam Radiation Therapy (EBRT)

  • May be considered in highly selected cases where patients have limited number of liver or lung metastases or in symptomatic patients or in the setting of a clinical trial
  • Should not replace surgical resection
  • Intensity-modulated radiation therapy (IMRT) should be reserved for special situations (eg reirradiation of previously irradiated patients with recurrent disease) or unique anatomical sites where tissue dose-volume constraints are necessary
  • Stereotactic body radiation therapy (SBRT) should be considered for patients with oligometastatic disease 
  • Image-guided RT (IGRT) with kilovoltage (kV) imaging or cone-beam CT imaging should be routinely used during treatment with IMRT and SBRT
  • Arterially-directed catheter therapy (ie yttrium-90 microsphere-selective internal radiation) is an option in highly selected patients with chemotherapy-resistant/refractory disease and with predominant hepatic metastases
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