Staging workup of newly diagnosed rectal cancer

MRI: magnetic resonance imaging; EUS: endoscopic ultrasound; CT: computed tomography; FDG-PET: fluorodeoxyglucose positron emission tomography.
* T1 tumors invade through the muscularis mucosa. Tumors that invade the muscularis propria or beyond are T2-4.
¶ Endoscopic excision alone is NOT appropriate for malignant polyps with any of the following:

• For both pedunculated and nonpedunculated polyps:
  • Piecemeal resection
  • Poorly differentiated histology
  • Lymphovascular invasion
  • Tumor budding (foci of isolated cancer cells or a cluster of five or fewer cancer cells at the invasive margin of the polyp)
• For pedunculated polyps, a positive margin variably defined as:
  • Cancer present at the resection margin
  • Cancer within 1 mm of resection margin
  • Cancer within 2 mm of resection margin
• For nonpedunculated polyps:
  • Cancer at resection margin
  • Submucosal invasion depth ≥1 mm

Δ CT is appropriate for all except those with clinical T1N0 cancers with favorable histologic features.

• If pelvic MRI has been done, we perform CT of the chest and abdomen
• If pelvic MRI has not been done, we perform CT of the chest, abdomen, and pelvis

◊ Practice Parameters Committee of the American College of Gastroenterology (ACG) and the European Society for Medical Oncology (ESMO), recommend performing either transrectal ultrasound or high-resolution MRI to determine the local tumor stage and assess for lymph node positivity for all patients with an invasive rectal cancer, including those with pT1 malignant polyps with favorable prognostic factors.