Definition of High Rectal Tumor
A high rectal tumor is a malignant neoplasm located in the upper portion of the rectum, specifically between 10-15 cm from the anal verge as measured by rigid sigmoidoscopy or MRI. 1
Anatomical Classification
Rectal cancers are categorized by their distance from the anal margin, with tumors extending up to 15 cm from the anal verge classified as rectal (beyond 15 cm are considered colonic) 1:
- Low rectal cancer: Up to 5 cm from the anal verge 1
- Middle rectal cancer: >5 to 10 cm from the anal verge 1
- High rectal cancer: >10 to 15 cm from the anal verge 1
Clinical Significance and Treatment Implications
High rectal tumors are treated fundamentally differently than mid-to-low rectal cancers, following treatment principles similar to colon cancer rather than standard rectal cancer protocols. 1
Key Treatment Distinctions
Surgical approach: High rectal cancers undergo wide mesorectal excision with removal of at least 5 cm of rectal mesentery, rather than complete total mesorectal excision (TME) required for mid-low rectal tumors 1
Radiation therapy volumes: When radiotherapy is indicated for high rectal tumors, it is sufficient to include only 4-5 cm of mesorectum distal to the tumor, with the lower border of radiation beams positioned 5-6 cm distal to the tumor 1
Lymph node coverage: Lateral pelvic lymph nodes (along the inferior rectal and obturator arteries) do not require prophylactic inclusion in high rectal tumors, as these nodes are seldom involved regardless of T-stage 1
Neoadjuvant therapy considerations: High rectal cancers with well-controlled risk stratification on MRI may not require the routine preoperative chemoradiotherapy that is standard for lower rectal cancers 1
Diagnostic Approach
The precise location must be determined using 1:
- Digital rectal examination (DRE) for palpable lesions
- Rigid sigmoidoscopy as the gold standard for measuring distance from the anal verge (flexible endoscopy measurements are less reliable)
- MRI for comprehensive staging and treatment planning 1
A critical pitfall is misclassifying tumor location, as this fundamentally alters the treatment algorithm—high rectal tumors treated with full TME and extensive pelvic radiotherapy represent overtreatment, while mid-low rectal tumors treated as colon cancer risk inadequate local control. 1