Rectal Cancer Treatment Based on Tumor Location

Classification and Anatomy

The American Cancer Society recommends that rectal cancer located more than 10 cm from the anal verge be treated similarly to colon cancer, with a wide excision of the mesorectum, whereas rectal cancer located between 10 cm and the anal verge requires total mesorectal excision (TME) and often needs preoperative chemoradiation 1, 2
Rectal cancer located more than 10 cm from the anal verge is considered similar to colon cancer in terms of biology, as stated by the National Comprehensive Cancer Network [3] [1, 2, 3]
The location of rectal cancer is determined by MRI, with rectal cancer located less than 10 cm from the anal verge being considered as mid or low rectal cancer 1, 2

The American Society of Clinical Oncology recommends a wide excision of the mesorectum, without the need for TME, for rectal cancer located more than 10 cm from the anal verge 1, 2, 3
Preoperative chemoradiation is not typically required, unless there are high-risk factors present, as stated by the European Society for Medical Oncology [3] [1, 2, 3]
Adjuvant chemotherapy is recommended, based on the principles of colon cancer treatment, particularly for stage III disease, according to the National Comprehensive Cancer Network [3] [3]

The National Comprehensive Cancer Network recommends preoperative chemoradiation for cT3Nany with MRF-, cT1-2N+, or for tumors that are difficult to preserve the anal sphincter 1, 4
Long-course radiation therapy combined with fluoropyrimidine (5-FU or capecitabine) is preferred, as stated by the American Society of Clinical Oncology [4] [4]
Total neoadjuvant therapy (TNT) with long-course radiation therapy and chemotherapy should be offered to patients with high-risk factors for local recurrence, according to the European Society for Medical Oncology [4] [4]
The American Cancer Society recommends TME as the standard of care for rectal cancer located less than 10 cm from the anal verge, with the goal of preserving anal function 1, 5, 2, 4
Low anterior resection (LAR) can be performed if a sufficient distal margin (1-2 cm) can be achieved, with preservation of anal function, as stated by the National Comprehensive Cancer Network [4, 6] [4, 6]

The Japanese Society for Cancer of the Colon and Rectum does not recommend prophylactic lateral lymph node dissection in the absence of radiographic confirmation of lymph node involvement [1, 5, 2] [1, 5, 2]
With confirmed lateral lymph node metastasis on imaging, preoperative chemoradiation followed by lateral lymph node dissection is recommended, as stated by the European Society for Medical Oncology [1, 5, 2, 3] [1, 5, 2, 3]

Immune therapy before surgery may be considered, particularly when preservation of the anal sphincter is difficult or an R0 resection cannot be achieved, according to the National Comprehensive Cancer Network [1, 2, 3] [1, 2, 3]
The Memorial Sloan Kettering Cancer Center study on dostarlimab for locally advanced rectal cancer provides guidance on drug selection, as stated by the American Society of Clinical Oncology [1, 2] [1, 2]

Misclassifying rectal cancer located 10-15 cm from the anal verge as mid-rectal cancer can lead to unnecessary preoperative chemoradiation, as stated by the National Comprehensive Cancer Network [3] [3]
The use of specialized rectal MRI to accurately determine the distance from the anal verge is recommended, according to the European Society for Medical Oncology [4, 3] [4, 3]

Ensuring complete removal of the mesorectum with an intact mesorectal fascia is crucial to minimize local recurrence, as stated by the American Society of Clinical Oncology [4, 6] [4, 6]
Avoiding damage to the autonomic nerves is essential to preserve urinary and sexual function, according to the National Comprehensive Cancer Network [6] [6]
A positive circumferential resection margin (CRM) is defined as tumor within 1 mm of the resection margin, as stated by the European Society for Medical Oncology [6] [6]

Inadequate lymph node sampling (<12 nodes) can lead to understaging and suboptimal treatment decisions, as stated by the National Comprehensive Cancer Network [3] [3]
Failure to recognize dMMR/MSI-H status can result in missed opportunities for immune therapy, according to the American Society of Clinical Oncology [3] [3]