What is the desired minimum distal margin of resected rectal (rectal) cancer?

From the Guidelines

The desired minimum distal margin of resected rectal cancer is 1 mm (not explicitly listed, but closest to option a: 1 cm), as a clear distal resection margin ≥ 1mm is considered adequate for oncological factors, indicating an adequate surgical resection, as shown in the AlaCaRT trial 1. This margin is generally considered sufficient to ensure complete removal of the tumor while minimizing the risk of local recurrence. The goal of surgical resection is to achieve a clear margin (R0 resection) while balancing functional outcomes. The distal margin requirement is based on the understanding that rectal cancer typically spreads circumferentially rather than longitudinally, making the radial margin often more critical than an extensive distal margin. Some studies suggest that a 1 cm margin may be acceptable in certain circumstances to preserve sphincter function, while for upper rectal tumors, a slightly larger margin might be preferred when feasible. Key considerations include:

• The type and location of the tumor
• The patient's overall health and performance status
• The potential for preserving sphincter function
• The risk of local recurrence and distant metastasis As noted in the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of rectal cancer, the standard of care for surgery is total mesorectal excision (TME), implying that all of the mesorectal fat, including all lymph nodes, should be meticulously excised 1. Recent studies, such as the AlaCaRT trial and the ACOSOG Z6051 trial, have investigated the outcomes of laparoscopic versus open surgery for rectal cancer, with a focus on the adequacy of surgical resection and the impact on disease-free survival and recurrence 1. These studies have shown that laparoscopic-assisted resection of rectal cancer can be a safe and effective alternative to open resection, with comparable short-term oncological outcomes. However, careful patient selection is advocated to choose the adequate surgical approach based on the patient's performance status and tumor characteristics.

From the Research

Desired Minimum Distal Margin of Resected Rectal Cancer

The desired minimum distal margin of resected rectal cancer is a topic of ongoing debate.

• Studies have shown that a distal resection margin (DRM) of less than 1 cm may be sufficient in certain cases, particularly after preoperative chemoradiotherapy 2, 3, 4.
• However, other studies have found that a DRM of less than or equal to 1 cm may be associated with a higher risk of local recurrence and worse oncologic outcomes 5, 6.
• The generally accepted practice is to aim for a 2-cm DRM, but this may not always be possible, especially in cases where sphincter-sparing surgery is desired 3.
• The use of preoperative chemoradiotherapy may allow for a smaller DRM, as it can help to reduce the size of the tumor and minimize the risk of local recurrence 2, 4.
• Ultimately, the decision on the minimum distal margin should be made on a case-by-case basis, taking into account the individual patient's circumstances and the specific characteristics of the tumor 3, 5.

Key Findings

• A study published in 2019 found that a DRM of less than 1 cm was not associated with an increased risk of local recurrence or worse overall survival in patients with stage II or III rectal cancer who underwent preoperative chemoradiotherapy 2.
• A 2010 study suggested that a DRM of less than or equal to 1 cm may be sufficient in cases where preoperative chemoradiotherapy is used, but that a 2-cm margin is generally preferred 3.
• A 2022 systematic review and meta-analysis found that a DRM of less than or equal to 1 cm was associated with a higher risk of local recurrence, but that the overall survival rate was not significantly different from that of patients with a DRM of more than 1 cm 5.
• A 2001 study found that sphincter-sparing surgery with a DRM of less than or equal to 1 cm was not associated with an increased risk of local recurrence or worse disease-free survival in patients who underwent preoperative chemoradiotherapy 4.
• A 2017 study found that a distal margin of less than or equal to 1 mm was associated with worse oncologic outcomes, including a higher risk of local recurrence and worse disease-free survival 6.