Role of donuts and safe resection margins in rectal cancer surgery

Nisar Ahmad Chowdri; Asif Mehraj

doi:10.4103/ijcs.ijcs_9_21

REVIEW ARTICLE

Year : 2022 | Volume : 5 | Issue : 1 | Page : 10-12

Role of donuts and safe resection margins in rectal cancer surgery

Nisar Ahmad Chowdri¹, Asif Mehraj²
¹ Department of General and Minimal Access Surgery, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India
² Department of Colorectal Surgery, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India

Date of Submission	18-May-2021
Date of Acceptance	06-Jun-2021
Date of Web Publication	12-Sep-2022

Correspondence Address:
Dr. Asif Mehraj
Department of Colorectal Surgery, Sher I Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijcs.ijcs_9_21

Abstract

Resection margins in rectal cancer surgery have a pivotal role in assessing the adequacy of surgery as well as playing an important role in determining the prognosis for the patient. With better understanding of tumor biology, more importance is being laid on circumferential resection margin (CRM) rather than distal/proximal resection margin. Positive CRM is an important predictor for increased local recurrence rates. The length of safe distal resection margin in rectal cancer surgery has reduced significantly over the past few decades, with no significant change in the prognosis of patients. To avoid permanent stoma, more and more sphincter saving procedures are being performed, and this has been made possible as a result of more and more use of staplers. While using staplers, donuts are produced from the two resected ends and there is controversy whether these should be sent for histopathological examination or not. In this article, we discuss the importance of resection margins and donuts in rectal cancer surgery.

Keywords: Circumferential resection margin, distal resection margin, donuts

How to cite this article:
Chowdri NA, Mehraj A. Role of donuts and safe resection margins in rectal cancer surgery. Indian J Colo-Rectal Surg 2022;5:10-2

How to cite this URL:
Chowdri NA, Mehraj A. Role of donuts and safe resection margins in rectal cancer surgery. Indian J Colo-Rectal Surg [serial online] 2022 [cited 2023 Mar 26];5:10-2. Available from: https://www.ijcrsonweb.org/text.asp?2022/5/1/10/355941

Introduction

There is no controversy in the management of upper and mid rectal cancer. Everyone will attempt an anterior or low anterior resection. Similarly, proximal margin is not an issue and extent of resection is determined by technical considerations to obtain adequate lymph adenectomy and reconstruction with a minimum of 5 cm margin.

The difficult decision lies in deciding what to do for a low rectal cancer, the one that lies just around the levators, as whether to go for sphincter-preserving procedure or abdominoperineal resection, with permanent stoma. Factors which should be considered for deciding the type of resection are:

Physical handicap which results in significant difficulty in managing a stoma
Body habitus and patient gender influence surgeon's ability to perform a sphincter-saving operation because of pelvic anatomy. In obese male with a narro pelvis, it is difficult, but in multiparous thin females, resection is usually straight forward
Difficult dissection because of pelvic irradiation for non rectal pelvic malignancies.

For favorable tumors (well differentiated, early lesions, low carcinoembryonic antigen levels, downstaged tumors, or complete regression after preoperative radiation) with short margins, sphincter preservation is recommended. For unfavorable tumors, abdominoperineal resection and those with long distal margins low anterior resection is advised.

Donuts

There is also misunderstanding about donuts [Figure 1]. Actually, donuts do not represent the whole/real circumference of proximal and distal margins. With positive donuts, distal resection margin (DRM) will also be positive and negative donuts do not rule out involvement of distal margin as it contains only part of a distal staple or suture line. Hence, it is not important to send donuts routinely for histopathological examination. Of course, donuts need to be looked for completeness of anastomosis.

Figure 1: Proximal and distal resection donuts

Click here to view

Distal Resection Margin

The extent of resection of DRM in rectal cancer especially for distal tumors remains controversial and continues to decrease. Increasing knowledge about microscopic distal intramural spread usually occurs within 2 cm of the tumor unless it is poorly differentiated, widely metastatic, obstructed, or with proximal lymphatic obstruction. The 5 cm rule was changed to 2 cm since intramural spread more than 1–2 cm was found to be related to advanced and metastatic tumors in which the length of DRM has little importance in terms of outcome. Therefore, it is reasonable to conclude that 2 cm distal margin is justified for low rectal cancers. In expert hands, negative margin of <2 cm can be oncologically adequate to facilitate very low colorectal anastomosis. Smaller margin may be acceptable in patients for whom there is no option for sphincter preservation. However, frozen section should be done to confirm cancer free margin. Positive resection margin means presence of tumor 1 mm or less from the margin according to the American Joint Committee on Cancer. Oncologically, safe DRM should be 1 cm for T1-2 lesions and 2 cm for T3-4 lesions. However, DRM of less than 1 cm does not seem to have adverse effect on the survival and recurrence rates.^[1],[2] However, for upper and midrectal tumors, distal margin of 5 cm is adequate to remove lymph nodes in the perirectal fat as provision is there, since determinants of acceptable outcome are adequate clearance of intramural cancer (1–2 cm) and lymph nodes in pericolic fat (up to 5 cm distally).

Technical Tips for Safe Margins

Distal margin length should be measured in fresh anatomically stored ex vivo conditions immediately after removing
Distal aspect of the tumor should be marked or carefully measured at the time of initial assessment
Mesorectum in bowel edge must be transacted transversally to avoid coning toward distal margin and possible loss of lymph nodes. This can be made possible by adequate retraction of other pelvic organs for the placement of clamps
The bowel shrinkage occurs during the first 10–20 min after removal of specimen and additional shrinkage occurs after fixation
Correction factor of 12% reduction in anatomically restored (pinned) fixed specimens and 50% reduction in nonrestored fixed specimens has been proposed
A systematic review reported by Krzysztof Bujko et al.^[3] included 17 studies with DRM <1 cm (948 patients versus >1 cm (4626 patients), 5 studies with DRM <5 mm (173 patients) versus >5 mm (1277 patients), and 5 studies with DRM <2 mm (72 pts). In most studies, pre- or postoperative radiation was provided. Local recurrence was found to be 1% higher in the <1 cm margin group compared to the >1 cm margin group (P = 0.175). For <5 mm group, it was 1.7% (P = 0.375%), and for <2 mm margins, it was 2.7% (95% confidence interval: 0–6.4). Long-term survival did not differ statistically in all the three groups. In selected group of patients, <1 cm margin did not jeopardize oncological safety.

Circumferential Resection Margin

A circumferential resection margin (CRM) of <1 mm, whether as direct tumor extension, lymph node metastasis, or intravascular growth, should be considered as a positive margin.^[4] Local failure with a margin of <1 mm is significantly higher than a margin >1 mm.

We now know that CRM is not maximized by doing an abdominal perineal resection, unless a tumor has invaded the sphincter complex; therefore, we legitimately believe that the sphincter complex and the anus should not be removed unless involved in the tumor. Radial margins are most critical in determining prognosis as compared to distal margin, since positive CRM is associated with high risk of local recurrence and distal metastasis. Lin et al.^[5] reported local recurrence rates and distant metastasis rates of 15.4% versus 1.8% and 61.5% versus 13.4% (P < 0.001) in patients with positive versus negative CRM, respectively. The 5-year cancer-specific survival rates were 75.8% and 0% for patients with tumors having negative and positive CRMs, respectively (P < 0.001).

Summary

Donuts do not represent the real DRM
For proximal rectal tumors, distal margin should be 5 cm
For low rectal tumors, distal margin of 1–2 cm is safe depending on various patient and surgeon related factors
A negative distal margin must not be compromised in an effort to avoid permanent colostomy
When in doubt, do frozen section to confirm cancer free margin.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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