Rectal CancerNCT07398716
Intraoperative Assessment of Distal Resection Margins Using Frozen Section in Mid and Low Rectal Cancer Surgery
A study testing Intraoperative Frozen Section Assessment and Standard Surgery Without Frozen Section in people with Rectal Cancer, run by Bakirkoy Dr. Sadi Konuk Research and Training Hospital at 1 site in Turkey (Türkiye).
Trial summary
This study aims to improve the safety of distal surgical margins in patients with middle and low rectal cancer who receive neoadjuvant radiotherapy. Although magnetic resonance imaging and colonoscopic evaluation after neoadjuvant radiotherapy may suggest complete or near-complete tumor regression, residual tumor… Read more about this study
- Who is it for?
- Ages 18 to 90 years
- Conditions the study is for
- Rectal Cancer
- What is being tested?
- Intraoperative Frozen Section Assessment and Standard Surgery Without Frozen Section
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 99 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Jan 2022to 1 Jan 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 90 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients diagnosed with mid or low rectal cancer (Stage I-III)
- Patients who have received short-course or long-course neoadjuvant radiotherapy
- Patients evaluated and approved for surgery by a multidisciplinary oncology board
- Patients scheduled for total mesorectal excision (TME)
- Age ≥ 18 years
- Patients who provide written informed consent
Who cannot join
- Stage IV rectal cancer
- Upper rectal tumors
- Patients undergoing emergency surgery
- Patients planned for local excision or palliative surgery
- Patients with distant metastasis
- Patients with a history of previous rectal surgery
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Bakırköy Dr. Sadi Konuk Training and Research Hospital
Bakırköy, Istanbul, 34147
About this study
This study aims to improve the safety of distal surgical margins in patients with middle and low rectal cancer who receive neoadjuvant radiotherapy. Although magnetic resonance imaging and colonoscopic evaluation after neoadjuvant radiotherapy may suggest complete or near-complete tumor regression, residual tumor cells can still be present in the submucosal and muscular layers of the rectal wall. This may increase the risk of inadequate surgical margins and local recurrence.
In this study, patients with middle and low rectal cancer who are scheduled for surgery after neoadjuvant radiotherapy will be randomized into two groups. In the frozen section group, intraoperative frozen section analysis of the resection specimen will be performed immediately after specimen removal to assess the distal resection margin, and the surgical procedure will be guided according to the frozen section results. In the control group, standard surgical resection will be performed without intraoperative frozen section evaluation.
Pathological findings, distal margin status, operative time, tumor stage, and recurrence during follow-up will be compared between the two groups to evaluate the impact of intraoperative frozen section analysis on surgical margin safety and oncological outcomes.
Read the detailed description
Middle and low rectal cancers often show a good response to neoadjuvant radiotherapy or chemoradiotherapy. However, despite apparent tumor regression or disappearance on preoperative magnetic resonance imaging and intraoperative colonoscopic evaluation, residual tumor cells may persist within the submucosal or muscular layers of the rectal wall. This residual disease may not be detected by mucosal inspection alone and may lead to inadequate distal resection margins, increasing the risk of local recurrence or the need for more radical surgery.
The primary aim of this study is to evaluate whether intraoperative frozen section analysis of the distal resection margin improves surgical margin safety in patients with middle and low rectal cancer undergoing surgery after neoadjuvant radiotherapy.
This is a prospective, randomized clinical study conducted at Bakırköy Dr. Sadi Konuk Training and Research Hospital. Patients diagnosed with middle or low rectal adenocarcinoma (stage I-III) who have undergone short-course or long-course neoadjuvant radiotherapy and have been discussed in a multidisciplinary oncology council will be included. Following restaging with pelvic magnetic resonance imaging, patients deemed suitable for surgical treatment will be enrolled.
Eligible patients will be randomized into two groups using a sealed-envelope method. All patients will undergo total mesorectal excision according to standard oncologic principles. Immediately before rectal transection, intraoperative colonoscopy will be performed in all patients, and rectal transection will be planned at 2 cm distal to the tumor site identified during colonoscopy using an endoscopic linear stapler.
In the frozen section group, after specimen removal, the resection specimen will be immediately evaluated by an experienced gastrointestinal pathologist using intraoperative frozen section analysis. A distal margin of at least 1 cm will be considered oncologically safe. If the distal margin is found to be positive or closer than 1 cm, further rectal resection will be performed until a safe margin is achieved. If a safe distal margin cannot be obtained despite additional resection, abdominoperineal resection will be performed.
In the control group, after specimen removal, anastomosis will be performed without intraoperative frozen section analysis, and the operation will be completed according to standard surgical practice.
At the end of surgery, all specimens from both groups will undergo routine formalin-fixed pathological examination, including tumor staging and assessment of distal and circumferential resection margins.
Patient demographics, operative time, pathological tumor stage, distal margin status, need for additional resection or abdominoperineal resection, and recurrence during follow-up will be recorded and compared between the two groups.
The results of this study aim to determine whether intraoperative frozen section analysis contributes to safer distal surgical margins and improved oncological decision-making in the surgical treatment of middle and low rectal cancer following neoadjuvant radiotherapy.
- Conditions
- Rectal Cancer
- Being tested
- Intraoperative Frozen Section Assessment, Standard Surgery Without Frozen Section
- Keywords
- frozen section, Distal resection margin, Low rectal cancer, Mid rectal cancer
- Medical subject headings
- Rectal Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Intraoperative Frozen Section AssessmentProcedure or surgery
Intraoperative pathological evaluation of distal resection margins using frozen section to guide surgical decision-making.
Standard Surgery Without Frozen SectionProcedure or surgery
Standard surgical resection without intraoperative frozen section assessment of distal margins.
| Study group | Role | What they receive |
|---|---|---|
| Intraoperative Frozen Section Group | Experimental | Patients undergo total mesorectal excision followed by intraoperative colonoscopy.
After specimen removal, distal resection margins are assessed using intraoperative frozen section by an expert pathologist.
Additional resection is performed if margins are positive or less than 1 cm. Abdominoperineal resection is performed if a safe margin cannot be achieved. Receives: Procedure: Intraoperative Frozen Section Assessment |
| Control Group | Active comparator | Patients undergo total mesorectal excision followed by intraoperative colonoscopy.
Resection is performed 2 cm distal to the tumor using a stapler, and anastomosis is completed without intraoperative frozen section assessment. Receives: Procedure: Standard Surgery Without Frozen Section |
What is being measured
The primary outcome is the main question the study is designed to answer.
Rate of Negative Distal Resection Margin (R0)
Patients who obtained a negative result at the distal resection margin (defined as a tumor-free margin of at least 1 cm) according to intraoperative frozen section examination.
Measured: During surgery
Secondary outcomes (3)
Need for Additional Resection or Conversion to Abdominoperineal Resection (APR)
The proportion of patients requiring additional distal rectal resection or conversion to abdominoperineal resection due to positive or insufficient distal resection margins.
Measured: During surgery
Local Recurrence Rate
The incidence of local tumor recurrence during postoperative follow-up, confirmed by imaging, endoscopy, or pathological evaluation.
Measured: During postoperative follow-up (12- 24 months)
Operative Time
Total duration of the surgical procedure measured from skin incision to completion of wound closure.
Measured: During surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Feb 2026
- Study start1 Jan 2022
- Primary completion1 Jan 2025
- Study completion1 Jan 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Rectal CancerStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This is a prospective, randomized, two-arm, parallel-group interventional study comparing intraoperative frozen section assessment of distal resection margins versus standard surgery in mid and low rectal cancer.
- Masking
- None (open label)
- Enrolment
- 99 participants (actual)
Sponsor and investigators
- Lead sponsor
- Bakirkoy Dr. Sadi Konuk Research and Training Hospital
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Nurettin Şahin, Bakirkoy Dr. Sadi Konuk Research and Training Hospital
- Investigators
- Nurettin Sahin, MD, Principal investigator, Bakirkoy Dr. Sadi Konuk Research and Training Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07398716
- Sponsor's protocol ID
- IOFS-DM
- Status last verified
- Feb 2026
- First submitted
- 25 Jan 2026
- Last updated
- 11 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared, as the study is a single-center trial and data sharing was not included in the original ethics committee approval. De-identified aggregate data may be available upon reasonable request to the corresponding investigator
Publications
Gomes RM, Bhandare M, Desouza A, Bal M, Saklani AP. Role of intraoperative frozen section for assessing distal resection margin after anterior resection. Int J Colorectal Dis. 2015 Aug;30(8):1081-9. doi: 10.1007/s00384-015-2244-4. Epub 2015 May 16.
PubMed 25982468Khoury W, Abboud W, Hershkovitz D, Duek SD. Frozen section examination may facilitate reconstructive surgery for mid and low rectal cancer. J Surg Oncol. 2014 Dec;110(8):997-1001. doi: 10.1002/jso.23758. Epub 2014 Sep 2.
PubMed 25183166
Study at a glance
From the registry record, last updated by the sponsor on 11 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Intraoperative Assessment of Distal Resection Margins Using Frozen Section in Mid and Low Rectal Cancer Surgery
- ClinicalTrials.gov ID
- NCT07398716
- Acronym / sponsor ID
- IOFS-DM
- Conditions
- Rectal Cancer
- Keywords
- frozen section, Distal resection margin, Low rectal cancer, Mid rectal cancer
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 99 participants (actual)
- Lead sponsor
- Bakirkoy Dr. Sadi Konuk Research and Training HospitalOther government
- Study start
- 1 Jan 2022 (actual)
- Primary completion
- 1 Jan 2025 (actual)
- Study completion
- 1 Jan 2026 (actual)
- First posted
- 10 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study aims to improve the safety of distal surgical margins in patients with middle and low rectal cancer who receive neoadjuvant radiotherapy. Although magnetic resonance imaging and colonoscopic evaluation after neoadjuvant radiotherapy may suggest complete or near-complete tumor regression, residual tumor cells can still be present in the submucosal and muscular layers of the rectal wall. This may increase the risk of inadequate surgical margins and local recurrence.
In this study, patients with middle and low rectal cancer who are scheduled for surgery after neoadjuvant radiotherapy will be randomized into two groups. In the frozen section group, intraoperative frozen section analysis of the resection specimen will be performed immediately after specimen removal to assess the distal resection margin, and the surgical procedure will be guided according to the frozen section results. In the control group, standard surgical resection will be performed without intraoperative frozen section evaluation.
Pathological findings, distal margin status, operative time, tumor stage, and recurrence during follow-up will be compared between the two groups to evaluate the impact of intraoperative frozen section analysis on surgical margin safety and oncological outcomes.
Detailed description
Middle and low rectal cancers often show a good response to neoadjuvant radiotherapy or chemoradiotherapy. However, despite apparent tumor regression or disappearance on preoperative magnetic resonance imaging and intraoperative colonoscopic evaluation, residual tumor cells may persist within the submucosal or muscular layers of the rectal wall. This residual disease may not be detected by mucosal inspection alone and may lead to inadequate distal resection margins, increasing the risk of local recurrence or the need for more radical surgery.
The primary aim of this study is to evaluate whether intraoperative frozen section analysis of the distal resection margin improves surgical margin safety in patients with middle and low rectal cancer undergoing surgery after neoadjuvant radiotherapy.
This is a prospective, randomized clinical study conducted at Bakırköy Dr. Sadi Konuk Training and Research Hospital. Patients diagnosed with middle or low rectal adenocarcinoma (stage I-III) who have undergone short-course or long-course neoadjuvant radiotherapy and have been discussed in a multidisciplinary oncology council will be included. Following restaging with pelvic magnetic resonance imaging, patients deemed suitable for surgical treatment will be enrolled.
Eligible patients will be randomized into two groups using a sealed-envelope method. All patients will undergo total mesorectal excision according to standard oncologic principles. Immediately before rectal transection, intraoperative colonoscopy will be performed in all patients, and rectal transection will be planned at 2 cm distal to the tumor site identified during colonoscopy using an endoscopic linear stapler.
In the frozen section group, after specimen removal, the resection specimen will be immediately evaluated by an experienced gastrointestinal pathologist using intraoperative frozen section analysis. A distal margin of at least 1 cm will be considered oncologically safe. If the distal margin is found to be positive or closer than 1 cm, further rectal resection will be performed until a safe margin is achieved. If a safe distal margin cannot be obtained despite additional resection, abdominoperineal resection will be performed.
In the control group, after specimen removal, anastomosis will be performed without intraoperative frozen section analysis, and the operation will be completed according to standard surgical practice.
At the end of surgery, all specimens from both groups will undergo routine formalin-fixed pathological examination, including tumor staging and assessment of distal and circumferential resection margins.
Patient demographics, operative time, pathological tumor stage, distal margin status, need for additional resection or abdominoperineal resection, and recurrence during follow-up will be recorded and compared between the two groups.
The results of this study aim to determine whether intraoperative frozen section analysis contributes to safer distal surgical margins and improved oncological decision-making in the surgical treatment of middle and low rectal cancer following neoadjuvant radiotherapy.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- This is a prospective, randomized, two-arm, parallel-group interventional study comparing intraoperative frozen section assessment of distal resection margins versus standard surgery in mid and low rectal cancer.
| Arm | Type | Receives |
|---|---|---|
| Intraoperative Frozen Section Group | Experimental | Procedure: Intraoperative Frozen Section AssessmentPatients undergo total mesorectal excision followed by intraoperative colonoscopy. After specimen removal, distal resection margins are assessed using intraoperative frozen section by an expert pathologist. Additional resection is performed if margins are positive or less than 1 cm. Abdominoperineal resection is performed if a safe margin cannot be achieved. |
| Control Group | Active comparator | Procedure: Standard Surgery Without Frozen SectionPatients undergo total mesorectal excision followed by intraoperative colonoscopy. Resection is performed 2 cm distal to the tumor using a stapler, and anastomosis is completed without intraoperative frozen section assessment. |
Who may qualify
- Ages
- 18 to 90 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Patients diagnosed with mid or low rectal cancer (Stage I-III)
- Patients who have received short-course or long-course neoadjuvant radiotherapy
- Patients evaluated and approved for surgery by a multidisciplinary oncology board
- Patients scheduled for total mesorectal excision (TME)
- Age ≥ 18 years
Key exclusion criteria (6 listed)
- Stage IV rectal cancer
- Upper rectal tumors
- Patients undergoing emergency surgery
- Patients planned for local excision or palliative surgery
- Patients with distant metastasis
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Intraoperative Frozen Section AssessmentIntraoperative pathological evaluation of distal resection margins using frozen section to guide surgical decision-making. | Procedure or surgery | Intraoperative Frozen Section Group |
| Standard Surgery Without Frozen SectionStandard surgical resection without intraoperative frozen section assessment of distal margins. | Procedure or surgery | Control Group |
Primary outcome
Rate of Negative Distal Resection Margin (R0)
Time frame: During surgery
Patients who obtained a negative result at the distal resection margin (defined as a tumor-free margin of at least 1 cm) according to intraoperative frozen section examination.
3 secondary outcomes
Need for Additional Resection or Conversion to Abdominoperineal Resection (APR)
Time frame: During surgery
Local Recurrence Rate
Time frame: During postoperative follow-up (12- 24 months)
Operative Time
Time frame: During surgery
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Feb 2026.
- Results publication: PubMed 25982468Gomes RM, Bhandare M, Desouza A, Bal M, Saklani AP. Role of intraoperative frozen section for assessing distal resection margin after anterior resection. Int J Colorectal Dis. 2015 Aug;30(8):1081-9. doi: 10.1007/s00384-015-2244-4. Epub 2015 May 16.
- Results publication: PubMed 25183166Khoury W, Abboud W, Hershkovitz D, Duek SD. Frozen section examination may facilitate reconstructive surgery for mid and low rectal cancer. J Surg Oncol. 2014 Dec;110(8):997-1001. doi: 10.1002/jso.23758. Epub 2014 Sep 2.
- Individual participant dataSharing planned: No. Individual participant data will not be shared, as the study is a single-center trial and data sharing was not included in the original ethics committee approval. De-identified aggregate data may be available upon reasonable request to the corresponding investigator
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Nurettin Sahin, MD principal investigator
Bakirkoy Dr. Sadi Konuk Research and Training Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Intraoperative Frozen Section Assessment and Standard Surgery Without Frozen Section in people with Rectal Cancer, run by Bakirkoy Dr. Sadi Konuk Research and Training Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 11 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Rate of Negative Distal Resection Margin (R0) (time frame: During surgery). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07398716, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Feb 2026.