p.1
Risk Factors for Bowel Obstruction
What was the objective of the study on bowel obstruction in patients undergoing neoadjuvant chemotherapy for high-risk colon cancer?
To identify risk criteria available before treatment initiation that can be used to stratify the risk of obstruction.
p.1
FOxTROT Trial Overview
What is the significance of the FOxTROT trial in relation to neoadjuvant chemotherapy?
It informs the global implementation of NAC for colon cancer and may increase the risk of bowel obstruction.
p.1
Clinical Outcomes of Obstruction
How many patients in the FOxTROT trial received neoadjuvant chemotherapy and developed bowel obstruction?
699 patients received NAC, of whom 30 (4.3%) developed obstruction.
p.3
Clinical Outcomes of Obstruction
What type of obstruction outcomes were coded into a single variable?
Proven and symptomatic obstruction.
p.7
Pathologic Features and Tumor Characteristics
What tumor location had the highest percentage in cases?
Sigmoid, with 23.3% in cases.
p.5
Clinical Outcomes of Obstruction
What did the study not detect an association between?
The occurrence and timing of obstruction and treatment response (tumor regression grade) or mismatch repair deficient status.
p.4
Risk Factors for Bowel Obstruction
What percentage of obstructed cases had one or more risk criteria?
93.3% (28 out of 30 obstructed cases).
p.3
Pathologic Features and Tumor Characteristics
What was the comparison of tumor characteristics between obstructed and unobstructed patients?
Obstructed patients were more likely to have tumors at the hepatic flexure, splenic flexure, or transverse colon.
p.2
FOxTROT Trial Overview
What was the primary aim of the FOxTROT trial?
To test the feasibility, safety, and efficacy of preoperative chemotherapy for colon cancer.
p.4
Risk Factors for Bowel Obstruction
What was the agreement percentage between radiologic and endoscopic evaluations for stricturing disease?
59.7% agreement with a Cohen κ value of 0.37.
p.9
Patient Stratification for Treatment
What tool does the study provide for oncologists?
A risk stratification tool to assist in the safer introduction of NAC for patients with colon cancer.
p.9
Risk Factors for Bowel Obstruction
What assumption is made regarding the prevalence of risk criteria in the study?
It assumes that the prevalence of risk criteria is similar in the control sample to other unobstructed patients who received NAC.
p.8
Pathologic Features and Tumor Characteristics
What was the difference in T4 tumor proportions between obstructed and unobstructed patients?
37.9% of obstructed patients had T4 tumors compared to 23.8% of unobstructed patients.
p.2
Clinical Outcomes of Obstruction
What were the primary and secondary outcome measures in the FOxTROT trial?
Primary: colonic obstruction; Secondary: surgical decision-making, pathologic outcomes, and clinical outcomes.
p.4
Risk Factors for Bowel Obstruction
Which tumor location carried the highest risk of obstruction?
Tumors at the flexures (67.8% risk).
p.7
Pathologic Features and Tumor Characteristics
What percentage of controls had well/moderate differentiation?
86.7% of controls had well/moderate differentiation.
p.6
Clinical Outcomes of Obstruction
What was the rate of obstruction in patients where traversing a tumor was attempted?
Only 10.7% (3 out of 28 patients) went on to obstruct.
p.5
Implications for Multidisciplinary Team (MDT) Decision-Making
What are the four proposed uses of the data from the study?
1. To inform patient consent. 2. To provide enhanced monitoring for at-risk patients. 3. To inform a decision to proceed straight to surgery. 4. To support colonic stenting or diversion.
p.4
Risk Factors for Bowel Obstruction
Was there an independent association between tumor location or T-stage and obstruction?
No, there was no independent association.
p.2
Case-Control Study Design
How were controls defined in the FOxTROT trial?
Patients randomized to receive NAC and AC but did not develop proven or symptomatic colonic obstruction before surgery.
p.9
Risk Factors for Bowel Obstruction
What was the estimated absolute risk of obstruction for patients receiving NAC in the FOxTROT trial?
The risk was categorized into very low risk (<1%), low risk (1%-10%), and high risk (>10%).
p.3
Patient Stratification for Treatment
What were the cut-offs defined for risk groups?
Very low-risk, low-risk, and high-risk groups based on clinically important thresholds.
p.4
Risk Factors for Bowel Obstruction
What were the two features strongly associated with obstruction after risk adjustment?
1) Obstructing disease on endoscopy or inability to pass through the lumen (OR: 9.09); 2) Stricturing disease on radiology or endoscopy (OR: 7.18).
p.2
Case-Control Study Design
What criteria were used to define cases in the FOxTROT trial?
Patients who met inclusion criteria, randomized to receive NAC and developed proven or symptomatic colonic obstruction before surgery.
p.5
Risk Factors for Bowel Obstruction
What tumor location had a significant difference in obstruction cases compared to other patients?
Cecum (6.7% in cases vs. 17.8% in others, P < 0.001).
p.2
Statistical Analysis Methods
What statistical method was used to assess the association between covariates and bowel obstruction?
Bayesian hierarchical unconditional logistic regression analysis.
p.4
Risk Factors for Bowel Obstruction
What percentage of patients were classified as very low risk for obstruction?
63.4% (443 out of 698 patients).
p.9
Clinical Outcomes of Obstruction
What was observed about tumors that demonstrated a pathologic complete response in relation to obstruction?
No tumors demonstrating a pathologic complete response obstructed.
p.5
Pathologic Features and Tumor Characteristics
What factors were identified that could define tumors at higher risk of obstruction?
Physical tumor factors identifiable by endoscopy and radiology.
p.3
Clinical Outcomes of Obstruction
What was the outcome for obstructed patients in terms of perforation?
No perforation with frank peritonitis was seen; microperforation occurred in 5 patients.
p.6
Risk Factors for Bowel Obstruction
What are the two risk criteria identified for colonic tumors?
Anatomic properties of the tumor, specifically transmural disease and obstructing phenotype.
p.2
Implications for Multidisciplinary Team (MDT) Decision-Making
What was the role of the Independent Data Monitoring Committee in the FOxTROT trial?
To review the database annually.
p.6
Implications for Multidisciplinary Team (MDT) Decision-Making
What is suggested to be added to MDT assessment criteria for high-risk colon cancer?
A complete luminal assessment.
p.8
Neoadjuvant Chemotherapy (NAC) for Colon Cancer
What is hypothesized to contribute to favorable outcomes in patients attending the hospital for neoadjuvant therapy?
Enhanced monitoring enabling early intervention in the event of obstructive signs and symptoms.
p.7
Pathologic Features and Tumor Characteristics
What percentage of cases had proficient MMR status?
96.3% of cases had proficient MMR status.
p.4
Risk Factors for Bowel Obstruction
What was the baseline risk for patients with neither high-risk feature?
0.2% across different tumor locations.
p.6
Risk Factors for Bowel Obstruction
Where was obstruction most commonly found in colonic tumors?
At the hepatic and splenic flexures.
p.4
Risk Factors for Bowel Obstruction
What classification was given to patients with both high-risk features?
They were classified as high risk (> 10%).
p.6
Clinical Outcomes of Obstruction
What percentage of obstructed patients completed adjuvant therapy?
33.3% of obstructed patients completed therapy, compared to 65.3% of other patients.
p.7
Clinical Outcomes of Obstruction
What was the mean age at randomization for cases and controls?
Both cases and controls had a mean age of 61.6 years.
p.8
FOxTROT Trial Overview
What improved perioperative outcomes were observed in the FOxTROT trial?
Reduced rates of an anastomotic leak following NAC compared to patients who proceeded directly to surgery.
p.3
Clinical Outcomes of Obstruction
What percentage of patients undergoing NAC developed obstruction?
4.3% (30 out of 698 patients).
p.9
Risk Factors for Bowel Obstruction
What does the study define in terms of risk for obstruction?
A prospectively identifiable subgroup of patients at greater than 10% risk of obstruction.
p.8
Risk Factors for Bowel Obstruction
What was the odds ratio for stricturing disease associated with obstruction?
7.18, indicating a strong association.
p.1
Risk Factors for Bowel Obstruction
What is the relationship between neoadjuvant chemotherapy and the risk of bowel obstruction?
Deferring surgery for patients undergoing NAC can put them at risk of colonic obstruction.
p.7
Clinical Outcomes of Obstruction
What percentage of cases were female?
36.7% of cases were female.
p.8
Clinical Outcomes of Obstruction
What was the impact of obstruction on the initiation or completion of adjuvant therapy?
The rate was lower in obstructed patients, likely due to prolonged recovery after urgent surgery.
p.5
Implications for Multidisciplinary Team (MDT) Decision-Making
What is the significance of the study's ability to prospectively observe a large patient cohort?
It allows for better understanding and management of risks associated with NAC for colon cancer.
p.7
Statistical Analysis Methods
What was the P-value for the comparison of extramural vascular invasion between cases and controls?
The P-value was 0.26, indicating no significant difference.
p.8
Risk Factors for Bowel Obstruction
What was the odds ratio for obstructing findings on endoscopy?
9.09, indicating a significant association with obstruction.
p.7
Statistical Analysis Methods
What was the P-value for the comparison of stricturing in radiology between cases and controls?
The P-value was 0.002, indicating a significant difference.
p.8
Patient Stratification for Treatment
What may be helpful for patients developing progressive obstruction concerning the primary tumor?
Colonic defunctioning or stenting to facilitate NAC.
What was the percentage of cases unable to pass the scope?
10.0% of cases were unable to pass the scope.
p.3
Clinical Outcomes of Obstruction
What was the two-year overall recurrence rate for obstructed versus unobstructed patients?
23.3% for obstructed patients vs 17.8% for unobstructed patients.
p.1
Clinical Outcomes of Obstruction
What impact does bowel obstruction have on patients with colon cancer?
It accounts for 50% of mortality within a year of diagnosis and has a detrimental impact on longer-term survival and oncological outcomes.
p.2
FOxTROT Trial Overview
What was the randomization ratio for patients in the FOxTROT trial?
2:1 ratio to short course NAC and standard AC or standard AC alone.
p.9
Patient Stratification for Treatment
What limitation was noted regarding patients who were not randomized in the trial?
Outcomes for these patients could not be compared due to lack of consent and management through an emergency pathway.
p.3
Surgical Approaches and Outcomes
How were obstructed patients managed?
With colonic stenting for 8 patients and expedited surgery for 21 patients.
p.2
FOxTROT Trial Overview
What type of study design was the FOxTROT trial?
A multicenter, randomized controlled trial.
p.6
Pathologic Features and Tumor Characteristics
What was the significance of margin status in pathologic outcomes?
pR0 status was significantly higher in nonobstructed patients (95.8%) compared to obstructed patients (84.0%).
p.8
Case-Control Study Design
What were the limitations of the case-control study regarding obstruction?
Low absolute number of obstructions and potential residual sampling bias due to simple matching variables.
p.1
Patient Stratification for Treatment
What percentage of patients were classified as very low risk for bowel obstruction?
63.4% (443/698) were at very low risk (< 1%).
p.6
Clinical Outcomes of Obstruction
How did the rate of stoma formation compare between obstructed and nonobstructed patients?
It was comparable, with 88.9% of obstructed patients and 88.4% of nonobstructed patients not forming a stoma.
p.1
Risk Factors for Bowel Obstruction
What were the two independent risk criteria identified for bowel obstruction?
1) Obstructing disease on endoscopy and/or being unable to pass through the tumor; 2) Stricturing disease on radiology or endoscopy.
p.2
Case-Control Study Design
What was the significance of the matching process for cases and controls?
Each case was matched with 3 controls based on gender and age group to ensure comparability.
p.6
Risk Factors for Bowel Obstruction
What does the presence of a circumferential tumor indicate?
It may cause luminal stricturing that is statistically significant.
p.1
Implications for Multidisciplinary Team (MDT) Decision-Making
What is the role of multidisciplinary teams (MDT) in managing patients at risk of bowel obstruction?
Recognizing patient risk factors informs the consent process, enriches MDT decision-making, and enables targeted active monitoring.
p.6
Clinical Outcomes of Obstruction
What was the mean length of stay for obstructed patients compared to others?
10.8 days for obstructed patients versus 7.3 days for others.
