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OUTCOMES OF IBD-ASSOCIATED RECTAL CANCER FOLLOWING TREATMENT WITH MULTIMODAL THERAPY: A MATCHED COHORT STUDY
Imran Khan
*, Jacob G. Mansell, Sudha A. Amarnath, Stefan D. Holubar, Benjamin L. Cohen, Taha Qazi, Emre Gorgun, Michael Valente, Scott Steele, David Liska
Cleveland Clinic, Cleveland, OH
Background: Patients with inflammatory bowel disease (IBD) are at increased risk for rectal cancer. Neoadjuvant RT has been shown to be associated with improved outcomes in sporadic locally advanced rectal cancer (LARC). This study aims to compare treatment outcomes and long-term survival between patients with IBD-LARC and sporadic LARC. We hypothesized that LARC in IBD was associated with decreased neoadjuvant treatment efficacy and worse outcomes.
Methods: Our institutional cancer registry identified patients with LARC who received neoadjuvant chemoradiotherapy (CRT), short-course radiotherapy (scRT), or total neoadjuvant therapy (TNT) followed by oncologic proctectomy and had an established diagnosis of IBD. Patients with stage IV disease, or recurrent cancer were excluded. IBD-LARC patients were matched 1:1 with patients with sporadic LARC based on age, sex, clinical stage, and treatment modality. Our primary outcomes was pathological treatment response; other outcomes included Kaplan-Meier estimated recurrence-free survival (RFS) and overall survival (OS). Cox proportional hazards analysis was used to identify factors independently predictors of survival.
Results: A total of 92 IBD patients were matched to 92 controls. Baseline ECOG P.S ?1 was more common in IBD (53.7% vs. 34.1%, p=0.08). There were no differences between groups in nodal involvement (p=0.66) or clinical stage at diagnosis (p=0.75). Poorly differentiated adenocarcinoma was more frequent in IBD (32.7% vs. 7.4%, p=0.01). Surgical approaches inherently differed, with total proctocolectomy more common in the IBD and low anterior resection in the sporadic group. Robotic procedures were less common in IBD (8% vs. 23.8%, p=0.02). Pathologic complete response was less frequent following any neoadjuvant treatment in IBD (6.8% vs.22.6%, p=0.03). Margin positivity was more common in IBD: 13% vs. 4.3%, p=0.02
(Table 1). After a median follow-up of 37 months IQR (5.25-66.75) in the IBD group and 47 (11.5-82.5) in the sporadic group the recurrence rates were higher in the IBD group at 37% vs. 22.8% in the sporadic group (p<0.05) and there was a trend for decreased 5-year RFS (HR=0.58, 95% CI 0.33–1.02, p=0.06). Five-year OS was not significantly different (HR=0.73, 95% CI 0.45–1.17, p=0.19. On univariate Cox regression, IBD was associated with similar OS (HR=1.37, 95% CI 0.86–2.20, p=0.19). Factors independently associated with decreased OS included age >65 years, ECOG ?1, poor neoadjuvant response with a Tumor Regression Grade >2, ypT stage ?3, and ypN+ disease.
(Table 2)Conclusion: Patients with IBD-associated LARC had worse baseline P.S and higher rates of poorly differentiated tumors when compared to sporadic patients. Pathologic CR in IBD are rare and surgeries were more complex with higher rates of margin positivity, factors potentially responsible for higher recurrence rates.
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