E0093 - Appendiceal Adenocarcinomas Are Associated With Better Prognosis Than Cecal Adenocarcinomas: A Population-Based Comparative Survival Study

Tuesday, October 25, 2022

3:00 PM – 5:00 PM ET

Location: Crown Ballroom

Presenting Author(s)

GC

George Chen, MD

Yale University School of Medicine
New Haven, CT

George Chen, MD¹, Kay Chen, MD¹, Laura Rotundo, MD¹, Saif Zaman, MD², Petr Protiva, MD¹
¹Yale University School of Medicine, New Haven, CT; ²Yale New Haven Hospital, New Haven, CT

Introduction: The incidence of appendiceal cancer in the U.S. has increased over the past two decades despite stable rates of appendectomies. Although the appendix is embryologically derived from the cecum, appendiceal adenocarcinomas have distinct molecular profiles from those of cecal adenocarcinomas. However, treatment protocols are the same and differences in survival outcomes between these malignancies have not been compared extensively. To this end, we conducted a comparative survival analysis of appendiceal and cecal adenocarcinomas.

Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, we identified individuals ≥30 years of age with appendiceal or cecal adenocarcinomas from 1975 to 2016. Demographic and clinical data, including sex, age at diagnosis, year of diagnosis, race, ethnicity, marital status, tumor histology, tumor stage, tumor grade, chemotherapy, surgery, and survival in months, was extracted using SEER*Stat software. Relative hazard ratios for death in the five-year period following diagnosis were calculated using multivariate Cox regression analysis, adjusted for other covariates. Survival was compared by Mantel-Haenszel Log-Rank test, and survival curves were generated using the Kaplan-Meier method. The p-value level of significance was set at < 0.05 for a two-tailed test. Data was analyzed using SAS 9.4 software and R.

Results: We identified 16,738 appendiceal and 87,047 cecal adenocarcinomas. Male sex, age >60, earlier year of diagnosis, black race, and non-Hispanic ethnicity were independently associated with higher mortality rates (Table 1). Those who were divorced, separated, never married, or widowed had worse survivorship compared to married individuals. Non-mucinous histology and advanced stage and grade were associated with worse prognosis, while surgery and chemotherapy were associated with improved survival. Multivariate Cox regression analysis demonstrated significantly lower mortality in appendiceal adenocarcinomas (HR 0.61; p< 0.0001). The five-year cancer-specific and overall survival curves for appendiceal and cecal cancers are shown in Figure 1.

Discussion: In this first large comparative survival study of appendiceal and colon cancers, appendiceal adenocarcinomas were associated with improved survival compared to that of cecal adenocarcinomas. Further investigation of prognostic factors and molecular mechanisms of appendiceal cancers is needed to establish standardized treatment guidelines.

Figure: Figure 1. Cecal and appendiceal adenocarcinomas - cancer-specific and overall survival experience by site

Table 1: Demographic and clinical factors associated with five-year mortality following diagnosis of appendiceal or cecal adenocarcinoma using multivariate Cox regression analysis
Parameter		P-value	Hazard Ratio	95% Confidence Interval
Sex	Male		1
Sex	Female	< 0.0001	0.89	0.87-0.91
Age	>60		1
Age	≤60	< 0.0001	0.78	0.76-0.80
Year of Diagnosis	2005-2016		1
	1991-2005	< 0.0001	1.56	1.49-1.63
	1975-1990	< 0.0001	1.25	1.22-1.29
Race	White		1
	Asian/Pacific Islander	0.0003	0.91	0.87-0.96
	Black	< 0.0001	1.13	1.10-1.17
Ethnicity	Non-Hispanic		1
Ethnicity	Hispanic	0.003	0.94	0.90-0.98
Marital status	Married		1
	Divorced	< 0.0001	1.14	1.10-1.19
	Separated	0.02	1.11	1.02-1.21
	Never married	< 0.0001	1.15	1.12-1.19
	Widowed	< 0.0001	1.21	1.18-1.24
Histology	Non-mucinous		1
Histology	Mucinous	< 0.0001	0.89	0.86-0.91
Stage	Local		1
	Regional	< 0.0001	3.60	3.43-3.77
	Distant	< 0.0001	17.61	16.79-18.47
Grade	I: Well differentiated		1
	II: Moderately differentiated	< 0.0001	1.32	1.26-1.37
	III: Poorly differentiated	< 0.0001	1.99	1.90-2.08
	IV: Undifferentiated; anaplastic	< 0.0001	2.11	1.96-2.28
Surgery	Surgical excision		1
	Biopsy only	< 0.0001	3.55	3.38-3.74
	No surgery or biopsy	< 0.0001	5.39	4.87-5.97
Chemotherapy	Chemotherapy		1
Chemotherapy	No chemotherapy	< 0.0001	1.06	1.03-1.08
Site	Cecum		1
Site	Appendix	< 0.0001	0.64	0.61-0.67

Disclosures:

George Chen indicated no relevant financial relationships.

Kay Chen indicated no relevant financial relationships.

Laura Rotundo indicated no relevant financial relationships.

Saif Zaman indicated no relevant financial relationships.

Petr Protiva indicated no relevant financial relationships.

George Chen, MD¹, Kay Chen, MD¹, Laura Rotundo, MD¹, Saif Zaman, MD², Petr Protiva, MD¹. E0093 - Appendiceal Adenocarcinomas Are Associated With Better Prognosis Than Cecal Adenocarcinomas: A Population-Based Comparative Survival Study, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.