[708] A Bayesian Analysis of the Ratio, T1N1/T1N0, as a Marker of Relative Aggressive Potential in Colon Cancer

Ankita Patel, Nisrene Tabbara, Arnold M Schwartz, Donald E Henson, Kristen Batich. George Washington University Cancer Institute, Washington, DC; George Washington University, Washington, DC

Background: Colo-rectal carcinomas may present in a minority of cases with nodal metastases despite limited invasion in the submucosa (pT1). Cancers that are T1N1 relative to T1N0 are associated with increases in recurrence and decreases in overall survival. We have compared our surgical pathology experience with 93 pT1 colon cancers, of which 11 were pT1N1, with the SEER registry to identify pathologic and epidemiologic markers for relative tumor aggressive behavior in the form of increased ratios of T1N1/T1N0.
Design: Data were retrieved using NCI's SEER Program from 1988-2003. Extent of disease (EOD) codes from 1988-2003 were used to assess T1 invasion and positive/negative lymph node involvement (N1 and N0 respectively). Tumors greater or equal to T2, N2, and M1 were excluded. A Bayesian analysis was used to calculate the odds ratio of T1N1 rates to T1N0 rates according to age, gender, race, histologic type, and location in the colon. Epidemiologic data were compared and amplified by pathologic data. Age groups were separated into <45 years, 45-60, and >60. Five year relative survival rates were calculated for positive and negative lymph node involvement among age cohorts and different histologic types (adenoca., mucinous adenoca., and signet ring cell ca.).
Results: The overall ratio T1N1/T1N0 was 0.12 for pathology cases and 0.09 for SEER cases. Pathologic features that increase the ratio are high histologic grade, lymphatic invasion, and near muscularis propria invasion. Epidemiologic factors that increase nodal positivity are younger ages (age <45 years, ratio 0.24; >60 years, ratio 0.1), signet ring cell component (ratio 0.35), racial group (Blacks, ratio 0.12; Whites, ratio 0.09), and gender (male, ratio 0.09; female, ratio 0.08).
Conclusions: The rate ratio is higher among men than women only in the <45 year cohort. The odds of nodal positivity given T1 are greater in blacks than whites in all age groups. The rate ratio reflects the histologic type of the adenocarcinoma and decreases among all age cohorts. Using the odds of each prognostic variable (age, gender, race, histologic type) a combined risk for nodal metastases can be assessed for colorectal cancer.
Category: Gastrointestinal

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 85, Wednesday Morning

 

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