Background: Substantial data support efficacy of ASA in colorectal adenoma and cancer (CRC) chemoprevention. In 2011, the CaPP2 Phase 3 trial showed benefit of 600 mg ASA daily for prevention of LS-associated CRC (HR 0.41,p=0.02) in persons w/ASA adherence >2 yrs. Anecdotally, uptake of ASA by LS pts has been low, but few data exist. We examined uptake and predictors of ASA chemoprevention among LS pts receiving follow-up at our center since 2011. Methods: Pts evaluated by Fox Chase’s Risk Assessment Program receive in-person medical recommendations and written information about cancer (CA) prevention measures including ASA. Medical records of 127 LS pts were retrospectively reviewed. Demographics, gene affected, personal Hx of CA, ASA use, and ASA dose were collected. Majority (94.5%) of cohort had documentation of ongoing LS endoscopic screening at our center—only 3.2% had no recent follow-up (past 3 yrs) and 2.4% had recently died (past 3 yrs). Chi-square tests and multivariable logistic regression were used in analyses. Results: Overall 24.4% (31/127) of pts reported ASA use for chemoprevention (see Table). Nearly half (48.4%) of ASA users took 81 mg ASA daily, and only 22.6% reported taking >600 mg ASA daily. ASA use was associated with older age, MLH1/MSH2+ vs MSH6/PMS2+, and personal Hx of CRC. In the multivariable logistic model, older age (OR 2.80, p=0.04) and MLH1/MSH2+ (OR 2.64,p=0.07) were significant and borderline significant, respectively. Adding race/ethnicity and gender strengthened the effect of age>60 (OR 3.11, p=0.03), and improved fit (pseudoR²=16.8%). Conclusions: Uptake of ASA chemoprevention by LS pts is overall modest, but older age is associated with ASA uptake for chemoprevention. Among ASA users, fewer than 1 in 4 take the 600 mg daily dose shown effective in CaPP2. Confirmatory trials as well as efforts to elucidate barriers to ASA chemoprevention in LS are needed.

A: p compares ASA use in all 4 genes B: p compares ASA use in MLH1+MSH2 vs MSH6+PMS2

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