Differences in pathology and mutational status among colorectal cancer (CRC) patients pre-, post-, and during screening age.

Abstract

3596 Background: Screening protocols for CRC are broadly recommended and effective in reducing mortality. However, populations from different age groups can harbor distinct pathological and molecular profiles that can also be influenced by screening and polyp resection, especially in older ages. Methods: We retrospectively analyzed tumors from stage IV CRC patients from a central pathology laboratory in Brazil that is a reference for mutational profiling countrywide. Patients were classified into age groups as the following: pre-screening (PrSA; <45yo), screening(SA; 45-75yo) and post-screening age (PoSA; >75yo). Every tumor has been centrally reviewed by the pathologist. Groups were compared regarding clinicopathologic features and presence of RAS and BRAF mutations. Results: We included 1244 pts (164 PrSA, 919 SA and 161 PoSA). There were no difference among groups regarding sidedness(p= .68)and KRASmutations (p=.0.97). Stage IV at diagnose (p =.001), presence of signet-ring cell component (p< .001) along with poorly differentiated tumors (p= .006) were most found on young patients, while BRAFand NRASmutations where significantly more common among PosSA (table). Conclusions: PosSA and PreSA CRCs seem to present a distinct profile from SA populations, including differences in the molecular and pathologic aspects. This could impact the frequency of screening tests among different age groups. [Table: see text]