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. Author manuscript; available in PMC: 2020 Jan 24.
Published in final edited form as: Annu Rev Pathol. 2018 Aug 20;14:83–103. doi: 10.1146/annurev-pathmechdis-012418-012818

Figure 4:

Figure 4:

Analytical framework of molecular pathological epidemiology research using. Studies of aspirin use and colorectal carcinoma PTGS2 (cyclooxygenase-2) expression are shown as examples. PTGS2 expression can be measured by RNA analysis or immunohistochemistry. One can test a hypothesis that aspirin use reduces the incidence of the PTGS2-positive colorectal carcinoma subtype but not that of the PTGS2-negative subtype (52) and another hypothesis that aspirin use reduces mortality in patients with the PTGS2-positive colorectal carcinoma subtype but not that of patients with the PTGS2-negative subtype (53). The study findings support both of these hypotheses, indicating the dependency of the PTGS2-positive subtype tumor cells on PTGS2 activity, leading to sensitivity to aspirin chemoprevention and treatment. The consistency of findings both before and after the diagnosis of colorectal cancer provides further evidence supporting the hypotheses.