BACKGROUND: Regular use of aspirin reduces the risk of a colorectal neoplasm, but the mechanism by which aspirin affects carcinogenesis in the colon is not well understood. METHODS: We estimated cyclooxygenase-2 (COX-2) expression by immunohistochemical assay of sections from paraffin-embedded colorectal-cancer specimens from two large cohorts of participants who provided data on aspirin use from a questionnaire every 2 years. We applied Cox regression to a competing-risks analysis to compare the effects of aspirin use on the relative risk of colorectal cancer in relation to the expression of COX-2 in the tumor. RESULTS: During 2,446,431 person-years of follow-up of 82,911 women and 47,363 men, we found 636 incident colorectal cancers that were accessible for determination of COX-2 expression. Of the tumors, 423 (67%) had moderate or strong COX-2 expression. The effect of aspirin use differed significantly in relation to COX-2 expression (P for heterogeneity=0.02). Regular aspirin use conferred a significant reduction in the risk of colorectal cancers that overexpressed COX-2 (multivariate relative risk, 0.64; 95% confidence interval [CI], 0.52 to 0.78), whereas regular aspirin use had no influence on tumors with weak or absent expression of COX-2 (multivariate relative risk, 0.96; 95% CI, 0.73 to 1.26). The age-standardized incidence rate for cancers that overexpressed COX-2 was 37 per 100,000 person-years among regular aspirin users, as compared with 56 per 100,000 person-years among those who did not use aspirin regularly; in contrast, the rate for cancers with weak or absent COX-2 expression was 27 per 100,000 person-years among regular aspirin users, as compared with 28 per 100,000 person-years among nonregular aspirin users. CONCLUSIONS: Regular use of aspirin appears to reduce the risk of colorectal cancers that overexpress COX-2 but not the risk of colorectal cancers with weak or absent expression of COX-2. Copyright 2007 Massachusetts Medical Society.
BACKGROUND: Regular use of aspirin reduces the risk of a colorectal neoplasm, but the mechanism by which aspirin affects carcinogenesis in the colon is not well understood. METHODS: We estimated cyclooxygenase-2 (COX-2) expression by immunohistochemical assay of sections from paraffin-embedded colorectal-cancer specimens from two large cohorts of participants who provided data on aspirin use from a questionnaire every 2 years. We applied Cox regression to a competing-risks analysis to compare the effects of aspirin use on the relative risk of colorectal cancer in relation to the expression of COX-2 in the tumor. RESULTS: During 2,446,431 person-years of follow-up of 82,911 women and 47,363 men, we found 636 incident colorectal cancers that were accessible for determination of COX-2 expression. Of the tumors, 423 (67%) had moderate or strong COX-2 expression. The effect of aspirin use differed significantly in relation to COX-2 expression (P for heterogeneity=0.02). Regular aspirin use conferred a significant reduction in the risk of colorectal cancers that overexpressed COX-2 (multivariate relative risk, 0.64; 95% confidence interval [CI], 0.52 to 0.78), whereas regular aspirin use had no influence on tumors with weak or absent expression of COX-2 (multivariate relative risk, 0.96; 95% CI, 0.73 to 1.26). The age-standardized incidence rate for cancers that overexpressed COX-2 was 37 per 100,000 person-years among regular aspirin users, as compared with 56 per 100,000 person-years among those who did not use aspirin regularly; in contrast, the rate for cancers with weak or absent COX-2 expression was 27 per 100,000 person-years among regular aspirin users, as compared with 28 per 100,000 person-years among nonregular aspirin users. CONCLUSIONS: Regular use of aspirin appears to reduce the risk of colorectal cancers that overexpress COX-2 but not the risk of colorectal cancers with weak or absent expression of COX-2. Copyright 2007 Massachusetts Medical Society.
Authors: Li Liu; Reiko Nishihara; Zhi Rong Qian; Fred K Tabung; Daniel Nevo; Xuehong Zhang; Mingyang Song; Yin Cao; Kosuke Mima; Yohei Masugi; Yan Shi; Annacarolina da Silva; Tyler Twombly; Mancang Gu; Wanwan Li; Tsuyoshi Hamada; Keisuke Kosumi; Kentaro Inamura; Jonathan A Nowak; David A Drew; Paul Lochhead; Katsuhiko Nosho; Kana Wu; Molin Wang; Wendy S Garrett; Andrew T Chan; Charles S Fuchs; Edward L Giovannucci; Shuji Ogino Journal: Gastroenterology Date: 2017-09-01 Impact factor: 22.682
Authors: Xiaoyun Liao; Paul Lochhead; Reiko Nishihara; Teppei Morikawa; Aya Kuchiba; Mai Yamauchi; Yu Imamura; Zhi Rong Qian; Yoshifumi Baba; Kaori Shima; Ruifang Sun; Katsuhiko Nosho; Jeffrey A Meyerhardt; Edward Giovannucci; Charles S Fuchs; Andrew T Chan; Shuji Ogino Journal: N Engl J Med Date: 2012-10-25 Impact factor: 91.245