Andrew T. Chan

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CONTEXT Aspirin reduces risk of colorectal neoplasia in randomized trials and inhibits tumor growth and metastases in animal models. However, the influence of aspirin on survival after diagnosis of colorectal cancer is unknown. OBJECTIVE To examine the association between aspirin use after colorectal cancer diagnosis on colorectal cancer-specific and(More)
CONTEXT Randomized trials of short-term aspirin use for prevention of recurrent colorectal adenoma have provided compelling evidence of a causal relationship between aspirin and colorectal neoplasia. However, data on long-term risk of colorectal cancer according to dose, timing, or duration of therapy with aspirin and other nonsteroidal anti-inflammatory(More)
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(More)
PURPOSE PIK3CA mutation and subsequent activation of the AKT pathway play an important role in colorectal carcinogenesis. However, little is known about the prognostic role of PIK3CA mutation in colon cancer. PATIENTS AND METHODS Using 450 resectable colon cancers (stage I to III) in two independent prospective cohorts, we detected PIK3CA mutation in 82(More)
BACKGROUND Colonoscopy and sigmoidoscopy provide protection against colorectal cancer, but the magnitude and duration of protection, particularly against cancer of the proximal colon, remain uncertain. METHODS We examined the association of the use of lower endoscopy (updated biennially from 1988 through 2008) with colorectal-cancer incidence (through(More)
Although the composition of the human microbiome is now well-studied, the microbiota's >8 million genes and their regulation remain largely uncharacterized. This knowledge gap is in part because of the difficulty of acquiring large numbers of samples amenable to functional studies of the microbiota. We conducted what is, to our knowledge, one of the first(More)
PURPOSE Physically active individuals have a lower risk of developing colorectal cancer but the influence of exercise on cancer survival is unknown. PATIENTS AND METHODS By a prospective, observational study of 573 women with stage I to III colorectal cancer, we studied colorectal cancer-specific and overall mortality according to predefined physical(More)
OBJECTIVE Colorectal cancer is typically classified into proximal colon, distal colon and rectal cancer. Tumour genetic and epigenetic features differ by tumour location. Considering a possible role of bowel contents (including microbiome) in carcinogenesis, this study hypothesised that tumour molecular features might gradually change along bowel subsites,(More)
Colorectal cancer is a complex disease resulting from somatic genetic and epigenetic alterations, including locus-specific CpG island methylation and global DNA or LINE-1 hypomethylation. Global molecular characteristics such as microsatellite instability (MSI), CpG island methylator phenotype (CIMP), global DNA hypomethylation, and chromosomal instability(More)