Gamma glutamyltransferase, alanine aminotransferase and risk of cancer: systematic review and meta-analysis.

The prospective evidence for the associations of gamma glutamyltransferase (GGT) and alanine aminotransferase (ALT) with risk of cancer in the general population is uncertain. We conducted a systematic review and meta-analysis of published prospective observational studies evaluating the associations of baseline levels of GGT and ALT with risk of overall (incidence and/or mortality) and site-specific cancers. Relevant studies were identified in a literature search of MEDLINE, EMBASE, Web of Science, reference lists of relevant studies to April 2014 and email contact with investigators. Study specific relative risks (RRs) were meta-analyzed using random effects models. Fourteen cohort studies with data on 1.79 million participants and 57,534 cancer outcomes were included. Comparing top versus bottom thirds of baseline circulating GGT levels, pooled RRs (95% confidence intervals) were 1.32 (1.15-1.52) for overall cancer, 1.09 (0.95-1.24) for cancers of the breast and female genital organs, 1.09 (1.02-1.16) for cancers of male genital organs, 1.94 (1.35-2.79) for cancers of digestive organs and 1.33 (0.94-1.89) for cancers of respiratory and intrathoracic organs. For ALT, corresponding RRs for overall cancer were 0.96 (0.94-0.99) and 1.65 (1.52-1.79) in European and Asian populations, respectively. There was an increased risk of cancers of the digestive organs 2.44 (1.23-4.84). The pooled RR for overall cancer per 5 U/L increment in GGT levels was 1.04 (1.03-1.05). Available observational data indicate a positive log-linear association of GGT levels with overall cancer risk. The positive association was generally evident for site-specific cancers. There are geographical variations in the association of ALT and overall cancer.