Cancer risk in long-term users of vitamin K antagonists: A population-based case-control study

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Some evidence suggests that long-term use of vitamin K antagonists (VKAs) has a cancer chemopreventive effect. Such an
effect would have considerable implications in terms of understanding tumor biology. To evaluate if long-term VKA treatment
influences the risk of developing cancer, we performed a matched case–control analysis. We used data from four Danish
nationwide registers. Cases were all Danish individuals with a first-time cancer diagnosis (except nonmelanoma skin cancer)
between 2000 and 2009. For each case, eight controls, matched by birth year and gender, were selected from the source
population by risk-set sampling. Long-term VKA use was defined as exposure to VKA for a period of 3 or more years.
Conditional logistic regression was used to compute odds ratios (ORs) for cancer associated with long-term VKA exposure,
adjusting for potential confounders. Prespecified subanalyses were performed for selected cancer sites, subgroups and
measures of exposure. A total of 238,196 cases and 1,713,176 controls were included. The adjusted OR for cancer associated
with long-term VKA exposure was 0.99 (95% CI: 0.95–1.02). Long-term VKA use was associated with increased ORs for
alcohol- or obesity-related cancer sites, whereas we observed a decreased risk of prostate cancer (OR: 0.86; 95% CI:
0.78–0.95). Our study does not support a general chemopreventive effect of VKA drugs. However, in accordance with findings
from previous studies, we found an inverse association between use of VKA and prostate cancer.
TidsskriftInternational Journal of Cancer
Udgave nummer11
Sider (fra-til)2606-2612
StatusUdgivet - 2013