In cancer treatment, detection of a tumor in an early stage markedly increases the chance of favorable outcomes.
Can the much-aligned blood thinner, warfarin, occasionally help in early detection of cancer?
Few pharmacologic agents receive more bad press than warfarin. Stories, which are too numerous to count, like “Did warfarin kill my father,” can be widely found on Internet forums, search engines, and are often quoted by reluctant patients — whose numerator of bad warfarin experiences is one.
It is true that warfarin has a narrow therapeutic window — a small difference between an effective dose and dangerous dose.
Here is the story of two recent patients I have seen who may have had their life saved by the blood-thinning effect of warfarin. Both were older patients taking warfarin for stroke prevention: one had some minor GI bleeding and the other some GYN-type bleeding. Upon evaluation of both patient’s bleeding episodes, an early-stage malignancy was found. Each have undergone appropriate treatment and both told me their cancer had not spread. Although there will never be proof that warfarin prevents cancer — as it doesn’t — this is not the first time I have seen a malignancy discovered, perhaps at an earlier stage because of warfarin-induced bleeding.
No, I am not saying that warfarin should be used for the purpose of early stage cancer prevention, but rather, this may be an occasional “favorable” side effect of its blood thinning properties.
Paradoxically, in these two cases, a seemingly unfavorable effect (bleeding) turned out to be a positive.
Without dismissing the importance of bleeding issues with warfarin, I try and convince most patients that bleeding is statistically far better than stroke. And the science of warfarin’s efficacy in appropriately selected patients is incontrovertible.
Anecdotes do not always make for sound medical practice.
Warfarin is a highly effective agent for stroke prevention in appropriately selected patients. Its efficacy requires the maximal amount of time in the therapeutic range of INR (International Normalized Ratio). The INR measures the degree of blood-thinning effects. If the blood is too thin (high INR) there is an enhanced risk of bleeding, and if the blood is too thick (INR<2.0), there is no benefit. Maximizing the time in therapeutic range requires a motivated, well-educated patient along with skillful monitoring. A well-informed doctor is the best person to provide counseling on the risk-benefit ratio of any medical therapy.
*This blog post was originally published at Dr John M*