Many cancer patients who have heart attacks often are not treated with lifesaving aspirin given the belief in the medical community that they could experience lethal bleeding. Researchers at The University of Texas M. D. Anderson Cancer Center, however, say that notion is now proven wrong and that without aspirin, the majority of these patients will die.
Common Assumptions Overturned
Researchers say that their study, published in a recent issue of the journal Cancer, turns common medical assumptions upside down and will likely change medical practice for cancer patients. Because aspirin can thin blood and cancer patients experience low platelet counts and abnormal clotting, physicians view aspirin as a relative contraindication. Given that blood platelets are responsible for the clotting process, physicians do not eagerly prescribe aspirin as a standard treatment.
In this study, however, the investigators found that 9 of 10 cancer patients with thrombocytopenia (low platelet count) who were experiencing a heart attack and who did not receive aspirin died, whereas only one patient died in a group of 17 similar cancer patients who received aspirin. They also found aspirin helps cancer patients with normal platelet count survive heart attacks, just as it does for people without cancer.
"The notion that heart attacks in patients with low platelets should be treated with clot-dissolving aspirin defies logic, that is unless you suspect that the cancer is interfering with platelet function," says the study's senior investigator and author, Jean-Bernard Durand, MD, assistant professor in the department of cardiology at M.D. Anderson Cancer Center.
"We believe tumors may be releasing chemicals that allow the cancer to form new blood supplies which makes blood more susceptible to forming clots," says Durand, a heart failure specialist. "There appears to be a platelet paradox suggesting that cancer may affect the mechanism of the way that blood clots, and from this analysis, we have found that the single most important predictor of survival in these patients is whether or not they received aspirin." Durand says more research is needed to better understand this contraindication.
According to the World Health Organization, there are approximately 10 million cancer patients worldwide, of which 1.5 million may develop blood clots during their cancer treatment and, as such, are at a much higher risk of dying from heart disease if not treated properly. "Now that we have this study, it would be a travesty if you survive treatment for cancer only to die of a heart attack soon thereafter," Durand says.
According to Durand, no guidelines currently exist for treatment of heart attacks in patients with cancer. He says that physicians are especially perplexed about what to do for cancer patients with thrombosis, a condition that affects about 15% of all cancer patients and can be due to the use of chemotherapy or the presence of cancer.