Fivefold increase seen in month before diagnosis in older adults
Older adults are at increased risk of suffering a heart attack or stroke in the months leading up to a cancer diagnosis, according to a new study.
Researchers from Weill Cornell Medicine, NewYork-Presbyterian, and Memorial Sloan Kettering Cancer Center in New York City found that these individuals are 70% more likely to suffer these cardiovascular events in the year before diagnosis compared with their counterparts not diagnosed with cancer over the same time period.
Babak Navi, MD, who led the study and is affiliated with all three institutions, told MedPage Todaythat previous research he and his colleagues had conducted focused on the association between cancer and arterial thromboembolism after cancer has been diagnosed. "But we hadn't really looked backwards to the time before cancer was diagnosed -- but presumably present," he explained.
"Here, in some people at least, we expected there would be some biological activity, and that's what we found," he said.
For the study, published online in Blood, Navi and colleagues used the population-based Surveillance, Epidemiology, and End Results-Medicare linked dataset; the team identified 374,331 patients ages 67 and over with a new diagnosis of breast, lung, prostate, colorectal, bladder, uterine, pancreatic, or gastric cancer, or non-Hodgkin lymphomas during 2005-2013. These patients were matched by demographics and comorbidities to Medicare beneficiaries without cancer.
The researchers compared the risk of arterial thromboembolic events between cancer and non-cancer patients in 30-day intervals in the year prior to the date when cancer was diagnosed.
A total of 6,567 cancer patients (1.75%) were diagnosed with an arterial thromboembolic event, compared with 3,916 patients (1.05%) without cancer, in the 360 days before cancer diagnosis (OR, 1.69; 95% CI, 1.63-1.76).
However, the team found that in the 150 days before cancer diagnosis the interval 30-day risks of heart attack or stroke were even higher in cancer patients. And those risks progressed as the date of cancer diagnosis approached, peaking in the 30 days before cancer diagnosis, when 2,313 (0.62%) cancer patients were diagnosed with an arterial thromboembolic event compared with 413 (0.11%) cancer-free patients (OR, 5.63; 95% CI, 5.07-6.25).
The researchers noted that cancer can be associated with blood clots in several ways, such as by damage to the lining of blood vessels or circulating tumor cells that attract clots.
"We've known for a long time that cancer is associated with a heightened risk of clotting, particularly in veins," Navi said. "If someone is older, say over 65, and has an unprovoked venous thromboembolism, observational data suggest that about 10% of those patients will have an occult cancer, and because of that, such an unprovoked deep vein thrombosis will often trigger physicians to surveil for cancer. This [current study] is the arterial corollary."
Navi said that while the absolute risk of these arterial events is not as high as these venous events, "we need prospective studies to determine what are some biomarkers that can increase the diagnostic yield of screening for cancer, and what that yield is worth. That needs to be investigated before practice can change."
As for how physicians should determine which patients who have had cardiovascular events like heart attacks or stroke are at risk for cancer, Navi said they should see whether there are any symptoms of potential cancer -- such as unexplained weight loss or anemia, abnormal liver enzymes, or blood in the stool or cough -- in these patients.
"I'm a stroke neurologist, and when I see a stroke patient, and I don't see an obvious cause, and there are some symptoms that suggest a systemic process like cancer, I definitely consider screening in some way for cancer," he said. "And at the very least I'll make sure patients are up to date with their age- and gender-specific cancer screening."
Navi and co-authors reported having no conflicts of interest.
Source Reference: Navi B, et al "Arterial thromboembolic events preceding the diagnosis of cancer in older patients" Blood 2o18; DOI: 10.1182/blood-2018-06-860874.