There's a significant rise in the risk of heart attack and stroke in older people in the months before they're diagnosed with cancer, a new study finds.

"Our data show there is an associated risk of ischemic stroke and heart attack that begins to increase in the five months before the cancer is officially diagnosed, and peaks in the month just before," said study author Dr. Babak Navi, associate professor of neurology with the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine in New York City.

For the study, Navi's team analyzed data from more than 748,000 Medicare beneficiaries, aged 67 and older who were diagnosed with breast, lung, prostate, colorectal, bladder, non-Hodgkin lymphoma, uterine, pancreatic, and gastric cancers from 2005 through 2013.

Those types of cancers account for two-thirds of all cancer diagnoses in the United States. Overall, the risk of heart attack and stroke surged by 70 percent in the year before cancer diagnosis, the findings showed.

The highest risk was seen in the month before cancer diagnosis. During this time, the risk of heart attack and stroke was more than five times higher among patients who were later diagnosed with cancer than among people the same age who didn't have cancer, the study authors said.

The risk of heart attack or stroke was highest in adults with lung and colorectal cancers, and those with stage 3 or 4 disease. Heart attack risk was slightly higher than stroke risk, the researchers added.

"These results suggest that cancer's effect on the clotting system may be what's predominantly driving the associated risk of heart attacks and stroke," Navi said in a news release from the American Society of Hematology.

"Our findings suggest that cancer could be a risk factor for arterial thromboembolism [blood clots], so people who have a heart attack or stroke should be up-to-date with their age- and gender-specific cancer screenings, such as mammograms and colonoscopies," Navi said.

"If someone has a heart attack or stroke and there are any concerning signs for an undiagnosed malignancy, such as weight loss or unexplained anemia, then perhaps a cancer screening should be considered," Navi added.

The report was published online Dec. 21 in the journal Blood.