WEDNESDAY, April 4 (HealthDay News) -- When people learn they have cancer, they might face a heightened risk of suicide or a fatal heart attack in the days and weeks that follow, according to a large new study.

Using nationwide census and death registry data that covered more than 6 million people over a 15-year period ending in 2006, Swedish researchers tabulated the suicides and cardiovascular fatalities among people with new cancer diagnoses and compared them to similar deaths in those without cancer.

Suicide risk was more than 12 times higher for people with cancer during the first week after diagnosis and nearly five times higher during the first three months, they found.

Death from cardiovascular causes -- particularly heart attack -- was 5.6 times higher in the week after a cancer diagnosis and 3.3 times higher in the first month.

Hard-to-treat cancers with poor odds for survival, including cancers of the esophagus, pancreas, liver, lung and central nervous system, were most common in these types of deaths, the researchers said.

"That the risk increase appeared so quickly after cancer diagnosis and then decreased in magnitude during the first year after diagnosis really illustrated the role of the diagnosis itself on these adverse outcomes," said study co-author Dr. Katja Fall, a senior lecturer in epidemiology at the University of Orebro. "It largely argues against [death] from cancer treatment and progression that presumably take time to accumulate."

The researchers found a prevalence of 0.18 suicides for cancer-free people and a prevalence of 0.36 for people with any type of cancer when they looked at deaths per 1,000 person-years.

Suicide risk decreased as time passed, but it was still about three times higher during the first year, and remained higher after. For heart-related death, risk leveled off after a year.

Researchers accounted for other factors that might predispose people to sudden heart death or suicide, such as seasonal differences and previous psychiatric illness, or demographic factors such as age or sex. Only adults aged 30 or older were included.

The study was published in the April 5 New England Journal of Medicine.

Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society, noted that because the study took place in Sweden, it's not certain how the results apply to the United States. Nevertheless, he said, "this study is saying we have to be aware that this is a very real problem."

"We believe that the words 'you have cancer' certainly can be associated with distress, but we also like to believe with support and care and love that people will find a way to confront their illness and move through that process under the best possible circumstances," Lichtenfeld added.

"But we can't always be optimistic that that's going to happen, and we have to be sensitive to the warning signals that somebody who has a history of depression or may be currently depressed could become more so -- we can't pass that off: 'Well, they've been told they have cancer, what do you expect?'" he said.

"Patients who have a history of depression need to be counseled and observed more carefully -- by their health professionals, by their family, by their friends, by their colleagues," Lichtenfeld said.

Nearly 550,000 cardiovascular deaths occurred during the study, with a prevalence of 23.1 in people with cancer diagnoses compared with 7.53 among cancer-free people. Heart attacks were the biggest cause, followed by strokes.

Both experts said that severe emotional stress could provoke physical changes.

"Psychological stress induces an array of physiological reactions, including the release of stress hormones such as catecholamines and corticosteroids that have impact on the cardiovascular system," Fall said.

Lichtenfeld noted that many U.S. patients are already under treatment for coronary artery and vascular disease.

"Certainly, if someone starts having increased symptoms of coronary artery disease, such as angina (chest pain), or decreased ability to walk, or increased shortness of breath with walking, once again that could be a medical emergency -- not just that someone's not feeling well because they've been told they have cancer," he said.

Although cancer treatments and survival rates continue to improve, study author Fall said it's impossible to predict whether statistics in studies like hers might also improve.

"We do observe higher risk increases among patients diagnosed with cancers of less favorable prognosis," she noted. "If the prognosis improves, one could, of course, hope that the risks for adverse stress-related health outcomes would decrease."

The study did not measure suicide attempts or serious but nonfatal heart attacks after a cancer diagnosis.

More information

The U.S. National Cancer Institute describes how it feels to learn you have cancer.