New York: Some men with prostate cancer may have increased risks of dying from causes other than the cancer itself, a new study finds.
Researchers found that when men had their prostate cancer diagnosed after developing symptoms -- and not after screening tests -- they had heightened risks of dying from heart problems or other cancers.
It`s not clear what to make of the findings at this point. Mainly, they raise questions for future studies, said Dr. Anthony D`Amico, of the Dana-Farber Cancer Institute and Harvard Medical School in Boston.
"This is a study of associations, and does not prove cause-and-effect. It`s really hypothesis-generating," said D`Amico, who was not involved in the research.
One possibility, according to the study authors, is that hormonal therapy has something to do with the increased risk of heart disease death.
D`Amico agreed that could be a factor. A number of studies, he said, have suggested that hormonal therapy for prostate cancer could raise the risk of heart disease death.
But, D`Amico added, that link has only been seen in men with a history of heart disease going into the therapy.
SCREENING VS. USUAL CARE
The findings, reported in the British Journal of Urology International, are based on a subgroup of men who took part in a European clinical trial on prostate cancer screening.
The men, who were ages 55 to 74, were randomly assigned to either undergo periodic prostate cancer screening or be part of a control group that stuck with "usual" health care.
The researchers followed death rates among 372 men who were diagnosed with prostate cancer through screening, comparing them with 1,488 men who`d been screened but found cancer-free.
They also followed 221 men in the usual-care group who`d been diagnosed with prostate cancer after developing symptoms. Those men were compared with 884 men from the control group who had not been diagnosed with the cancer.
Looking at that latter group, the researchers found that men with prostate cancer were more likely to die from cardiovascular disease or other types of cancer over the next six years.
Just under 12 percent died of cancers other than prostate tumors, versus 7 percent of men who had not been diagnosed with prostate cancer. And 5 percent died of heart disease or stroke, compared with just over 3 percent of other men.
In contrast, men who`d had their prostate cancer caught through screening showed no increased risk of death compared with men free of prostate cancer.
Prostate cancer screening, such as with PSA blood tests, often catches very early tumours that may or may not be life-threatening. Prostate cancer is often slow-growing, and may never progress to the point of being lethal.
But when men are diagnosed because they`ve developed symptoms (like problems passing urine and low back pain), the cancer is often at a more-advanced stage.
For those men, one treatment option is hormonal therapy to lower a man`s levels of testosterone, which can fuel prostate tumors` growth.
Several studies have linked the therapy to higher-than-normal risks of cardiovascular "events," like blood clots or heart attacks, or death from heart complications.
In this study, 27 percent of men diagnosed with prostate cancer based on symptoms ended up having hormonal therapy, according to the researchers, led by Dr. Pim J. van Leeuwen of Erasmus Medical Center in Rotterdam.
So, they say, hormonal therapy might help explain the increased risk rate of death from cardiovascular problems.
D`Amico agreed that that`s a possibility, and called it the most "interesting" point from the findings.
As for the increased rate of death from other cancers, D`Amico speculated that men with more-aggressive prostate cancer may be genetically vulnerable to other cancers as well.
Or, he added, being part of a medical study may have meant they were more likely to have screening tests for other cancers.
For now, the reasons for the findings are unclear. "This is not something that would change clinical practice," D`Amico said.
Like with any treatment for prostate cancer, experts say the risks of hormone therapy have to be weighed against the potential benefits. For men with "high-risk" cancer that is likely to progress, for example, studies have shown that a combination of hormonal therapy and radiation can boost survival.
Men with early prostate cancer diagnosed through screening would not be the ones given hormone therapy, D`Amico said.
For those men, surgery may be an option -- and so may "active surveillance." That means putting off treatment altogether and monitoring the cancer over time.
According to the National Cancer Institute, about half of the more than 190,000 US men diagnosed with prostate cancer in 2009 fell into the "low-risk" category -- meaning their cancer had low odds of progressing.