CHICAGO — One of the longest studies of early prostate cancer suggests that untreated, slow-growing tumors become more lethal after 15 years — findings that argue for more aggressive treatment in younger men.
The Swedish study looked at a widely used practice known as "watchful waiting," in which doctors forgo surgery or radiation and merely keep an eye on the patient's tumor.
It is an option doctors choose for many patients with slow-growing tumors, particularly older men who might die of other causes before the cancer spreads. Another reason for waiting is that surgery and radiation can cause impotence and urinary incontinence.
The study found that the death rate from prostate cancer increased almost threefold after 15 years. The research could indicate that some tumors become increasingly aggressive, said one of the study's authors, Dr. Jan-Erik Johansson of Orebro University Hospital in Sweden.
Johansson said the findings suggest that doctors should consider radical treatment in younger men who have more than 15 years left to live.
The study involved 223 Swedish men with initially untreated, early stage prostate cancer. They were followed for an average of about 21 years, until 2001. The men were 72 on average when they joined the study.
The findings appear in Wednesday's Journal of the American Medical Association.
The study began before the development of many current prostate cancer treatments. It also predated the standard screening test: the prostate-specific antigen test, or PSA, which has greatly increased the number of men diagnosed with prostate cancer.
PSA testing was called into question in a study published last month showing that the tests miss many tumors in older men. Those results, in the New England Journal of Medicine, also added to the debate over when to recommend aggressive treatment.
In the latest study, 203 of the participants died from various causes.
The death rates from prostate cancer remained fairly constant during the first three five-year periods after diagnosis — about 5 percent to 7 percent.
But after 15 years, 16.7 percent of the 48 participants left in the study died of prostate cancer. The number of instances in which cancer spread beyond the prostate also became more frequent.
Dr. Alfred Neugut, the head of medical oncology at Columbia University Medical School, said it is possible that detection methods became so much more sophisticated in the study's final years that prostate cancers that had turned aggressive earlier were only detected then. A totally new cancer could also have developed in the prostate, he said.
Johansson said his group's research might be most useful for doctors who currently recommend aggressive treatment for men under 70 with early prostate cancer.
"For those patients with early prostate cancer, perhaps one can choose watchful waiting down to 65 years of age if the tumor is more 'benign' in the microscope," he said.
He said it would not be wise for younger men to choose watchful waiting, because of the danger after 15 years.