Trouble with prostate cancer tests

(CNN) -- Doctors who treat prostate cancer disagree on the value of the prostate specific antigen, or PSA, test. But they agree on one thing.

Men are often hurt by overdiagnosis and treatment for prostate cancer.

"There are clearly people we harm with therapy," said Dr. Bruce Roth, professor of medicine at Washington University in St. Louis. "I don't think there's doubt about that. We wouldn't be having this conversation if the therapy was nontoxic."

Prostate cancer treatments are known for side effects such as sexual dysfunction, incontinence, difficulty urinating and controlling bowel functions.

At least 20% to 30% of patients who get radiation therapy or surgery will experience incontinence and erectile dysfunction, according to a report released last week by a federal advisory board. At the same time, prostate cancer survivors say their lives have been saved by PSA tests and subsequent treatments.

The PSA test has become increasingly controversial as more doctors and studies question its effectiveness.

To examine that topic, the U.S. Preventive Services Task Force, an independent panel of experts, reviewed the existing evidence and released a draft recommendation against PSA testing.

There is convincing evidence that "PSA-based screening leads to substantial overdiagnosis of prostate tumors," the draft stated. The task force found "small or no reduction" in prostate cancer deaths and that the test was also "associated with harms related to subsequent evaluation and treatments."

The task force will open the recommendation Tuesday for a comment period before issuing a final recommendation.

It reported that the majority of men who have prostate cancer have a tumor that "will not progress or is so indolent and slow-growing that it will not affect the man's lifespan or cause adverse health effects, as he will die of another cause first."

This results in men undergoing invasive treatments such as surgery, radiation or hormone therapies that have painful and sometimes life-altering side effects.

For doctors, the difficulty lies in distinguishing which patients have the quick, harmful cancers and the slow, harmless ones.

"The Holy Grail of prostate cancer research is to figure out a test that can tell the difference between a relatively indolent cancer and one that will grow and kill the patient," said Dr. Scott Eggener, assistant professor of surgery at the University of Chicago.

The lifetime risk of dying from prostate cancer is 2.8%. Prostate cancer is rare at 50 and younger, and the majority of deaths from prostate cancer occur after men are 75, according to a National Cancer Institute study.

"The majority of people with prostate cancer are destined to not die from it," said Roth, who specializes in oncology. They're more likely to die of more common causes such as stroke or heart attack, he said.

For treatment, doctors consider several factors such as the grade and volume of the tumor, level of PSA and the patient's overall health.

Sometimes, the doctor may recommend active surveillance, which means holding off active treatment and monitoring the patient. This is also called "watchful waiting."

Some patients understand the rationale and agree with the plan. But most people are uncomfortable with the idea of living with cancer.

"There are people who never sleep again until they get some therapy," Roth said. "They think about cancer growing and not doing something. You have to let patients make that decision for themselves and do what they feel most comfortable doing."

According to the task force's report, about 90% of men undergo early treatment with surgery, radiation or hormone therapy.

In radical prostatectomy, surgeons remove the prostate gland. This procedure is associated with a 20% increased absolute risk of urinary incontinence and a 30% increased absolute risk of impotence compared with watchful waiting, according to the task force report.

Another treatment option is radiation therapy, which kills cancer cells using energy beams directed at the tumor. Alternatively, patients can elect to have radioactive seeds planted into their prostates. It's also associated with bowel dysfunction and rectal pain.

For more about the likelihood of side effects: Screening for Prostate Cancer: A Review of the Evidence for the U.S. Preventive Services Task Force

Hormone therapy is used when the tumor is spreading. The patient receives medication that prevents the body from producing testosterone, since prostate cancer cells rely on this male hormone. While this is not a cure, it helps shrink the tumor. But long-term hormone treatment could cause weight gain, cardiovascular risks such as unexpected death, heart attack and higher rates of diabetes.

The task force concluded: "The vast majority of men who are treated do not have prostate cancer death prevented or lives extended from that treatment, but are subjected to significant harms."

Many readers of CNN.com disagreed and wrote that PSA tests and prostate cancer treatments saved their lives.

"I got a PSA blood test five years ago when I turned 50 and it saved my life," wrote a CNN commenter.

"These scores are invaluable in detecting the prostate specific antigens associated with the cancer diagnosis and treatment. ... An ounce of prevention is worth a pound of cure," wrote one prostate cancer survivor.

Eggener, a urologic oncologist, criticized the recommendation from the task force, saying it was "throwing the baby out with the bath water."

"Everyone agrees there are men who don't benefit from screening and don't benefit from treatment. I feel equally as strongly there are men who benefit from screening and benefit from treatment and have their lives saved from treatment," he said.

Roth said the one-size-fits-all approach isn't working.

"We're using a sledgehammer to prognosticate how the patient is going to do," he said. "What we need is a dissecting microscope."

The challenge is that the science hasn't caught up to distinguish between killer and slow-growing prostate cancers.

"Our hope is someday we can figure out, by some biomarker, by some genetic profiling, that would tell us who's going to have an aggressive tumor," Roth said.

Source