The American Cancer Society recommends that men age 50 and older have a blood test to screen for prostate cancer. But several leading authorities fear that this advice will spark unnecessary medical treatment and escalate health care costs.
The test measures PSA--prostate specific antigen--a protein produced by a cancerous or large, noncancerous prostate, the fig-sized gland alongside the rectum that makes seminal fluid in men.
The guidelines announced in November recommend adding the PSA test to the standard exam of feeling for prostate tumors next to the rectum. This was the first time the American Cancer Society formally recommended guidelines for the early detection of prostate cancer.
The fierce debate among cancer experts is not whether PSA works--all agree it is one of the best blood tests for spotting cancer--but whether it is worthwhile spending in excess of $20 billion a year on tests when no studies have proved that early detection for prostate cancer reduces the death rate.
Dr. Willet Whitmore, a leading authority on prostate cancer and professor of surgery at Cornell University in New York, said that if the treatment “is not reducing mortality, you’re telling a patient he has cancer several years before he needed to find out.”
Prostate cancer will claim 34,000 lives in the United States this year, the American Cancer Society estimates.
But some doctors believe the risk of side effects from treatment, which include impotence and incontinence, are far worse than the risk of living with prostate cancer.
The National Cancer Institute, among others, believes the cancer society acted hastily, without waiting for proof that mass screening reduces mortality.
Prostate cancer, which typically strikes men over 65, is a peculiar malignancy. The vast majority grow so slowly that there are no symptoms, the cancer does not spread and the men eventually die of something else.
Some prostate cancers grow more quickly and spread, but no one knows how to distinguish the so-called safe cancers from the killers. Even if they could, no one knows for sure whether treatment prevents the slow ones from growing or stops the spread of the faster ones.
There is no evidence that lives are saved by early diagnosis or any of the available treatments--removing the prostate, radiation, and testosterone-blocking drugs.
“We don’t have evidence of the benefits (of PSA screening), but we do know the risks. That is why we are running a trial,” said Dr. John Gohagan, chief of the Early Detection Branch at the National Cancer Institute in Bethesda, Md.
He said studies have shown a 1% to 2% risk of death after surgery and also a 25% risk of impotence and 6% to 18% risk of incontinence. Gohagan presented these data to the President’s Cancer Panel, a mid-November meeting of prostate cancer experts at NCI.
“It’s a very serious ethical issue and counter to what medicine is all about. You can do a lot of harm and you don’t know if you’ll do any good,” Gohagan said.
But Dr. Gerald Murphy, the Cancer Society’s chief medical officer, said, “Physicians and the public are demanding to be told what to do.”
Prostate cancer has catapulted into the limelight much the way breast cancer did some 15 years ago. Both diseases were ushered into the public domain when luminaries began going public with their personal stories of cancer. Prominent prostate cancer sufferers include Sen. Bob Dole (R-Kan.), musician Frank Zappa, and ABC News President Roone Arledge.
Like all medical tests, PSA is not failproof, sometimes indicating a lurking cancer when none exists and setting off a series of further diagnostic exams.
Dr. Ian Thompson, chief of urology at Brooke Army Medical Center in Texas, estimated an annual cost of $23.6 billion for nationwide PSA screening, including subsequent tests.
Thompson said the number of prostate cancers detected has doubled in the last 10 years, but the death rate has not changed in 25 years.
Dr. Gabriel Haas, chief of urological oncology at Wayne State University School of Medicine, said an autopsy study of men who died accidentally revealed microscopic prostate cancers in 31% of 55 men, age 30 to 39; and 38% of 56 men, age 40 to 49. He reported those findings at the American Urological Assn. meeting in May.
The NCI is putting off making recommendations for least 16 years, until it has results from a 74,000-man prostate cancer screening trial that starts in April, 1993. Investigators will measure PSA levels in half the men, follow up with further diagnostic tests and treatment if appropriate, and compare death rates between the two groups.
Advocates of screening concede that the test is not perfect, but would rather overdiagnose and overtreat than overlook one man with a deadly cancer.
“The dilemma we are in right now is we don’t have the evidence of the ultimate benefit of these procedures,” said Dr. Curtis Mettlin, chairman of the Cancer Society’s Prevention and Detection Committee. “We are trying to make a good judgment based on incomplete information.”
Screening advocate Dr. Patrick Walsh, chairman of urology at Johns Hopkins School of Medicine, said new surgical techniques he pioneered, which avoid destroying nerves that regulate potency and urinary function, have dramatically reduced the risk of side effects.
Dr. William Catalona, chief of urology at Barnes Hospital and Washington University in St. Louis, said there is emerging evidence--not yet conclusive--that suggests that PSA will save lives. He adamantly opposes waiting for the results of the NCI study.
“In 16 years, half a million men will die before the results of the study,” he said. “If you have data that looks promising, is it reasonable to wait 16 years to start this test for one of the most common cancers among American men?”
Given such mixed messages from leading experts, what’s a fiftysomething man to do?
Dr. Gerald Chodak, a urologist at the University of Chicago, said patients need to understand the limitations of the test and then make an informed decision.
“We need to give patients a more balanced message,” Chodak said. “PSA will increase our ability to find localized tumors. We do not know whether finding the cancer earlier will allow people to live longer. We do not know whether we will find cancer in some men who will die of something else. This cancer can kill you, but we don’t know yet whether screening will make a difference. And some men may get treatment they don’t need.”
Prostate cancer, the most common cancer among American men, will strike 132,000 American men and kill 34,000 this year, the American Cancer Society says. It is also common among men in northwestern Europe, but for unknown reasons rare in the Near East and Central and South America. It is also rare in Africa, but black Americans have the highest rate of prostate cancer worldwide. No one knows why.
Prostate cancer runs in families, but doctors do not know if it is due to genetics or environmental factors, such as diet.
The U.S. Food and Drug Administration recently approved two testosterone-blocking drugs, goserelin acetate (Zoladex, ICI Pharma) and luprolide acetate (Lupron, TAP Pharma). They are given to men with cancers that have spread beyond the prostate.
Risk of prostate cancer . . .
over total to age over next in next life span 85 20 years year For a man at age 30 12% 10.6% 0.05% 0% At age 40 12.3% 10.8% 0.7% 0% At age 50 12.8% 11.2% 3.9% 0.03% At age 60 13.4% 11.6% 9.4% 0.31%
Source: American Cancer Society