A discussão sobre a recomendação do uso do PSA em homens saudáveis como forma de "screening".
Neste texto de Zosia Chustecka, ela coloca um ponto de vista complementar, mas não muito distante da visão geral.
Prostate Cancer Experts Defend PSA Screening
October 13, 2011 — Many prostate cancer experts in the United States have condemned the recommendation by the US Preventive Services Task Force (USPSTF), announced last week, against the routine screening of healthy men with the prostate-specific antigen (PSA) test.
The draft form of the recommendation, published online October 7 in the Annals of Internal Medicine, is now open for comments. In it, the USPSTF extended its recommendation against PSA screening to all men (it had previously specified men older than 75 years), after it found little evidence of benefit in terms of prostate cancer mortality, but plenty of evidence of potential harm. The recommendation has a "D" rating, which signifies that "there is moderate or high certainty that the service has no benefit or that the harms outweigh the benefits."
This is the wrong message."This is the wrong message at this point in time," said Philip Kantoff, MD, director of Dana-Farber's Lank Center for Genitourinary Oncology in Boston, Massachusetts.
"The whole issue of PSA-based screening is complex. It involves multiple steps and multiple decision points. The blanket statement saying that PSA-based screening is of no value is the wrong message right now," he noted in a statement.
"There is no question that we need to be more careful with whom we screen, and we need to recognize that not every man needs to be screened," Dr. Kantoff explained. He acknowledged that the PSA test has issues with specificity and sensitivity, but he concludes that it is a useful screening tool when it is used appropriately.
This is a stance similar to the one taken by the American Urological Association (AUA), which has long emphasized that the PSA test needs to be considered alongside other data, and that, when interpreted appropriately, it offers "important information." The current clinical guidelines of the AUA support the use of the PSA test, although they are due to be updated soon.
The AUA reacted immediately to the news, warning that the recommendation might "ultimately do more harm than good to the many men at risk for prostate cancer, both here in the United States and around the world."
"The dueling recommendations from the USPSTF and the AUA — along with passionate responses on all sides — are probably only going to further confuse men," said Marc Garnick, MD, a clinical professor of medicine at Harvard Medical School with an oncology practice at Beth Israel Deaconess Medical Center in Boston.
Dr. Garnick is also editor-in-chief of Harvard's Annual Report on Prostate Diseases; his comments appeared on a Harvard health blog.
"It's true that long-term studies have found that PSA screening and early diagnosis of prostate cancer does not save lives," Dr. Garnick acknowledged, "but it's also important to remember that certain men — such as African American men and those with a family history of prostate cancer — are at higher risk of developing prostate cancer than others, and may want to undergo regular PSA tests."
The USPSTF statement is "a recommendation, not an edict," Harvey Simon, MD, associate professor of medicine at Harvard and editor-in-chief of Harvard Men's Health Watch, said on the same blog.
An evolutionary development, not a revolutionary change.Dr. Simon noted that the recommendation reflects research studies published over the past few years that have questioned the benefit of screening and, as such, "the USPSTF statement really is an evolutionary development, not a revolutionary change." The debate is ongoing and "we are still a long way from concluding the discussion," he said.
Both Dr. Garnick and Dr. Simon urged men to discuss PSA testing with their physicians and to carefully weigh all the risks and benefits.
Task Force Emphasizes Harm
The main message from the task force — that PSA screening can result in more harm than benefit — was emphasized in an opinion piece in USA Today, written by the chair of the USPSTF, Virginia Moyer, MD, MPH, professor of pediatrics at Baylor College of Medicine in Houston, Texas.
Dr. Moyer used numbers to illustrate her point. PSA screening has been in widespread use in the United States for 2 decades, during which about 1.3 million cases of prostate cancer have been discovered, and 1 million men have chosen aggressive treatment for these newly discovered cancers.
However, for every 1000 men treated, 5 will die from complications of surgery, between 10 and 70 will have serious complications but survive, and 200 to 300 will develop urinary incontinence, impotence, or both, she noted.
If there is significant benefit, it should have been apparent by now, and it is not.At the same time, there is "no clear evidence that we are saving lives," Dr. Moyer writes. She acknowledges that the studies reviewed by the task force have weaknesses, but adds that "the reality is that if there is significant benefit, it should have been apparent by now, and it is not."
"Men choosing screening today should know that the chance of benefiting is small to none, while the chance of harm is greater and more certain," she concludes.
Dr. Moyer's article ran as an opposing view to the opinion piece, which argued forcibly that "averages don't matter." It emphasized that the test has saved some people's lives and, "as for the major complications — urinary incontinence and erectile dysfunction — they're usually temporary and highly treatable. They're also a lot better than being dead."
More numbers appear in another opinion piece, this time in the New York Times. H. Gilbert Welch, professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, in Hanover, New Hampshire, says screening for cancer is like gambling. There are a few big winners, but there are a lot more losers.
They are few and far between.Winners are individuals who have their lives saved by screening and, "while there is some debate about whether they really exist, my reading of the data is that they do, but they are few and far between," he writes. For screening with PSA for prostate cancer and screening with mammography for breast cancer, the order of lives saved per individuals screened is around 1 per 1000 — less than 0.1%.
The odds of being harmed from overdiagnosis and unnecessary treatment are much greater. For mammography, the numbers are around 5 to 15 per 1000 women screened; for PSA screening, the numbers are around 30 to 100 per 1000 men screened.
"The truth is that neither test works that well," Dr. Welch concludes.
Urologists Object to Decision
Elsewhere in the New York Times, Carl Olsson, MD, chief medical officer of Integrated Medical Professionals, the largest urology practice in the United States, is quoted. He pointed out that deaths from prostate cancer in the United States have steadily declined since widespread PSA testing began. "I think the concept of having us give up on the identification of people who have prostate cancer, as well as on their treatment, is a backward step, to say the least," he said.
Gerald Andriole, MD, chief of urology at Washington University School of Medicine in St. Louis, Missouri, and lead author of the large Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), which found no mortality benefit from PSA screening, urged a compromise, the newspaper reports.
"Rather than throw PSA away, we should make a plausible adjustment that only certain men should be screened," he said. Instead of screening all men, screening should be focused on those at high risk of the disease, including black men and those with a family history of prostate cancer, he explained.
Another urologist objected to the fact that the task force had considered only the primary end point of prostate cancer mortality, and believed that by doing so, it missed the impact that screening has had on picking up the disease at a much earlier stage, when it is more treatable.
"As an elderly urologist who spent nearly half of his career in the pre-PSA era, I can personally attest to another and perhaps even more important factor that is being overlooked — suffering from advanced prostate cancer," said Murray Feldstein, MD, from Phoenix, Arizona.
In a comment to the Annals of Internal Medicine after the recommendation was published, Dr. Feldstein said: "No longer do I see patients with bulky cancer who bleed and obstruct their urinary tracts," many of whom required emergency procedures and were left with permanent indwelling catheters. In addition, patients presenting with diffuse painful osseous metastases are now rare, he reported.
They will not register as a success of PSA screening if only mortality is considered."Patients like this could live for years and still die of other disease," he pointed out. "They will not register as a success of PSA screening if only mortality is considered."
Gerald Chodak, MD, director of the Midwest Prostate and Urology Health Center, Michiana Shore, Indiana, in his Chodak on Urology Medscape commentary, notes that this recommendation will fuel the debate over PSA screening, which is a "complicated challenge." His take-home message is that "men need to be better informed about the whole process and about the controversy before they get tested," which increases the burden on physicians who need to explain the whole issue and counsel the patient on the pros and cons of each decision.
Evidence Is Not There
Michael LeFevre, MD, a family medicine doctor at the University of Missouri School of Medicine, in Columbia, who is covice chair of the USPSTF, said that he understands why the recommendation has met with a "chilly reception."
"Any time a medical test or treatment that we believe should work is subjected to science and the science doesn't show what we hoped for, it's very disturbing to the medical establishment and to patients," he told the Los Angeles Times. He added: "We have to eat a pretty big chunk of crow and say this didn't turn out to be true."
It's always hard to learn that the emperor in fact has no clothes."It's always hard to learn that the emperor in fact has no clothes," writes Len Lichtenfeld, MD, deputy chief medical officer at the American Cancer Society (ACS), on his blog.
"We have invested over 20 years of belief that PSA testing works. Catch it early, treat it early, and get it out. Save a life. That's the mantra many of us — including me, as a practicing physician — believed," Dr. Lichtenfeld writes.
"And here we are all of these years later and we don't know for sure," he adds.
The ACS reviewed the same evidence as the task force, he points out, and "we elected to say that we did not know whether or not PSA testing saved lives." The ACS recommends that men discuss the issue with health professionals before embarking on a program of PSA testing.
The USPSTF stance against screening is "pretty radical," Dr. Lichtenfeld writes, and "it is certain to raise a firestorm from those who believe that PSA testing saves lives." There are many men out there who truly believe that PSA testing did save their life, including a number of high-profile politicians and celebrities, he notes. That is what they have been told, and if "you hear it often enough, you believe it."
"But just saying so often enough, loud enough, and clear enough does not make it so," he writes. "Anecdote is not a form of evidence." The USPSTF has decided that for PSA screening, "the evidence just isn't there," he adds.
The firestorm has already begun. Patient advocate groups have reacted angrily.
"Some men will die" as a result of this recommendation, warned the Prostate Cancer Foundation. "The USPSTF recommendation is a disservice to the majority of men. While it would eliminate some short-term health costs, the long-term health costs of treating metastatic disease would be higher," chair Michael Milken writes in www.delawareonline.com.
"The decision of the panel sends the wrong message to men whose lives might now be in danger because they will be discouraged from getting screened," according to the Men's Health Network (MHN).
Such men include African Americans, those with a family history of disease, and veterans exposed to Agent Orange, noted Ana Fadich, MPH, director of programs at MHN.
"Every man should be entitled to an informed discussion with his physician about whether PSA testing is appropriate for him," an MHN news release declares.
The fact that the task force's recommendation against PSA screening has a D rating is "particularly disturbing," because the new legislation in the Affordable Care Act requires health plans to cover without cost-sharing only preventive services that are rated A or B by the USPSTF, it explains.
PSA testing is estimated to cost around $3 billion annually in the United States, according to another report, with much of it paid for by Medicare, Medicaid, and the Veterans Administration.
"If insurance companies start listening,...men fear they'll lose their right to testing and they'll spend their lives worrying and wondering," according David Samadi, MD, vice-chair of urology and chief of robotics and minimally invasive surgery at the Mount Sinai Medical Center in New York City. The task force has "just made our jobs much harder," he said in a news release.
"We are no longer just fighting prostate cancer, we're fighting misguided government guidelines," he added.
Dr. Samadi acknowledged that the PSA test has limitations, but he believes that it is a "viable and useful tool," and maintains that "there is proof that early detection saves lives and there are treatment options that work."
He does not understand the stance taken by the task force. "It's as if they said, 'some people are injured by seatbelts during car accidents, so let's tell everyone to stop using them until someone invents something better.' They're completely discounting the lives that are saved. It makes no sense and it's irresponsible," Dr. Samadi noted in the news release.
Decision Is "Correct"
The scientist who discovered PSA, Richard Ablin, PhD, research professor of pathology at the University of Arizona College of Medicine in Tucson, told Medscape Medical News that he is "elated" about the recommendation. He has long argued that the PSA test should not be used for routine screening of healthy men because it is not specific for prostate cancer.
"Perhaps the best way to view PSA is to place it within the context of the difference between a smoke alarm and a fire alarm," Dr. Ablin wrote recently (Biomark Med. 2011;5;515-526). "A smoke alarm indicates that there is smoke, not necessarily fire." The PSA can draw attention to irregularities in the prostate, but this may turn out to be prostatitis or benign prostatic hyperplasia, he pointed out.
There is no level of PSA that is diagnostic, and the test cannot differentiate between aggressive and indolent forms of the disease, he added.
"I never envisaged that it would be used as a diagnostic test," Dr. Ablin said in an interview. He agrees with the task force that its use as such in routine screening has led to more harm than benefit.
Although he did originally set out to find a prostate-cancer-specific marker, he didn't manage to find one; in fact, such a marker has still not been found, he said. When he found the prostate-specific marker PSA, he envisioned that it could be used as a " harbinger for recurrence of the disease." This is still a use that he supports for the test.
Its use for routine screening in the general population has been "a hugely expensive public health disaster," he said previously. He sees the new recommendation as vindication: "It shows that I was correct in my original thoughts