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Prostate Cancer Screening: What Do the Recent Studies Mean?

Article date: March 18, 2009

Two important studies about prostate cancer were published online March 18, 2009 in the New England Journal of Medicine. Both were undertaken to try to learn whether early detection tests for prostate cancer in large groups of men can lower the prostate cancer death rate. Below are some questions and answers about these studies.

RESOURCES:

Read the ACS news story about these studies

Read comments from Otis W. Brawley, MD, ACS's chief medical officer

Read Dr. Len's Cancer Blog, an ACS expert's take on the news

1. What did these two studies show?

The US Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a 17-year project of the National Cancer Institute (NCI), included 76,693 men in the United States. It compared results of an annual screening program with usual care (men in this group were neither encouraged nor discouraged to get screened and about half chose to be tested). The study found 6 annual screenings for prostate cancer led to more diagnoses of the disease, but no fewer prostate cancer deaths.

The second report in the same journal is from the large European Randomized Study of Screening for Prostate Cancer (ERSPC). It included 162,243 men and showed a 20 percent reduction in the rate of death from prostate cancer but with a high risk of overdiagnosis.

2. Will these studies change the ACS recommendations for prostate cancer testing?

No, and in fact, an accompanying editorial by Dr. Michael Barry also concludes that "a shared decision-making approach to PSA screening, as recommended by most guidelines, seems more appropriate than ever." The American Cancer Society (ACS) does not support routine testing for prostate cancer in men at average risk at this time. The Society believes that health care professionals should discuss the potential benefits and limitations of prostate cancer early detection testing with men before any testing begins. Following this discussion, those men who favor testing should be tested. Men should actively take part in this decision by learning about prostate cancer and the pros and cons of early detection and treatment of prostate cancer.

3. Why has the ACS recommended against mass screening?

The ACS has recommended against mass screening since 1997 because we have not had sufficient scientific evidence to support that recommendation. Rather, we believe that individual testing should only occur when the man can have a good conversation with a health care professional about the limitations and potential benefits of screening and treatment. This conversation should be tailored to the individual and take into account his health and his personal concerns.

4. What do other organizations say about prostate cancer screening?

Since the mid to late 1990’s, most major organizations that have formally assessed the scientific data have either recommended against prostate cancer screening, or said there was insufficient evidence to recommend for or against prostate cancer screening. For individual men, all organizations endorse some process of shared decision making for those men interested in testing for early prostate cancer detection.

5. I am black and have been told black men have a higher risk of prostate cancer. Should I be tested?

Men of sub-Saharan African heritage in the US and Caribbean have a greater risk of both prostate cancer diagnosis and prostate cancer death compared to men of European ancestry. These new studies do not specifically address men of higher risk due to ethnic background. Based on past research, there is good reason to assume that the conclusions of these two new studies are relevant to all men regardless of their race.

6. I have a family history of prostate cancer. Should I be tested?

These studies and others demonstrate that prostate cancer is so common among aging men that a simple family history of prostate cancer does not necessarily mean a man is at higher risk of the deadly kind of prostate cancer. You may want to take your family history and your family’s experience with the disease into consideration when making the decision whether or not to get screened and, if diagnosed, whether or not to get treated. Factors to consider are the age at diagnosis in your family member, and the number of affected relatives.

7. I’ve heard that any PSA level lower than 4 is normal. If I choose to be tested, should I rely on that number?

Several studies have now shown us that there is no natural PSA cut-off under which a man will not have prostate cancer. Indeed, some men with a PSA of 1 to 1.5 have been found to have prostate cancer. Men in the placebo arm of the Prostate Cancer Prevention Trial published in 2003 have given us important insights into PSA levels. Men with PSA levels between 1 and 4 had more cancers than men with higher PSAs. But the cancers in the group of men with low PSA seemed similar in size and pathology to those in men with PSA levels over 4.

8. I have been getting tested regularly. Should I continue?

For more than a decade the ACS has advocated shared decision making within the physician-patient relationship. Rather than recommend screening for all men, the ACS recommends that average risk men ages 50 and over, and men with a family history or of sub-Saharan African heritage age 45 and over should be offered the test and they should be informed of the potential risks and potential benefits, so that they can make a decision about testing for early prostate cancer detection after hearing the facts. These new study results actually support that recommendation and give men more information to base their choice. The American study suggests no change in risk of death after seven years of follow-up among men invited to screening compared to men not invited to screening.

The European study suggests that, within the current follow-up period, for every 48 men diagnosed through screening and treated, one life was saved. These treatments have significant side effects for the remaining 47 men, among whom are men who may have had a prostate cancer that was not life threatening, or men whose quality of life was further diminished even though their treatment was not successful.

9. Is the PSA used for reasons other than screening?

The PSA is FDA approved for early detection of prostate cancer, meaning it is appropriate for a man with symptoms that may be related to prostate cancer. Men with urinary symptoms such as frequent urination, difficulty establishing a urinary stream or other urinary symptoms should possibly get the PSA. If you have any symptoms that concern you, you should discuss them with your doctor. Most men with these symptoms do not have prostate cancer.

PSA is also appropriately used after prostate cancer treatment to see if the treatment has been effective or whether the cancer is recurring or continuing to grow and spread.

10. I was recently diagnosed with localized prostate cancer. What does this new information mean for me?

You should have an open and frank conversation with your physician about your plan of care. These studies and others, such as the Prostate Cancer Prevention Trial (published in 2003), demonstrate that there are prostate cancers that grow slowly and are not life threatening, and there are those that are aggressive and are life threatening. Unfortunately, we do not have a very good test that accurately distinguishes one from the other. Through screening we find a large number of prostate cancers, and because most men will be treated, the inescapable conclusion is that some men are “cured” who did not need to be cured because the cancer really was of no threat to their life. This is of great concern because prostate cancer treatments have significant and serious side effects.

The data from the American study does not really speak to the effectiveness of treatment. It does demonstrate that men invited to screening do not have a lower death rate from prostate cancer after seven years of follow-up. The data from the European study suggests that a large proportion of men who are diagnosed with localized prostate cancer benefit equally well from observation as aggressive treatment. Radical prostatectomy, radiation therapy (external beam and internal or brachytherapy) and hormonal therapy are still appropriate treatment options for some men with localized disease. Ultrasonic treatments and cryotherapy or freezing are used, but should be thought of as experimental since long term outcomes data are not available.

11. What does the American Cancer Society think needs to be done now?

In the immediate future, it will be important so see how other scientists interpret these findings so we can have a fairly broad consensus about what the data mean and how doctors should use the information when advising their patients. In addition, we will need to see what happens as these two studies continue to turn out data over the next several years. Long term follow-up of these patients may give clarity to the issue. Also, because these issues are still difficult to interpret, we will need to bring together experts from a variety of disciplines to create clear, understandable messages so the public can understand these issues and play an active role in deciding whether to be tested.

Finally, it is critical to continue to have public support for research to find new and better ways to predict which prostate cancers are aggressive and likely to spread and kill and which are the kinds of tumors that may not require treatment, so we can save as many lives as we can while minimizing the risks of overdiagnosis and overtreatment. Basic biomedical research into understanding cancer, especially during the past few years, has provided considerable insight into the specific molecular differences between normal cells and cancer cells, and between slowly-growing cancers and more deadly ones. Researchers are currently making progress toward developing clinical tests that apply this fundamental knowledge to the practical goal of guiding decisions about prostate cancer screening and treatment.

For more information on this topic, see "Can Prostate Cancer Be Found Early?"

 

Reviewed by: Members of the ACS Medical Content Staff


ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.

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