Screening & Diagnosis of Prostate Cancer

 

Deciding on When a Prostate Biopsy Should be Done

Estimating Your Risk of Harboring Prostate Cancer

Prostate Biopsy Risk Calculator

About Prostate Biopsy: Interpretation & Limitations

Screening for Prostate Cancer

Prostate Cancer on the Web

 

Prostate Cancer Screening Is Controversial - There is the potential for benefit and harm. Read these links for more detail.


American Urological Association Guidelines on Prostate Cancer Screening

Canadian Urological Association Guidelines on Prostate Cancer Screening & Response to CTFPHC Recommendations

Canadian Taskforce on Preventative Health Care

National Institutes for Health/NCI PSA

New York Times Editorial on Prostate Cancer Screening 2016

 

Should I have a prostate biopsy?

The decision to have a biopsy is based on the comparitive risks and benefits of 2 courses of action - those of not doing a biopsy (i.e. continued observation) vs. those associated with doing a biopsy.

 

 

The decision to have a prostate biopsy is ultimately a personal decision since only you can determine what level of risk is acceptable and what your values are. The basic tenant of making such a decision is to make an informed decision based on some facts in consultation with an expert.

 

Facts regarding prostate cancer to keep in mind when deciding if a biopsy is right for you.

  1. There is no currently available test which can exclude the presence of prostate cancer with 100% certainty . Therefore every man has some risk of having prostate cancer no matter what his family history, age, race, PSA, or prostate exam findings. Having favorable features can significantly reduce the risk that you have prostate cancer, but the risk is never 0%.
  2. Not all prostate cancers require treatment because not all men who have prostate cancer either need or will benefit from treatment. This is discussed in the 'Natural History of Prostate Cancer' page.
  3. Some prostate cancers definitely benefit from treatment - in terms of increasing both the length and quality of life.

 

Questions which you should be asking before making a decision on having a prostate biopsy.

  1. What is the risk that I have cancer? More specifically, what is the risk that I have a high-grade cancer?
  2. If I have prostate cancer, what are the risks and benefits of receiving treatment vs. not receiving treatment (observation)?
  3. What are the risks of the biopsy itself and how can those risks be reduced?
  4. What are the limitations of biopsy?

 

What is the risk that I have cancer?

 

Before assessing what an individual's risk of having prostate cancer is, it is important to understand the baseline risk of prostate cancer - the prevalence of prostate cancer. It is not feasible or reasonable to biopsy every male, and therefore, it is helpful to know how one's risk compares to that of one's peers. There are a few ways in which prostate cancer can be diagnosed:

  1. At the time of autopsy: this gives the true prevalence of prostate cancer and is assessed after a man has passed away. Allows for complete evaluation of the entire prostate gland.
  2. Prostate biopsy in men 'for cause': in men who are felt to be at 'increased risk' of having cancer.

 

AUTOPSY PREVALENCE VS. BIOPSY PREVALENCE. A frequently quoted saying is that 'all men would eventually develop prostate cancer if they lived long enough'. Without question, the prevalence of prostate cancer increases in any age group over time. When based on autopsy data the prevalence of prostate cancer in 80-year-old men is between 50% and 80%. While it is true that most elderly men harbour prostate cancer, only about 20% of men receive a diagnosis of prostate cancer during their lifetime and furthermore fewer than one and 5 of these men (3-4% of all man) specifically die from prostate cancer. Therefore, there are striking differences between the prevalence of diagnosis when made at the time of autopsy compared to biopsy while a man is alive. Chosing to compare onself to an 80 year old man diagnosed at the time of autopsy is not appropriate.

 

The group that is the most important for comparison is that of peers in your age group who have a similar risk of harbouring prostate cancer as you. This sort of data has only been available since 2003 and was generated by doing biopsies in a large number of men as part of the Prostate Cancer Prevention Trial (PCPT) - including many who would have been previously been considered at low risk and never subjected to a prostate biopsy. Prior to this, it was felt that men with low PSA's (less than about 2.5 mcg/L) and normal prostate exams had a negligible risk of prostate cancer. Note that prostate biopsy underestimates the prevalence of prostate cancer compared to autopsy diagnosis because only part of the prostate is examined.

 

Estimating an individual's risk of harboring prostate cancer

 

Our understanding of an individual's risk of harbouring prostate cancer has changed significantly since the PCPT trial in 2003. Prior to this trial, only men with abnormalities on prostate exam or who were felt to have increased PSA levels were sent for biopsy. The PSA level at which a man was felt to be at risk was usually above 4 mcg/L, though other 'cut points' were used by various authorities. Some physicians tried to better select men by using different PSA thresholds based on age or race; others attempted to calculate the rate of change of PSA over time (PSA velocity); still others tried to evaluate the contribution to the overall PSA level by benign enlargement of the prostate (PSA density). Then the PCPT trial came along and demonstrated that:

 

THERE NO 'NORMAL' LEVEL OF PSA AND THAT THE USE OF SPECIFIC PSA VALUES ('CUT POINTS') TO DECIDE IF A MAN SHOULD HAVE A BIOPSY IS INAPPROPRIATE.

 

Despite this, as of 2011 laboratory requisitions are still printed with 'Reference' or 'Normal' ranges and decisions to perform prostate biopsies are often made on the basis of a PSA level alone. The risk of harboring prostate cancer in men who were previously considered to have neglible risk of having prostate cancer if a biopsy is performed*:

 

 

Age Range Overall Risk of Any Cancer
Risk of High Grade Cancer
50-60  14%  1.0%
60-70  14%  1.4%
70-80  14%  1.9%
80-90  14%  2.6%

* Men with no family history of prostate cancer, PSA less than 1 mcg/L, and no abnormality on prostate exam.

 

Therefore, virtually all men have at least a 1 in 10 risk of harboring prostate cancer. This can be quite alarming, until one recognizes that the majority of prostate cancers do not represent lethal tumors and are unlikely to affect the quality or quantity of life in most men when left untreated. Fortunately, the most important number is the risk of high-grade tumor since these tumors are much more likely to have an impact on a man's quality and quantity of life. The chances of a high-risk cancer are much lower than the risk of harboring prostate cancer overall.

 

Estimating Your Risk of Having Prostate Cancer

The following factors have been demonstrated to predict a man's risk of harbouring biopsy-detectable prostate cancer:

  1. PSA level
  2. Prostate exam abnormalities
  3. Age
  4. Race
  5. Family history of prostate cancer
  6. Prior biopsy not showing cancer (negative biopsy)

Note that PSA velocity (PSA change over time) has NO bearing on the risk of harboring prostate cancer once these other factors are considered. You can estimate your own risk of having a biopsy-detectable cancer by clicking the link below. There are some very important caveats when using the risk calculator:

  1. The accuracy of the estimate is only as good as the quality of information put into the calculator. The calculator does NOT take into account important information such as:
    1. The severity of the prostate exam abnormality. Some findings are very subtle where as others are quite striking.
    2. The strength of the family history. For example, prostate cancer which developed in a brother at a young age is of great importance where as cancer in a relative such as a cousin or maternal uncle has very little importance.
    3. Normal, non-cancer related fluctuations in PSA. For example, sudden large rises in PSA are usually due to non-cancerous causes such as infection or prostate infarction.
  2. The estimate of risk is a 'point estimate' based on the data available at the time of the calculation. Changes in the clincal picture can affect the calculated risk.
  3. The estimate is APPROXIMATE. There is inherent inprecision in any sort of calculation.
  4. Use of the calculator may not be appropriate in your particular situation. The PCPT data was generated from men who started with PSA's less than 3 mcg/L and normal prostate exams. Extrapolation to men outside of these circumstances may not be appropriate.

 

THE PRIMARY VALUE OF THE CALCULATOR IS TO RECOGNIZE THAT FACTORS OTHER THAN PSA PLAY AN IMPORTANT ROLE IN ASSESSING RISK AND TO PROVIDE A BALLPARK ESTIMATE OF THAT RISK

 

 

On The Web

General Prostate Cancer Web-Resources

Memorial Sloan-Kettering Cancer Center in New York is an excellent resource for information on prostate cancer. Balanced, unbiased discussions of the disease, including discussion regarding some of the controversies in prostate cancer.

General Information on Cancer

UNDERSTANDING CANCER - Metrovan Urology info on the principles of diagnosis, staging, prognosis and more.

American Cancer Society

BC Cancer Agency: Good general website from the British Columbia Cancer Agency. Has contact information on locations.

National Cancer Institute: Excellent source of understandable and mainly unbiased information. Several very good brochures on every stage of prostate cancer.

National Comprehensive Cancer Network: peer-reviewed expert content/prostate cancer guidance on evidence-based cancer diagnosis and management. Best for Prostate and Kidney Cancer. The most in-depth information is located in the physician section and requires registration.