The Sunnybrook prostate cancer risk calculator was the second online prostate cancer risk assessment tool that allowed a man to assess his risk for prostate cancer in consultation with his primary care physician. The first was the PCPT prostate cancer risk calculator, developed from data collected in the Prostate Cancer Prevention Trial.
Developed by Nam et al., the Sunnybrook tool is based on data developed from over 3,100 Canadian men who underwent a prostate biopsy, including a subset of 408 volunteers with PSA levels of < 4.0 ng/ml. However, it should be noted that (to date) this nomogram has not been validated by a third party.
In addition to PSA and DRE results, the nomogram is based on knowledge of the following patient characteristics: age, family history of prostate cancer, ethnicity, urinary voiding symptoms, and free:total PSA ratio.
Since urinary voiding symptoms and free:total PSA ratios are not currently measures available to the majority of patients (or necessarily requested or assessed by primary care physicians), the current utility of this nomogram may be questionable. However, The “New” Prostate Cancer InfoLink sees this calculator as a key step toward better decision making with respect to the value of undergoing prostate cancer biopsy. We expect this calculator to act more as a stimulus for the development of more accurate nomograms and calulators moving forward than we see it as an “end result.”
Full information about the Sunnybrook prostate cancer risk model, together with a “plug and play” calculator, are provided on the Sunnybrook Health Sciences Centre web site. If you want to use the calculator, all you need to do is enter the following data:
- Your age
- Your urinary voiding symptom score or IPSS
- Your (total) prostate specific antigen (PSA) level
- Your free:total PSA ratio
- Your ethnic background
- Your family history of prostate cancer and
- Whether your have a positive or negative digital rectal exam result
You can calulate your urinary voiding symptom score using the IPSS calculator on the UCSF web site.
We have used data from the same man as we worked with using the PCPT risk calculator to assess his risk using the Sunnybrook calculator. In this case we entered the following data into the calulator:
- Age: 61 years
- Urinary voiding symptom score or IPSS: 4
- (Total) prostate specific antigen (PSA) level: 1.3 ng/ml
- Free:total PSA ratio: 0.7
- Ethnic background: Caucasian
- Family history of prostate cancer: None
- Positive or negative digital rectal exam result: Negative
When these data are inserted into the Sunnybrook calulator, the results for this man are:
- Probability prostate cancer of any grade: 12.5 percent (compared to 14 percent for the PCPT calculator)
- Probability prostate cancer of Gleason score 7-10: 5.2 percent (compared to 2 percent for the PCPT calculator)
Do we know which calculator is more accurate? No, not yet … but the PCPT calculator has been validated, and was initially based on data from larger numbers of men.