Between 1981 and 1983 researchers collected and stored blood samples from 4,500 men in Copenhagen, Denmark, as part of the Copenhagen City Heart Study. These blood samples had been carefully stored — and otherwise unused — for nearly 30 years. In 2010, a new research team decided to measure the PSA levels in these blood samples.
The research team was then able to correlate these 28-year-old PSA data with data from the Danish Health Registries to identify which of the blood donors had subsequently been diagnosed with or died of prostate cancer between 1983 and 2010.
Their findings appear to suggest a correlation between baseline PSA level, risk for prostate cancer diagnosis, and risk for prostate cancer-specific mortality — according to a report by Sussman on MedPage Today.
After stratifying the men into six groups based on their PSA levels, Orsted and his colleagues were able to show that:
- Among men with a baseline PSA of < 2 ng/ml in 1981-83, 90 percent were free of prostate cancer 30 years later (inclusive of men in their 90s).
- Among men with a baseline PSA of ≥ 10 ng/ml in 1981-83, 75 percent had developed prostate cancer by the time they were 80 years of age.
- Elevated baseline PSA levels correlated with an increased risk of prostate cancer depending on the baseline level of PSA (between three and 44 times the risk of those with a baseline PSA of < 2 ng/ml).
- Elevated baseline PSA levels correlated with an 2-fold-to-12-fold increased risk of prostate cancer-specific mortality (between two and 12 times the risk of those with a baseline PSA of < 2 ng/ml).
Quoted in discussing these results, Dr. Orsted said that,
This study supports the idea that a baseline test is maybe a good idea. It suggests that in men 40-45 years of age we can use a first measurement of PSA as a way to move forward.
He also stated that:
For the large majority — more than 90 percent of men — there was a very low 10-year risk. This finding can be used to reassure these men and may reduce some of the major problems in prostate cancer — over-diagnosis or too many PSA tests with also unnecessary prostate biopsies.
This is yet another study presented at the European Multidisciplinary Cancer Conference (EMCC) over the weekend.
The data from this study appear to be supportive of data previously published by Lilja, Vickers, and others based on Swedish patients. As with the Swedish data, they appear to offer a rationale for much less frequent PSA testing among men with a low baseline PSA level unless PSA testing is suggested by other clinical events.