A new study published in the Archives of Internal Medicine suggests that many men diagnosed with prostate cancer appear to under undergo overly aggressive therapy, even if they have a low prostate-specific antigen (PSA) level and low-risk disease.

According to background information provided by the authors, more than 90% of all prostate cancers are diagnosed before the disease has spread to other parts of the body; almost 100% of  these men will survive for at least 5 years. The 5-year survival rate from all stages of disease has increased from 69% to almost 99% between 1975 and 2003, driven mostly by early detection and treatment. This has led some researchers to advocate for PSA levels < 4 ng/mL, the current upper threshold at which biopsy is often recommended.

To determine current diagnostic and treatment patters of men with prostate cancer and PSA levels ≤ 4 ng/mL at time of diagnosis, a team of New Jersey-based researchers used data from the Surveillance, Epidemiology and End Results (SEER) system. Of 123,934 men with newly diagnosed prostate cancer from 2004 to 2006, PSA levels ranged from ≤ 4 (n=17,343; 14%), 4.1 to 20 (n=91,047; 73.5%), and > 20 (n=15,544; 12.5%). 

The researchers established that among the men with PSA ≤ 4, 38% had prostate cancer that was diagnosed by PSA screening. They were also younger and had lower Gleason scores. Of these men, 54% had low-risk cancers compared with 48% of men with PSA values between 4.1 and 10 (P<0.001).  However, 77% of the men with PSA ≤ 4 received radical prostatectomy or radiation therapy. Men with screen-detected prostate cancer and PSA values ≤ 4 were 51% more likely to undergo radical prostatectomy, 61% more likely to undergo radiation therapy, and 33% less likely to  have high-grade disease than men who had nonscreen-detected prostate cancer. 

The authors estimate that if the threshold PSA value for biopsy were decreased from 4.0 to 2.5,  the number of men with abnormal PSA levels would double to approximately 2 million. More than 80% of these men would likely receive treatment, despite that only 2.4% would have a high-grade cancer. They also point out a paucity of evidence showing that keeping the upper PSA level at 4.0 would result in “an excessive number of potentially non-curable disease cases.”

The key point of this study is that the PSA level alone is an insufficient biomarker to inform treatment decisions, as it cannot distinguish between slow growing and aggressive cancers. And as this study points out, many screen-detected cancers—regardless of their growth and risk potential—will be treated with radical prostatectomy (RP) or radiation therapy (RT). In addition to having little information regarding the efficacy of these treatments on patient outcomes, both treatments also produce side effects that diminish quality of life.

1. Shao YH, Albertsen PC, Roberts CB, et al.  Risk profiles and treatment patterns among men diagnosed as having prostate cancer and a prostate-specific antigen level below 4.0 ng/mL. Arch Intern Med. 2010;170(14):1256-1261. Abstract available at:
   http://www.ncbi.nlm.nih.gov/pubmed/20660846. Accessed August 17, 2010.

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This entry was posted on Tuesday, August 17th, 2010 at 12:00 pm.