PSA Screening May Exaggerate Familial Predisposition

Oncology researchers have known for a long time that when it comes to prostate cancer, familial risk is more relevant than it is in many other cancers; in fact, according to the Journal of the National Cancer Institute, genetic factors may be more important in prostate cancer etiology than in any other cancer.  

But Swedish researchers launched a study to determine if the genetic link is exaggerated because of prostate-specific antigen (PSA) screening, a diagnostic tool that’s been around for nearly 20 years.

Specifically Dr. Ola Bratt from the Department of Urology at Helsingborg Hospital led a team that set out to discover whether or not an increase in diagnostic testing is associated with the incidence of prostate cancer among men with brothers and fathers who have been diagnosed with it.

Research Data

The researchers gathered information from the National Prostate Cancer Database to isolate a group of index patients; i.e. prostate cancer patients of whom they could locate brothers and their fathers through Sweden’s Multi-Generational Register, which includes familial information on every Swede born since 1932.

They located 13,975 index patients and a total of 22,511 brothers of those patients.  To determine the ratio between the incidence of prostate cancer in the brothers of index patients and that of the general population, Bratt and her team analyzed:

*tumor characteristics of the index patients
*the time that had elapsed after the index patient’s diagnosis
*geographical location
*socio-economic status

Study Results and Implications

After gathering and studying the relevant data, Bratt and her colleagues determined the following:

*Brothers of index patients had a higher risk of prostate cancer diagnosis than men of the same age in the general populace.
*That risk rose even higher if the brothers’ father also had prostate cancer.
*The greatest risk was among those who had two brothers who had been previously diagnosed.
*The rate of diagnosis was the highest the following year after the index patient was diagnosed
*Additionally, the rate was higher among brothers with a higher economic status

After careful analysis and deliberation, the Dr. Bratt and her colleagues determined that, indeed, PSA testing does elevate the familial link associated with prostate cancer, simply because those who have siblings that have been previously diagnosed are more likely to proactively seek out PSA screening than will the general population.

Specifically, the team states, per the study abstract (currently published in the Journal of the National Cancer Institute), “Increased diagnostic activity among men with a family history of prostate cancer appears to contribute to their increased risk of prostate cancer and to lead to detection bias in epidemiological and genetic studies of familial prostate cancer.”

Adding to the Controversy

The current Swedish study could very well fuel some of the controversy already swirling around PSA screening.  This is due in part to the fact that in the world of oncology, prostate cancer is an anomaly for a couple of reasons:

*It’s very common; 80% of men over the age of 80 will be diagnosed with it.
*In many cases, prostate cancer stays localized in the prostate and does not spread to other parts of the body.
And, according to a 2009 study by the American Cancer Society, those who do test positive through PSA screening might be better off taking a “wait and see” approach, when it comes to treatment, which can have unpleasant side effects, such as incontinence and impotence.

Commonly referred to as “benign neglect,” this tactic involves waiting to see if symptoms of the disease actually occur; in many cases, mortality comes in other forms before slow growing prostate cancer becomes a problem.

However, benign neglect is not a completely passive approach; rather, after diagnosis it consists of PSA testing every three months and a biopsy once a year to track progression of the disease.