More frequent screening for prostate cancer, as expected, finds more tumors, but does not lead to lower rates of aggressive interval cancers, European researchers reported on Tuesday. by Will Dunham

The findings, published in the Journal of the National Cancer Institute, added to the controversy over the value of screening tests for prostate cancer and how frequently they should be performed.

Dutch and Swedish researchers tracked about 4,000 men who every two years were given a PSA test in Gothenburg, Sweden, and another 13,000 men tested every four years in Rotterdam. They were 55 to 65 years old at the time of the first screening.

Over a ten-year period ending in December 2005, detection of any form of prostate cancer was higher among the Swedish men who were screened more frequently - 13 per cent - compared to the Dutch men who were screened less often - eight per cent.

However, there was no statistically significant difference in the two groups in the cumulative rates of interval cancers (0.43 vs. 0.74 per cent; p = 0.51) or aggressive interval tumors (0.11 vs. 0.12 per cent; p = 0.72), as might have been expected, the researchers said.

Asked about the implications of the findings on how often men should be screened, study leader Dr. Monique Roobol of Erasmus Medical Centre in Rotterdam said, "That's a tricky question."

The researchers note that every PSA test may lead to prostate cancer diagnoses among some men who may have "clinically insignificant disease."

"We here in Europe feel that over-diagnosis and over-treatment is certainly something you should avoid," Dr. Roobol said in a telephone interview.

Diagnoses of prostate cancer have risen substantially since screening using PSA tests began in the late 1980s. While the death rate has dropped, it is unclear if this is a direct result of this screening, the American Cancer Society said.

The American Cancer Society recommends doctors offer the PSA test or digital rectal exam, annually to men beginning at age 50. Screening generally is less frequent in Europe. Most institutions taking part in a large European study assessing prostate cancer gave the tests to men every four years.

"Although many of us believe that early detection is saving lives, definitive evidence is lacking," Dr. David Crawford of the University of Colorado Health Sciences Center wrote in an editorial accompanying the study.

"Critics of the four-year screening interval have voiced concerns that clinically significant cancers could be missed by such an extended interval," Crawford added, saying he was not convinced that the new study has allayed these fears.

The World Health Organization said the results of studies already underway into the effectiveness of prostate cancer screening are needed before making any recommendation.


Source: Reuters