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USPSTF todavía dice “no” a la investigación del cáncer del testículo

por Brendon Nafziger, DOTmed News Associate Editor | September 21, 2010
In a draft resolution up for public comment, the U.S. Preventive Services Task Force said no new evidence came to light for them to overturn its 2004 recommendation not to screen the public for testicular cancer.

The group examined scores of articles published over the last decade searching for new evidence for the benefits, and harms, of screening asymptomatic men for the cancer, but said they came up short.

Testicle cancer is the most common cancer for men aged 15 to 34, the group said. The incidence is around one out of 20,000 men. In 2008, nearly 8,000 men in the United States had the cancer, and 380 died of it.

The problem with most of the 113 articles examined for the current resolution was that none dealt with asymptomatic men. A 2003 article in the Journal of Urology did screen 1,320 men with ultrasound scans and found 27 tumors. However, all men involved in the study had symptoms.

"Because symptomatic men have a higher pretest probability of cancer than asymptomatic men, one would expect the number needed to screen to detect one case of testicular cancer to be considerably greater, and the false-positive rate substantially higher, than those in the study by [L.] Carmignani and colleagues," the group wrote.

However, one study did provide hope for a possible biomarker - the XIST gene.

The gene, which deactivates the X chromosome, is normally methylated in men, and earlier research has shown that some testicular tumors have an unmethylated version of the gene, the group said.

In research for the resolution, the group looked at a 2001 study published in Radiology. In the study, scientists compared plasma samples from 25 patients with testicular cancer against 24 patients with other cancers and six healthy patients. They found that 16 of the testicular cancer patients had unmethylated XIST genes, whereas none of the others did.

"Although the study suggests that the XIST gene may have promise as a marker for testicular cancer, the study's small sample size and lack of clinical outcomes make drawing conclusions impossible," the group said.

USPSTF said researchers would have to establish the prevalence of both forms of the gene in asymptomatic men and track them for years to see what their lifetime risks were.

Another condition, known as testicular microlithiasis and characterized by the build-up of calcium clusters in the testes, is thought to be linked to cancer. However, the study examined by the group wasn't promising: Of 104 men with microlithiasis, three-fourths had follow-up ultrasound scans, and none had cancer.

Still, the group urged doctors to be vigilant.

“[A]lthough the average primary care physician may see only one patient with testicular cancer over 20 to 25 years, 26 percent to 56 percent of patients with testicular cancer had an initially incorrect diagnosis of another testicular disorder," the USPSTF said.

The public can comment on the draft recommendation until Oct. 19.