SAN DIEGO — The incidence of testicular cancer continued its puzzling rise through the end of the last decade, according to a study reported here.

Caucasian men continued to lead the rise with an incidence of 8.6 cases per 100,000 in 2009. However, Hispanic males had the biggest increase, from 4.9/100,000 in 2003 to 6.3/100,000 by the end of the decade.

Rates among black men and Asian/Pacific Islanders also increased, but remained substantially lower compared with men in the other two racial/ethnic groups.

An explanation for the increase has yet to be identified, Scott Eggener, MD, of the University of Chicago, said at the American Urological Association meeting.

“No one really knows,” said Eggener. “There are all sorts of hypotheses, but it’s purely conjecture. The proposals environment exposures, a birth-cohort effect, maternal exposure to estrogen in utero, diet and lifestyle. There’s no way to know from this data why it’s happening.

“Interestingly, there have been some recently reported data showing that the same thing is happening in Europe, sort of a slow, steady increase in the incidence, and no one knows why.”

Testicular cancer is the most common cancer among men 20 to 34. Historically, white men have had the highest incidence, followed by intermediate rates in Hispanic and Asian/Pacific men and blacks with the lowest rate. From 1973 to 1992, the incidence of testicular cancer increased by more than 50%, and the incidence continued to rise through 2o03.

Whether the rates had continued to increase since 2o03 had not been determined, said Eggener. Additionally, recent epidemiologic trends in subtypes of testicular cancer had not been examined.

To update the epidemiologic status of the disease, investigators analyzed data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results program, which has collected data on cancer incidence and mortality in a representative sample of the U.S. population since 1992. Complete data extend through 2009.

The overall incidence of testicular cancer increased from 5.7 cases per 100,000 in 1992 to 6.8/100,000 in 2009, representing an annual rise of 1.1% (P<0.001 for trend). The incidence increased steadily in all racial/ethnic groups except Asian/Pacific Islanders, who had a decline from 2.0/100,000 in 1992 to 1.7/100,000 in 2003 before increasing to 2.8/100,000 in 2009 (0.77% annual increase).

Rates of testicular cancer increased from 7.5/100,000 in 1992 to 8.4 in 2003 and to 8.6 in 2009 among white men (annual increase of 1.2%, P<0.001). The incidence in black men increased from 0.7/100,000 in 1992 to 1.4 in 2003 and to 1.7 in 2009 (annualized increase of 1.4%).

Among Hispanic males, testicular cancer incidence increased across the entire study period but accelerated dramatically during the last decade. From 1992 to 2002, the rate of testicular cancer increased by 0.7% annually. From 2002 to 2009, the annualized increase jumped to 5.6% (P<0.01).

Further analysis showed increases in seminomas and nonseminomatous testicular cancer in in three of four age groups analyzed. The rising incidence included both localized testicular germ-cell tumors (1.21% per year, P<0.001) and metastatic tumors (1.43% annually, P<0.01).

The rate of localized cancer increased significantly in white men (1.56% annually, P<0.001), whereas Hispanic males had significant annualized increases in localized (2.6%, P<0.001), regional (16.5% from 2002 to 2009, P<0.01), and distant metastatic disease (2.6%, P<0.01).

Source: MedPage Today.