Prostate cancer incidence in older adolescent and young adult men has increased in most countries, but the cause for the rise is uncertain, according to a new study published online September 25 in the journal Cancer . "Men as young as 17 years are experiencing an increasing incidence of carcinoma of the prostate in much of the world," write an international team of authors, led by Archie Bleyer, MD, Oregon Health and Science University's Knight Cancer Institute in Portland. They report that the incidence of prostate cancer has increased in all groups between ages 15 and 40 years and increased globally at a steady rate averaging 2% per year since 1990 ( P < .01). However, prostate cancer is rare in young men, with incidence rates not rising above about 0.2 cases per 100,000 men until age 35 and being even lower at younger ages, per US data from the last two decades; notably, the rate spikes dramatically between ages 35 and 39, approaching 1.8 cases. However, at...