Prostate cancer, one of the deadliest forms of cancer for men in the United States and worldwide, is on the decline, according to new research.
Researchers looked at World Health Organization data from five continents from 1980 to 2012 and saw an encouraging trend. In most parts of the world, the rate of men diagnosed with and dying of prostate cancer decreased or stabilized, according to the study, presented Tuesday at the American Association of Cancer Research meeting in Atlanta.
A walnut-shaped gland under the bladder, the prostate secretes seminal fluid, which provides nutrition for and allows the transport of sperm.
Dr. Alex Krist, vice chairman of the US Preventive Services Task Force and professor of family medicine and population health at Virginia Commonwealth University, who was not involved in the study, explained that prostate cancer "is one of the most common cancers that affects men. Usually, prostate cancer grows slowly."
The survival rate of patients with prostate cancer depends on factors such as how far it has spread.
The new study notes that prostate cancer is the second leading cause of cancer diagnoses and sixth most common cause of death from cancer among men worldwide. The authors also note that, since 2012, prostate cancer has led male cancer incidence, or new diagnoses, in 96 countries, and it is the most common cause of death among men in 51 countries.
"By comparing rates from different countries, we can assess differences in detection practices and improvements in treatment," MaryBeth Freeman, lead study author and senior associate scientist of surveillance research at the American Cancer Society, said in a statement. "Previous studies have indicated significant variation in prostate cancer rates, due to factors including detection practices, availability of treatment, and genetic factors."
Prostate cancer diagnosis rates decreased in seven countries from 2008 to 2012, and 33 countries showed a stabilization in diagnosis rates, the study found. From 2008 to 2012, the United States had the greatest decrease in the number of men diagnosed with prostate cancer.
Freeman and her colleagues found these results encouraging and believe that the research supports the use of prostate-specific antigen screening.
This test was approved by the US Food and Drug Administration in 1986 to monitor prostate cancer, and Freeman says its increased use resulted in a decline in diagnoses from the 2000s to 2015. In low-income countries, where screening is less available, later diagnoses and increased mortality rates are more common, she noted.
Countries with the most cases of prostate cancer from 2008 to 2012 were Brazil, Lithuania, and Australia. The highest mortality rates from prostate cancer included Caribbean countries such as Barbados, Trinidad and Tobago, and Cuba as well as South Africa, Lithuania, Estonia and Latvia.
Although prostate-specific antigen screening has revolutionized prostate cancer management, it is not perfect. There is a risk of overdiagnoses and overtreatment.
"The current recommendations from the US Preventive Services Task Force say that the decision of whether or not to screen for prostate cancer in men ages 55 to 69 should be an individual one, made only after a discussion of the benefits and harms with their doctor," Krist said. "Men age 70 and above should not be screened for prostate cancer, as the harms outweigh the benefits for this age group."
While Freeman acknowledges limitations in the scope of the data and how it was collected, she argues that overall, the research provides a more comprehensive look at prostate cancer globally.
"Further studies should monitor trends in mortality rates and late-stage disease to assess the impact of reduction in [prostate-specific antigen] testing in several countries," she said.