The number of new cases of an incurable prostate cancer has climbed 72 per cent.
The number of new cases of an incurable prostate cancer has climbed 72 per cent in the past decade from 2004 to 2013 in the US, according to a new study which suggests that the deadly disease may have become more aggressive.
Researchers studied whether a recent trend of fewer men being screened may be contributing to the rise, or whether the disease has become more aggressive - or both.
The largest increase in new cases was among men 55 to 69 years old, which rose 92 per cent in the past decade.
This rise is particularly troubling because men in this age group are believed to benefit most from prostate cancer screening and early treatment, researchers said.
The average PSA (prostate-specific antigen) of men who were diagnosed with metastatic prostate cancer in 2013 was 49, nearly double that for men diagnosed in 2004 with an average PSA of 25, indicating a greater extent of disease at diagnosis.
The blood level of PSA, a protein produced by cells of the prostate gland, is often elevated in men with prostate cancer.
"One hypothesis is the disease has become more aggressive, regardless of the change in screening," said Edward Schaeffer, from the Northwestern University Feinberg School of Medicine.
"The other idea is since screening guidelines have become more lax, when men do get diagnosed, it's at a more advanced stage of disease," he said.
Researchers analysed information of 767,550 men from 1,089 facilities nationwide who had been diagnosed with prostate cancer between 2004 and 2013.
Over the past decade, there has been a substantial reduction in the number of men being screened for prostate cancer and an associated decline in the overall number of new cases of prostate cancer being reported.
"The fact that men in 2013 who presented with metastatic disease had much higher PSAs than similar men in 2004 hints that more aggressive disease is on the rise," Schaeffer said.
If a patient is diagnosed with localised prostate cancer that is aggressive, treatment can be curative.
If men present with metastatic prostate cancer, treatments are not curative and only slow disease progression. Most patients with metastatic prostate cancer die from the disease.
"There could be a significant increase in prostate cancer death rates if more people are diagnosed with metastatic disease, because treatments can only slow progression, it's not curable," Schaeffer said.
The study measured the total number of cases of metastatic prostate cancer of cases per 100,000.
Three per cent of those included in the study had metastases, which means prostate cancer cells had spread to other parts of their bodies by the time the cancer was diagnosed.
The number of cases of metastatic prostate cancer in 2013 (2,890) was 72 per cent greater than that in 2004 (1,685).
In middle-aged men 55 to 69 years old, the number rose 92 per cent from 702 new cases in 2004 to 1,345 in 2013. The findings appear in the journal Prostate Cancer and Prostatic Diseases.
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