Trending Clinical Topic: Prostate Cancer

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Amid an uptick in metastatic prostate cancer diagnoses, a team is calling for reclassification of certain tumors. That, along with recent findings about screening, risk factors, and treatment, drove interest in prostate cancer, which is this week's top trending clinical topic. To avoid anxiety among patients and families and help reduce unnecessary treatment, some experts are calling for a major change in how certain prostate tumors are labeled (see Infographic below).

Men with low-risk prostate tumors are often advised to undergo "active surveillance" because low-grade tumors rarely cause harm and treatments can come with more serious side effects, including impotence and urinary leakage. But because these lesions are still called "cancer," many men opt for intervention that isn't necessary, according to a paper recently published in the Journal of Clinical Oncology. Dropping the "C word" for GS6 tumors, which make up about half of the nearly 270,000 prostate cancer diagnoses annually in the United States, is not a new idea. In 2011, an independent panel convened by the National Institutes of Health proposed just that. With active surveillance increasing dramatically to about 60% of patients with GS6, the time may be right for the change.

Distinguishing low-grade tumors from dangerous ones may be more critical than ever, as the incidence of metastatic prostate cancer has jumped. In 2008, the US Preventive Services Task Force recommended against routine prostate-specific antigen (PSA) screening in men older than 75 years. In 2012, they extended that recommendation to all men. From that time through 2018, among men 45-75 years of age, the incidence of metastatic prostate cancer increased 41%, which translated to an annual percentage change (APC) of 5.3%. Among men aged 75 years or older, rates jumped 43% through 2018, for an APC of 6.5%. Researchers did not find an increase in deaths from prostate cancer; however, given the 5- to 7-year median survival, it may be too early to tell.

As far as PSA screening itself goes, new data indicate that accounting for nongenetic cancer factors that influence PSA levels may improve the test's accuracy. In a large genome-wide association study of PSA levels in men without prostate cancer, researchers identified a total of 129 genetic variants associated with PSA and used them to construct a polygenic score to measure individual predisposition to elevated PSA levels. The investigators then validated the polygenic score by applying it to two cancer prevention trial cohorts: 5737 men enrolled in the Prostate Cancer Prevention Trial (PCPT) and 22,247 participants in the SELECT cancer prevention trial. They found that the PSA polygenic score accounted for 7.3% of the variation in baseline PSA levels in the PCPT cohort and 8.7% of variation in the SELECT cohort. The variations were not associated with prostate cancer in either cohort, indicating that they were due to benign factors. Using the genetically adjusted PSA would have avoided about 1 in 5 biopsies that were ultimately negative.

In terms of risk factors for the development of prostate cancer, a new study that included data from more than 100,000 individuals found an increase of close to 60% in prostate cancer risk among those who frequently consumed nitrite-containing food products. The risk for prostate cancer was increased by 58% (hazard ratio, 1.58; 95% CI, 1.14-2.18; P = .008), particularly for sodium nitrite exposure. Foods high in these nitrates include ham, bacon, deli meat, and hot dogs. The study found no association with regard to exposure to natural sources of nitrites and nitrates.

Numerous studies are underway to explore various prostate cancer treatments. The usual approach is androgen-deprivation therapy (ADT) plus radiation treatment. A phase 2 trial that avoids ADT in patients with unfavorable intermediate-risk prostate cancer is recruiting participants. So too is a National Cancer Institute –partnered phase 3 study that takes a randomized approach to the question of whether ADT can be avoided in men with low-risk Decipher scores. Adults with prostate cancer that has spread to the bones and who have already undergone prostatectomy or "definitive radiation therapy" are being sought for a phase 2 trial testing the addition of radium-223 dichloride to SBRT. Other studies in advanced-stage and castration-resistant prostate cancer have also recently been initiated.

From risk factors to screening concerns, treatment studies, and redefining "cancer," news from across the entire spectrum of prostate cancer–related concerns resulted in this week's top trending clinical topic.