Study Finds Prostate Cancer Tests Underestimate Disease in Half of Cases

“A study published in the British Journal of Cancer suggests that tests to grade and stage prostate cancer underestimated the severity of the disease in half of men whose cancers had been classified as ‘slow growing’.

“Scientists from the University of Cambridge compared the staging and grading of cancer in over 800 men before and after they had surgery to remove their prostate. They found that of the 415 men whose prostate cancer was classified as slow growing and confined to just the prostate after an initial biopsy, half (209) had cancer which was more aggressive than originally thought when assessed again after surgery and almost a third (131) had cancer that had spread beyond the prostate.”

Low-Fat Fish Oil Diet May Alter Prostate Tumor Biology

“Men with early stage prostate cancer who ate a low-fat diet supplemented with fish oil had lower amounts of proinflammation molecules in their blood and lower prostate tumor cell proliferation compared with men who ate a high-fat Western diet. Men on the low-fat fish oil diet had lower serum levels of omega-6 fatty acids and high levels of serum omega-3 fatty acids compared with the prostate cancer patients who consumed a Western diet. The experimental group also had lower levels of the proinflammatory eicosanoid 15(S)-hydroxyeicosatetraenoic acid, or 15(S)-HETE, which has been previously shown to be associated with cancer. The decline in mean 15(S)-HETE was 7.2% in the low-fat diet group compared with 24.7% in the high-fat diet group (P = .02). The men in the low-fat diet group also had a lower cell cycle progression score, a marker for the aggressiveness of a cancer.”

Study Suggests Low-Grade Prostate Cancers May Not Progress Over Time

“Data analyzed from a large cohort study of men diagnosed with prostate cancer found that prostate cancer aggressiveness may be established when the tumor is formed and not change over time. The researchers of the study, Kathryn L. Penney, ScD, Instructor in the Department of Medicine at Harvard Medical School and Associate Epidemiologist at Brigham and Women’s Hospital, and colleagues compared data from 420 participants recruited to the Physicians’ Health Study and 787 participants recruited to the ongoing Health Professionals Follow-Up Study. All of the men were diagnosed with prostate cancer between 1982 and 2004 and treated with prostatectomy. The researchers determined that after the first introduction of widespread prostate-specific antigen (PSA) screening, the proportion of patients diagnosed with advanced-stage cancers was reduced by more than sixfold in 22 years, but that the proportion diagnosed with high Gleason-grade cancers did not change substantially. The findings suggest that low-grade prostate cancers do not progress to higher grade over time. The study is published in Cancer Research.”

Targeting Aggressive Prostate Cancer

“A team of researchers from UC Davis, UC San Diego, and other institutions has identified a key mechanism behind aggressive prostate cancer. Published on August 14, 2013 in Nature, the study shows that two long, non-coding RNAs (PRNCR1 and PCGEM1) activate androgen receptors, circumventing androgen-deprivation therapy. In their active state, these receptors turn on genes that spur growth and metastasis, making these cancers highly treatment-resistant. The study illustrates how prostate cancer can thrive, even when deprived of hormones, and provides tempting targets for new therapies.”

Gene Test Increases Percentage of Men Recommended for Active Surveillance

Standard risk criteria says that between 5% and 10% of men with prostate cancer should receive active surveillance in place of immediate aggressive therapy. However, a new gene test that accounts for biological response, androgen signaling, and tumor growth and proliferation more than doubled that figure. Researchers found that patient data from the Gene Prostate Score (GPS), a 17-gene test, combined with the standard criteria yielded results indicating that 25% of men with prostate cancer would be eligible for active surveillance. The GPS is scored on a 100-point scale, and researchers found that each 20-point increase in a patient’s score was associated with a doubling of the risk for adverse pathology. A study involving 395 patients found that nearly half of the participants had at least a 5% shift in risk when evaluated just by standard criteria and then reevaluated by the GPS in conjunction with standard criteria. Researchers say the GPS should increase the number of men confidently able to choose active surveillance as their initial treatment strategy.