In a second study, M. Scott Lucia, M.D., of the University of Colorado Health Sciences Center in Denver and colleagues investigated whether finasteride changes the appearance of tumor tissue so that lower-grade tumors are diagnosed as high-grade. The researchers examined surgically-removed prostates and high-grade prostate cancer biopsies from men treated with finasteride and a placebo for signs that finasteride affected prostate size, tumor size, or disease stage.
Like Cohen and colleagues, they found that men treated with finasteride had smaller prostate glands. High-grade tumors were not larger in men taking finasteride, but when they were present in surgically-removed prostates, the tumors were more likely to be detected because the prostates were usually smaller. They also found no major differences in tumor features between the two groups, indicating that it is unlikely that low-grade tumors were being classified as high-grade.
Although the evidence does not exclude the possibility that finasteride may have induced high-grade prostate cancer in some men, the analysis of prostatectomies from the PCPT does indicate that the relative increase in high-grade tumors in the finasteride group is less than originally believed. This evidence further suggests that increased detection may have contributed to the finasteride-associated increase in high-grade disease, the authors write.
In an accompanying editorial, Gerald Andriole, M.D., of Washington University School of Medicine in St. Louis, Mo., and colleagues find the evidence from these two studies important and convincing. Taken together, the studiesprovide substantial reassurance that the increased proportion of high-grade cancer on biopsy in PCPT is not likely to be clinically relevant, the editorialists write. Nevertheless it is necessary, they say, to continue research on the effects of finasteride and other similar drugs such as dutasteride on prostate cancer inciden
|Contact: Liz Savage|
Journal of the National Cancer Institute