Common Prostate Cancer Diagnostic Test Does Not Detect Some Tumors, Study Finds
About 15% of elderly men who received normal scores on the prostate-specific antigen test -- a common diagnostic test for prostate cancer -- had malignant tumors, according to a study in Thursday's New England Journal of Medicine, the Wall Street Journal reports (Tomsho, Wall Street Journal, 5/27). In the study, researchers led by Ian Thompson, chief of urology at the University of Texas Health Science Center at San Antonio, performed prostate biopsies on 2,950 men whose PSA test scores were under four nanograms per milliliter of blood -- the threshold at which most doctors choose to perform a diagnostic biopsy to detect cancer. Researchers found prostate cancer cells in 449 of the men, or 15.2%. According to the Washington Post, "while most of the cancers appeared to be the type that would not be likely to pose a health risk, 67 of those cancers -- 14.9% -- were found to be aggressive" (Stein, Washington Post, 5/27). The study "raises questions about what a normal test score should be and whether these men are better off left alone or treated when, through biopsies, cancer cells are discovered," the New York Times reports. The study was not designed to determine what the PSA cut-off level should be (Kolata, New York Times, 5/27). The National Cancer Institute funded and partially staffed the study (Donn, AP/Albany Times Union, 5/27).
The study, "the first to validate the suspicion that PSA testing is missing many cancers, rekindled a debate among physicians about how aggressively the tests should be used," the Post reports (Washington Post, 5/27). The National Comprehensive Cancer Network, a group of 19 hospitals that provide cancer care, recommends that physicians consider performing biopsies on patients with PSA scores at or above 2.5 (Szabo, USA Today, 5/27). Dr. H. Ballentine Carter, a prostate cancer researcher at Johns Hopkins University, said, "We desperately need a new marker to tell us who needs to be treated aggressively" (AP/Albany Times Union, 5/27). However, the study's authors say that "PSA tests give doctors few clues about which cancers will even threaten a man's life," because high scores could be caused by conditions ranging from cancer to infections and benign prostate swelling that is common in elderly men, USA Today reports (USA Today, 5/27). Dr. Howard Parnes, director of NCI's division of cancer prevention, said he is concerned that lowering the PSA level would cause "huge numbers of men to have biopsies, learn they have cancer and opt for treatment that may not have been necessary" (Ackerman, Houston Chronicle, 5/26). According to the Times, while prostate cancer "is exceedingly common," it "tends to smolder silently, never spreading or causing problems in a man's lifetime." Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, said that decisions to have a PSA test or receive a biopsy "have to be discussed between people and their health care providers" (New York Times, 5/27). An abstract of the study appears online.
Several broadcast programs reported on the study:
- NBC's "Nightly News": The segment includes comments from Thompson (Bazell, "Nightly News," NBC, 5/26). The complete segment is available online in Windows Media.
- NPR's "Morning Edition": The segment includes comments from Parnes and Thompson (Knox, "Morning Edition," NPR, 5/27). The complete segment is available online in RealPlayer. Expanded NPR coverage is available online.
- PBS' "NewsHour with Jim Lehrer": The segment includes comments from Carter; Leonard Gomella, a urologist at Jefferson Medical College; and Thompson ("NewsHour with Jim Lehrer," PBS, 5/26). The complete transcript is available online.