Tips for nephrologists
Similar advice is doled out to nephrologists by J. Charles Jennette, MD, chairman of the department of pathology and laboratory medicine and executive director of the nephropathology laboratory at the University of North Carolina in Chapel Hill. “It’s very important for clinicians to check whether their specimens are going to a competent renal pathologist,” he affirms.
Specifically, nephrologists should be sure the lab is competent to prepare the tissues for light microscopy, immunofluorescence, and electron microscopy, and that a well-trained, experienced renal pathologist will not only be analyzing the specimen but also willing to help the clinician understand how those findings should guide the care of the patient.
“My own opinion is that a practicing renal pathologist needs to see at least 200 kidney specimens a year to be likely to be fully competent.”
Yet the nature of renal pathology is such that these specimens probably will only be seen by highly qualified personnel. Dr. Jennette explains: “Kidney biopsy specimens generally need to be referred to a center that has substantial volume of renal biopsy specimens, because small community hospitals and even some small academic medical centers don’t have the special expertise and the histology laboratory that’s required to cut the very thin sections needed for renal biopsy evaluation, nor to perform the battery of stains both for light microscopy and immunofluorescence microscopy that are routinely applied.”
The commercial labs that do offer renal pathology services generally use renal pathologists, “not general pa-thologists or even urologic pathologists,” Dr. Jennette says. Of the five million tests that his own department processes each year, only 2,000 are kidney biopsies. “And it takes us getting specimens from 250 to 300 nephrologists to get that many.”
Dr. Jennette has some important instructions for nephrologists regarding how to obtain an adequate sample for the nephropathologist: Clinicians should be sure that the person performing the kidney biopsy —often a radiologist—uses a 14- or 16-gauge needle rather than the smaller 18-gauge needles that are typically used for tumor biopsies at sites other than the kidney. “With the kidney, you need the bigger needle because you must have enough of the architecture to be able to make the diagnosis,” Dr. Jennette notes.
In addition, the sample must come from the surface cortex of the organ, not from deep within as is often the case with tumors.
Nephrologists should be aware that with new therapies come new potential renal risks. “For example, the adverse effects of VEGF on kidneys weren’t recognized a year ago, but now they are,” Dr. Jennette says.
Molecular testing is very much on the minds of pathology experts and the clinicians they serve. “I think in the next five to 10 years there’s going to be a significant change in pathology services through molecular testing,” predicts James R. Miller, MD, a hospital pathologist and owner of Pathology Services, Inc., in St. Louis.
“We’ll certainly be better able to tell a clinician that this particular prostate biopsy, for example, is a pre-malignant condition that probably needs to be managed aggressively, or that this is a malignant condition that’s going to be best treated by this particular type of tumor therapy.”
Such events are already in the works at Aureon Laboratories in Yonkers, N.Y. CEO Vijay Aggarwal, PhD, tells Renal & Urology News that the independent lab has just launched Prostate Px+, a test designed to predict outcomes in patients with prostate cancer.
“From a needle biopsy sample that’s taken at the time of diagnosis of prostate cancer,” Dr. Aggarwal reports, “we can now determine whether this is an aggressive tumor that needs aggressive therapy, or a slow-growing, indolent tumor that needs no treatment, less aggressive treatment, or no treatment until a later date.”
Dr. Aggarwal believes many pathologists would like to be able not only to diagnose disease, but also give the clinician some guidance in terms of how aggressive the disease is and what sort of treatment might be indicated.
Prostate Px+ testing is the only service that Aureon offers “because we really think there’s a specific need for this type of testing,” says Dr. Aggarwal. “Prostate cancer is a widely diagnosed disease today, and more important, it’s a field in which the decision about what to do is very unclear; some of the tools used to stage tumors today are fairly inaccurate, and because of human intervention, also subjective.”
Dr. Aggarwal points out that elevated PSA levels may be caused by other conditions, which can be misleading. In addition, Gleason grading has become less helpful to the urologist because on the Gleason scale of 2 to 10, 85% of the grades come in at 6 or 7. “So it really doesn’t provide much guidance to the phy-sician about how aggressive the disease might be when diagnosed. The molecular variables incorporated in Prostate Px+ fill this gap.”