New prostate cancer test holds promise, but many challenges remain

November 1, 2005

There are many questions and avenues of study yet to be clarified before broad clinical translation can occur.

The test detects antibodies produced by the patient's own immune system in response to prostate cancer. These antibodies appear as a distinct pattern (signature) on a microarray of peptides, each of which can bind cancer-specific antibodies. The research team thus far has screened a finite number of serum samples from known prostate cancer patients as well as controls (without prostate cancer) and has found encouraging sensitivity (81.6%) and specificity (88.2%) rates.

The immune system reacts to cancer by mounting an orchestrated response consisting of a repertoire of antibodies against various antigens confined to, or produced by, the cancer cell. This new test raises the possibility that the unique identity and specific characteristics of the repertoire may provide a more accurate diagnostic tool than is presently available.

Because it offers a snapshot of the immune response to a continually changing stimulus and environment, the test-or subsets of it-may be able to distinguish between indolent and more aggressive strains of the cancer and perhaps even become a progression (or regression) marker of the cancer. This, however, is only a projected dream at present. Indeed, our problem today is both detecting the cancer by a test with fewer false positives and then predicting the aggressive potential of the cancer, once identified.

Finally, it is not too much of a stretch to think that one or a group of these prostate cancer-specific antigens could be isolated and used to stimulate the immune system as a vaccine to treat prostate cancer cells or that the autoantibodies could be isolated and used directly against the cancer or as carriers to deliver other treatment modalities, such as radiation or chemotherapy, directly to the cancer.

This is a lot to ask of any new technology. Thus, it must be re-emphasized that a lot of work and many challenges lie ahead. We should, however, anticipate many exciting new developments from this burgeoning new field of study.

Dr. Williams, a Urology Times editorial consultant, is professor and chair, department of urology, University of Iowa, Iowa City.