This is the old clinical staging system. Prostate cancer
This is the old clinical staging system, which is worth looking over historically because it tells something about the way prostate cancer used to be diagnosed. This is all in the handout, as is the new staging system. I just want you to understand the concepts here. In the old days a very common entity was so-called stage A cancer. These were cancers that were detected by transurethral resection. These rarely occur these days because medical therapy for BPH has increased and because of the PSA most people are being diagnosed as a result of a biopsy. B cancers are those that are palpable, C cancers are those that extend beyond the prostate, and D are metastatic tumors. So A has gone away almost completely, B is now T2, C is now T3. What now has emerged is the so-called T1C tumors which are tumors that are detected solely as a result of an elevated PSA. These represent, as I said before, 60-70% of the tumors that we now see.
Now if a patient is diagnosed with prostate cancer what does one do to stage the disease? Bone scans are rarely necessary in the individual with a PSA of less than 10. Six studies have now demonstrated that less than 1% of patients will have a true positive bone scan. The only exceptions, I would say, are those individuals with PSA’s less than 10 that have T3 tumors or high grade tumors where the likelihood of having a true positive bone scan is higher. So routine bone scans are not necessary in routine prostate cancer. CT scans are probably even less useful and we only reserve this test if an endorectal coil MRI is not done in men who have high PSA’s, high grade tumors or T3 tumors. Endorectal coil MRI remains the best imaging tool for imaging the prostate but its utility is probably only in individuals with PSA’s in the intermediate range, between 10-20. These are patients who may benefit from an endorectal coil MRI as a staging tool in addition to all the other tools that we have.
Now we know something now about risk stratification based on PSA, grade and clinical stage. We can now tell patients what their likelihood of being cured with different treatments is, as a function of these three factors. I’m not going to go into this in detail but it’s in your handout. Just to illustrate to you, good risk patients; PSA is less than 10, Gleason scores of 6 or less. These patients are cured the majority of time no matter what form of treatment they undergo. Intermediate risk patients; PSA is between 10-20, Gleason is 7, cancers. About 50% of them are cured with different forms of therapy. Poor risk patients; no matter what you do, PSA is greater than 20, high grade tumors. Most of these patients will ultimately relapse with single modality therapy; either radiation or surgery. As I alluded to before, in a study that will be published soon, the number of biopsies that contain cancer helps us out a little bit more in terms of stratifying patients, in terms of curability. This is a large study of 960 men that Anthony D’Amico and his colleagues performed looking at PSA outcomes as a function of percent positive biopsies. I’m not going to go into this in detail but this particular factor, percent positive biopsies, adds further information to PSA, clinical stage and grade which further stratifies patients into different subgroups. I would hold that at the present time that we can do a pretty good job at telling patients in advance their likelihood of being cured of their prostate cancer with local therapy.