Every day across America and around the world, newly diagnosed patients are told they have ?localized? prostate cancer ? with the associated implication that this is a relatively ?good thing? compared to a diagnosis of ?advanced? prostate cancer.? But what does ?localized? prostate cancer really mean in individual cases?
First of all, let?s be very clear about the difference between ?localized? prostate cancer and truly ?advanced? prostate cancer.
Truly clinically advanced prostate cancer comes in one or other of two forms:
- Prostate cancer that can be easily identified in organs and tissues well away from your prostate and the immediately surrounding tissues, i.e., in tissues such as your bones, your lungs, your liver, perhaps even your brain. Such cancers are evident (because actual tumors can be seen on things like CT scans or bone scans) and metastatic (meaning that such tumors are secondary tumors that have grown as a consequence of transmission of cancerous cells from the original primary tumor in your prostate to a new location elsewhere in the body).
- Prostate cancer that can not yet be easily identified in organs and tissues well away from your prostate and the immediately surrounding tissues (usually because the tumors are too small to identify accurately) but which may be suspected for any one of several possible reasons, and which can sometimes be accurately identified (through, for example, the pathologic examination of cells from a bone marrow biopsy or some highly sophisticated types of imaging test, including some types of MRI scan and PET scan). Such cancers are not usually evident, but they are often described as micrometastatic.
Arguably, any other form of prostate cancer can be described as ?localized? to the prostate and the immediately surrounding tissues in the region of the pelvis, even if in some cases the process of metastasis (the transmission of cancerous cells from an original site to one or more sites elsewhere in the body) may have been initiated. (Remember; just because something can?t be seen doesn?t mean it isn?t there.)
So let?s see if we can define the different types of ?localized? prostate cancer in ways that will make sense to the individual patient.
- The first sub-type is truly ?organ-confined? prostate cancer. In such situations, all actively cancerous cells appear to be confined to the actual prostate itself. In other words, if you were to have surgery, and the surgery was perfectly carried out, and the prostate was examined by the pathologist after surgery, there would be no evidence whatsoever to suggest that cancer existed outside the actual prostate (no positive surgical margins; no cancer in the seminal vesicles; etc.). Such a cancer is a true pathological stage T2N0M0 cancer.
- The second sub-type is truly ?organ- and seminal vesicle-confined? prostate cancer. In this situation, all actively cancerous cells appear to be confined to the prostate and the associated seminal vesicles (which are almost always surgically removed along with the prostate during a radical prostatectomy). Again, if the surgery was perfectly carried out, and the surgical specimen was examined by the pathologist, there would be no evidence whatsoever to suggest that cancer existed outside the actual prostate (no positive surgical margins) except within one or both of the seminal vesicles. Such a cancer is one type of pathological stage T3bN0M0 cancer (but not the only one; see below).
- The third sub-type is truly ?specimen-confined? prostate cancer. In these cases (again assuming that the surgery is perfectly carried out), it will appear to the pathologist after surgery that although the cancer has escaped through the so-called capsule (the wall) of the prostate into nearby tissues, the surgeon was able to cut out all of the tumor that had escaped through the wall of the prostate into these nearby tissues, and there is every reason to believe that any cancer is was removed when the prostate itself, the seminal vesicles and the immediately surrounding tissues were all removed. Such cancers may be categorized as pathological stage T3aN0M0, T3bN0M0, or T4N0M0, depending on exactly how much tissue had to be removed and from exactly where in order to remove all of the cancer in the surgical specimen.
Now for each of the three subtypes of prostate cancer described above, there are equivalent cases in which the surgery either could not be or was not ?perfectly carried out;? under such circumstances, although the cancer appeared to be localized to the pelvis, there is clear risk for later progressive disease, and either immediate (adjuvant) or later (salvage) treatment will be necessary.
- There is one more sub-type of prostate cancer in which the cancer appears to still be ?localized? to the pelvis: pelvic lymph node-positive disease. In this situation, regardless of any other clinical situation that may be evident in the three sub-types described above, there is clear evidence of cancer in the regional, pelvic lymph nodes, which can be determined either at the time of surgery (through a perioperative lymph node dissection) or independently (though a laparoscopic lymph node dissection). Patients with positive lymph nodes are always classified as having pathological stage TxN1M0 disease (assuming that there is no evidence of metastatic disease).
So there are arguably at least four subtypes of ?localized? prostate cancer ? and their degree of ?localization? clearly affects the likelihood that patients can be treated with curative intent.
Men with truly organ-confined prostate cancer (especially if they have a PSA level < 10 ng/ml and a Gleason score of 7 or less) have a very good chance of long-term biochemical recurrence-free survival after any form of expertly conducted first-line treatment. But once the cancer has started the process of escape out of the prostate and into the immediately surrounding tissues, the potential for biochemical recurrence does start to rise.
The way that The ?New? Prostate Cancer InfoLink actually likes to think about the sub-categorization of ?localized? prostate cancer is therefore into two basic categories:
- Truly organ-confined disease (pT2N0M0 disease)
- Regionally or locally advanced disease, meaning any cancer that has escaped the ?normal? confines of the prostate itself (pT3-4NoM0 or pTxN1M0 disease)
Only the first of these is cancer that appears to be truly confined to the prostate.
One final comment.
From the time that a man starts to grow a cancerous tumor in his prostate, cancerous cells can be and commonly are ?shed? into the surrounding tissues and out into the blood stream and the lymphatic system. Most such cells do not survive because they do not reach a hospitable microenvironment where they can settle and grow into new tumors. BUT ? What this also means is that the process of metastasis can start extremely early in the development of prostate cancer. In turn, this means that a man with what gives every appearance of truly organ-confined prostate cancer (especially if he has a Gleason 8 to 10 tumor) may already have tiny micrometastases, much too small to be seen, even at the time of diagnosis.
The process of biochemical progression after first-line prostate cancer treatment can occur for one of dozens of reasons in a specific patient, but one of the most common of these is that a cancer which appeared to be truly localized to the prostate was not, in fact, truly localized to the prostate at all. One of the great advantages of surgery compared to other forms of first-line therapy is that it does, in fact, give the doctor and his/her patient some very clear insight into the possibility that what looked like organ-confined disease was in fact regionally or locally advanced at the time of treatment. This insight is not available for men treated with any type of radiation or cryotherapeutic technique because there is no post-treatment specimen to examine. However, on its own this benefit is not sufficient to justify surgery as being ?better? than other forms of first-line treatment. Surgery comes with downsides that are equally striking.
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Filed under: Diagnosis, Management, Risk Tagged: | localized, definition, category, sub-category
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