Cancer cells leaving the prostate appears not to be uncommon--these are circulating tumor cells or CTC. (Procedures like a TURP or biopsies are not thought to promote metastases). Fortunately these CTCs have have an exceptionally difficult time establishing themselves in tissue outside the process--mets in lymph nodes, bone, the lungs, liver, bone, etc. However, in some men, over time, prostate cancer cells do gain the this ability. One study that looked the genetic variations in prostate lesions and mets found that in many cases all the mets
a patient has can be traces to a single
lesion in the prostate--not a single Gleason grade set of lesions, but a single lesion! This would attest to just how difficult it is for PCa to metastasize. (I have read that men with mPCa do have larger number of circulating tumor cells, but I believe men who would never develop mPCa can have CTC as well.)
Why do these men go on to recurrent disease? In some cases it is thought that the metastatic process began and micromets formed even though the cancer was apparently prostate-confined with no positive surgical margins at the time of surgery. In other cases microscopic positive margins might have been missed, or a fragment of viable prostate tissue was left behind. (Also, we should limit the discussion to truly prostate-confined cases as determined by the path staging and not include cases where the surgeon said "essentially prostate confined" or "that small margin or small EPE isn't significant.) We tend to see Forum Brothers who are in this 5-10% and not the other 90-95% who don't have BCR. Finally, not all cases of BCR go on to clinical recurrence (detectable lesions/mets).
------------------Oncologic outcomes of organ-confined Gleason grade group 4-5 prostate cancer after radical prostatectomy
(2021) (Abstract only is free).
From the Full Text:
"Radical prostatectomy (RP) is one of the main treatment options for localized prostate cancer. RP in patients with organ-confined prostate cancer (CaP), defined as pathological stage T2 (pT2), and negative surgical margins (NSM) is associated with good long-term outcomes. Those patients are considered to have the least risk of biochemical recurrence (BCR). But in a small subset of patients, recurrence does occur. At 5 years, even in patients with favorable pathologic characteristics at RP, BCR occurs in 5%-10% of patients.
To clarify, micromets are just microscopic metastases in place somewhere
that escape detection by the current best imaging techniques. They are distinct from CTCs. There are now commercial tests to measure CTC (e.g. CELLSEARCH®-, ISET®-CTC), but, so far at least, I don't think CTC measurement has gone from application in research studies to everyday PCa diagnosis, but this may change:New Screening Test Improves Detection of Prostate Cancer Using Circulating Tumor Cells and Prostate-Specific Markers
Take home message: the name of the game is early diagnosis
of PCa coupled with expert advice to know if and when it is necessary to take action to prevent
metastatic disease before it begins.