New paper below, [1] full text.
Oligometastatic PCa has been controversial from the start, with some denying that it exists. "If you have one met, you have many - you just can't see them."
Then there is the counting problem. One study indicated that a few spinal mets visible on a bone scan were oligometastatic, even if another type of scan were to find more.
This influenced my thinking when I had a solitary lesion at L5 ten years ago. My doctor sent me to a radio-oncologist who might agree to ratiate. The man warned me that there was no data to suggest a survival benefit. He did agree to treat L5 - he would not have treated two lesions. (My regular doctor was surprised that I had been treated, because I was not in pain.)
When I returned 4 years later, his view had changed. He hadn't expected me to be alive. He said that he would now be prepared to treat multiple lesions because I was proof of concept that there might be survival benefit.
Mostly, men interested in oligometastatic treatment are hoping for a cure. I'm inclined to view treatment in terms of management. L5 wasn't being controlled by my current protocol - albeit that it was growing very slowly. I would wory about other mets, if they occurred, only when they became big enough to be of concern.
"The term “oligometastatic prostate cancer” refers to a heterogeneous group of disease states currently defined solely on the basis of clinical features. Oligorecurrent disease, de novo oligometastases, and oligoprogressive disease likely have unique biologic underpinnings and natural histories. Evidence suggesting the existence of a subset of patients who harbor prostate cancer with limited metastatic potential currently includes disparate and overwhelmingly retrospective reports. Nevertheless, emerging prospective data have corroborated the “better‐than‐expected,” retrospectively observed outcomes, particularly in the setting of oligorecurrent prostate cancer. Improved functional imaging with prostate‐specific membrane antigen‐targeted strategies may enhance the identification of patients with oligometastatic prostate cancer in the short term. In the long term, refinement of the oligometastatic case definition likely will require biologic risk‐stratification schemes. To determine optimal treatment strategies and identify patients most likely to benefit from metastasis‐directed therapy, future efforts should focus on conducting high‐quality, prospective trials with much‐needed molecular correlative studies."
... from the Intro ...
"Metastasis has been conceptualized on a scale ranging from sequential, echelon‐level spread to de facto, widespread dissemination. More recently, a paradigm shift was prompted by Weichselbaum and Hellman, who hypothesized the existence of an oligometastatic state. Their assertion that a subset of metastases may be limited in number and location has since been both the subject of criticism and the inspiration for pioneering clinical trials investigating local ablative therapy for tumors that previously would have been treated with solely systemic approaches. Acceptance of an oligometastatic paradigm with the resultant impact on treatment recommendations is poised to potentially change the landscape of prostate cancer management, given evidence suggesting that as much as 75% of patients with recurrence after primary therapy will have ≤3 involved sites."
...
Conclusion
The term “oligometastatic prostate cancer” currently refers to a heterogeneous group of clinically defined disease states, including oligorecurrence and de novo oligometastases. Commonly used features to distinguish such individuals with limited metastatic disease include the absolute number of lesions (e.g., ≤5 metastases) and, less frequently, caveats like lesion location. This reliance on clinical features for case definition necessarily makes investigation into superior imaging modalities for the detection of prostate cancer oligometastases of considerable import. To this end, PSMA‐targeted functional imaging currently has the greatest promise, and its inclusion as part of the prospective ORIOLE randomized, phase 2 trial in the oligorecurrent setting should provide further insights into its utility. While awaiting the results from this and other protocols currently registered on clinicaltrials.gov for patients with oligometastatic prostate cancer, evidence from a disparate group of previously published outcomes suggests that an oligometastatic state likely exists for at least a subset of patients with prostate cancer. The most convincing testament to this possibility comes from the groundbreaking phase 2 trial in the oligorecurrent setting published by Ost et al, in which individuals in both the surveillance and metastasis‐directed therapy arms had higher than expected rates of ADT avoidance. Nevertheless, the appropriateness of metastasis‐directed therapy within the context of tumor‐related molecular factors and clinical variables like comorbidities is a separate issue that remains relatively less well answered. To better risk stratify patients who have oligometastatic disease and to determine optimal treatment strategies, future efforts should focus on conducting high‐quality, prospective trials and determining a biologic categorization of patients who have disease with limited metastatic potential.
-Patrick
