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Page 2 of 8 Wagaskar et al. Mini-invasive Surg 2022;6:14 https://dx.doi.org/10.20517/2574-1225.2021.106

INTRODUCTION
Oligometastatic prostate cancer (OMPC) is generally defined as cancer in patients with 3-5 metastatic
deposits in a single organ or multiple organs on conventional imaging. With the advent of modern
diagnostic techniques and improved patient monitoring in the setting of clinical trials, OMPC is
[1,2]
increasingly diagnosed in men who were in the past considered to have organ-confined disease . OMPC
occurs at the transition between localized prostate cancer and widespread metastases. Recent data suggest
that molecular differences exist between OMPC and polymetastatic prostate cancer (PMPC) {metastases at
> 5 sites}. It is known, as well, that OMPC patient populations behave differently from PMPC in the clinical
setting . A compelling difference in overall survival in men with OMPC vs. PMPC has also been shown (<
[3-5]
[6]
5 metastases at the time of diagnosis) .
Men with localized prostate cancer are managed with active surveillance, focal therapy, or radical therapy,
[7]
either radical prostatectomy or radiotherapy . Robot-assisted radical prostatectomy (RARP) is the most
common form of surgical treatment for localized prostate cancer. The current standard of care for men with
metastatic prostate cancer (MPC) is chemohormonal therapy or androgen deprivation therapy with/without
[8]
abiraterone acetate/prednisone . Treatment of a primary tumor in the metastatic setting is pursued only as
a palliative measure (e.g., patients with significant local symptoms secondary to primary tumor) . It is
[9]
biologically feasible, however, that an unchecked local tumor may encourage the progression of metastases,
possibly acting as a source for tumor seeding, which has been shown in other types of metastatic cancer.
This would mean that the longer the primary tumor remains in the body, the greater the chances of new
metastatic deposits . It is logical to say that treating primary tumor can delay the progression of metastases
[10]
and improve survival in men with MPC.

Regardless of unsatisfactory evidence from survival statistics, local treatment is sometimes used in the
management of OMPC. Our review evaluates the available evidence regarding robot-assisted cytoreductive
prostatectomy (CRP) feasibility and oncological outcomes in oligometastatic settings. We also consider the
limitations and future directions for this approach.

EVIDENCE ACQUISITION AND SEARCH STRATEGY
A non-systematic PubMed and Google Scholar search were performed for English language publications
from January 2014 to May 2021. Key search terms included “prostate cancer” and “oligometastatic” or
“cytoreductive prostatectomy” or “robot-assisted prostatectomy” AND “oligometastatic”. At first, we
searched the abstracts of studies for relevant inclusion. Next, we retrieved full-text original articles from the
selected abstracts. We utilized two reviewers (VW, FB) to independently assess abstracts and original
articles for eligibility. We classified the relevant materials as inclusion, unsure, or exclusion. In the case of
dispute between the two reviewers, consensus was reached to resolve the difference of opinion. Detailed
screening of relevant full-text-articles’ references was performed to identify additional pertinent articles not
found in the PubMed database and through Google Scholar. Following studies were excluded: non-relevant
or partially relevant secondary publications and systematic reviews, unavailable full-text articles. Figure 1
demonstrates flow chart of search strategy and final number of articles included in the current review.

Studies were eligible for inclusion in our review if they included patients who opted for open or robot-
assisted cytoreductive prostatectomy for histologically proven prostate cancer and evidence of
oligometastatic disease on relevant imaging or biopsy. As a primary outcome, we evaluated whether the
proposed open or robot-assisted CRP was associated with progression-free survival (PFS), cancer-specific
survival (CSS) or overall survival (OS). Studies without CRP or oncological outcomes were excluded.