Current Treatment Paradigms and Clinical Outcomes in Oligometastatic Prostate Cancer Patients: A Targeted Literature Review

Combined Fixed-duration Systemic Treatment and Metastasis-directed Radiotherapy for Oligometastatic Hormone-sensitive Prostate Cancer

BACKGROUND AND OBJECTIVE

It is unclear whether "total therapy" (androgen deprivation therapy [ADT] with or without an androgen receptor pathway inhibitor [ARPI], metastasis-directed therapy, and local therapy to the prostate if de novo) may lead to long-term durable remission in oligometastatic hormone-sensitive prostate cancer (omHSPC). This study aims to evaluate the outcomes after the completion of total therapy in patients with omHSPC.

METHODS

A retrospective single-institution cohort of consecutive patients with omHSPC identified on conventional or molecular imaging treated with total therapy was assembled. All patients had prostate-specific antigen ≤0.1 ng/ml at the completion of systemic therapy. Kaplan-Meier and Cox regression models were used to evaluate the key outcomes of interest: clinical progression-free survival (cPFS), eugonadal progression-free survival (PFS), and time to restart of ADT (TTrADT).

KEY FINDINGS AND LIMITATIONS

Eighty-nine patients were included, of whom 23 were with de novo omHSPC; the median number of metastases was 1, and detection of disease by molecular imaging was performed in 43 patients (48%). Forty-nine patients (55%) received ADT + ARPI doublet and 40 (45%) received ADT alone. At a median follow-up of 37 mo, there were 46 cPFS events; 3-yr cPFS rate was 45% (95% confidence interval 33-56) and the median eugonadal PFS was 12 mo. The median TTrADT was 47 mo, and 60% had not restarted ADT at 3 yr. Duration of systemic therapy ≥12 mo was the only significant predictor of better outcomes.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Of the patients receiving total therapy for omHSPC, 45% remained progression free at 3 yr after completing therapy, hinting at the potential for long-term remission and possible cure with this strategy in a subset of patients with omHSPC. Prospective trials evaluating this approach are needed.

PATIENT SUMMARY

In this report, we looked at outcomes in men who had received a fixed duration of hormonal therapy along with radiotherapy to metastatic sites (and prostate radiotherapy or surgery in those with newly diagnosed disease) for oligometastatic prostate cancer. We found that nearly half of the patients had no evidence of cancer recurrence at 3 yr after completing therapy, and 60% had not resumed any therapy at this time point.

Prostatectomy and other local treatments for oligometastatic prostate cancer: recent and ongoing trials

PURPOSE OF REVIEW

Oligometastatic prostate cancer (OMPCa) is an intermediary state between localized and disseminated metastatic disease that has historically been treated with androgen deprivation therapy (ADT) and more recently with additional systemic therapies in combinations. However, cytoreductive control of the primary tumor may offer an opportunity to control the disease and enhance the response from systemic treatment. In this review, the use of local therapy to the prostate including cytoreductive prostatectomy (CRP), whole pelvis radiotherapy (RT), and focal therapies will be evaluated in the treatment of patients with newly diagnosed OMPCa.

RECENT FINDINGS

Retrospective studies have demonstrated that some patients with OMPCa may indeed benefit from CRP. With preliminary trials demonstrating that CRP is safe and feasible, there are several phase II and III trials that are currently underway to investigate the role of CRP among patients with OMPCa. Results from several clinical trials have demonstrated that RT and ADT may benefit patients with OMPCa. Lastly, the evidence for focal and cryotherapy remains limited and further clinical trials are required.

SUMMARY

OMPCa is a unique disease state that may benefit from local therapy to the primary tumor. Further study is required to guide treatment selection and patient candidacy. Several trials specifically are awaited to better define the treatment options for patients.