[Metachronous oligometastatic prostate cancer-the more the better or only local treatment?]

BACKGROUND

Prostate cancer metastases may occur at diagnosis (de novo) or metachronous after treatment for localized disease.

OBJECTIVE

To describe location, prognosis, and individual treatment concepts for metachronous oligometastatic prostate cancer.

MATERIALS AND METHODS

Analysis of current treatment guidelines and literature for hormone sensitive, metachronous metastatic prostate cancer.

RESULTS

Modern imaging modalities lead to earlier diagnosis of metachronous oligometastatic prostate cancer, which offers the opportunity to develop metastasis-directed treatment concepts. Oligometastatic recurrence may occur in locoregional lymph nodes (N1) or as distant disease (M1). N1 disease is predominantly treated by salvage lymph node dissection or radiation. Distant metastasis may be radiated in order to delay systemic treatment. The combination of androgen deprivation and novel androgen receptor-targeted drugs such as apalutamide or enzalutamide are associated with a significant survival benefit compared to castration alone in bone or visceral oligometastatic metachronous disease.

CONCLUSION

Metachronous oligometastatic prostate cancer is heterogeneous with slow progression compared to men with high volume metastasis. Individual treatment concepts may decrease risk of progression and, thus, delay time to medical treatment. Multimodal approaches are currently being evaluated in clinical trials.

Curative-intent Metastasis-directed Therapies for Molecularly-defined Oligorecurrent Prostate Cancer: A Prospective Phase II Trial Testing the Oligometastasis Hypothesis

BACKGROUND

The hypothesis of a curable oligometastatic prostate cancer (PCa) state remains to be clinically-proven. Conventional imaging often fails to localize early recurrences, hampering the potential for radical approaches.

OBJECTIVE

We hypothesize that prostate-specific membrane antigen (PSMA)-targeted PET-MR/CT allows for earlier detection and localization of oligorecurrent-PCa, unveiling a molecularly-defined state amenable to curative-intent metastasis-directed treatment (MDT).

DESIGN/SETTING/PARTICIPANTS

Single-institution single-arm phase-two study. Patients with rising PSA (0.4-3.0 ng/mL) after maximal local therapy (radical prostatectomy and post-operative radiotherapy), negative conventional staging, and no prior salvage hormonal therapy (HT) were eligible.

INTERVENTIONS

All patients underwent [¹⁸F]DCFPyL PET-MR/CT. Patients with molecularly-defined oligorecurrent-PCa had MDT (stereotactic ablative body radiotherapy [SABR] or surgery) without HT.

OUTCOME MEASUREMENTS/STATISTICAL ANALYSIS

Primary endpoint was biochemical response (complete, i.e. biochemical 'no evidence of disease' [bNED], or partial response [100% or ≥50% PSA decline from baseline, respectively]) after MDT. Simon's two-stage design was employed (null and alternate hypotheses <5% and >20% response rate, respectively), with α and β of 0.1.

RESULTS

Seventy-two patients were enrolled (May/2017-July/2019). Thirty-eight (53%) had PSMA-detected oligorecurrent-PCa amenable for MDT. Thirty-seven (51%) agreed to MDT: 10 and 27 underwent surgery and SABR, respectively. Median follow-up was 15.9 months (IQR 9.8-19.1). Of patients receiving MDT, the overall response rate was 60%, including 22% rendered bNED. One (2.7%) grade 3 toxicity (intra-operative ureteric injury) was observed.

CONCLUSIONS

PSMA-defined oligorecurrent-PCa can be rendered bNED, a necessary step towards cure, in 1 of 5 patients receiving MDT alone. Randomized trials are justified to determine if MDT +/- systemic agents can expand the curative therapeutic armamentarium for PCa.

PATIENT SUMMARY

We studied men treated for prostate cancer with rising PSA. We found PSMA imaging detected recurrent cancer in three-quarters of patients, and targeted treatment to these areas significantly decreased PSA in half of patients.