PEARLS: Is Our Use of Prostate-specific Membrane Antigen Positron Emission Tomography-Computed Tomography Meaningful for Our Patients?

Pelvic Irradiation for Node-Positive Prostate Cancer After Prostatectomy: Long-Term Results of the Prospective PLATIN-4 and PLATIN-5 Trials

PURPOSE

After radical prostatectomy (RP), adjuvant or salvage radiation treatment in node-positive prostate cancer is offered to prevent systemic disease. Prospective long-term survival and toxicity data on patients with radiation for nodal disease are still scarce. This study evaluates safety and feasibility of salvage radiation therapy to the pelvic lymph nodes in node-positive prostate cancer after RP.

METHODS AND MATERIALS

Between 2009 and 2018, 78 patients with lymph node recurrence after RP (PLATIN-4 trial) or after RP and prostate bed radiation therapy (PLATIN-5 trial) were treated with salvage pelvic lymph node radiation therapy with boost to the involved nodes as field abutment (PLATIN-5) and boost to the prostate bed (PLATIN-4). Androgen deprivation therapy was started 2 months before radiation and recommended for 24 months. The primary endpoint was safety and feasibility of the intensity modulated radiation therapy-image guided radiation therapy technique based on the rate of treatment discontinuations and incidence of Common Terminology Criteria for Adverse Events grade 3+ toxicity. Secondary endpoints were progression-free survival and overall survival.

RESULTS

No treatment discontinuations were reported in either trial. Median overall survival was not reached in PLATIN-4 and was 117 months in PLATIN-5. Median progression-free survival was 66 months in PLATIN-4 and 39 months in PLATIN-5. Late grade 3+ genitourinary and gastrointestinal toxicities were observed in 4% of patients at 24 months of follow-up.

CONCLUSIONS

Salvage radiation therapy to the prostate bed and pelvic lymphatic drainage combined with long-term androgen deprivation therapy is a curative treatment option for patients with node-positive prostate cancer after RP, with excellent in-field disease control. Pelvic lymph node radiation therapy as field abutment after prostate bed radiation therapy is feasible with long-term survival and no high-grade toxicity.

Common iliac node positive prostate cancer treated with curative radiotherapy: N1 or M1a?

PURPOSE

Common iliac (CI) nodes are staged as (oligo)metastatic M1a for prostate cancer. It is unclear if outcomes of pelvic node-positive (cN1) differ from CI node-positive (CI-M1a) prostate cancer after curative treatment. Present study compares outcomes in these patients treated with radical whole pelvic radiotherapy and long-term ADT.

MATERIALS AND METHODS

Patients with node positive adenocarcinoma prostate were identified, either CI-M1a or cN1, from a prospectively maintained database. Over 75% of these patients were staged with Ga68PSMA-PETCT at diagnosis. All patients received long-term ADT and moderately or extremely hypofractionated radiotherapy to the prostate and pelvis including the CI region. At biochemical failure (BCF), restaging was done with Ga68PSMA-PETCT to establish the patterns of failure. CI-M1a cohort was classified as proximal or distal CI nodal location and studied for outcomes.

RESULTS

Of the 130 patients analyzed, 87 had cN1 and 43 had CI-M1a stage. Median duration of ADT before RT was 7 months and total duration was atleast 24 months. Majority (65%) had Gleason grade group IV-V while 75% had ≥T3 disease. After a median FU of 61 months, BCF in the 2 groups were similar, cN1, 21/87 (24.1%); CI-M1a, 11/43 (25.6%), p=0.86. At BCF, restaging Ga68-PSMA-PET-CT located distant metastases in 20 (63%) of the 32 patients (57% in cN1, and 73% in CI-M1a, p=0.47). Five-year biochemical failure-free survival (cN1; 77.4% and CI-M1a; 70.4%, p=0.43), distant metastasis-free survival (cN1; 86.9% and CI-M1a; 79.4%, p=0.23) and overall survival (cN1 92.6% and CI-M1a 90.1%, p=0.80) were similar in the two groups. Outcomes within CI-M1a were similar for proximal versus distal CI nodal location, 5-year BFFS 73.6% vs 58.6% (p=0.81).

CONCLUSION

Oligometastatic CI-M1a and cN1 prostate cancer patients showed similar outcomes when treated with curative whole pelvic radiotherapy and long-term ADT. The treatment for these 'oligometastatic' patients should be prospectively evaluated and optimized accordingly.