ASCO GU 2020: Updated Results from the STOMP Trial: Targeted Therapy in the Context of Low-Volume Metastatic Prostate Cancer

San Francisco, CA (UroToday.com) Piet Ost, MD, PhD, gave an update on the STOMP trial after a median follow up of 5 years. Before this trial began the standard of care treatment of recurrent metastatic prostate cancer was androgen deprivation therapy (ADT) for symptomatic disease and either observation or ADT for asymptomatic disease.

The STOMP trial included patients who underwent previous local therapy in the form of radiation or surgery. All patients had a testosterone level above 50 ng/dl and had experienced asymptomatic biochemical recurrence with up to 3 N1 or M1 lesions on choline PET/CT, which was the only PET/CT available at that time. The trial design is shown in figure one, and the primary endpoint was time to start of ADT.

stomp trial design

Figure 1
. STOMP trial design

Assessing the outcome of ADT-free survival, the results demonstrated a hazard ratio of 0.57 (80% CI: 0.38-0.84, p=0.06) in the intention to treat analysis favoring MDT (figure 2).The hazard ratio in the per protocol analysis was 0.53 (80% CI 0.35-0.79, p=0.04). No significant difference was shown in the CRPC free survival outcome (Figure 3).

ITT

Figure 2
. STOMP trial intention to treat analysis ADT-free survival results

ITT and PP

Figure 3. CRPC free survival

The 5-year overall survival rate was 80 to 90%. Only 6 out of the 14 deaths were attributed to prostate cancer.

Dr. Ost concluded his talk stating metastasis directed therapy improves ADT free survival as compared to observation with delayed ADT. Additionally, prostate cancer mortality is low within the first five years of diagnosis of oligo-recurrent prostate cancer.

There are significant questions that still remain and must be answered. These include whether other PET CT tracers would influence the results, as in this trial only Choline PET CT was used. It is still unclear what is the correct standard of care for PET-detected metachronous oligorecurrent prostate cancer. Additionally, we need to figure out what endpoints are the ideal ones to be used. Finally, we need to answer the question of whether SBRT needs to be given with temporary systemic therapy.

Presented by: Piet Ost, MD, PhD, Assistant Professor, Ghent University Hospital, Ghent, Belgium

Written By: Hanan Goldberg, MD, Urology Department, SUNY Upstate Medical University, Syracuse, NY, USA, Twitter: @GoldbergHanan, at the 2020 Genitourinary Cancers Symposium, ASCO GU #GU20, February 13-15, 2020, San Francisco, California

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