(UroToday.com) The 2023 European Society of Medical Oncology (ESMO) Annual Congress held in Madrid, Spain between October 20th and 24th, 2023 was host to a non-prostate, genitourinary tumors mini oral session. Dr. Srikala Sridhar presented the results of PET-MUSE, a study evaluating the impact of positron emission tomography (PET) imaging for the staging of patients with muscle invasive bladder cancer (MIBC).
MIBC accounts for approximately 25% of all urothelial cancers. Despite aggressive therapies, outcomes remain poor in this patient population. MIBC has a high propensity for lymph node metastases, which can have significant prognostic and therapeutic implications. Unfortunately, nodal metastases can be occult on standard CT imaging. PET-CT imaging provides both structural and functional disease information and may improve staging accuracy. PETMUSE was an investigator-initiated, prospective, randomized trial, open across 5 centers in Ontario, Canada. This study aimed to compare CET +/- PET-CT for the staging of patients with MIBC.
PETMUSE included patients with cT2-4aN0-3M0 urothelial cancer, staged using CT scan and TURBT, and were planned for radical cystectomy or trimodality therapy. This patient population (n=292) were planned for a 2:1 randomization to the FDG PET-CT experimental arm (n=194) or no FDG PET-CT control arm (n=98). Following imaging, patients proceeded to neoadjuvant chemotherapy (if clinically indicated), followed by surgery or radiotherapy. The primary outcome was proportion of patients not receiving the expected treatment, with secondary outcomes including change in treatment plan, disease-free survival, overall survival, and quality of life outcomes.
The baseline patient characteristics are summarized below and were well-balanced across the two arms. The median patient age was 70 years. Just over 75% of patients had cT2 disease, with the remaining 25% cT3-4. cN+ disease was present in 12.4 – 13.3% of patients. The planned primary therapy was surgery in 66 – 72.4% of patients.
PET-CT was able to identify a primary bladder tumor in 42% of imaged patients. Lymph node positive disease, with no primary tumor visualized, was observed in 10% of patients. Two patients (1%) had evidence of distant metastases.
Significantly, 11.2% of patients in the PET-CT arm did not receive the expected treatment, compared to 4.3% in the no PET-CT arm (OR 2.87, 95% CI: 0.95 - 8.70, p=0.062). Fewer patients in the PET-CT arm underwent a radical cystectomy (50% versus 65%) and with more undergoing trimodality therapy compared to those in the no PET-CT arm (36% versus 31%). 60% of patients in both arms received neoadjuvant chemotherapy. Notably, 10.2% of patients in the PET-CT arm were treated with a palliative intent, compared to 3.2% in the no PET-CT arm.
Disease-free and overall survivals were similar in both arms but remained immature at the time of analysis.
Dr. Sridhar concluded the presentation with the following take home messages:
- Although there was a trend towards a change in management with PET-CT, this did not reach statistical significance. Thus, at present, she does not recommend routine PET-CT staging for all MIBC patients
- There were threefold more patients receiving palliative intent treatment in the PET-CT arm
- Encouragingly, the uptake of neoadjuvant chemotherapy was almost 60% in both arms, and this could have in part impacted the results
- Long-term follow up data is awaited and understanding outcomes irrespective of local modality approach (surgery or trimodality therapy) will be of ongoing interest
- Future analyses will explore whether there are subgroups of MIBC patients that would benefit from additional PET-CT staging
Presented by: Srikala Sridhar, MD, MSc, FRCPC, Professor, Department of Medicine, Princess Margaret Cancer Centre, Toronto, ON
Written by: Rashid K. Sayyid, MD, MSc – Society of Urologic Oncology (SUO) Clinical Fellow at The University of Toronto, @rksayyid on Twitter during the 2023 European Society of Medical Oncology (ESMO) Annual Meeting, Madrid, Spain, Fri, Oct 20 – Tues, Oct 24, 2023.
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