PSMA PET/CT Adds Survival Insight in Prostate Cancer

PSMA PET/CT Adds Survival Insight in Prostate Cancer

Initial staging in unfavourable intermediate-risk and high-risk prostate cancer needs to identify patients who may proceed to local treatment and those with nodal or metastatic disease requiring different planning. Conventional imaging with MRI, CT and bone scintigraphy remains routine, but has limitations in detecting small lymph nodes and early metastatic disease. A multicentre trial supported by the International Atomic Energy Agency and published in The Journal of Nuclear Medicine evaluated whether 68Ga-PSMA-11 PET/CT predicts survival outcomes in newly diagnosed, treatment-naïve patients who were candidates for radical prostatectomy. The trial included 775 patients across 11 countries whose disease appeared nonmetastatic on conventional imaging. PET/CT staging separated patients into groups with different event-free and overall survival, with distant metastatic disease linked to the poorest outcomes.

Imaging Groups and Patient Profile

The cohort included men with biopsy-confirmed unfavourable intermediate-risk or high-risk prostate cancer. Patients with another malignancy, apart from non-melanoma skin cancer, were excluded. Participating centres were based across Asia, Europe, the Middle East and the Americas, with all centres having more than five years of experience reporting PSMA PET/CT results. Most patients met high-risk criteria, and prostate-specific antigen levels and tumour grade were included in the clinical profile. Local ethical clearance applied at each centre, and patients provided written consent before recruitment. Standardised data collection covered PET/CT positivity, the localisation of positive findings and the effect of imaging on management.

All patients underwent 68Ga-PSMA-11 PET/CT according to existing international procedural guidance. Imaging assessment considered the prostate, seminal vesicles, lymph nodes and metastatic involvement. Disease status then fell into three broad PET/CT-defined categories: no local nodal involvement or metastases, pelvic lymph node involvement without distant metastases, and distant metastatic disease. These categories were used to compare subsequent outcomes. Overall survival was the primary outcome, while event-free survival captured treatment failure through biochemical recurrence after surgery or radiotherapy, radiologic progression or death. This structure allowed PET/CT disease extent to be assessed against clinical follow-up without relying only on conventional imaging findings.

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Different Survival Patterns

PET/CT-defined disease extent separated patients into groups with clearly different outcomes. Patients without nodal involvement or metastases had the most favourable event-free survival pattern. Those with pelvic lymph node involvement had intermediate results, while those with distant metastatic disease had the lowest event-free survival. Two-year event-free survival was just over half in the group without local nodal involvement or metastases, lower in the pelvic nodal group and about a quarter in the metastatic group.

Overall survival showed a sharper distinction for distant metastases. Two-year overall survival remained very high in the groups without distant metastatic disease, regardless of whether pelvic lymph nodes were involved. In contrast, patients with distant metastatic disease had a lower two-year overall survival rate and accounted for most deaths recorded across the cohort. Biochemical recurrence followed a similar gradient, occurring least often in patients without nodal or metastatic disease and most often in those with distant metastases. The survival curves for event-free and overall survival showed significant separation across the imaging categories. These patterns indicate that PSMA PET/CT adds prognostic information at initial staging, especially when it identifies metastatic disease that was not apparent on conventional imaging. The largest survival separation appears between patients without distant spread and those with PET/CT-detected metastases at two years.

Prognostic Role in Treatment Planning

Statistical modelling identified PSMA PET/CT status as the key prognostic factor for treatment failure. Pelvic nodal disease and distant metastatic disease were both associated with poorer event-free survival compared with disease limited to the prostate region. After adjustment for age, tumour grade, high-risk status and prostate-specific antigen level, the PET/CT categories remained associated with event-free survival, while those clinical variables were not significant predictors in the model.

For overall survival, metastatic disease carried the strongest prognostic signal. Pelvic nodal involvement did not significantly worsen overall survival after adjustment, but distant metastatic disease remained strongly associated with poorer overall survival. This distinction is clinically relevant because PET/CT can separate patients likely to have more favourable outcomes from those with a markedly poorer prognosis. The trial also notes that simple PSMA-based staging categories may be easier to apply across diverse practice settings than more complex approaches requiring specialised software, quantification methods and additional expertise. The practical implication is a stronger basis for risk-adapted treatment planning, including more individualised management for patients with PSMA-detected metastatic disease. Important limitations remain, including the absence of a randomised comparison with conventional imaging alone, variation in treatment regimens across centres and the need for longer follow-up.

68Ga-PSMA-11 PET/CT provides prognostic value during initial staging of unfavourable intermediate-risk and high-risk prostate cancer in patients considered for radical prostatectomy. Its staging categories identify different risks of treatment failure and survival, with distant metastatic disease carrying the clearest adverse signal. The results support routine integration of PSMA PET/CT into initial staging for survival prediction and more tailored treatment planning. The remaining uncertainty concerns direct comparison with conventional imaging alone, centre-level treatment variation and longer-term outcomes in patients with more favourable disease who may experience later events.

Source: Journal of Nuclear Medicine

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