Results of Using PSMA PET in a Public Health Service in Brazil for Patients with Prostate Cancer and Biochemical Recurrence

Introduction: Prostate cancer is one of the most prevalent cancers in men, and biochemical recurrence (BCR), characterized by an increase in PSA levels after treatment, represents a significant management challenge. The detection and monitoring of recurrent prostate cancer have significantly advanced with the introduction of novel imaging technologies, particularly PET-CT with PSMA. PSMA PET is a promising tool for detecting BCR, using radiotracers that specifically bind to PSMA, a protein highly expressed on prostate cancer cells, allowing for the detection of local recurrences and metastases even at low PSA levels. The objective of this study is to demonstrate the results of using PSMA PET in a public hospital in Brazil in patients with prostate cancer who had biochemical recurrence.

Materials and Methods: This study selected 50 prostate cancer patients who underwent PSMA PET for BCR. The patients were categorized into high and low disease volume groups based on the CHAARTED study. Data were analyzed using GraphPad Prism v. 8.0, excluding patients with neuroendocrine differentiation and those without initial PSA or BCR data.

Results: Among the patients, 48% had low-volume disease, 20% had high-volume disease, and 30% were non-metastatic. There were significant differences in Gleason scores between biopsy and pathology. The Gleason 6 (3+3) was predominantly non-metastatic (55.56%), while Gleason 9 (4+5) showed a predominance of high-volume disease (100%). The PSMA PET results were more sensitive in detecting BCR than other imaging modalities such as bone scintigraphy and MRI. Additionally, patients with higher initial PSA and PSA at BCR had a significant association with high-volume disease on PSMA PET.

Discussion: PSMA PET-CT proved to be highly effective in detecting BCR, with superior sensitivity and specificity compared to conventional imaging methods like bone scintigraphy and MRI. Higher Gleason scores were associated with a larger volume of disease detected by PSMA PET, confirming its ability to assess the extent of metastasis more accurately. The study also demonstrated that the use of PSMA PET could significantly impact clinical management, especially in early-stage recurrence.

Conclusion: The study highlights the efficacy of PSMA PET in detecting biochemical recurrence of prostate cancer, particularly in patients with low PSA levels. Despite the high cost, the technology shows promise in improving diagnostic accuracy and treatment outcomes in Brazil's public healthcare system. The integration of PSMA PET in public hospitals may enhance the management of prostate cancer, but it requires careful consideration of cost-benefit and infrastructure investments. With adequate training and policy support, PSMA PET can lead to better clinical results and provide more personalized treatment for patients with prostate cancer.

Categories: Radiology, Urology, Oncology

Prostate cancer is one of the most prevalent cancers among men, and biochemical recurrence, characterized by an increase in PSA levels after treatment, represents a significant challenge in its management. The detection and monitoring of recurrent prostate cancer have evolved significantly with the introduction of new imaging technologies, particularly PET/CT with PSMA. Positron Emission Tomography (PET) with Prostate-Specific Membrane Antigen (PSMA) has proven to be a valuable tool in detecting biochemical recurrence (BCR) of prostate cancer. PSMA PET uses radiotracers that specifically bind to PSMA, a protein highly expressed in prostate cancer cells, enabling the detection of local recurrences and metastases with high sensitivity and specificity, even at very low PSA levels [1-3]. The use of PSMA PET has shown promise in detecting biochemical recurrence of prostate cancer, particularly when compared to other imaging modalities such as multiparametric magnetic resonance imaging (mpMRI) and bone scintigraphy. The objective of this study is to demonstrate the results of using PSMA PET in a public hospital in Brazil in patients with prostate cancer who had biochemical recurrence. This article was previously presented as an electronic poster at the XVIII Paulista Congress of Urology from September 4 to 7, 2024.

Fifty patients with prostate cancer who underwent PSMA PET for biochemical recurrence were selected. They were divided into high- and low-volume disease groups according to the CHAARTED study. Data were analyzed using GraphPad Prism software v. 8.0, excluding patients with neuroendocrine differentiation in the pathological analysis and those who did not have initial PSA data or biochemical recurrence.

In the randomization of the cases (p < 0>48%), with 20% classified as high-volume and 30% as non-metastatic.

Comparisons between the Gleason score for biopsy and for pathological anatomy showed a significant difference in classification according to the CHAARTED study. Regarding the Gleason score in biopsy (p = 0.01), Gleason 6 (3+3) was predominantly non-metastatic (55.56%); Gleason 7: (3+4) and (4+3) were mostly low-volume (66.6% and 57.14%, respectively); Gleason 8 (4+4) showed cases distributed between non- metastatic and low-volume; Gleason 9: (4+5) and (5+4) had a predominance of high-volume (44.4% and 100%, respectively). Therefore, higher Gleason scores in biopsy are related to larger disease volumes detected by PSMA PET. Additionally, there was no significant difference between the pathological Gleason score and PSMA PET results (p > 0.1). No statistical significance was found between the positive results of scintigraphy (p > 0.8) and MRI (p > 0.3) in relation to volume classification by PSMA PET. However, when comparing low- and high-volume classifications using Cox regression, significance was found regarding positive scintigraphy results (p < 0> 0.3) when comparing MRI data.

Comparative data between initial PSA levels, PSA at biochemical recurrence, and metastatic disease volume classification identified by PSMA PET showed a significant difference. 

Initial PSA values for patients classified as high-volume by PSMA PET were higher compared to non- metastatic and low-volume classifications. 

Regarding PSA at biochemical recurrence, significant values were presented for low- and high-volume classifications compared to non-metastatic patients on PSMA PET, indicating the relevance of these diagnostic results for this analysis.

The results of this study demonstrate that PSMA PET is a highly effective tool for detecting biochemical recurrence of prostate cancer, especially in cases of low disease volume, as evidenced by comparisons with conventional imaging tests, such as bone scintigraphy and MRI. This finding corroborates previous studies highlighting the high sensitivity and specificity of PSMA PET in identifying metastatic lesions in patients with biochemical recurrence, even when PSA levels are still relatively low [4, 5].

The AUA/ASTRO/SUO guidelines emphasize the superiority of PSMA PET/CT in detecting biochemical recurrence of prostate cancer compared to conventional imaging, especially in detecting metastases in non- enlarged lymph nodes and bone metastases [6]. Cerci et al. conducted a multicenter prospective study that evaluated the diagnostic performance and clinical impact of Ga-PSMA-11 PET/CT in patients with early biochemical recurrence after radical therapy [7]. The study showed that PSMA PET/CT had a positivity rate of 65.1% and led to changes in therapeutic management in 56.8% of patients, underscoring its superiority over conventional imaging.

The significant correlation between Gleason score in biopsy and disease volume detected by PSMA PET, as observed in this study, is consistent with findings from other researchers. Studies such as those by Haidar 2022 et al. and Jain et al. (2021) suggest that higher Gleason scores are often associated with a greater volume of metastatic disease, reflected in PET/PSMA imaging [8,9]. This suggests that Gleason score may be an important predictor for disease volume, and PSMA PET can be a useful tool for characterizing disease extent more accurately than conventional tests.

The lack of statistical significance between PSMA PET and MRI results (p > 0.3) was an interesting finding and reinforces the superiority of PSMA PET in detecting biochemical recurrence at low PSA levels. This is consistent with studies such as Fendler et al. (2023), which showed that PSMA PET is more sensitive than MRI in detecting recurrences, especially in early stages [3]. The study also found a significant association between positive scintigraphy and higher risk of biochemical recurrence (p < 0>

Furthermore, elevated PSA values, both at the start of treatment and at biochemical recurrence, were associated with the diagnosis of high-volume disease by PSMA PET. This finding is consistent with the literature, which suggests that elevated PSA levels are often indicative of a larger disease volume and higher risk of metastases [11]. Additionally, a systematic review and meta-analysis by Crocerossa et al. evaluated the detection rate of various PSMA PET/CT tracers in patients with biochemical recurrence [12]. The analysis showed that PSMA PET/CT has a detection rate of over 70% for PSA levels below 1 ng/mL, being more effective than older tracers such as choline PET.

The implementation of PSMA PET in public health services has a significant impact. While PSMA PET is a high-cost technology, its application can improve diagnostic accuracy and provide better risk stratification, resulting in more effective and personalized treatments. As discussed by Hamed et al. (2018), the ability of PSMA PET to detect early recurrences allows for more timely therapeutic intervention, which can lead to better clinical outcomes for patients [13].

In the Brazilian context, especially in public hospitals, the use of cutting-edge imaging technologies like PSMA PET should be carefully evaluated in terms of cost-benefit. Bogoni et al. (2024) suggest that introducing exams like PSMA PET in public services could improve prostate cancer management but requires investment in infrastructure and adequate training for healthcare professionals [14] Thus, the feasibility of its implementation will depend on public policies ensuring equitable access to th.ese technologies, aligning with public health and social justice principles.

This study demonstrated the effectiveness of PSMA PET in detecting biochemical recurrence of prostate cancer, highlighting its superiority over conventional imaging methods such as bone scintigraphy and MRI. The high sensitivity and specificity of PSMA PET allowed for accurate identification of metastatic lesions, even in patients with low PSA levels, which is crucial for monitoring disease in the early stages of recurrence.

Additionally, the correlation between Gleason score and disease volume detected by PSMA PET reinforces the prognostic value of the test, enabling more accurate risk stratification and personalized treatment. The results also suggest that, although PSMA PET is a high-cost technology, its use in the context of public health services in Brazil could represent a significant advancement in prostate cancer management, provided that careful consideration is given to costs and the infrastructure necessary for its implementation.

The introduction of cutting-edge technologies like PSMA PET in public hospitals can improve diagnostic accuracy and healthcare quality but depends on public policies that ensure accessibility and equity in access to these exams. Therefore, the adoption of PSMA PET within the Unified Health System (SUS) has the potential to provide better clinical outcomes, but it requires adequate investment in training and infrastructure, as well as efficient resource management. Ultimately, the use of PSMA PET could be an important step forward in improving the diagnosis and treatment of prostate cancer in Brazil, offering a more promising future for patients with biochemical recurrence.