The advent of highly sensitive PSMA PET imaging is changing the management of biochemically recurrent prostate cancer. Rather than relying on fixed PSA thresholds from older trials like EMBARK to restart therapy, clinicians now use PET imaging at lower PSA levels to guide decisions, aiming to extend treatment-free intervals.

In a patient with high-risk features and a rapidly rising PSA, a negative PSMA PET scan should not be the final word. It may indicate the presence of PSMA-negative disease, a possibility that must be investigated with conventional cross-sectional imaging (CT scans) to ensure no tumors are being missed.

The AKT pathway, activated by PTEN loss, drives cancer growth independently of the androgen receptor, which controls PSA production. This discordance means clinicians cannot rely on PSA alone and must use systematic imaging to detect progression in this specific patient subgroup.

Intensive treatments like ADT plus an ARPI can suppress a patient's PSA so effectively that it becomes an unreliable marker of disease status. Patients may show radiographic progression on scans even while their PSA remains low and they feel clinically well. This discordance necessitates periodic imaging to avoid missing actual disease progression.

Data from the CAPItello trial showed a significant number of patients with PTEN deficiency experienced radiological progression without a corresponding PSA increase. This challenges the standard reliance on PSA for monitoring in high-risk prostate cancer and suggests a need for more frequent, personalized imaging protocols to detect progression earlier.

Experts believe molecular tests like Decipher and PTEN status are superior to simply counting bone lesions for guiding treatment. While not yet standard practice for all decisions, this represents a significant shift towards using underlying tumor biology to determine therapy, like adding docetaxel.

Landmark clinical trials (CONDOR, SPOTlight) demonstrate that PSMA PET imaging effectively identifies recurrent prostate cancer in a high percentage of patients even with very low PSA levels. This challenges the traditional paradigm of waiting for higher PSA thresholds before imaging, enabling earlier and more precise intervention.

Unlike androgen receptor mutations that arise under treatment pressure, PTEN loss is an earlier event. Therefore, tissue from an original biopsy or prostatectomy remains informative for testing PTEN status when a patient relapses with metastatic disease, simplifying the diagnostic process and avoiding invasive re-biopsies.

While seen early, even in low-grade cancers, PTEN loss is primarily associated with the cancer's progression to more aggressive forms. It correlates with transitions to higher grades, more advanced stages, and ultimately, metastatic states, marking it as a critical event in the disease's natural history.