Page 8 - The Contemporary Role of Conventional Imaging for Staging, Re-staging, and Monitoring Prostate Cancer: Impact on Management

Few studies have correlated imaging findings with Guidance for Imaging Use During
pathological diagnosis of metastatic disease. In the
metastatic state, biopsy is usually not possible nor Systemic Therapy
acceptable to patients, and the performance of an
imaging technique is typically correlated with clinical ecommendations are provided for patients
evolution. The detection of treatment response is an Rreceiving systemic therapy in hormone-naïve,
indicator that a lesion was a true positive of metastatic hormone-sensitive, and castration-resistant advanced
disease. False positives are not often considered. prostate cancer states (Table 4). The terminology used
However, because imaging often triggers a change to in the source guidance document is reflected in the
the next line of therapy, clinicians must be cautious table that follows.
in the interpretation of a radiological progressive
disease without PSA rise and clinical progression. In general, imaging at baseline is recommended upon
Pseudoprogression can occur, especially early on initiation of a new therapy. During treatment for
after the introduction of a new line of therapy. Such hormone-sensitive disease, imaging is recommended
a pseudoprogression has been identified as a flare at PSA progression or new onset of symptoms. In
phenomenon after re-imaging with bone scan early CRPC, patients receiving novel androgen receptor
after therapeutic change. axis inhibitors (such as abiraterone or enzalutamide)
should be monitored regularly with conventional
Development of new bone lesions around 8-12 weeks imaging, given that a quarter of patients may progress
post initiation of treatment may actually represent a radiographically only (without PSA rise).
favourable response to therapy. As a result, the Prostate
Cancer Clinical Trials Working Group has provided
recommendations to avoid declaring early new lesions
incorrectly as metastases, by comparing positive
findings against repeat imaging conducted 8 weeks
later. Only the appearance of two or more new lesions
after the second bone scan would confirm radiographic
progression. 25

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