Study: mpMRI Findings in Prostate Cancer Patients Unaffected by TRT

Multiparametric magnetic resonance imaging (mpMRI) findings remain stable following testosterone replacement therapy (TRT), suggesting that this imaging technique may be a useful option for active surveillance, preliminary results of a study show.

As many as one fifth of prostate cancer (PCa)patients have testosterone deficiency (total testosterone less than 300 ng/dL), but TRT treatment has been controversial in this population due to fears that testosterone may fuel the cancer. According to the saturation theory, once testosterone reaches a threshold, it no longer spurs prostate tissue growth.

In addition, how best to monitor these patients remains debatable. PSA measurements have shown potential limitations. A PSA increase can occur with TRT without signaling cancer progression, for example. 

In light of these concerns, Herbert Alberto Vargas, MD, and colleagues from Memorial Sloan Kettering Cancer Center in New York, reviewed the performance of mpMRI for active surveillance (AS) of 12 patients with low-risk PCa treated with TRT at their institution from 2005 to 2015. They compared mpMRI findings before and after TRT and tested mpMRI against PSA. All but 1 of the mpMRIs included diffusion-weighted images and 18 included dynamic contrast sequences.

According to results published online ahead of print in Urologic Oncology, significant increases occurred in serum testosterone (516.5 vs 203.0 ng/dL at 6 months after TRT), PSA (4.2 vs 3.3 ng/mL), and prostate volume (55.2 vs 39.4 cm3) following TRT. Some PSA increases were not associated with PCa progression.

In addition, mpMRI features after TRT remained stable in 10 patients without disease progression, whereas PI-RADSv2 score increased for 2 patients, with Gleason score upgrading on follow-up biopsy. One patient with clinical progression underwent radical prostatectomy, and the suspicious lesion on mpMRI coincided with the prostatectomy specimen.

With regard to disease recurrence, mpMRI and PI-RADSv2 score demonstrated a greater ability to detect PCa progression after TRT than PSA alone (area under the curve 0.90 vs 0.48).

“Although the patient numbers were small, the AUC for PI-RADSv2 score was 0.90. This hints that validated mpMRI may help the clinician to monitor patients treated with TRT even if PSA elevation is observed while on AS,” Dr Vargas and colleagues explained. 
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They suggest future studies investigate changes in the size and volume of prostate lesions according to mpMRI and test interreader agreement.

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