Prostate Metabolism After the Completion of Exclusive Radiation Is More Depleted After Seeds Brachytherapy Compared to External Beam Radiation Therapy for Prostate Cancer Patients
Résumé
Biochemical outcome after radiation therapy requires a protracted time. PSA decreases slowly over time so that it is difficult to differentiate immediately after the completion of radiation the impact of radiation in the prostate using brachytherapy or external radiotherapy. At 3 months, the mean PSA values were similar between the 2 groups: 2.54 ng/mL (±1.59) in the EBRT group and 1.88 ng/mL (±1.14) in the PPI group (p=0.23). For Choline levels, 3-months Choline / Baseline Choline ratios were 1.13 (±0.60) after EBRT vs. 0.45 (±0.23) in the PPI group (p=0.003). Similar results were observed for Citrate levels: 3-months Citrate level / Baseline Citrate level ratios were 0.32 (±0.23) in the EBRT group vs. 0.13 (±0.05) in the PPI group (p=0.014). Metabolism of the prostate as determine with MRSI is more severely depleted early after prostate seeds brachytherapy in comparison with patients treated with exclusive radiotherapy. Although, the dose delivered inside the prostate with PPI is much higher than with external beam radiotherapy, these early findings could explain the differences observed in PSA time course after brachytherapy or radiotherapy.