Relation between intraprostatic temperature and clinical outcome in microwave thermotherapy

The study was designed to explore the relation between prostatic temperature and the clinical outcome of transurethral microwave thermotherapy (TUMT).

Forty-nine patients with symptomatic benign prostatic hyperplasia (BPH) were treated. Baseline evaluation included Madsen score, flowmetry, and pressure-flow study. Two fiberoptic thermosensors were placed in the prostate targeted to the region 10 and 20 mm below the bladder neck and 5 to 15 mm lateral to the prostatic urethra. The TUMT was carried out using either the low-energy (2.0) or high-energy (2.5) Prostasoft program. Follow-up was at 6, 12, and 26 weeks.

A moderate correlation between intraprostatic temperatures and energy output (r = 0.409; P < or = 0.046) and prostate volume (r = 0.303; P < or = 0.0424) was observed. Outlet obstruction was associated with higher temperatures (obstructed 49.6+/-5.8 v unobstructed 46.1+/-4.2 degrees C; P < or = 0.033). A significant relation between temperature and clinical outcome was found. Patients with intraprostatic temperatures <46 degrees, 46-50 degrees, and < or = 50 degrees C had significant differences in Madsen score change (-50%, -68% and -86%) and in maximum flow rate (+26%, +32%, and +48%). Patients with temperatures >50 degrees C had a significant improvement in obstruction status (86% to 18%). A slight worsening in voiding dynamics was observed in patients with temperatures <50 degrees C.

A significant relation exists between intraprostatic temperatures achieved during TUMT and the clinical outcome. Temperatures in excess of 50 degrees C seem to be associated with a greater improvement in lower urinary tract symptoms and bladder outlet obstruction. These data provide a sound rationale for monitoring intraprostatic temperatures and developing invasive thermometry feedback mechanisms for thermal treatments of BPH.