Modified concept for radioisotope-guided sentinel lymph node dissection in prostate cancer.

PURPOSE

To present a modified concept for sentinel lymph node (SLN)-guided pelvic lymph node dissection in prostate cancer.

METHODS

A total of 463 patients with histologically proven prostate cancer underwent SLN-guided lymph node dissection. The day before surgery patients received intraprostatic injection of Tc-99 m-labeled nanocolloid (Tc-NC) under transrectal ultrasound guidance. At the time of surgery, the lymph nodes of the obturator fossa were dissected routinely in all patients. After meticulous testing with a handheld gamma probe, all lymphatic tissues in predefined anatomic regions (external iliac, internal iliac, common iliacal and presacral) with Tc-NC uptake were additionally resected.

RESULTS

In 146 (12.8%) patients, SLN were located exclusively in the obturator fossa, but 317 patients (87.2%) underwent resection of additional sentinel regions. In 28 (6.1%) patients, 62 lymph node metastases were detected, and 32 (51.6%) of these were located outside the obturator fossa. Eight (28.6%) patients displayed lymph node metastases exclusively outside the obturator fossa and had been resected only because of positive SLN probing.

CONCLUSIONS

The obturator fossa comprises the major landing site of lymph node metastases, but more than half of the metastases are located outside this anatomic region. Routine resection of the obturator fossa with additional resection of positive sentinel regions improves staging accuracy compared to resection of the obturator fossa only.