Sentinel lymph node biopsy in penile cancer: evolution and insights.

INTRODUCTION: Defining the presence or absence of microscopic metastases in the inguinal lymph nodes in patients with invasive penile squamous carcinoma and no palpable adenopathy remains crucial but difficult short of performing inguinal lymphadenectomy.

METHODS: We reviewed the results of less invasive procedures such as traditional sentinel node biopsy and contemporary dynamic sentinel node biopsy aided by intraoperative lymphatic mapping (IOLM) to determine their role in the management of patients without palpable inguinal adenopathy

RESULTS: Inguinal node biopsy directed to the sentinel node area or region although initially promising was associated with a recurrence rate of 16% (24/150) among seven series reported. Extending the dissection to a wider region did not improve these results (20% recurrence, 5/25 patients). Preoperative lymphoscintigraphy combined with IOLM (with blue dye and a hand held gamma probe to detect radioactive counts) routinely detected sentinel nodes in the Netherlands Cancer Institute experience. However IOLM was associated with a false negative rate of 18% (6/34 patients). IOLM using an open incision approach at M.D. Anderson Cancer Center provided evidence for inguinal lymph drainage to alternate areas within the inguinal field confirming proof of principle for IOLM.

CONCLUSION: Inguinal lymph node biopsy directed to the sentinel node area to detect microscopic metastases is no longer recommended. Dynamic sentinel node biopsy utilizing IOLM is a promising technique in evolution that requires further testing among high volume centers for penile cancer. Contemporary superficial and modified inguinal dissection techniques with intraoperative frozen section remain the "gold standard" for defining the presence of microscopic metastases.