Prostate cancer topography and patterns of lymph node metastasis

Pelvic lymph node (LN) metastasis is a well-recognized route of prostate cancer spread. However, the relationship between topography and the pathologic features of primary prostatic cancers and patterns of pelvic LN metastasis has not been well studied. We reviewed original slides of radical prostatectomies and pelvic LN dissections from 125 patients with LN metastasis and recorded a total number of LN excised/laterality of positive LN, and localization, staging parameters, lymphovascular invasion, and volume of primary tumors.

14.6 (mean) and 13 (median) LNs were resected. Seventy-six (61%), 33 (26%), and 16 (13%) cases had 1, 2, and >2 positive LNs; whereas 58, 44, and 20 cases had LN metastasis on the right, left, and bilaterally.

Eighty-six percent (108 of 125) and 37% (46 of 125) of the cases showed extraprostatic extension and seminal vesicle invasion, whereas 64% cases showed lymphovascular invasion. Mean and median total tumor volumes were 6.39 and 3.92 cm, with ≥50% and ≥90% Gleason patterns 4/5 in 105 (84%) and 73 (58%) cases, respectively.

Dominant lesions on radical prostatectomy were as follows: 50 right lobe, 44 left lobe, and 31 bilateral lobe tumors. Fifteen of 50 (30%) right lobe and 18 of 44 (41%) left lobe dominant tumors had LN metastasis on the contralateral side. Only 4% (5 of 125) of the cases were associated with anterior dominant tumors.

Thirty percent to 40% of LN metastases occurred contralateral to the dominant tumor. LN metastasis is overwhelmingly associated with high-grade, high-stage, and large volume disease. LN positivity is rarely associated with anterior dominant tumors.