A systematic review of pN0 testicular seminoma: a new clinical entity and future directions.

Retroperitoneal lymph node dissection (RPLND) for testicular seminoma with enlarged retroperitoneal lymph nodes has received increased consideration and exposed a new clinical entity: pN0 disease. Enlarged, nonmetastatic retroperitoneal lymph nodes provide insight into the natural history of seminoma while offering a benchmark for improving the accuracy of staging. The purpose of this systematic review was to report the pN0 rates, describe risk factors associated with it, and discuss emerging research that may reduce its incidence. We performed a systemic review of published literature on PubMed, Embase, Web of Science, as well as oncology meeting abstracts evaluating histology of lymph nodes in patients with testicular seminoma treated primarily with retroperitoneal lymph node dissection. Studies were excluded if histology was not reported. A total of 15 publications and abstracts were included. Although study designs were heterogeneous, there was a minimal risk of bias. Overall, the reported pN0 rates were 0% to 22%. In prospective clinical trials it was 9% to 16%. The presence of pN0 was associated with preoperative smaller lymph nodes, a solitary enlarged lymph node, or negative serum miRNA-371. The incidence of pN0 seminoma is concerning as it points to a potential historical overtreatment; however, it also represents an important inflection for testicular cancer research as quantifiable improvements in clinical staging will translate to clear benefits to patients.