Presentation Authors: Adam Calaway*, Ryan Speir, Marcelo Barboza, Antoin Dougwali, Timothy Masterson, Richard Foster, Lawrence Einhorn, Clint Cary, Indianapolis, IN
Introduction: Presence of teratoma in the orchiectomy and residual retroperitoneal (RP) mass size are known predictors of teratoma in retroperitoneum at the time of post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND). We sought to determine if the percentage of teratoma in the orchiectomy specimen could better stratify the risk of teratoma in the retroperitoneum.
Methods: A retrospective review of the Indiana University testis cancer database was performed to identify all patients who underwent PC-RPLND for non-seminomatous germ cell tumors from January 2010 to April 2018. Men with primary retroperitoneal tumors and without documented histologic composition of the orchiectomy were excluded. Teratoma in the orchiectomy was categorized into: none, 1-33%, 34-66%, 67-99% and pure teratoma. A logistic regression model was fit to predict the presence of teratoma in the retroperitoneum. The interaction between percentage of teratoma in the orchiectomy and residual RP mass size was assessed in a second logistic model.
Results: A total of 422 men were included in the study. Presence of yolk sac tumor in the orchiectomy (OR 3.64, p < 0.001), residual mass size (OR 1.19, p < 0.001) and percent teratoma in orchiectomy (OR 1.02, p < 0.001) were predictors of teratoma in the retroperitoneum. The interaction between RP mass size and percent teratoma in the orchiectomy predicts for the probability of teratoma in the retroperitoneum (Figure 1). For patients with no teratoma in the orchiectomy specimen, the probability of teratoma in the retroperitoneum ranges from 40% for small RP masses to >80% for mass over 10cm. In RP masses < 2cm, the probability of finding teratoma in the RP ranges from 40% to 80% depending on the percentage of teratoma in the orchiectomy. For RP masses greater than 15cm, the pathology is highly probable to be teratoma irrespectively of teratoma in the testicle.
Conclusions: Presence of yolk sac tumor in the orchiectomy, residual mass size and percentage of teratoma in the orchiectomy are predictors of teratoma at the time of PC-RPLND. As the percentage of teratoma in the orchiectomy specimen increases, the incremental risk of RP teratoma increases as a function of RP mass size.