Abstract
This thesis concerns testicular germ cell tumor (TGCT).
Testicular germ cell tumor is introduced in chapter 1, describing the epidemiology, etiology, diagnosis and disease management.
Chapter 2 reviews the literature on the two main histopathological risk factors for relapse in clinical stage I (CS I) nonseminomatous germ cell tumor: lymphovascular invasion
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(LVI) and embryonal carcinoma (EC). Our findings show that LVI in the primary tumor is the strongest histopathological predictor for relapse. The prognostic value of EC is also high, but there is no consensus on a threshold value. Our research suggests that the mere presence of EC is already sufficient for the classification of EC.
The sentinel node (SN) procedure for CS I TGCT was developed at the Netherlands Cancer Institute. We retrospectively analyzed the results of this procedure in 27 consecutive patients in chapter 3. This study shows that the SN procedure is feasible in patients with CS I TGCT. Our findings suggest that patients with a negative SN can be managed with surveillance.
Chapter 4 concerns a systematic review of the literature on the relapse rate in NSGCT after postchemotherapy retroperitoneal lymph node dissection (PC-RPLND). The retroperitoneal relapse rates were 4.6% after open PC-RPLND and 1.7% after minimally-invasive PC-RPLND. The higher relapse rates after an open procedure are most likely due to selection bias. The average retroperitoneal relapse rate after a bilateral dissection was 6.1%, compared to 3.1% after a unilateral dissection. An important takeaway is that, based on this literature review, a unilateral dissection seems to be feasible in appropriately selected patients.
In chapter 5 we retrospectively compared the outcome of two approaches of retroperitoneal lymph node dissections: template-based resection (TBR) and residual mass resection (RMR). The retroperitoneal relapse rate was higher in the RMR group (5.9%), compared to the TBR group (3.9%). The five-year cumulative incidence of retroperitoneal relapse was also higher in the RMR group (4.2%), compared to the TBR group (3.0%).
In chapter 6 we retrospectively analyzed the morbidity of PC-RPLND in a cohort of 124 patients treated in two intermediate-volume hospitals. Our study showed that patients with IGCCCG intermediate/poor prognosis and high-volume disease can be classified as high-risk patients. In these patients, extra attention to possible tumor ingrowth and precautionary measures (such as assistance from a vascular surgeon) are advised.
Chapter 7 evaluates the outcome of robot-assisted RMR. Our study suggests that robot-assisted RMR is an appropriate treatment option in carefully selected patients, although long-term data is necessary to support this hypothesis.
In chapter 8 we evaluated the risk of developing metachronous contralateral TGCT (CTGCT) in a cohort of 4,755 patients with TGCT. Our study showed that approximately one in every 30 patients with TGCT will develop a CTGCT and that the incidence increases for up to 20 years after a primary TGCT. Treatment with platinum-based chemotherapy decreases the risk of developing CTGCT and this association is dose-dependent.
Chapter 9 provides a reflection on the findings of our research, places our results in a broader perspective and postulates future perspectives.
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