Surgical management and outcomes of patients with bone metastases in germ cell tumors: A case series

Metastasis-directed therapy in testicular cancer

PURPOSE OF REVIEW

This review highlights the importance of addressing testicular cancer metastasizing beyond the retroperitoneum, focusing on multidisciplinary approaches and advances in treatment.

RECENT FINDINGS

Recent literature emphasizes on the evolving landscape of metastasis-directed therapy, including surgical interventions, chemotherapy regimens, and radiation therapy. The effectiveness of these treatments varies depending on the site of metastasis, with various approaches improving survival rates and quality of life for patients. We divide our review in an organ-specific manner and focus on chemotherapeutic, surgical, and radiation therapy approaches pertaining to each site of metastasis.

SUMMARY

Our review suggests the pressing need for continued research to refine and personalize treatment strategies. These efforts are important for enhancing clinical practice, ultimately leading to better outcomes for patients with metastatic testicular cancer.

Bone Metastases in Non-Seminomatous Germ Cell Tumors: A 20-Year Retrospective Analysis

Background: Non-seminomatous germ cell tumors (NSGCTs) represent a rare yet the most prevalent malignancy among young men. Bone metastases (BMs) are exceedingly uncommon in this neoplasm, and available data regarding the initial disease presentation, survival outcomes, and prognostic significance of BMs are limited. Methods: We conducted a retrospective analysis of 40 NSGCT patients with BMs treated between 2001 and 2021 in our tertiary care center. The cohort was stratified into synchronous (n = 29) and metachronous (n = 11) groups based on the presence of BM at diagnosis or only at relapse, respectively. We assessed overall survival (OS), progression-free survival (PFS), disease presentation, and treatments. Results: After a median follow-up of 93 months, the 5-year PFS and OS rates were 37.6% and 53.9% in the synchronous group and 18.2% and 36.4% in the metachronous group, respectively. At the initial diagnosis, most patients were classified into the IGCCCG poor prognostic group (n = 34, 85%). BMs were mostly asymptomatic (n = 23, 57.5%), involved the spine (n = 37, 92.5%), and could become visible only after disease response (n = 4, 10%). A pathological examination of resected bone lesions after first-line treatment revealed necrosis (n = 5, 71.4%), teratoma, or seminoma (both n = 1, 14.3%). At first relapse, eight patients in the synchronous group did not experience bone recurrence, while eight patients experienced recurrence at the initial affected bone site. Conclusions: In NSGCT patients, BMs often present asymptomatically and may initially be unnoticed. However, these patients may have a poorer prognosis compared to those in the IGCCCG poor prognostic group. Further studies including control groups are needed to assess the independent prognostic significance of BMs.

Diagnostic Value of the Texture Analysis Parameters of Retroperitoneal Residual Masses on Computed Tomographic Scan after Chemotherapy in Non-Seminomatous Germ Cell Tumors

After chemotherapy, patients with non-seminomatous germ cell tumors (NSGCTs) with residual masses >1 cm on computed tomography (CT) undergo surgery. However, in approximately 50% of cases, these masses only consist of necrosis/fibrosis. We aimed to develop a radiomics score to predict the malignant character of residual masses to avoid surgical overtreatment. Patients with NSGCTs who underwent surgery for residual masses between September 2007 and July 2020 were retrospectively identified from a unicenter database. Residual masses were delineated on post-chemotherapy contrast-enhanced CT scans. Tumor textures were obtained using the free software LifeX. We constructed a radiomics score using a penalized logistic regression model in a training dataset, and evaluated its performance on a test dataset. We included 76 patients, with 149 residual masses; 97 masses were malignant (65%). In the training dataset (n = 99 residual masses), the best model (ELASTIC-NET) led to a radiomics score based on eight texture features. In the test dataset, the area under the curve (AUC), sensibility, and specificity of this model were respectively estimated at 0.82 (95%CI, 0.69-0.95), 90.6% (75.0-98.0), and 61.1% (35.7-82.7). Our radiomics score may help in the prediction of the malignant nature of residual post-chemotherapy masses in NSGCTs before surgery, and thus limit overtreatment. However, these results are insufficient to simply select patients for surgery.

Additional surgical procedures and perioperative morbidity in post-chemotherapy retroperitoneal lymph node dissection for metastatic testicular cancer in two intermediate volume hospitals

Purpose

To evaluate the perioperative morbidity of PC-RPLND in two intermediate volume centers and to identify predictors of high morbidity.

Methods

Retrospective analysis of 124 patients treated with open PC-RPLND at two tertiary referral centers between 2001 and 2018. Perioperative morbidity was determined by analyzing additional surgical procedures, intra-operative blood loss, and postoperative complications.

Results

An additional procedure was necessary for 33 patients (26.6%). The risk was higher in patients with IGCCCG intermediate/poor prognosis (OR 3.56; 95% CI 1.33–9.52) and residual tumor size > 5 cm (OR 3.53; 95% CI 1.39–8.93). Blood loss was higher in patients with IGCCCG intermediate/poor prognosis (β = 0.177; p = 0.029), large residual tumor (β = 0.570; p < 0.001), an additional intervention (β = 0.342; p < 0.001) and teratoma on retroperitoneal histology (β = − 0.19; p = 0.014). Thirty-one patients had a postoperative complication Clavien-Dindo Grade ≥ 2 (25.0%). Complication risk was highest in patients undergoing an additional intervention (OR 3.46; 95% CI 1.03–11.60; p = 0.044).

Conclusions

The rate of additional interventions in our series is comparable to what has been reported in high-volume centers. IGCCCG intermediate/poor prognosis patients with high-volume disease and patients undergoing an additional surgical procedure can be classified as high-risk patients.

Electronic supplementary material

The online version of this article (10.1007/s00345-020-03229-5) contains supplementary material, which is available to authorized users.

Radiomics allows for detection of benign and malignant histopathology in patients with metastatic testicular germ cell tumors prior to post-chemotherapy retroperitoneal lymph node dissection

OBJECTIVES

To evaluate whether a computed tomography (CT) radiomics-based machine learning classifier can predict histopathology of lymph nodes (LNs) after post-chemotherapy LN dissection (pcRPLND) in patients with metastatic non-seminomatous testicular germ cell tumors (NSTGCTs).

METHODS

Eighty patients with retroperitoneal LN metastases and contrast-enhanced CT were included into this retrospective study. Resected LNs were histopathologically classified into "benign" (necrosis/fibrosis) or "malignant" (viable tumor/teratoma). On CT imaging, 204 corresponding LNs were segmented and 97 radiomic features per LN were extracted after standardized image processing. The dataset was split into training, test, and validation sets. After stepwise feature reduction based on reproducibility, variable importance, and correlation analyses, a gradient-boosted tree was trained and tuned on the selected most important features using the training and test datasets. Model validation was performed on the independent validation dataset.

RESULTS

The trained machine learning classifier achieved a classification accuracy of 0.81 in the validation dataset with a misclassification of 8 of 36 benign LNs as malignant and 4 of 25 malignant LNs as benign (sensitivity 88%, specificity 72%, negative predictive value 88%). In contrast, a model containing only the LN volume resulted in a classification accuracy of 0.68 with 64% sensitivity and 68% specificity.

CONCLUSIONS

CT radiomics represents an exciting new tool for improved prediction of the presence of malignant histopathology in retroperitoneal LN metastases from NSTGCTs, aiming at reducing overtreatment in this group of young patients. Thus, the presented approach should be combined with established clinical biomarkers and further validated in larger, prospective clinical trials.

KEY POINTS

• Patients with metastatic non-seminomatous testicular germ cell tumors undergoing post-chemotherapy retroperitoneal lymph node dissection of residual lesions show overtreatment in up to 50%. • We assessed whether a CT radiomics-based machine learning classifier can predict histopathology of lymph nodes after post-chemotherapy lymph node dissection. • The trained machine learning classifier achieved a classification accuracy of 0.81 in the validation dataset with a sensitivity of 88% and a specificity of 78%, thus allowing for prediction of the presence of viable tumor or teratoma in retroperitoneal lymph node metastases.

External validation of 2 models to predict necrosis/fibrosis in postchemotherapy residual retroperitoneal masses of patients with advanced testicular cancer

OBJECTIVES

Nonseminomatous testicular germ cell tumors with residual retroperitoneal lesions >1 cm are treated with postchemotherapy retroperitoneal lymph node dissection (pcRPLND). However, up to 50% of patients are overtreated since the histology shows only residual necrosis/fibrosis. We aim to validate the 2 currently best performing prediction models (Vergouwe and Leao) for postchemotherapy residual mass histology.

METHODS AND MATERIALS

We performed a retrospective analysis including 402 patients who underwent a pcRPLND from 2008 to 2015. The study cohort was used to validate the 2 prediction models by Vergouwe and Leao using the published formulas and thresholds.

RESULTS

Using our validation cohort, the Vergouwe model reached a significantly better area under the curve compared to the Leao model (0.760 (confidence interval 0.713-0.807) vs. 0.692 (0.640-0.744), P = 0.002) in the prediction of benign histology. At a threshold of >70% for the predicted probability of benign disease, the Leao model revealed that pcRPLND would be avoided in 10.2% of patients with benign disease with an error rate of 3.8% for viable tumor, while the Vergouwe model would avoid pcRPLND in 27.4% of all patients with benign disease with an error rate of 10.1% for viable tumor and 2.9% for teratoma. Adjusting the models to our data had no significant improvement. Limitations include the retrospective design.

CONCLUSIONS

The discriminatory accuracy of both models is not sufficient to safely select patients for surveillance strategy instead of pcRPLND. Therefore, further studies including new biomarkers are needed to optimize the accuracy of potential prediction models and to minimize pcRPLND overtreatment.

Management of extraretroperitoneal masses in germ cell tumor

PURPOSE OF REVIEW

Management of extraretroperitoneal (ERP) germ cell tumor (GCT) is a complex clinical scenario faced by urologic oncologists. This article reviews the indications and approach to management of ERP GCT masses.

RECENT FINDINGS

ERP GCT management starts with chemotherapy, and for any residual masses, a careful consideration of surgical intervention versus salvage chemotherapy. Decision-making regarding residual ERP masses hinges on tumor markers, and also the anatomical location. These factors should be contextualized by the patient's risk for teratoma or active GCT, which will impact outcome and thus weigh on decision-making conversations with patients who have advanced disease. Technical challenges of surgical management in the postchemotherapy setting also apply in ERP mass resection. The risks of surgical management in the lung and liver, in particular, add special considerations for morbidity. Surgical resection is often the only recourse for a patient who may have chemoresistant disease and may be an important step in achieving cure.

SUMMARY

Surgical management of ERP GCT requires multidisciplinary input, and the urologic oncologist can help guide management with particular emphasis on the indication, timing, and approach to surgical resection.