Risk of residual cancer after complete response following first-line chemotherapy in men with metastatic non-seminomatous germ cell tumour and International Germ Cell Cancer Cooperative Group intermediate/poor prognosis: A multi-institutional retrospective cohort study

INTRODUCTION

Current guidelines recommend surveillance in metastatic non-seminomatous germ cell tumour patients treated with first-line-chemotherapy and a complete clinical response (normalisation of serum tumour markers and residual masses <1 cm). However, this recommendation is based on a series including patients with good prognosis according to International Germ Cell Cancer Cooperative Group prognostic group (IGCCCG-PG). The aim of this study was to analyse the proportion of residual teratoma and survival among patients with intermediate/poor IGCCCG-PG and a complete clinical response after first-line-chemotherapy.

MATERIAL & METHODS

This is a retrospective study of men with intermediate/poor IGCCCG-PG, who had a complete clinical response after first-line chemotherapy. Patients were either followed by surveillance or treated with post-chemotherapy retroperitoneal lymph node dissection (pcRPLND).

RESULTS

Between 2009 and 2018, 143 men with intermediate (n = 83) or poor (n = 60) IGCCCG-PG were treated at 11 international centres. Among 33 patients treated with pcRPLND, the specimen showed teratoma and viable cancer in 16 (48%) and 4 (12%). During a median a 7-year follow-up, 20/110 (18%) patients managed with surveillance relapsed, of whom seven (6%) had a retroperitoneal-only relapse versus 2/33 patients managed with pcRPLND relapsed. No difference was observed regarding overall survival (OS) among men treated with pcRPLND or surveillance (5-year OS, 93% and 89%, p-value = 0.35). The median time-to-recurrence among men on surveillance was 1.3 years (range: 0.3-9.1), and the most common sites of relapses included retroperitoneum (11%), chest (5%), and bones (4%).

CONCLUSIONS

While most men with intermediate/poor IGCCCG-PG harbour teratoma/cancer in the retroperitoneum despite a complete response to first-line-chemotherapy, only 6% managed with surveillance relapsed in the retroperitoneum. There was no significant difference in OS between the two groups.

Surveillance of postchemotherapy subcentimeter residual retroperitoneal mass in metastatic nonseminomatous germ cell tumor: Does how you measure matter?

BACKGROUND

Approximately 70% to 80% of patients with metastatic nonseminomatous germ cell tumor (NSGCT) treated with cisplatin-based chemotherapy achieve a complete response, defined as normalization of serum tumor markers and either no residual retroperitoneal mass (RRM) or an RRM <1.0 cm. While there is universal agreement that patients with an RRM ≥1.0 cm should undergo retroperitoneal lymph node dissection (RPLND), many institutions including ours recommend surveillance for patients who achieve a complete response. However, studies have not defined which axis of the RRM should be considered when deciding between surveillance and RPLND.

PATIENTS AND METHODS

Good-risk metastatic NSGCT patients treated with cisplatin-based chemotherapy who achieved a complete response and underwent surveillance were identified using our institution's electronic medical records. A post-hoc review was performed by a blinded radiologist. The RRM dimensions in the transaxial short axis (TSA), transaxial long axis (TLA), and craniocaudal axis (CCA) were recorded. Differences in the frequency of recurrence between groups with an RRM <1.0 cm and ≥1.0 cm in the TLA and CCA were assessed using the Fisher exact test.

RESULTS

Thirty-nine patients who met study criteria were included. At a median follow-up of 63.8 months, 2 patients (5.1%) recurred. Both were successfully treated with salvage chemotherapy and RPLND. Thirteen (33%) and 27 (69%) patients had an RRM ≥1.0 cm in the TLA and CCA, respectively. There were no statistically significant differences in the risk of recurrence between patients with an RRM <1.0 cm and ≥1.0 cm in the TLA (P = 0.54) or CCA (P = 0.53).

CONCLUSIONS

Surveillance is an effective strategy in good-risk NSGCT patients with a postchemotherapy RRM <1.0 cm in the TSA. Our study suggests referencing the TSA and not the TLA or CCA may avoid unnecessary postchemotherapy RPLNDs.

Pelvic Lymph Node Dissection in Patients Treated for Testis Cancer: The Memorial Sloan Kettering Cancer Center Experience

OBJECTIVE

To describe the pathologic findings and clinical outcome data for patients undergoing pelvic lymph node dissection (PLND) in the course of management of testicular germ cell tumors at Memorial Sloan Kettering Cancer Center (MSKCC).

PATIENTS AND METHODS

Following institutional review board approval, data on 2186 patients who underwent retroperitoneal lymph node dissection (RPLND) at MSKCC between 1989 and 2011 were retrospectively reviewed. Of these 2186 patients, we analyzed data for 44 patients (2%) who underwent PLND at the time of RPLND.

RESULTS

PLND was performed in 14/44 (31%) patients at time of primary RPLND (P-RPLND), and in 21/44(48%) patients at time of postchemotherapy RPLND (PC-RPLND), usually for suspicious radiologic or intraoperative findings, whereas 9/44 (21%) underwent PLND for treatment of relapse. Positive pelvic findings on imaging included pelvic disease ≤5 cm in 17/44 (39%) patients and >5 cm in 11/44 (25%) patients (median size = 4 cm). At the time of PC-RPLND, alpha-fetoprotein and beta human chorionic gonadotropin were elevated in 6/21 (29%) and 4/21 (19%) patients, respectively. Histology revealed teratoma in 15/44 (34%) and viable tumor in 5/44 (11%) patients. At a median follow-up of 46 months, 40/44 (91%) patients were living without disease, 3/44 (7%) were living with disease (1 after PC-RPLND and 2 after relapse), and 1/44 (2%) died of other causes.

CONCLUSION

PLND was performed infrequently in our series of patients who underwent RPLND for testis cancer. Teratoma was the dominant tumor histology in the resected tissue.

Defining optimum treatment of patients with pancreatic adenocarcinoma using regret-based decision curve analysis

OBJECTIVE

To use regret decision theory methodology to assess three treatment strategies in pancreatic adenocarcinoma.

BACKGROUND

Pancreatic adenocarcinoma is uniformly fatal without operative intervention. Resection can prolong survival in some patients; however, it is associated with significant morbidity and mortality. Regret theory serves as a novel framework linking both rationality and intuition to determine the optimal course for physicians facing difficult decisions related to treatment.

METHODS

We used the Cox proportional hazards model to predict survival of patients with pancreatic adenocarcinoma and generated a decision model using regret-based decision curve analysis, which integrates both the patient's prognosis and the physician's preferences expressed in terms of regret associated with a certain action. A physician's treatment preferences are indicated by a threshold probability, which is the probability of death/survival at which the physician is uncertain whether or not to perform surgery. The analysis modeled 3 possible choices: perform surgery on all patients; never perform surgery; and act according to the prediction model.

RESULTS

The records of 156 consecutive patients with pancreatic adenocarcinoma were retrospectively evaluated by a single surgeon at a tertiary referral center. Significant independent predictors of overall survival included preoperative stage [P = 0.005; 95% confidence interval (CI), 1.19-2.27], vitality (P < 0.001; 95% CI, 0.96-0.98), daily physical function (P < 0.001; 95% CI, 0.97-0.99), and pathological stage (P < 0.001; 95% CI, 3.06-16.05). Compared with the "always aggressive" or "always passive" surgical treatment strategies, the survival model was associated with the least amount of regret for a wide range of threshold probabilities.

CONCLUSIONS

Regret-based decision curve analysis provides a novel perspective for making treatment-related decisions by incorporating the decision maker's preferences expressed as his or her estimates of benefits and harms associated with the treatment considered.

A meta-analysis of patient outcomes with subcentimeter disease after chemotherapy for metastatic non-seminomatous germ cell tumor

BACKGROUND

Approximately a quarter of men with metastatic non-seminomatous germ cell tumor (NSGCT) have a residual mass, typically in the retroperitoneum, after chemotherapy. The management of small residual masses (≤1 cm) is controversial, with good outcomes seen with either post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND) or surveillance. We sought to review our experience of surveillance and synthesize the cumulative findings with the current literature in the form of a meta-analysis.

PATIENTS AND METHODS

We searched PubMed, EMBASE and abstracts from ASCO and AUA to identify relevant, English-language studies for the meta-analysis. The DFCI (Dana Farber Cancer Institute) database was constructed from a database of men undergoing cisplatin-based chemotherapy for metastatic NSGCT. The outcomes of interest were the proportion with necrosis, teratoma or active cancer on histology at PC-RPLND (literature) and the total number of relapses, RP-only relapses and overall survival in men undergoing surveillance (literature and DFCI cohort).

RESULTS

Three of 47 men undergoing post-chemotherapy surveillance at our institution relapsed over a median follow-up of 5.4 years. All three were alive at a median of 4.2 years after relapse. On meta-analysis, the pooled estimates of necrosis, teratoma and active cancer in the 588 men who underwent PC-RPLND were 71, 24 and 4%, respectively. Of the combined 455 men who underwent surveillance, the pooled estimate of the relapse rate was 5%, with an RP-only relapse rate of 3%. Of the 15 men who suffered an RP-only relapse on surveillance, two died of disease.

CONCLUSION

Surveillance is a reasonable strategy for men with minimal residual RP disease after chemotherapy and avoids an RPLND in ∼97% of men who are cured with chemotherapy alone.

Assessing the incremental value of diagnostic and prognostic markers: a review and illustration

BACKGROUND

New markers may improve prediction of diagnostic and prognostic outcomes. We review various measures to quantify the incremental value of markers over standard, readily available characteristics.

METHODS

Widely used traditional measures include the improvement in model fit or in the area under the receiver operating characteristic (ROC) curve (AUC). New measures include the net reclassification index (NRI) and decision-analytic measures, such as the fraction of true-positive classifications penalized for false-positive classifications [net benefit (NB)]. For illustration, we discuss a case study on the presence of residual tumour vs. benign tissue in 544 patients with testicular cancer. We assessed three tumour markers [Alpha-fetoprotein (AFP), Human chorionic gonadotropin (HCG) and Lactate dehydrogenase (LDH)] for their incremental value over currently standard clinical predictors.

RESULTS

AUC and R(2) values suggested adding continuous LDH and AFP whereas NB only favoured HCG as a potentially promising marker at a clinically defendable decision threshold of 20% risk. The NRI suggested reclassification potential of all three markers.

CONCLUSIONS

The improvement in standard discrimination measures, which focus on finding variables that might be promising across all decision thresholds, may not detect the most informative markers at a specific threshold of particular clinical relevance. When a marker is intended to support decision-making, calculation of the improvement in a decision-analytic measure, such as NB, is preferable over an overall judgment as obtained from the AUC in ROC analysis.

Management of the residual post-chemotherapy retroperitoneal mass in germ cell tumors

The management of the residual mass in the retroperitoneum following induction chemotherapy for metastatic testicular cancer has evolved over the past three decades. A multidisciplinary approach involving cisplatin-based chemotherapy and postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) has increased long-term survival rates above 80%. Advances into the appropriate patient selection and timing of surgery have lowered morbidity while improving oncologic outcomes. However, areas of controversy still exist within the field. Management of the small residual mass, predictors of the histology of the residual mass, the extent of PC-RPLND, the role of PC-RPLND in the setting of elevated serum tumor markers, and the role of positron-emission tomography are all topics of ongoing research and debate. We will discuss these issues and review the current guidelines for the management of the residual postchemotherapy retroperitoneal mass in this review.

[The surgery after. . . retroperitoneal lymph node dissection and surgery of the residual masses after chemotherapy for advanced testicular cancer]

Thirty-six cases of retroperitoneal lymph node dissections for residual mass after chemotherapy for testicular cancer are reported. In a reference center, the recruitment is modified by the severity of the situations related to very big masses, tumors of poor prognosis and resistant tumors. Lymph node dissection is often atypical and surgery of metastatic residual masses is frequent (13 operations). The 8-year global survival remains stable, over 90%. The 5-year cumulated risk of recurrence is 20%, but these situations can be overtaken.

Assessing the performance of prediction models: a framework for traditional and novel measures

The performance of prediction models can be assessed using a variety of methods and metrics. Traditional measures for binary and survival outcomes include the Brier score to indicate overall model performance, the concordance (or c) statistic for discriminative ability (or area under the receiver operating characteristic [ROC] curve), and goodness-of-fit statistics for calibration.Several new measures have recently been proposed that can be seen as refinements of discrimination measures, including variants of the c statistic for survival, reclassification tables, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Moreover, decision-analytic measures have been proposed, including decision curves to plot the net benefit achieved by making decisions based on model predictions.We aimed to define the role of these relatively novel approaches in the evaluation of the performance of prediction models. For illustration, we present a case study of predicting the presence of residual tumor versus benign tissue in patients with testicular cancer (n = 544 for model development, n = 273 for external validation).We suggest that reporting discrimination and calibration will always be important for a prediction model. Decision-analytic measures should be reported if the predictive model is to be used for clinical decisions. Other measures of performance may be warranted in specific applications, such as reclassification metrics to gain insight into the value of adding a novel predictor to an established model.

Role of post-chemotherapy surgery in germ cell tumors

Surgery after systemic chemotherapy for advanced testicular cancer has maintained its role in staging and therapeutic management. The clinical outcome is strongly influenced by patient selection and extent of extirpative surgery. Although extensive predictive modeling has attempted to define appropriate post-chemotherapy surgical candidates based on various clinical and pathologic parameters, the accuracy of these models remains controversial. Complete removal of all post-chemotherapy residual masses in nonseminomatous germ cell tumors remains the standard of care and allows for improved prognostication of the long-term oncologic and functional outcome.

Polytomous logistic regression analysis could be applied more often in diagnostic research

OBJECTIVE

Physicians commonly consider the presence of all differential diagnoses simultaneously. Polytomous logistic regression modeling allows for simultaneous estimation of the probability of multiple diagnoses. We discuss and (empirically) illustrate the value of this method for diagnostic research.

STUDY DESIGN AND SETTING

We used data from a study on the diagnosis of residual retroperitoneal mass histology in patients presenting with nonseminomatous testicular germ cell tumor. The differential diagnoses include benign tissue, mature teratoma, and viable cancer. Probabilities of each diagnosis were estimated with a polytomous logistic regression model and compared with the probabilities estimated from two consecutive dichotomous logistic regression models.

RESULTS

We provide interpretations of the odds ratios derived from the polytomous regression model and present a simple score chart to facilitate calculation of predicted probabilities from the polytomous model. For both modeling methods, we show the calibration plots and receiver operating characteristics curve (ROC) areas comparing each diagnostic outcome category with the other two. The ROC areas for benign tissue, mature teratoma, and viable cancer were similar for both modeling methods, 0.83 (95% confidence interval [CI]=0.80-0.85) vs. 0.83 (95% CI=0.80-0.85), 0.78 (95% CI=0.75-0.81) vs. 0.78 (95% CI=0.75-0.81), and 0.66 (95% CI=0.61-0.71) vs. 0.64 (95% CI=0.59-0.69), for polytomous and dichotomous regression models, respectively.

CONCLUSION

Polytomous logistic regression is a useful technique to simultaneously model predicted probabilities of multiple diagnostic outcome categories. The performance of a polytomous prediction model can be assessed similarly to a dichotomous logistic regression model, and predictions by a polytomous model can be made with a user-friendly method. Because the simultaneous consideration of the presence of multiple (differential) conditions serves clinical practice better than consideration of the presence of only one target condition, polytomous logistic regression could be applied more often in diagnostic research.

Postchemotherapy retroperitoneal surgery remains necessary in patients with nonseminomatous testicular cancer and minimal residual tumor masses

PURPOSE

To determine preoperative parameters that predict the histology of specimens obtained by retroperitoneal lymph node dissection (RPLND) in patients with nonseminomatous germ cell cancer (NSGCT) whose residual mass was </= 20 mm in diameter after modern cisplatin-based induction chemotherapy.

PATIENTS AND METHODS

Eighty-seven patients with metastatic NSGCT underwent RPLND after having received cisplatin- or carboplatin-based induction chemotherapy. In all patients, the largest diameter of the residual mass on the transaxial plane was </= 20 mm, as assessed by abdominal computed tomography (CT) immediately before RPLND.

RESULTS

Complete fibrosis or necrosis was found in 58 patients (67%), teratoma was found in 23 patients (26%), and vital malignant germ cell tumor was found in six patients (7%), including one patient with rhabdomyosarcoma in the RPLND specimen. In five of the six latter patients, the residual lesion was </= 10 mm at pre-RPLND CT. No pre- or postchemotherapy clinical or radiologic parameter was identified that significantly predicted the histology of the residual mass.

CONCLUSION

One third of retroperitoneal postchemotherapy lesions </= 20 mm contained residual vital tumor tissue, despite modern chemotherapy regimens. Therefore, postchemotherapy RPLND remains necessary in patients with minimal-size residual lesions to facilitate easy and safe follow-up and initiate additional therapy as early as possible, thus avoiding recurrences.

External validity of a prediction rule for residual mass histology in testicular cancer: an evaluation for good prognosis patients

We assessed the external validity of a prediction rule for nonseminomatous testicular cancer patients. The rule was developed to predict the probability of retroperitoneal metastases being benign (only necrosis/fibrosis) after chemotherapy treatment. Patients with a high probability of benign residual masses might be offered surveillance as opposed to patients with a low probability, who should undergo retroperitoneal lymph node dissection (RPLND). We compared the observed histology with the predicted probability in 105 patients with good prognosis germ cell cancer who underwent RPLND between 1995 and 1998. We found that predicted probabilities higher than 5% were in good agreement with the observed frequencies of benign masses. The area under the receiver operating characteristic curve was 0.76, suggesting that the rule could reasonably discriminate between benign masses and tumour. However, nearly all predicted probabilities (n=101) were lower than 70%, which might be considered as the lowest value at which surveillance offers a reasonable alternative to RPLND. Further, 35% of patients currently under surveillance (84 out of 241) had predicted probabilities lower than 70%. In conclusion, the clinical relevance of the prediction rule was limited for the patients who underwent RPLND; use of the rule would change the policy from RPLND to surveillance in only a few. On the other hand, the rule might support selection of patients for RPLND, who currently are under surveillance.

Metastatic nonseminomatous germ cell tumors of the testis: results of elective and salvage surgery for patients with residual retroperitoneal masses

BACKGROUND

A mass may persist in the para-aortic region after patients undergo chemotherapy for metastatic, nonseminomatous germ cell tumor of the testis (NSGCT). Retroperitoneal lymphadenectomy removes the mass, which may contain residual active malignancy, and allows histologic assessment of the effectiveness of the chemotherapy. Whereas some have favored early, elective removal of such masses, others have chosen to observe them, reserving salvage surgery for patients who experience disease recurrence. A retrospective analysis was undertaken to define the outcome in these two groups of patients.

METHODS

After receiving chemotherapy for metastatic NSGCT, 442 men underwent lymphadenectomy for residual masses (measuring > or = 1 cm in greatest dimension) between 1976 and 1999, inclusive. Three hundred thirty men underwent elective surgery within 3 months of the completion of chemotherapy, and 112 men underwent salvage surgery after receiving reinduction chemotherapy for tumor recurrence.

RESULTS

The residual mass was removed completely in 87% and 72% of patients in the elective and salvage lymphadenectomy groups, respectively; was removed with difficulty and possibly incompletely in 9% and 21% of patients, respectively; and was definitely removed incompletely in 4% and 7% of patients, respectively. The operative mortality rate was 0.9% in the elective surgery group and 1.8% in the salvage surgery group. There was malignant teratoma, undifferentiated in 8.5% of patients in the elective surgery group and in 49% of patients in the salvage surgery group (P < 0.001). Differentiated teratoma and necrosis/fibrosis were present in 66.0% and 25.4% of patients in the elective surgery group, respectively, and in 38.4% and 12.5% of patients in the salvage surgery group, respectively. The authors were unable to produce a clinically useful model to predict the presence of necrosis/fibrosis only in either group. The 5-year recurrence free and overall survival rates were 83% and 89%, respectively, in the elective surgery group and 62% and 56%, respectively, in the salvage surgery group. For the salvage surgery group, the completeness of surgical excision and the presence of undifferentiated teratoma were of overriding importance for overall survival. A variety of other patient-related, tumor-related, and surgery-related factors also were significant in the final model for the elective surgery group.

CONCLUSIONS

The current results demonstrate the low level of morbidity that can be obtained, even in the salvage surgery group, and the importance of complete surgical resection in this setting. Because it is not possible to predict with sufficient accuracy which patients will have favorable pathology (necrosis/fibrosis), the authors continue to recommend elective surgery for all suitable men with residual masses after they receive first-line chemotherapy.

Residual mass histology in testicular cancer: development and validation of a clinical prediction rule

After chemotherapy for metastatic non-seminomatous testicular cancer, surgical resection is a generally accepted treatment to remove remnants of the initial metastases, since residual tumour may still be present (mature teratoma or viable cancer cells). In this paper, we review the development and external validation of a logistic regression model to predict the absence of residual tumour. Three sources of information were used. A quantitative review identified six relevant predictors from 19 published studies (996 resections). Second, a development data set included individual data of 544 patients from six centres. This data set was used to assess the predictive relationships of five continuous predictors, which resulted in dichotomization for two, and a log, square root, and linear transformation for three other predictors. The multiple logistic regression coefficients were reduced with a shrinkage factor (0.95) to improve calibration, based on a bootstrapping procedure. Third, a validation data set included 172 more recently treated patients. The model showed adequate calibration and good discrimination in the development and in the validation sample (areas under the ROC curve 0.83 and 0.82). This study illustrates that a careful modelling strategy may result in an adequate predictive model. Further study of model validity may stimulate application in clinical practice.

Treatment of testicular tumours based on risk factors

Germ cell cancer is highly sensitive to cisplatinum-based chemotherapy, resulting in cure rates of over 90% for patients with minimal metastatic disease or low tumour markers, 70% for patients with intermediate prognosis features, and 50% for patients with poor prognosis criteria. Whereas current clinical studies aim to improve the survival of patients with poor prognosis by means of high-dose chemotherapy, or the survival of intermediate prognosis patients by more intensive chemotherapy, for patients with good prognosis the reduction of doses, number of drugs or cycles is investigated to reduce the short-term and, in particular, long-term treatment sequelae. However, apart from these clinical studies, the current treatment standard of three cycles of platinum/etoposide/bleomycin for good prognosis patients and four cycles for intermediate and poor prognosis patients with advanced germ cell cancer has not been changed by recent trial results. The excellent cure rate with cisplatinum-based chemotherapy in the case of early metastatic disease with three cycles of platinum/etoposide/bleomycin as well as the high efficacy of adjuvant chemotherapy with two cycles of platinum/etoposide/bleomycin in the case of microscopic disease did change the treatment standards in stage I and II non-seminomatous germ cell cancer, with defined treatment options depending on prognostic factors. The treatment of testicular cancer based on prognostic factors is mandatory in all stages of seminoma and non-seminoma; however, molecular biological factors might make a major contribution to a more precise determination of prognosis and therefore enable a tailored selection of an individual treatment in the future.