The influence of anastomotic techniques on postoperative anastomotic complications: Results of the Oesophago-Gastric Anastomosis Audit

BACKGROUND

The optimal anastomotic techniques in esophagectomy to minimize rates of anastomotic leakage and conduit necrosis are not known. The aim of this study was to assess whether the anastomotic technique was associated with anastomotic failure after esophagectomy in the international Oesophago-Gastric Anastomosis Audit cohort.

METHODS

This prospective observational multicenter cohort study included patients undergoing esophagectomy for esophageal cancer over 9 months during 2018. The primary exposure was the anastomotic technique, classified as handsewn, linear stapled, or circular stapled. The primary outcome was anastomotic failure, namely a composite of anastomotic leakage and conduit necrosis, as defined by the Esophageal Complications Consensus Group. Multivariable logistic regression modeling was used to identify the association between anastomotic techniques and anastomotic failure, after adjustment for confounders.

RESULTS

Of the 2238 esophagectomies, the anastomosis was handsewn in 27.1%, linear stapled in 21.0%, and circular stapled in 51.9%. Anastomotic techniques differed significantly by the anastomosis sites (P < .001), with the majority of neck anastomoses being handsewn (69.9%), whereas most chest anastomoses were stapled (66.3% circular stapled and 19.3% linear stapled). Rates of anastomotic failure differed significantly among the anastomotic techniques (P < .001), from 19.3% in handsewn anastomoses, to 14.0% in linear stapled anastomoses, and 12.1% in circular stapled anastomoses. This effect remained significant after adjustment for confounding factors on multivariable analysis, with an odds ratio of 0.63 (95% CI, 0.46-0.86; P = .004) for circular stapled versus handsewn anastomosis. However, subgroup analysis by anastomosis site suggested that this effect was predominantly present in neck anastomoses, with anastomotic failure rates of 23.2% versus 14.6% versus 5.9% for handsewn versus linear stapled anastomoses versus circular stapled neck anastomoses, compared with 13.7% versus 13.8% versus 12.2% for chest anastomoses.

CONCLUSIONS

Handsewn anastomoses appear to be independently associated with higher rates of anastomotic failure compared with stapled anastomoses. However, this effect seems to be largely confined to neck anastomoses, with minimal differences between techniques observed for chest anastomoses. Further research into standardization of anastomotic approach and techniques may further improve outcomes.

Textbook outcome following oesophagectomy for cancer: international cohort study

Background

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

Methods

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

Results

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter ‘no major postoperative complication’ had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P &lt; 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P &lt; 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

Conclusion

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Textbook outcome following oesophagectomy for cancer: international cohort study

BACKGROUND

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

METHODS

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

RESULTS

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter 'no major postoperative complication' had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P < 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P < 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

CONCLUSION

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Postoperative outcomes in oesophagectomy with trainee involvement

BACKGROUND

The complexity of oesophageal surgery and the significant risk of morbidity necessitates that oesophagectomy is predominantly performed by a consultant surgeon, or a senior trainee under their supervision. The aim of this study was to determine the impact of trainee involvement in oesophagectomy on postoperative outcomes in an international multicentre setting.

METHODS

Data from the multicentre Oesophago-Gastric Anastomosis Study Group (OGAA) cohort study were analysed, which comprised prospectively collected data from patients undergoing oesophagectomy for oesophageal cancer between April 2018 and December 2018. Procedures were grouped by the level of trainee involvement, and univariable and multivariable analyses were performed to compare patient outcomes across groups.

RESULTS

Of 2232 oesophagectomies from 137 centres in 41 countries, trainees were involved in 29.1 per cent of them (n = 650), performing only the abdominal phase in 230, only the chest and/or neck phases in 130, and all phases in 315 procedures. For procedures with a chest anastomosis, those with trainee involvement had similar 90-day mortality, complication and reoperation rates to consultant-performed oesophagectomies (P = 0.451, P = 0.318, and P = 0.382, respectively), while anastomotic leak rates were significantly lower in the trainee groups (P = 0.030). Procedures with a neck anastomosis had equivalent complication, anastomotic leak, and reoperation rates (P = 0.150, P = 0.430, and P = 0.632, respectively) in trainee-involved versus consultant-performed oesophagectomies, with significantly lower 90-day mortality in the trainee groups (P = 0.005).

CONCLUSION

Trainee involvement was not found to be associated with significantly inferior postoperative outcomes for selected patients undergoing oesophagectomy. The results support continued supervised trainee involvement in oesophageal cancer surgery.

New Chest Drainage Unit with Integrated CO2-Detector Demonstrates False Air Leak

BACKGROUND

Postoperative observed air leakage does not always originate from parenchymal defects but may arise from defects in the chest drainage unit, connections or reverse airflow in water seals. We investigated such false air leakage using a new chest drainage unit with a built-in CO2-detector and an electronic chest drainage unit.

METHODS

Two types of chest drainage units were tested in a simple porcine model: A well-known electronic chest drainage unit and a new chest drainage unit with integrated CO2-detector. We created a setup of true air leakage-a parenchymal lesion, and false air leakage-allowing air to flow into the thoracic cavity alongside the chest drain.

RESULTS

We demonstrated that the new chest drainage unit with a built-in CO2-detector can distinguish between experimentally induced true air leakage and false air leakage.

CONCLUSION

Available chest drainage systems do not allow direct assessment of true or false air leakage, which may increase chest drain duration unnecessarily. The integration of a CO2-sensitive color indicator into a chest drainage unit allows simple distinction between false air leak and true air leak, which may improve postoperative management.

Clinically decisive (dis)agreement in multidisciplinary team assessment of esophageal squamous cell carcinoma; a prospective, national, multicenter study

BACKGROUND

Decisions regarding tumor staging, operability, resectability, and treatment strategy in patients with esophageal cancer are made at multidisciplinary team (MDT) conferences. We aimed to assess interobserver agreement from four national MDT conferences and whether this would have a clinical impact.

METHODS

A total of 20 patients with esophageal cancer were included across all four upper gastrointestinal (GI) cancer centers. Fully anonymized patient data were distributed among the MDT conferences which decided on TNM category, resectability, operability, curability, and treatment strategy blinded to each other's decisions. The interobserver agreement was expressed as both the raw observer agreement and with Krippendorff's α values. Finally, a case-by-case evaluation was performed to determine if disagreement would have had a clinical impact.

RESULTS

A total of 80 MDT evaluations were available for analysis. A moderate to near-perfect observer agreement of 79.2%, 55.8%, and 82.5% for TNM category was observed, respectively. Substantial agreement for resectability and moderate agreement for curability were found. However, an only fair agreement was observed for the operability category. The treatment strategies had a slight agreement which corresponded to disagreement having a clinical impact in 12 patients.

CONCLUSIONS

Esophageal cancer MDT conferences had an acceptable interobserver agreement on resectability and TM categories; however, the operability assessment had a high level of disagreement. Consequently, the agreement on treatment strategy was reduced with a potential clinical impact. In future MDT conferences, emphasis should be on prioritizing the relevant information being readily available (operability, T & M categories) to minimize the risk of disagreement in the assessments and treatment strategies, and thus, delayed or suboptimal treatment.

Mortality from esophagectomy for esophageal cancer across low, middle, and high-income countries: An international cohort study

BACKGROUND

No evidence currently exists characterising global outcomes following major cancer surgery, including esophageal cancer. Therefore, this study aimed to characterise impact of high income countries (HIC) versus low and middle income countries (LMIC) on the outcomes following esophagectomy for esophageal cancer.

METHOD

This international multi-center prospective study across 137 hospitals in 41 countries included patients who underwent an esophagectomy for esophageal cancer, with 90-day follow-up. The main explanatory variable was country income, defined according to the World Bank Data classification. The primary outcome was 90-day postoperative mortality, and secondary outcomes were composite leaks (anastomotic leak or conduit necrosis) and major complications (Clavien-Dindo Grade III - V). Multivariable generalized estimating equation models were used to produce adjusted odds ratios (ORs) and 95% confidence intervals (CI95%).

RESULTS

Between April 2018 to December 2018, 2247 patients were included. Patients from HIC were more significantly older, with higher ASA grade, and more advanced tumors. Patients from LMIC had almost three-fold increase in 90-day mortality, compared to HIC (9.4% vs 3.7%, p < 0.001). On adjusted analysis, LMIC were independently associated with higher 90-day mortality (OR: 2.31, CI95%: 1.17-4.55, p = 0.015). However, LMIC were not independently associated with higher rates of anastomotic leaks (OR: 1.06, CI95%: 0.57-1.99, p = 0.9) or major complications (OR: 0.85, CI95%: 0.54-1.32, p = 0.5), compared to HIC.

CONCLUSION

Resections in LMIC were independently associated with higher 90-day postoperative mortality, likely reflecting a failure to rescue of these patients following esophagectomy, despite similar composite anastomotic leaks and major complication rates to HIC. These findings warrant further research, to identify potential issues and solutions to improve global outcomes following esophagectomy for cancer.

Comparison of surgical outcomes after robotic assisted thoracic surgery, video-assisted thoracic surgery and open resection of thymoma

Background

Thymomas are the most common neoplasm in the anterior mediastinum. Surgical resection of thymomas remains the only curative treatment depending on the stage of the disease. Conventional resection has been performed through open surgery. However, minimal invasive and robotic assisted surgery are preferred if possible.

Methods

In a single center study three different surgical techniques were compared respectively, video-assisted thoracic surgery (VATS), robotic-assisted thoracic surgery (RATS) and open resection. In a period from 2006 to 2019 80 patients were included in the study and data were collected by retrospectively reviewing patient records.

Results

VATS and RATS had a significantly (P<0.05) shorter time with chest tube and shorter admission time compared to open surgery. Furthermore, VATS and RATS had significantly (P<0.05) lower blood loss per operatively compared to open surgery. There was no significant difference in operating time between the three groups.

Conclusions

Minimal invasive surgery seems to be a safe surgical method in the treatment of thymomas. RATS and VATS were associated with a lower blood loss through surgery, shorter admission time and shorter chest tube time compared to open resection. RATS surgery might be considered for patients with a more advanced thymoma stage. Larger international multicenter randomized controlled trials are required to draw any conclusions regarding the oncological point of view.

Comparison of short-term outcomes from the International Oesophago-Gastric Anastomosis Audit (OGAA), the Esophagectomy Complications Consensus Group (ECCG), and the Dutch Upper Gastrointestinal Cancer Audit (DUCA)

BACKGROUND

The Esophagectomy Complications Consensus Group (ECCG) and the Dutch Upper Gastrointestinal Cancer Audit (DUCA) have set standards in reporting outcomes after oesophagectomy. Reporting outcomes from selected high-volume centres or centralized national cancer programmes may not, however, be reflective of the true global prevalence of complications. This study aimed to compare complication rates after oesophagectomy from these existing sources with those of an unselected international cohort from the Oesophago-Gastric Anastomosis Audit (OGAA).

METHODS

The OGAA was a prospective multicentre cohort study coordinated by the West Midlands Research Collaborative, and included patients undergoing oesophagectomy for oesophageal cancer between April and December 2018, with 90 days of follow-up.

RESULTS

The OGAA study included 2247 oesophagectomies across 137 hospitals in 41 countries. Comparisons with the ECCG and DUCA found differences in baseline demographics between the three cohorts, including age, ASA grade, and rates of chronic pulmonary disease. The OGAA had the lowest rates of neoadjuvant treatment (OGAA 75.1 per cent, ECCG 78.9 per cent, DUCA 93.5 per cent; P < 0.001). DUCA exhibited the highest rates of minimally invasive surgery (OGAA 57.2 per cent, ECCG 47.9 per cent, DUCA 85.8 per cent; P < 0.001). Overall complication rates were similar in the three cohorts (OGAA 63.6 per cent, ECCG 59.0 per cent, DUCA 62.2 per cent), with no statistically significant difference in Clavien-Dindo grades (P = 0.752). However, a significant difference in 30-day mortality was observed, with DUCA reporting the lowest rate (OGAA 3.2 per cent, ECCG 2.4 per cent, DUCA 1.7 per cent; P = 0.013).

CONCLUSION

Despite differences in rates of co-morbidities, oncological treatment strategies, and access to minimal-access surgery, overall complication rates were similar in the three cohorts.

A Newly Developed Chest Drainage Unit with an Integrated CO2 Detector

PURPOSE

Postoperative air leakage does not always originate from parenchymal defects. In some cases, it may arise from defects in the chest drainage unit itself or connections, or from reverse airflow in water seals. The aim of the present study was to test a new chest drainage unit in the clinic, where an integrated CO2-sensitive colour indicator helps to distinguish false air leakage from true air leakage.

METHODS

Over a 3-week period, 14 consecutive patients were operated upon using either an open approach (for bilobectomies) or VATS (for diagnostic procedures or lobectomies). All patients received general anaesthesia with double-lumen intubation. All patients had a 24-Fr chest tube connected to a chest drainage unit with a built-in CO2-detector.

RESULTS

In all patients with air leakage after surgery, we found a colour change in the CO2-sensitive colour indicator, confirming "true air leakage". One patient had prolonged air leakage. None of the patients had pneumothorax after removal of the chest tube and no patients had wound infections or any other complications.

CONCLUSION

The chest drainage unit described here was easily implemented in the clinic and clearly confirmed true air leakage in all patients with air leakage after lung surgery. It allowed safe and appropriate timing for chest tube removal with no need for reinsertion in a broad cohort of patients referred for thoracic surgery.

Electromagnetic navigation bronchoscopy as an adjunct diagnostic tool in the Danish lung cancer diagnostic pathway: an initial retrospective single centre series

Background

The performance of electromagnetic navigation bronchoscopy (ENB) is reported with substantial variation, which may question its clinical usefulness. However, ENB may hold its true value when used as an additional minimal invasive diagnostic option before potential surgery in selected diagnostically challenging patients where traditional diagnostic methods have failed. We evaluated the safety and performance of ENB when used as an adjunct diagnostic tool in the Danish lung cancer diagnostic pathway (DLCDP) and its ability to reduce surgical diagnostic procedures.

Methods

A retrospective study was performed on eighty-two consecutive patients at Odense University Hospital from June 2016 to March 2018 with diagnostically challenging pulmonary lesions referred for ENB as an adjunct diagnostic procedure under the DLCDP. Patients with benign or inconclusive ENB pathology were either referred for further biopsies, surgery or repeated computer tomography (CT) scans for surveillance purposes.

Results

Eighty-one ENB procedures were performed in 80 patients. In 87.7% of the cases previous diagnostic methods had been unsuccessful. The mean target diameter was 1.55 cm and the average follow-up duration was 11 months. The diagnostic accuracy was 75%, while the diagnostic yield/sensitivity, negative predictive value and negative likelihood ratio was 51%, 67% and 0.49, respectively. No pneumothoraces and only one intrapulmonary haemorrhage was recorded, which was managed conservatively. The learning curve revealed an increase in diagnostic accuracy from 67.5% to 82.9% when comparing the first 40 ENB procedures with the last 41 procedures, however, this was not statistically significant (p-value: 0.11).

Conclusions

ENB was found to be a safe procedure with an acceptable diagnostic accuracy and yield in highly selected diagnostically challenging patients. The introduction of ENB carried a notable learning curve but proved to be a valuable adjunct diagnostic option in the DLCDP, which may help to reduce the number of potentially unnecessary or harmful surgical procedures in frail patients.

Short-term outcomes after minimally invasive oesophagectomy

INTRODUCTION

Minimally invasive oesophagectomy (MIO) has gained increasing popularity. This study reports the results of the first patients operated using this technique at our department.

METHODS

All procedures were prospectively registered in a database. Patients were followed until death, two years after surgery or 1 January 2019.

RESULTS

A total of 150 procedures were performed (from 23 November 2015 to 27 February 2018). The median proced-ure time decreased from 350 minutes for the initial 75 pa-tients to 320 minutes for the final 75 patients (p < 0.05). Blood loss decreased from 200 ml to 100 ml (p < 0.05), respectively. The conversion rate for the abdominal procedure was 7% for the initial 75 patients and 8% for the final 75 patients (not significant (NS)). For the thoracic procedure, the corresponding figures were 11% and 7% (NS), respectively. Anastomotic leakage was seen in 17% (initial patients) and 11% (final patients) (NS); however, less than 20% of the leakages needed surgical treatment. The median length of post-operative stay was nine days for both groups. For all 150 patients, pulmonary complications were observed in 18% and cardiac complications in 11%. The 30-day mortality rate was 2% and the one-year survival rate was 86% (124 registered patients).

CONCLUSIONS

MIO was introduced at our department with acceptable morbidity and mortality rates and the short-term oncological result was not compromised.

FUNDING

none.

TRIAL REGISTRATION

The study was approved as a quality project by the Region of Southern Denmark (18/37355).

Metastasis in the subcarinal lymph node with unknown primary tumor

A 59-year-old man with previous anaplastic large cell T-cell lymphoma stage 3A was admitted with an isolated positron emission tomography(PET)-positive spot in a subcarinal lymph node. Diagnosis was achieved with endobronchial ultrasound-guided fine-needle aspiration demonstrating a well-differentiated squamous cell carcinoma but no primary tumor was visible on PET-computed tomography. Because of his previous lymphoma the patient was scheduled for mediastinoscopy where the diagnosis was confirmed. Subsequent gastroscopy was normal and a right-sided thoracotomy showed no evidence of cancer elsewhere, only an inoperable metastasis in a subcarinal lymph node which infiltrated the trachea, esophagus and aorta. Such isolated squamous cell carcinoma in a subcarinal lymph node without a primary tumor despite invasive work-up has not been reported before.

High-activity samarium-153-EDTMP therapy followed by autologous peripheral blood stem cell support in unresectable osteosarcoma

Purpose: Despite highly efficacious chemotherapy, patients with osteosarcomas still have a poor prognosis if adequate surgical control cannot be obtained. These patients may benefit from therapy with radiolabeled phosphonates. Patients and Methods: Six patients (three male, three female; seven to 41 years) with unresectable primary osteosarcoma (n = 3) or unresectable recurrent sites of osteosarcomas (n = 3) were treated with high-activity of Sm-153-EDTMP (150 MBq/kg BW). In all patients autologous peripheral blood stem cells had been collected before Sm-153-EDTMP therapy. Results: No immediate adverse reactions were observed in the patients. In one patient bone pain increased during the first 48 hrs after therapy. Three patients received pain relief. Autologous peripheral blood stem cell reinfusion was performed on day +12 to +27 in all patients to overcome potentially irreversible damage to the hematopoietic stem cells. In three patient external radiotherapy of the primary tumor site was performed after Sm-153-EDTMP therapy and in two of them polychemotherapy was continued. Thirty-six months later one of these patients is still free of progression. Two further patients are still alive. However, they have developed new metastases. The three patients who had no accompanying external radiotherapy, all died of disease progression five to 20 months after therapy. Conclusion: These preliminary results show that high-dose Sm-153-EDTMP therapy is feasible and warrants further evaluation of efficacy. The combination with external radiation and polychemotherapy seems to be most promising. Although osteosarcoma is believed to be relatively radioresistant, the total focal dose achieved may delay local progression or even achieve permanent local tumor control in patients with surgically inaccessible primary or relapsing tumors.

Subcarinal Lymph Nodes Should be Dissected in All Lobectomies for Non-Small Cell Lung Cancer-Regardless of Primary Tumor Location

BACKGROUND

Mediastinal staging is of paramount importance for planning of treatment in non-small cell lung cancer (NSCLC). Single institution reports recently claimed that subcarinal lymph node dissection during resection of upper lobe NSCLC could be spared. We used a complete national lung cancer registry to investigate patterns of unsuspected mediastinal lymph node involvement after lobectomy.

METHODS

During an 11-year period (2004 to 2014) 5,577 consecutive patients who underwent operations for NSCLC were investigated for unsuspected mediastinal lymph node involvement (N2 disease) discovered at final histopathology. The analysis excluded patients with clinical N2 disease. We used a national registry to extract information for each patient about tumor location, histopathology, clinical and pathologic TNM stage, preoperative imaging modalities, and type of invasive mediastinal staging.

RESULTS

Mediastinal lymph node dissection was performed in 5,577 patients during the operation, and unsuspected N2 disease was discovered in 612 (11.0%), and 193 (3.5%) had subcarinal metastasis. Subcarinal N2 disease was significantly more common in patients with lower-lobe or middle-lobe cancers compared with upper-lobe cancers (5.8% vs 1.6%, p < 0.01). Preoperative invasive mediastinal staging was performed in 73.4% (4,097 of 5,577) of all patients and significantly more frequently in patients who eventually had N2 disease (87.3% [534 of 612], p < 0.01) as well subcarinal N2 disease (89.6% [173 of 193], p < 0.01).

CONCLUSIONS

Subcarinal lymph node metastases were common despite frequent use of preoperative invasive mediastinal staging in lower-lobe, middle-lobe, and upper-lobe NSCLC. Subcarinal lymph nodes should be dissected or sampled routinely during operations for NSCLC to avoid understaging-regardless of preoperative invasive mediastinal staging and tumor location.

Endobronchial ultrasound-guided transbronchial needle aspiration is a sensitive method to evaluate patients who should not undergo pulmonary metastasectomy†

OBJECTIVES

Pulmonary metastasectomy is considered an effective treatment in selected patients with extrapulmonary cancer and oligometastatic disease. We know that the presence of mediastinal lymph node metastases reduces survival significantly, but the mediastinum is rarely evaluated before metastasectomy in these patients. We prospectively evaluated how endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) could identify metastases to the mediastinal lymph nodes in patients referred for pulmonary metastasectomy.

METHODS

All patients with extrapulmonary cancer and oligometastatic disease confined to the lungs on positron emission tomography-computed tomography, and who were considered eligible for pulmonary metastasectomy, routinely underwent EBUS-TBNA of the mediastinal lymph nodes. If EBUS-TBNA did not reveal malignant spread, the patient subsequently underwent pulmonary metastasectomy with systematic sampling of mediastinal lymph nodes for histological evaluation.

RESULTS

One hundred and three eligible patients were referred for EBUS-TBNA during a 4-year period. The primary cancers were located in the colon/rectum (n = 64), kidney (n = 16) and other sites (n = 23). EBUS-TBNA sampled 248 lymph nodes and adequate cytology was obtained in 93 patients (90%). EBUS-TBNA found lymph node metastases in 17 patients (16.5%) and during subsequent pulmonary metastasectomy in the remaining 86 patients 1 (1.0%) had a lymph node metastasis. The sensitivity, specificity, NPV and PPV of EBUS-TBNA for diagnosis of mediastinal lymph node metastasis were 94.4, 100, 98.8 and 100%, respectively.

CONCLUSIONS

EBUS-TBNA is a sensitive minimally invasive modality for evaluation of mediastinal lymph node metastases in patients with oligometastatic pulmonary disease. It allows surgeons to select patients who will not benefit from pulmonary metastasectomy.

Thoracoscopic or open surgery for pulmonary metastasectomy: an observer blinded study

BACKGROUND

Video-assisted thoracic surgery (VATS) resection of pulmonary metastases has long been questioned because radiologically undetected parenchymal lesions may be missed when bimanual palpation is restricted to the portholes. Technology, however, has improved and advanced VATS resections are now performed routinely worldwide. This prompted us to conduct a prospective observer-blinded study on pulmonary metastasectomy.

METHODS

Eligible patients with oligometastatic pulmonary disease on computed tomography (CT) underwent high-definition VATS, with digital palpation by 1 surgical team and subsequent immediate thoracotomy during the same anesthesia by a different surgical team, with bimanual palpation and resection of all palpable nodules. Preoperative CT evaluations and surgical results were blinded. Primary endpoints were number and histopathology of detected nodules.

RESULTS

During a 3-year period 89 consecutive patients, with newly developed nodules suspicious of lung metastases from previous cancers in colon-rectum (n=59), kidney (n=15), and other malignancies (n=15) were included, with a total of 140 suspicious nodules visible on CT. During VATS, 122 nodules were palpable (87%). All nodules were identified during thoracotomy, where 67 additional and unexpected nodules were also identified; 22 were metastases (33%), 43 (64%) were benign lesions, and 2 (3%) were primary lung cancers.

CONCLUSIONS

In patients operated for nodules suspicious of lung metastases, a substantial number of additional nodules were detected during thoracotomy despite advancements in CT imaging and VATS technology. Many of these nodules were malignant and would have been missed if VATS was used exclusively. Consequently, we considered VATS inadequate if the intention is to resect all pulmonary metastases during surgery.

[Primary benign schwanomma in trachea]

We report a rare case of a primary schwanomma in trachea causing airway symptoms in a 78-year-old male. Benign tracheal tumours are often misdiagnosed as asthma or chronic lung disease and should be considered in patients who present with symptoms as upper airway obstruction and haemoptysis. In this case story the patient was treated with endoscopic resection of the tumour.

Boerhaave's syndrome and tension pneumothorax secondary to Norovirus induced forceful emesis

Boerhaave's syndrome or spontaneous esophageal perforation is a rare condition, with high mortality. We describe a case of Boerhaave's syndrome presenting with tension pneumothorax. The patient was infected with Norovirus and developed Boerhaave's syndrome, initially thought to be gastroenteritis but later developing with tension pneumothorax, and mediastinitis caused by esophageal perforation. The patient was treated with thoracotomy with primary suture and oesophageal stent placement. He had a long period of recovery and was discharged after 98 days. Boerhaaves syndrome is often delayed and must be considered in any patient with respiratory symptoms and a recent history of vomiting.

When should large benign tumours in posterior mediastinum be resected?

Benign tumours in the posterior mediastinum are often asymptomatic until they reach a considerable size. Technically it is easier to remove the tumour when it is small, but these patients are often asymptomatic and therefore the tumours are rarely found before the patients become symptomatic. During 2010 three patients underwent resection of large benign tumours in the posterior mediastinum with a diameter more than 10 centimetres. We discuss, when should large benign tumours in posterior mediastinum be resected. We conclude that symptomatic patients with large benign tumours should be referred directly for surgery independent of size while asymptomatic patients should be followed regularly and referred for surgical treatment if their tumour increases in size because surgery may be hazardous as size of the tumour increases and more likely to be associated with major postoperative morbidity.

Thoracoscopic versus open pulmonary metastasectomy: a prospective, sequentially controlled study

BACKGROUND

Patients with limited metastatic disease in the lung may benefit from metastasectomy. Thoracotomy is considered the gold standard, and video-assisted thoracoscopic surgery (VATS) is controversial because nonimaged nodules may be missed when bimanual palpation is restricted. Against guideline recommendations, metastasectomy with therapeutic intent is now performed by VATS by 40% of thoracic surgeons surveyed. The evidence base for optimal surgical approach is limited to case series and registries, and no comparative surgical studies were observer blinded.

METHODS

Patients considered eligible for pulmonary metastasectomy by VATS prospectively underwent high-definition VATS by one surgical team, followed by immediate thoracotomy with bimanual palpation and resection of all palpable nodules by a second surgical team during the same anesthesia. Both surgical teams were blinded during preoperative evaluation of CT scans and during surgery. Primary end points were number and histology of nodules detected.

RESULTS

During a 12-month period, 37 patients were included. Both surgical teams observed exactly 55 nodules suspicious of metastases on CT scans. Of these, 51 nodules were palpable during VATS (92%), and during subsequent thoracotomy 29 additional nodules were resected: Six (21%) were metastases, 19 (66%) were benign lesions, three (10%) were subpleural lymph nodes and one was a primary lung cancer.

CONCLUSIONS

Modern VATS technology is increasingly used for pulmonary metastasectomy with therapeutic intent, but several nonimaged, and therefore unexpected, nodules are frequently found during subsequent observer-blinded thoracotomy. A substantial proportion of these nodules are malignant, and, despite modern imaging and surgical technology, they would have been missed if VATS was used exclusively for metastasectomy with therapeutic intent.

Population screening for the mutation associated with osteogenesis imperfecta in dachshunds

Osteogenesis imperfecta (OI) is a genetic disorder causing defects in the development of collagen type I. Clinical signs of affected dachshunds include multiple fractures of bones, joint hyperlaxity and dentinogenesis imperfecta. Recently, a recessive mutation in the SERPINH1 gene was detected in dachshunds and enabled the development of a DNA test to identify dachshunds carrying the mutation. The purpose of the present study was to analyse the dachshund breeding population for the frequency of the SERPINH1 mutation among the nine different breed varieties in dachshunds, birth years and countries of origin. We genotyped the OI-associated SERPINH1 mutation in 1352 dachshunds from 12 different European countries including all nine varieties. Genotyping was done using a restriction fragment length polymorphism validated by DNA sequence analysis. The overall frequency of OI carriers was 12.9 per cent. Across all different size varieties, the SERPINH1 mutation was over-represented in wire-haired dachshunds with 17.3 per cent OI carriers. Among the different countries, the proportion of OI carriers was highest in Germany with 20.4 per cent. The test is useful for dachshund breeders to prevent the occurrence of OI-affected dogs and as a diagnostic tool for veterinarians.

Endobronchial ultrasound-guided transbronchial needle aspiration of lesions in mediastinum

BACKGROUND

Lesions in mediastinum can represent malignancy and warrants further workup. Commonly a diagnosis is achieved by conventional bronchoscopy, transbronchial needle aspiration or CT guided fine needle aspiration, however a number of patients remain undiagnosed despite these common investigations

METHODS

During a period of 36 months 601 patients underwent EBUS at our institution. Two hundred ninety three patients had an established diagnosis of lung cancer and were referred to us for mediastinal staging. The remaining patients had a radiologically suspicious intrathoracic lesion of which 107 had an undiagnosed lesion in mediastinum. All patients had been investigated by previous chest CT and bronchoscopy including brush cytology but remained undiagnosed.

RESULTS

Of the 107 patients with undiagnosed lesions in the mediastinum 89 enlarged lymph nodes and 18 mediastinal tumours. Forty-eight of the 89 patients (54%) with enlarged mediastinal lymph nodes were diagnosed by EBUS of the remaining 41 patients 11 went on to more invasive methods. In patients with undiagnosed tumours in mediastinum we achieved a final diagnosis by EBUS in 14 of the 18 patients (78%) and 3 went on to more invasive methods.

CONCLUSION

EBUS provides a final diagnosis in 78% of patients with tumour in mediastinum and in more than half of patients with enlarged lymph nodes despite previous workup.

Successful thrombolysis of major pulmonary embolism 5 days after lobectomy

Aggressive intravenous thrombolysis of pulmonary emboli after major thoracic surgery has rarely been reported and is controversial because of an assumed risk of fatal bleeding. We report a 62-year old female who underwent left upper lobectomy. Her postoperative course was complicated with symptomatic pulmonary embolism and on postoperative day 5 she was successfully treated with intravenous thrombolysis using alteplase (Actilyse(®)) without signs of bleeding. She was discharged from the hospital 12 days postoperatively.

Limitations of balloon sinuplasty in frontal sinus surgery

Balloon sinuplasty is a tool that is used to treat selected patients with paranasal sinus pathologies. No studies have investigated the aetiology of failed access to the frontal sinus. The aim of our study was to specify the intraoperative technical failure rate and to analyse the aetiology of the failed access to predict potential technical difficulties before surgery. We retrospectively analysed the charts of patients who underwent balloon sinuplasty from November 2007 to July 2010 at three different ENT-Centres. CT-analysis of the patients with failed access was performed. Of the 104 frontal sinuses, dilation of 12 (12%) sinuses failed. The anatomy of all failed cases revealed variations in the frontal recess (frontoethmoidal-cell, frontal-bulla-cell or agger-nasi-cell) or osteoneogenesis. In one patient, a lymphoma was overlooked during a balloon only procedure. The lymphoma was diagnosed 6 months later with a biopsy during functional endoscopic sinus surgery. In complex anatomical situations of the frontal recess, balloon sinuplasty may be challenging or impossible. In these situations, it is essential to have knowledge of classical functional endoscopic sinus surgery of the frontal recess area. The drawbacks of not including a histopathologic exam should be considered in balloon only procedures.

Isolated pleural metastases from renal cell carcinoma

A 71-year-old female was referred with three right-sided intrathoracic tumours. In 2003, she underwent radical left nephrectomy for renal cell cancer (RCC) clinical stage 1. She was since followed at her local hospital with annual computed tomography (CT)-scans during the first five years and did not present any symptoms until October 2009 when she was admitted with shortness of breath, cough and tiredness. The patient was scheduled for a diagnostic thoracoscopy when it was discovered that her lesions were not located in the lung parenchyma but were protruding nodules from the parietal pleura. Histology demonstrated metastases from RCC which apparently can reach the parietal pleura without lung metastases.

[Endobronchial ultrasound-guided transbronchial needle aspiration for mediastinal staging of lung cancer and diagnosis of intrathoracic lesions]

既往研究显示，经支气管超声引导针吸活检（endobronchial ultrasound-guided transbronchial needle aspiration, EBUS-TBNA）是一项微创技术，可用于肺癌患者的纵隔分期、胸腔内病变的诊断、不明原因淋巴结肿大的诊断以及非小细胞肺癌（non-small cell lung cancer, NSCLC）新辅助化疗后的纵隔再分期。

本综述旨在关注EBUS在NSCLC纵隔分期中的作用，以及EBUS在进一步评估通过常规检查仍诊断未明的胸腔内病变中的应用。总之，就NSCLC患者纵隔分期而言，由于EBUS的诊断敏感性和特异性均较高，其为纵隔镜检查的有效替代，亦可用于疑似胸腔病变的活检，且不会给患者带来任何并发症风险。

Minimally invasive diagnosis of sarcoidosis by EBUS when conventional diagnostics fail

BACKGROUND

Endobronchial ultrasound-guided transbronchial fine-needle aspiration (EBUS) is a minimally invasive method used routinely for mediastinal staging of patients with lung cancer. EBUS has also proved to be a valuable diagnostic tool for patients with different intrathoracic lesions who remain undiagnosed despite bronchoscopy and CT-guided fine-needle aspiration.

OBJECTIVE

The present study focused on EBUS for diagnosing sarcoidosis.

DESIGN

During a 3-year period 308 of 601 patients who underwent EBUS at our institution were referred for further diagnostic of a radiologically suspicious lesion in the lung parenchyma (n = 195), enlarged lymph nodes in the mediastinum (n = 89), a suspicious tumor in the mediastinum or pleural disease (n = 24) but no one had a definite histological diagnosis. All charts were reviewed retrospectively.

RESULTS

Of the 308 patients 43 (14%) were eventually diagnosed with sarcoidosis. Thirty-three (77%) were diagnosed with EBUS. In the remaining 10 patients EBUS did not provide adequate tissue samples in 4 (9%) and in 6 patients (14%) EBUS provided adequate tissue but no definite diagnosis. EBUS was significantly better to establish the diagnosis in patients with enlarged mediastinal lymph nodes compared with isolated lung parenchymal involvement (85% vs 63%, p < 0.05).

CONCLUSION

EBUS is a valuable minimally invasive diagnostic modality to establish the diagnosis of sarcoidosis of unselected patients with undiagnosed intrathoracic lesions after conventional work up--particularly if patients have enlarged mediastinal lymph nodes. This minimally invasive procedure provides a final diagnosis without exposing the patient to the risk of complications from more invasive procedures.

Long-term follow-up (>20 years) for one of the original randomized prospective trials evaluating adjuvant chemotherapy in patients with high-grade operable osteosarcoma

10514

Background: Neoadjuvant and adjuvant chemotherapy is now standard practice for patients who present with localized osteosarcoma. We present the long-term follow-up (>20years) for one of the original prospective randomized trials that compared adjuvant chemotherapy to no treatment in patients with high-grade operable osteosarcoma. Methods: The original study was performed at UCLA from 1981 to 1984. During this time, 59 patients with high-grade, operable, non-metastatic osteosarcoma were randomized to receive adjuvant chemotherapy (MSKCC T-10B protocol)(N=32; 24 men, 8 women, median age 15 yrs) vs. expectant management (N=27; 20 men, 7 women, median age 18 yrs). All patients received one neoadjuvant course of intra-arterial doxorubicin hydrochloride (90mg) and radiation (1750cGy). At a median follow-up of 2 years, there was a statistically significant improvement in both disease-free (55% vs. 20%, p<.01) and overall survival (80% vs. 48%, p<.01) for those who received immediate adjuvant chemotherapy. Upon recurrence, patients in the T-10B arm received salvage chemotherapy with doxorubicin hydrochloride and cisplatin while those in the expectant arm received the T-10B protocol. 27 years after the initiation of the trial, long-term follow-up was obtained on all patients. Results: Median follow-up time for survivors was 24 years. 18 patients in the adjuvant chemotherapy arm died of disease (DOD) while 14 have no evidence of disease (NED). 22 patients in the control arm DOD, 1 died of other causes and 4 have NED. The 5, 10, and 20 year disease specific survival (DSS) for the treatment arm (47%, 43%, 43% respectfully) was significantly better than that of the control arm (30%, 26%, 17% respectfully) (p=0.0254). Conclusions: Early administration of chemotherapy in patients with high-grade operable osteosarcoma provides a significant survival benefit that is maintained with long-term (>20 years) follow-up. These results support the idea that early systemic treatment offers the best opportunity to cure patients with this high-risk malignancy.

No significant financial relationships to disclose.

Impact of the lower energy threshold on the NEMA NU2-2001 count-rate performance of a LSO based PET-CT scanner

The aim of this study was to investigate the impact of the lower energy threshold (LET) on the NEMA NU2-2001 count-rate performance of a LSO-based PET scanner (Siemens PET-CT Biograph Sensation 16). The quantitative measurements were focused on three different aspects: noise equivalent count rate (NEC), scatter fraction, and absolute sensitivity.

METHODS

According to the NEMA-NU2-2001 protocol count-rate-performance (NEC-2R, scatter fraction) and sensitivity were evaluated performing serial measurements at LETs of 350, 375, 400, 410, 420, 430, 440, and 450 keV (the upper energy threshold was fixed to 650 keV). NEMA protocols were adapted to account for the intrinsic radioactivity of (176)Lu in the LSO crystals.

RESULTS

Up to a radioactivity concentration of 8 kBq/ml the highest NEC-rates were obtained at an LET of 410 keV, between 8 and 20 kBq/ml at an LET of 420 keV and above 20 kBq/ml at an LET of 430 keV. The overall NEC maximum was 67 kcps at 430 keV (at 28 kBq/ml). The minimum scatter fraction was measured at a radioactivity concentration of approximately 0.5 kBq/ml. The scatter fraction decreased continuously from 45% at an energy threshold of 350 keV to 24% at 450 keV. The maximum sensitivity of 5.8 kcps/MBq, was obtained at an LET of 350 keV and the minimum sensitivity of 4.2 kcps/MBq at an LET of 450 keV. At the LET with the maximum NEC-rate (430 keV) the sensitivity was 4.8 kcps/MBq.

CONCLUSION

The optimal count-rate performance of the LSO-based PET system was found at LETs between 410 keV and 430 keV depending on the actual radioactivity concentration placed in the scanner. A global maximum in NEC count rate was obtained at an LET of 430 keV.

A phase II study of picoplatin (pico) as second-line therapy for patients (pts) with small cell lung cancer (SCLC) who have resistant or refractory disease or have relapsed within 180 days of completing first-line, platinum (plat)-containing chemotherapy

7722

Background: Pico is a sterically hindered plat analogue designed to overcome plat resistance with improved safety and efficacy. In >600 pts pico had single-agent activity in lung, prostate, ovarian and other malignancies with rare significant nephro-, oto-, or neurotoxicity (∼2% grade 3 and 0% grade 4). In a previous phase 2 study of single agent pico as 2nd line therapy in SCLC, 4 of 48 pts (8%) had a partial response and 21 (44%) stable disease. Median survival was 27.0 (95% CI = 16–35) wks. This multi-center phase 2 trial was designed to confirm the activity of pico as 2nd line monotherapy for plat-resistant SCLC. Methods: Pts with SCLC who either 1) failed or progressed through 1st line plat-containing chemo (refractory disease), or 2) initially responded to 1st line plat-containing chemo and then relapsed/ progressed within 3 months (resistant disease), or 3) initially responded and then relapsed/progressed between 90 to 180 days (sensitive, relapsed 90 to 180 days), had measurable disease and ECOG PS 0–2 were treated with pico, 150 mg/m2 iv over1–2 hrs, q 21 days. Tumor response was assessed q 6 wks. Adverse events (AEs) were graded using the NCI CTCAE. Results: 77 pts received pico (45 refractory, 27 resistant, 5 sensitive). The median number of cycles received was 2 (mean = 2.9). The most frequently reported AEs of any severity were thrombocytopenia (39% of pts), anemia (35%), neutropenia (22%), nausea (20%), emesis (14%) and dyspnea (25%). Neutropenic fever occurred in 1 pt; there were no treatment related deaths. One pt had grade 3 neuropathy; there was no grade 3 or 4 ototoxicity or nephrotoxicity. Median overall survival is 28.1 (95% CI = 26–37) wks. Median progression free survival is 9.3 (95% CI = 7–12) wks. Of 63 pts with at least 1 post-treatment assessment of disease status, 33 (52%) had stable disease. Conclusion: Median survival compares favorably with other therapeutic options and toxicity is reduced in pico treated SCLC pts who have failed prior plat-containing first-line chemo or who have progressed within 180 days of first-line chemo. A phase III trial to confirm these results has been initiated.

No significant financial relationships to disclose.

Challenging the platinum combinations in the chemotherapy of NSCLC

In previously untreated patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) the combination of docetaxel and gemcitabine is active and well tolerated. In the phase II setting using a 3-week schedule, response rates (RR) ranged from 25 to 50%, and median survival from 11 to 13 months. Preliminary data with weekly and bi-weekly schedules indicate maintained efficacy while reducing the risk of neutropenia. A randomized phase III trial has shown that the combination of docetaxel and gemcitabine is as active as docetaxel plus cisplatin, achieving a 1-year survival rate of 39%, with significantly less neutropenia and gastro-intestinal toxicity. The combination of docetaxel with vinorelbine is equally active and the associated toxicities are manageable. In phase II studies the average response rate is 40%, and in one study using a 2-week schedule the 1-year survival rate was 60%. With this combination neutropenia is the commonest adverse event while clinically significant neuropathy is infrequent. In a randomized phase II trial, docetaxel plus cisplatin was compared to docetaxel plus irinotecan. The non-platinum doublet achieved comparable levels of activity, though with a different toxicity profile (more diarrhea but less nausea and vomiting). The combination of docetaxel with irinotecan and carboplatin has achieved 1-year survival of 55%. All three docetaxel combinations (gemcitabine, vinorelbine, and irinotecan) could provide a valuable alternative to platinum-based chemotherapy and should be further evaluated in phase III setting.

High-activity samarium-153-EDTMP therapy followed by autologous peripheral blood stem cell support in unresectable osteosarcoma

PURPOSE

Despite highly efficacious chemotherapy, patients with osteosarcomas still have a poor prognosis if adequate surgical control cannot be obtained. These patients may benefit from therapy with radiolabeled phosphonates.

PATIENTS AND METHODS

Six patients (three male, three female; seven to 41 years) with unresectable primary osteosarcoma (n = 3) or unresectable recurrent sites of osteosarcomas (n = 3) were treated with high-activity of Sm-153-EDTMP (150 MBq/kg BW). In all patients autologous peripheral blood stem cells had been collected before Sm-153-EDTMP therapy.

RESULTS

No immediate adverse reactions were observed in the patients. In one patient bone pain increased during the first 48 hrs after therapy. Three patients received pain relief. Autologous peripheral blood stem cell reinfusion was performed on day +12 to +27 in all patients to overcome potentially irreversible damage to the hematopoietic stem cells. In three patient external radiotherapy of the primary tumor site was performed after Sm-153-EDTMP therapy and in two of them polychemotherapy was continued. Thirty-six months later one of these patients is still free of progression. Two further patients are still alive. However, they have developed new metastases. The three patients who had no accompanying external radiotherapy, all died of disease progression five to 20 months after therapy.

CONCLUSION

These preliminary results show that high-dose Sm-153-EDTMP therapy is feasible and warrants further evaluation of efficacy. The combination with external radiation and polychemotherapy seems to be most promising. Although osteosarcoma is believed to be relatively radioresistant, the total focal dose achieved may delay local progression or even achieve permanent local tumor control in patients with surgically inaccessible primary or relapsing tumors.

Treatment-induced pathologic necrosis: a predictor of local recurrence and survival in patients receiving neoadjuvant therapy for high-grade extremity soft tissue sarcomas

PURPOSE

To determine whether treatment-induced pathologic necrosis correlates with local recurrence and overall survival in patients who receive neoadjuvant therapy for high-grade extremity soft tissue sarcomas.

PATIENTS AND METHODS

Four hundred ninety-six patients with intermediate- to high-grade extremity soft tissue sarcomas received protocol neoadjuvant therapy. All patients underwent surgical resection after neoadjuvant therapy and had pathologic assessment of tumor necrosis in the resected specimens.

RESULTS

The 5- and 10-year local recurrence rates for patients with > or = 95% pathologic necrosis were significantly lower (6% and 11%, respectively) than the local recurrence rates for patients with less than 95% pathologic necrosis (17% and 23%, respectively). The 5- and 10-year survival rates for the patients with > or = 95% pathologic necrosis were significantly higher (80% and 71%, respectively) than the survival rates for the patients with less than 95% pathologic necrosis (62% and 55%, respectively). Patients with less than 95% pathologic necrosis were 2.51 times more likely to develop a local recurrence and 1.86 times more likely to die of their disease as compared with patients with > or = 95% pathologic necrosis. The percentage of patients who achieved > or /= 95% pathologic necrosis increased to 48% with the addition of ifosfamide as compared with 13% of the patients in all the other protocols combined.

CONCLUSION

Treatment-induced pathologic necrosis is an independent predictor of both local recurrence and overall survival in patients who receive neoadjuvant therapy for high-grade extremity soft tissue sarcomas. A complete pathologic response (> or = 95% pathologic necrosis) correlated with a significantly lower rate of local recurrence and improved overall survival.