Resection and radiofrequency ablation in the treatment of hepatocellular carcinoma: a single-center experience

Efficacy of repeat hepatectomy versus radiofrequency ablation for recurrent hepatocellular carcinoma: a Systematic Review and meta-analysis

Background

This article compared the efficacy and safety of repeat hepatectomy (RH) and radiofrequency ablation (RFA) for the treatment of recurrent hepatocellular carcinoma (RHCC) from multiple perspectives.

Methods

We systematically searched PubMed, Embase, Web of Science, and CNKI from January 2008 to December 2023. We collected all relevant articles and assessed the quality of the data. We analyzed the data for the primary outcomes of overall survival (OS) and disease-free survival (DFS), and secondary outcomes of postoperative complications, recurrence rate, and survival benefit. Subgroup analyses were performed for tumor diameter, patient origin, and publication date.

Results

A total of 38 studies were included, comprising 5,339 patients. OS was similar in both groups (HR: 0.92, 95% CI: 0.84-1.00, P=0.04, Z=2.02), whereas DFS was better in the RH compared with the RFA group (HR: 0.80, 95% CI: 0.75-0.86, P<0.00001, Z=6.15). The incidence of major complications was lower in the RFA compared with the RH group (OR: 5.06, 95% CI: 3.29-7.81, P<0.00001, Z=7.35), but the postoperative recurrence rate was better in the RH compared with the RFA group. There was no significant difference in postoperative mortality between the two groups, but hospital stay was longer in the RH compared with the RFA group. In subgroup analyses, both OS and DFS were superior in the RH compared with the RFA group among patients with tumors ≤3 cm diameter with no significant difference in the >3 cm-diameter group. There was no significant difference in OS between the two groups among Chinese or non-Chinse patients; however, DFS was higher in the RH compared with the RFA group among Chinese and non-Chinese patients. There was no significant difference in OS between the two groups in studies published pre-2015 or post-2015 group; however, DFS was superior in the RH compared with the RFA group for both pre-2015 and post-2015 studies.

Conclusion

RH may be the first-choice treatment considering the long-term prognosis of patients with RHCC; RFA may be a better alternative in terms of postoperative and economic factors. RH is associated with a better prognosis in patients with tumors ≤3 cm in diameter.

Comparison of laparoscopic hepatectomy and radiofrequency ablation for small hepatocellular carcinoma patients: a SEER population-based propensity score matching study

This study was designed to compare the efficacy of laparoscopic hepatectomy (LH) and radiofrequency ablation (RFA) in terms of their therapeutic effect on small hepatocellular carcinoma (SHCC). The SEER database was employed to integrate SHCC patients who had received treatment with either LH (n = 1132) or RFA (n = 797). The LH group (n = 623) and the RFA group (n = 623) were matched with 1:1 propensity score matching (PSM) in order to reduce the possibility of selection bias. The Kaplan-Meier method and Cox proportional hazards regression method were employed to ascertain the prognostic factors associated with overall survival (OS) and disease-specific survival (DSS). Both before and after PSM, the 1, 3 and 5-years OS and DSS were significantly higher in the LH groups compared to the RFA group. Besides, for SHCC with tumor size ≤ 2cm (n = 418), even P values not reaching statistical significance, the survival curves were compatible with a superiority of LH over RFA for OS and DSS in overall (P = 0.054 and P = 0.077), primary SHCC (P = 0.110 and P = 0.058) and recurrent SHCC (P = 0.068 and P = 1.000) cohorts. In contrast, for SHCC with tumor size between 2 and 3 cm (n = 828), LH group always had a better OS and DSS in the all cohorts (all P < 0.05). In addition, higher AFP level, poor differentiation grade, recurrent tumor and treatment type were independent prognostic factors for OS, while poor differentiation grade, larger tumor size and treatment type were the independent prognostic factors for DSS (all P < 0.05). LH was associated with better OS and DSS than RFA in SHCC patients. Even in tumor size ≤ 2 cm, LH still should be the first choice as its long-term survival benefits.

Predicting cancer-specific mortality in T1/2 hepatocellular carcinoma after radiofrequency ablation by competing risk nomogram: A population-based analysis

BACKGROUND

Radiofrequency ablation (RFA) is one of the primary treatment methods for T1/2 hepatocellular carcinoma (HCC), but the risk factors after RFA remain controversial. This study aims to identify the key factors associated with cancer-specific mortality (CSM) in patients with T1/2 HCC after RFA using competing risk analysis and to establish a prognostic nomogram for improved clinical management.

METHODS

A total of 2,135 T1/2 HCC patients treated with RFA were obtained from the Surveillance, Epidemiology, and End Results (SEER) database and randomly categorized into training and validation sets. Univariate and multivariable competing risk analyses were performed to identify risk factors associated with CSM and construct a competing risk nomogram. Receiver operating characteristic (ROC) curves, concordance indices (C-indexes), calibration plots, and decision curve analysis (DCA) were conducted to evaluate the predictive efficiency and clinical applicability of the nomogram in the training and validation sets. Patients were stratified according to their nomogram score, and the different risk groups were compared using cumulative incidence function (CIF) curves and Gray's validation .

RESULTS

The 5-year CSM rate for HCC patients treated with RFA was 30.1 %. Grade, tumor size, tumor number, cirrhosis, and AFP level were identified as independent risk factors for CSM. A prognostic nomogram was developed based on these risk factors. The time-dependent C-indexes (0.65) were greater than those of the AJCC stage model (0.55) during the 12 to 60 months of follow-up. The calibration plots of the competing risk nomograms demonstrated excellent consistency between actual survival and nomogram predictions. ROC analyses showed that the 1-, 3-, and 5-year AUC values in both the training and validation cohorts were all greater than 0.63 and exceeded those of the AJCC stage model. DCA demonstrated the clinical usefulness of the nomogram. Patients were classified into low-, moderate-, and high-risk groups based on the nomogram scores, with the high-risk group showing significantly higher CSM rates after RFA compared to the other two groups.

CONCLUSIONS

We identified Grade, AFP, cirrhosis, tumor size, and tumor number as independent risk factors associated with CSM. The competing risk nomogram exhibited high performance in predicting the probability of CSM for HCC patients undergoing RFA.

Efficacy and safety of radiofrequency ablation versus laparoscopic hepatectomy for small hepatocellular carcinoma: A protocol for a randomized controlled trial

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common type of malignant tumors in adults, and is the most common cause of death in people with cirrhosis. Both laparoscopic hepatectomy (LH) and radiofrequency ablation (RFA) are radical treatments for small HCC. However, there is no international standard for the treatment of small HCC, and it is still controversial to choose LH or RFA in treating small HCC. We try to carry out a randomized, controlled, prospective study to compare the the short-term and long-term effects and safety of LH versus RFA in the treatment of small HCC.

METHODS

This study is a single-center, evaluator-blinded, randomized, controlled clinical trial (RCT). The patients will be randomly divided into RFA group and LH group in a 1:1 ratio according to a computer-generated randomization list. Postoperative complications rates, Alpha fetoprotein (AFP), hospital stay, 1, 2, 3-year overall survival (OS) rates, disease-free survival (DFS) rates and all possible adverse events will be recorded. Statistical analyses will be performed with SPSS v22.0 software.

CONCLUSIONS

The study will compare the the short-term and long-term effects and safety of LH versus RFA in the treatment of small HCC.

OSF REGISTRATION NUMBER

doi: 10.17605/OSF.IO/HNX2T.

Robotic Liver Resection Versus Percutaneous Ablation for Early HCC: Short- and Long-Term Results

BACKGROUND

The correct approach for early hepatocellular carcinoma (HCC) is debatable, since multiple options are currently available. Percutaneous ablation (PA) is associated in some series to reduced morbidity compared to liver resection (LR); therefore, minimally invasive surgery may play a significant role in this setting.

METHODS

All consecutive patients treated by robotic liver resection (RLR) or PA between January 2014 and October 2019 for a newly diagnosed single HCC, less than 3 cm in size (very early/early stages according to the Barcelona Clinic Liver Cancer (BCLC)) on chronic liver disease or liver cirrhosis, were enrolled in this retrospective study. The aim of this study was to compare short- and long-term outcomes to define the best approach in this specific cohort.

RESULTS

60 patients fulfilled the inclusion criteria: 24 RLR and 36 PA. The two populations were homogeneous in terms of baseline characteristics. There were no statistically significant differences regarding the incidence of postoperative morbidity (RLR 38% vs. PA 19%, p = 0.15). The cumulative incidence of recurrence (CIR) was significantly higher in patients who underwent PA, with the one, two, and three years of CIR being 42%, 69%, and 73% in the PA group and 17%, 27%, and 27% in the RLR group, respectively.

CONCLUSIONS

RLR provides a significantly higher potential of cure and tumor-related free survival in cases of newly diagnosed single HCCs smaller than 3 cm. Therefore, it can be considered as a first-line approach for the treatment of patients with those characteristics in high-volume centers with extensive experience in the field of hepatobiliary surgery and minimally invasive approaches.

Radiofrequency ablation versus hepatic resection for recurrent hepatocellular carcinoma: an updated meta-analysis

BACKGROUND

The clinical benefits of treatment with radiofrequency ablation (RFA) and repeat hepatic resection (RHR) for recurrent hepatocellular carcinoma (RHCC) remain controversial. This meta-analysis aims to evaluate the outcomes and major complications of RFA versus RHR in patients with early-stage RHCC.

METHODS

PubMed, Embase, Web of Science and the Cochrane Library were systematically searched for comparative studies on the evaluation of RHR versus RFA for RHCC. The primary outcome was overall survival (OS), and the secondary outcomes were progression-free survival (PFS) and major complications. Meta-analysis was performed using a random-effects model or fixed-effects model, and heterogeneity was tested by the Cochran Q statistic.

RESULTS

Ten studies with 1612 patients (RHR = 654, RFA = 958) were included in the meta-analysis. The meta-analysis showed that RHR had superior OS (HR 0.77, 95% CI =0.65-0.92, P = 0.004) and PFS (HR 0.81, 95% CI =0.67-0.98, P = 0.027) compared to RFA, whereas major complications may be less frequent in the RFA group (OR 0.15, 95% CI = 0.06-0.39, P < 0.001). In the subgroup analysis of patients with single RHCC ≤3 cm, OS (HR 1.03, 95% CI =0.69-1.52, P = 0.897) and PFS (HR 0.99, 95% CI = 0.71-1.37, P = 0.929) showed no significant differences in the comparison of RHR and RFA. In single RHCC> 3 cm and ≤ 5 cm, RFA showed an increased mortality in terms of OS (HR 0.57, 95% CI = 0.37-0.89, P = 0.014).

CONCLUSION

RHR offers a longer OS and PFS than RFA for patients with RHCC, but no statistically significant difference was observed for single RHCC ≤3 cm. The advantages of fewer major complications may render RFA an alternative treatment option for selected patients.

Minimally invasive surgery versus radiofrequency ablation for single subcapsular hepatocellular carcinoma ≤ 2 cm with compensated liver cirrhosis

BACKGROUND

There is currently no consensus regarding the relative applicability of minimally invasive treatment, including radiofrequency ablation (RFA) and minimally invasive surgery (MIS) in patients with a single small peripheral hepatocellular carcinoma (HCC) and compensated cirrhosis. This study investigated the clinical outcomes of MIS and RFA for single subcapsular HCC ≤ 2 cm in patients with compensated cirrhosis.

METHODS

In this retrospective study, we enrolled 75 patients who had a single subcapsular HCC ≤ 2 cm along with Child-Pugh class A cirrhosis and a preoperative platelet count ≥ 100 k/μl. These patients underwent RFA (n = 39) or MIS (n = 36) between 2010 and 2016. Clinical outcomes including disease-free survival (DFS), survival without recurrence beyond the Milan criteria (RBM), and overall survival (OS) were compared.

RESULTS

The 7-year DFS rates in the MIS and RFA groups were 86.1% and 35.9% (p < 0.001), respectively, the 7-year RBM rates were 88.9% and 66.7% (p = 0.014), respectively, and the 7-year OS rates were 97.2% and 82.1% (p = 0.008), respectively. RFA was associated with more ipsilateral lobe recurrence (20% vs. 83.4%, p = 0.004), and 40% were in direct contact with the ablation penumbra. A Cox proportional hazard analysis identified RFA as an independent predictor of mortality (adjusted hazard ratio, 9.625, p = 0.038). No major complications occurred in either group. RFA patients had a shorter hospital stay (median of 2 vs. 6 days, p < 0.001) and operation time (median of 23.5 vs. 216 min, p = 0.001).

CONCLUSIONS

MIS was associated with a better 7-year OS, RBM, and DFS among patients with single subcapsular HCC ≤ 2 cm, Child-Pugh A liver function, and no clinically significant portal hypertension when compared to those who underwent percutaneous RFA.

Videolaparoscopic microwave ablation in patients with HCC at a European high-volume center: Results of 815 procedures

BACKGROUND

Videolaparoscopic (VL) microwave ablation (MWA) is not included in most of the international guidelines as a therapeutic option for hepatocellular carcinoma (HCC). Aim of this study was to assess the safety of VL MWA in patients with HCC for whom resection or percutaneous ablation is unsuitable.

METHODS

A retrospective analysis was performed on a prospective database of patients with HCC treated with VL MWA at our institution from 2009 to 2016. Patient demographics, operational characteristics, and complications were recorded. Statistical analysis was performed to identify safety profile, overall survival and recurrence rate.

RESULTS

A total of 815 VL MWA were performed in 674 patients with a mean age of 64 years. Patients had a mean Model for End-stage Liver Disease score of 10 (±3); 32.8% were Child B, 44.1% Barcelona Clinic Liver Cancer B-C. Perioperative mortality was 0.4%. Overall morbidity was 30.8%, with Dindo-Clavien complications ≥3 in 2%. The median length of stay was 2 days. In 43.1% VL MWA was the first-line therapy. Overall 1-, 3-, and 5-year survival rates were 81.9%, 54.9%, and 35.9%.

CONCLUSIONS

The present is the largest series of VL ablation and the bigger number of patients with HCC treated with MW reported nowadays. It confirms the safety of a minimally invasive procedure for patients with HCC when resection or percutaneous ablation is not feasible.

Systematic review of the outcomes of surgical resection for intermediate and advanced Barcelona Clinic Liver Cancer stage hepatocellular carcinoma: A critical appraisal of the evidence

AIM

To perform a systematic review to determine the survival outcomes after curative resection of intermediate and advanced hepatocellular carcinomas (HCC).

METHODS

A systematic review of the published literature was performed using the PubMed database from 1st January 1999 to 31st Dec 2014 to identify studies that reported outcomes of liver resection as the primary curative treatment for Barcelona Clinic Liver Cancer (BCLC) stage B or C HCC. The primary end point was to determine the overall survival (OS) and disease free survival (DFS) of liver resection of HCC in BCLC stage B or C in patients with adequate liver reserve (i.e., Child's A or B status). The secondary end points were to assess the morbidity and mortality of liver resection in large HCC (defined as lesions larger than 10 cm in diameter) and to compare the OS and DFS after surgical resection of solitary vs multifocal HCC.

RESULTS

We identified 74 articles which met the inclusion criteria and were analyzed in this systematic review. Analysis of the resection outcomes of the included studies were grouped according to (1) BCLC stage B or C HCC, (2) Size of HCC and (3) multifocal tumors. The median 5-year OS of BCLC stage B was 38.7% (range 10.0-57.0); while the median 5-year OS of BCLC stage C was 20.0% (range 0.0-42.0). The collective median 5-year OS of both stages was 27.9% (0.0-57.0). In examining the morbidity and mortality following liver resection in large HCC, the pooled RR for morbidity [RR (95%CI) = 1.00 (0.76-1.31)] and mortality [RR (95%CI) = 1.15 (0.73-1.80)] were not significant. Within the spectrum of BCLC B and C lesions, tumors greater than 10 cm were reported to have median 5-year OS of 33.0% and multifocal lesions 54.0%.

CONCLUSION

Indication for surgical resection should be extended to BCLC stage B lesions in selected patients. Further studies are needed to stratify stage C lesions for resection.

Survival following redo hepatectomy vs radiofrequency ablation for recurrent hepatocellular carcinoma: a systematic review and meta-analysis

BACKGROUND

Redo hepatic resection (RHR) and radiofrequency ablation (RFA) are salvage treatment choices for recurrent hepatocellular carcinoma (RHCC). As yet, it is unclear as to which treatment modality is superior in terms of long term survival. The aim of this study was to compare the survival benefits and treatment efficacy of RHR and RFA for recurrent HCC.

METHODS

A literature review using the EMBASE, Medline, Google scholar, and Cochrane databases was performed. Meta-analyses were performed using an inference of variance, random effects model for 1, 3 and 5-year Disease Free Survival (DFS) and Overall Survival (OS). Secondary outcomes were major morbidity and mortality.

RESULTS

Five retrospective studies including 639 patients were eligible. Overall, there were no differences in 1, 3 and 5-year DFS or OS for patients undergoing RHR or RFA for recurrent HCC. Comparison between the two groups demonstrated similar 5-year DFS (HR 0.86, 95% CI 0.67-1.11, p = 0.250) and 5-year OS (HR 1.03, 95% CI 0.83-1.27, p = 0.082). However, RFA had a lower morbidity rate (2%) compared with RHR (17%, p < 0.001).

CONCLUSION

This study demonstrates, neither RHR nor RFA appeared to be superior in terms of DFS and OS. Well-constructed, randomised, multicenter trials will be required to determine if a true difference exists.

The clinical effect and relevant mechanism of combined sorafenib and radiofrequency ablation in the treatment of early small hepatocellular carcinoma

The number of cases with hepatocellular carcinoma (HCC) are on the increase. The aim of the present study was to investigate the clinical effect and relevant mechanism of combined sorafenib and radiofrequency ablation (RFA) in the treatment of the early small HCC. A total of 120 cases of patients with small HCC that presented during the period of May 2007 to June 2010 were selected and divided into the surgery (n=60) and RF (n=60) groups according to the treatment method employed. The surgery group was treated with a laparotomy resection and the RF group was treated with combined sorafenib and RFA, and a comparative analysis was made between the two groups with regard to recurrence rates, adverse reactions, and survival rates. After treatment of 1 month, the radical effective rate of the surgery and RF groups was 100%. Contrast-enhanced ultrasound images of the patients in the RF group were taken. During the 5-year follow-up, the tumor recurrence rate in the surgery group was 18.3%, significantly lower than that in the RF group where the tumor recurrence rate was 38.3% (P<0.05). The occurrence rate of postoperative pain, fever, abdominal bleeding, infection, and other complications of patients in the surgery group was significantly higher than the complication occurrence rate (P<0.05) of the patients in the RF group. The average survival time of the patients in the surgery group was 51.2±1.5 months and the survival rates during the first, third and fifth year were 90.7, 71.5 and 56.7%, respectively. Additionally, the average survival time of the patients in the RF group was 64.6±2.4 months and the survival rates during the first, third and fifth year were 91.1, 72.8 and 57.5%, respectively. The difference between the two groups was not statistically significant. The tumor-free survival rates in the surgery group during the first, third and fifth year were 87.8, 44.3 and 33.2%, respectively, while the tumor-free survival rates in the RF group during the first, third and fifth year were 86.2, 48.3 and 34.6%, respectively, and the difference between the two groups was not statistically significant. In conclusion, the combined sorafenib and RFA method, and laparotomy resection method have their advantages in the treatment of early small HCC, and under specific medical conditions, the former can partially replace the latter and be used as a preferred treatment means in the treatment of early small HCC.

The procedure outcome of laparoscopic resection for 'small' hepatocellular carcinoma is comparable to vlaparoscopic radiofrequency ablation

BACKGROUND

The aim of this study was to compare the effectiveness of laparoscopic liver resection (LLR) and laparoscopic radiofrequency ablation (LRFA) in the treatment of small nodular hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

We enrolled 50 cirrhotic patients with similar baseline characteristics that underwent LLR (n = 26) or LRFA (n = 24), in both cases with intraoperative ultrasonography. Operative and peri-operative data were retrospectively evaluated.

RESULTS

LLR included anatomic resection in eight cases and non-anatomic resection in 18. In LRFA patients, a thermoablation of 62 nodules was achieved. Between LLR and LRFA groups, a significant difference was found both for median diameters of treated HCC nodules (30 vs. 17.1 mm; P < 0.001) and the number of treated nodules/patient (1.29 ± 0.62 vs. 2.65 ± 1.55; P < 0.001). A conversion to laparotomy occurred in two LLR patient (7.7%) for bleeding. No deaths occurred in both groups. Morbidity rates were 26.9% in the LLR group versus 16.6% in the LRFA group (P = 0.501). Hospital stay in the LLR and LRFA group was 8.30 ± 6.52 and 6.52 ± 2.69 days, respectively (P = 0.022). The surgical margin was free of tumour cells in all LLR patients, with a margin <5 mm in only one case. In the LRFA group, a complete response was achieved in 90.3% of thermoablated HCC nodules at the 1-month post-treatment computed tomography evaluation.

CONCLUSIONS

LLR for small peripheral HCC in patients with chronic liver disease represents a valid alternative to LRFA in terms of patient toleration, surgical outcome of the procedure, and short-term morbidity.

Impact of clinically evident portal hypertension on the course of hepatocellular carcinoma in patients listed for liver transplantation

Liver transplantation (LT) is the best curative treatment for early hepatocellular carcinoma (HCC) in patients with cirrhosis. However, the current shortage of organs causes prolonged waiting times and poorer intention-to-treat (ITT) survival (i.e., after listing) owing to tumor progression and dropout. Portal hypertension (PH) is a recognized risk factor of HCC development in patients with cirrhosis and its recurrence after resection. The aim of this study was to evaluate the potential impact of PHT on the results of LT on an ITT basis. Patients with cirrhosis listed for LT for HCC were included and their outcomes after listing were compared according to the presence or absence of PH defined as presence of esophageal varices or ascites or low platelet count and splenomegaly. Among 243 consecutively listed patients, 70% were affected by PH, which was associated with a significantly higher risk of tumor progression (38% vs. 22%; P = 0.017) and a higher risk of dropout (22% vs. 8%; P = 0.01). Transarterial chemoembolization (TACE) was similarly applied to the two groups (60% vs. 67%; P = 0.325). An absence of TACE was the only other independent risk factor of dropout owing to tumor progression. Under an ITT analysis, PH reduced overall survival (OS), but there was no difference in OS and time to recurrence post-LT. The only pathological feature that could potentially explain this observation was the lower complete response to TACE in the PHT group (12% vs. 36%; P = 0.001).

CONCLUSION

PH should be regarded as a major risk factor of dropout owing to tumor progression and should be taken into consideration when managing patients with HCC who are waiting for LT.

Radiofrequency ablation plus devascularization is the preferred treatment of hepatocellular carcinoma with esophageal varices

BACKGROUND

Most hepatocellular carcinomas (HCCs) are associated with cirrhosis. Portal hypertension (PHT) and esophageal variceal bleeding (EVB) can limit the patient's treatment options. Surgical therapy in such patients is challenging. We performed devascularization plus liver resection or radiofrequency ablation (RFA) to treat HCC patients with concomitant EVB resulting from PHT secondary to cirrhosis. Such combined operations have never been reported for the management of HCC patients with variceal esophageal bleeding.

AIM

To evaluate two different treatment regimens for patients with HCC and EVB.

METHODS

We evaluated 35 BCLC stage 0/A patients with HCC and EVB who underwent either devascularization plus liver resection (Group A) or devascularization plus RFA (Group B). We reviewed the safety and outcomes of the two groups and assessed risk factors for patient survival and tumor recurrence.

RESULTS

Significant factors for overall survival were surgical approach and Child-Pugh classification. Child-Pugh classification was the only independent risk factor for overall postoperative survival [hazard ratio (HR) 8.320, 95 % confidence interval (CI) 1.739-39.799, P = 0.008]. Age was the only independent risk factor for tumor recurrence (HR 4.025, 95 % CI 1.343-12.062, P = 0.013).

CONCLUSIONS

RFA plus devascularization is the preferred treatment of HCC with EVB. RFA plus devascularization should be considered in Child-Pugh class A patients below 50 years of age.

Laparoscopic-assisted ablation of hepatic tumors: a review

Thermal ablation of hepatic tumors has been an evolving field over the last two decades. It is used in the treatment of both primary and metastatic neoplasms, and with evolutions in the technology, there has been an increasing interest in treating lesions where hepatic resection is not an option. Laparoscopic or minimally invasive surgical procedures have also advanced during this same time period, and the interface of these tools has been associated with the genesis of a new approach for treating hepatic lesions which are located in difficult to reach locations or found immediately adjacent to other intra-abdominal organs. This review summarizes the published literature focusing on the treatment of primary and metastatic neoplasms located in the liver, including a review of outcomes.