Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) randomised controlled trial: a systematic review of published responses

OBJECTIVES

The objective of this review was to assess the nature and tone of the published responses to the Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) randomized controlled trial.

METHODS

Published articles that cited the PulMiCC trial were identified from Clarivate Web of Science (©. Duplicates and self-citations were excluded and relevant text extracted. Four independent researchers rated the extracts independently using agreed scales for the representativeness of trial data and the textual tone. The ratings were aggregated and summarized. Two PulMiCC authors carried out a thematic analysis of the extracts.

RESULTS

Sixty-four citations were identified and relevant text was extracted and examined. The consensus rating for data inclusion was a median of 0.25 out of 6 (range 0 to 5.25, IQR 0-1.5) and for textual tone the median rating was 1.87 out of 6 (range 0 to 5.75, IQR 1-3.5). The majority of citations did not provide adequate representation of the PulMiCC data and the overall the textual tone was dismissive. Although some were supportive, many discounted the findings because the trial closed early and was underpowered to show non-inferiority. Two misinterpreted the authors' conclusions but there was acceptance that five-year survival was much higher than widely assumed.

CONCLUSIONS

Published comments reveal a widespread reluctance to consider seriously the results of a carefully conducted randomized trial. This may be because the results challenge accepted practice because of 'motivated reasoning'. But there is a widespread misunderstanding of the fact that though PulMiCC with 93 patients was underpowered to test non-inferiority, it still provides reliable evidence to undermine the widespread belief in a major survival benefit from metastasectomy.

From "getting things right" to "getting things right now": Developing COVID-19 guidance under time pressure and knowledge uncertainty

BACKGROUND

At the start of the COVID-19 pandemic, guidance was needed more than ever to direct frontline healthcare and national containment strategies. Rigorous guidance based on robust research was compromised by the emergence of the pandemic and the urgency of need for guidance. Rather than aiming to "get guidance right", guidance developers needed to "get guidance right now".

AIM

To examine how guidance developers have responded to the need for credible guidance at the start of the COVID-19 pandemic.

METHODS

An exploratory mixed-methods study was conducted among guidance developers. A web-based survey and follow-up interviews were used to examine the most pertinent challenges in developing COVID-19 guidance, strategies used to address these, and perspectives on the implications of the COVID-19 pandemic on future guidance development.

RESULTS

The survey was completed by 46 guidance developers. Survey findings showed that conventional methods of guidance development were largely unsuited for COVID-19 guidance, with 80% (n = 37) of respondents resorting to other methods. From the survey and five follow-up interviews, two themes were identified to bolster the credibility of guidance in a setting of extreme uncertainty: (1) strengthening end-user involvement and (2) conjoining evidence review and recommendation formulation. 70% (n = 32) of survey respondents foresaw possible changes in future guidance production, most notably shortening development time, by reconsidering how to balance between rigour and speed for different types of questions.

CONCLUSION

"Getting guidance right" and "getting guidance right now" are not opposites, rather uncertainties are always part of guidance development and require guidance developers to balance scientific robustness with usability, acceptability, adequacy and contingency. This crisis points to the need to acknowledge uncertainties of scientific evidence more explicitly and points to mechanisms to live with such uncertainty, thus extending guidance development methods and processes more widely.

The full cohort of 512 patients and the nested controlled trial in 93 patients in the Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) study raise doubts about the effective size at present claimed

A comparison of the relative merits of video-assisted pulmonary metastasectomy versus thoracotomy is predicated on the assumption that removal of asymptomatic lung metastases favourably influences survival and that it does so by a large degree. Recently published but long-awaited evidence from a prospective cohort study and a randomised trial of Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) challenges that assumption.

The Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) burden of care study: Analysis of local treatments for lung metastases and systemic chemotherapy in 220 patients in the PulMiCC cohort

AIM

The aim of this work was to examine the burden of further treatments in patients with colorectal cancer following a decision about lung metastasectomy.

METHOD

Five teams participating in the Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) study provided details on subsequent local treatments for lung metastases, including the use of chemotherapy. For patients in three groups (no metastasectomy, one metastasectomy or multiple local interventions), baseline factors and selection criteria for additional treatments were examined.

RESULTS

The five teams recruited 220 patients between October 2010 and January 2017. No lung metastasectomy was performed in 51 patients, 114 patients had one metastasectomy and 55 patients had multiple local interventions. Selection for initial metastasectomy was associated with nonelevated carcinoembryonic antigen, fewer metastases and no prior liver metastasectomy. These patients also had better Eastern Cooperative Oncology Group scores and lung function at baseline. Four sites provided information on chemotherapy in 139 patients: 79 (57%) had one to five courses of chemotherapy, to a total of 179 courses. The patterns of survival after one or multiple metastasectomy interventions showed evidence of guarantee-time bias contributing to an impression of benefit over no metastasectomy. After repeated metastasectomy, a significantly higher risk of death was observed, with no apparent reduction in chemotherapy usage.

CONCLUSION

Repeated metastasectomy is associated with a higher risk of death without reducing the use of chemotherapy. Continued monitoring without surgery might reassure patients with indolent disease or allow response assessment during systemic treatment. Overall, the carefully collected information from the PulMICC study provides no indication of an important survival benefit from metastasectomy.

The Pulmonary Metastasectomy in Colorectal Cancer cohort study: Analysis of case selection, risk factors and survival in a prospective observational study of 512 patients

AIM

We wanted to examine survival in patients with resected colorectal cancer (CRC) whose lung metastases are or are not resected.

METHODS

Teams participating in the study of Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) identified potential candidates for lung metastasectomy and invited their consent to join Stage 1. Baseline data related to CRC and fitness for surgery were collected. Eligible patients were invited to consent for randomization in the PulMiCC randomized controlled trial (Stage 2). Sites were provided with case report forms for non-randomized patients to record adverse events and death at any time. They were all reviewed at 1 year. Baseline and survival data were analysed for the full cohort.

RESULTS

Twenty-five clinical sites recruited 512 patients from October 2010 to January 2017. Data collection closed in October 2020. Before analysis, 28 patients with non-CRC lung lesions were excluded and three had withdrawn consent leaving 481. The date of death was known for 292 patients, 136 were alive in 2020 and 53 at earlier time points. Baseline factors and 5-year survival were analysed in three strata: 128 non-randomized patients did not have metastasectomy; 263 had elective metastasectomy; 90 were from the randomized trial. The proportions of solitary metastases for electively operated and non-operated patients were 69% and 35%. Their respective 5-year survivals were 47% and 22%.

CONCLUSION

Survival without metastasectomy was greater than widely presumed. Difference in survival appeared to be largely related to selection. No inference can be drawn about the effect of metastasectomy on survival in this observational study.

Pulmonary metastasectomy: limits to credibility

Lung metastases are a common site of spread for many malignant tumours. Pulmonary metastasectomy has been practiced for many years for sarcomas and is now becoming increasingly frequently advocated for patients with many other tumours, especially colorectal cancer. In this article we argue that this procedure is one framed by therapeutic opportunity and not supported by strong evidence. It is potentially harmful and may not be effective. Our argument is based on several important issues: (I) the vagueness of the concept of “oligometastases” and its biological implausibility; (II) the flaws in the often-cited observational evidence, especially selection bias; (III) the lack of any reliable randomised trial evidence of improved survival but evidence of harm; (IV) the failure of strategies to detect metastases earlier to influence overall survival. The introduction of stereotactic radiotherapy and image-guided thermal ablation have made the urge to treat lung metastases stronger but without any good evidence to justify their use. We acknowledge the problems of carrying out randomised trials when there is a clear lack of equipoise in the clinical teams involved but believe that there is an ethical need to do so. Many patients are probably being given false hope of cure or prolonged survival but are at risk of harm from pulmonary metastasectomy or ablation. It is possible that a few patients may benefit but without better evidence we do not know which, if any, do.

American Society of Hematology 2021 guidelines for management of venous thromboembolism: prevention and treatment in patients with cancer

BACKGROUND

Venous thromboembolism (VTE) is a common complication among patients with cancer. Patients with cancer and VTE are at a markedly increased risk for morbidity and mortality.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about the prevention and treatment of VTE in patients with cancer.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The guideline development process was supported by updated or new systematic evidence reviews. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess evidence and make recommendations.

RESULTS

Recommendations address mechanical and pharmacological prophylaxis in hospitalized medical patients with cancer, those undergoing a surgical procedure, and ambulatory patients receiving cancer chemotherapy. The recommendations also address the use of anticoagulation for the initial, short-term, and long-term treatment of VTE in patients with cancer.

CONCLUSIONS

Strong recommendations include not using thromboprophylaxis in ambulatory patients receiving cancer chemotherapy at low risk of VTE and to use low-molecular-weight heparin (LMWH) for initial treatment of VTE in patients with cancer. Conditional recommendations include using thromboprophylaxis in hospitalized medical patients with cancer, LMWH or fondaparinux for surgical patients with cancer, LMWH or direct oral anticoagulants (DOAC) in ambulatory patients with cancer receiving systemic therapy at high risk of VTE and LMWH or DOAC for initial treatment of VTE, DOAC for the short-term treatment of VTE, and LMWH or DOAC for the long-term treatment of VTE in patients with cancer.

Randomised Controlled Trial Evidence Questions the Assumption that Pulmonary Metastasectomy Benefits Patients with Colorectal Cancer

Pulmonary metastasectomy for sarcoma is surgery without proven benefit, and in the light of a randomized controlled trial examining pulmonary metastasectomy in colorectal cancer, it should be questioned.

Pulmonary metastasectomy in colorectal cancer: health utility scores by EQ-5D-3L in a randomized controlled trial show no benefit from lung metastasectomy

AIM

The aim was to assess the health utility of lung metastasectomy in the treatment of patients with colorectal cancer (CRC) using the EQ-5D-3L questionnaire.

METHODS

Multidisciplinary CRC teams at 14 sites recruited patients to a two-arm randomized controlled trial-Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC). Remote randomization was used, stratified by site and with minimization for seven known confounders. Participants completed the EQ-5D-3L questionnaire together with other patient reported outcome measures at randomization and then again at 3, 6, 12 and 24 months. These were returned by post to the coordinating centre.

RESULTS

Between December 2010 and December 2016, 93 participants were randomized, 91 of whom returned questionnaires. Survival and patient reported quality of life have been published previously, revealing no significant differences between the trial arms. Described here are patient reported data from the five dimensions of the EQ-5D-3L and the visual analogue scale (VAS) health state. No significant difference was seen at any time point. The estimated difference between control and metastasectomy patients was -0.23 (95% CI -0.113, 0.066) for the composite 0 to 1 index scale based on the descriptive system and 0.123 (95% CI -7.24, 7.49) for the 0 to 100 VAS scale.

CONCLUSIONS

Following lung metastasectomy for CRC, no benefit was demonstrated for health utility, which alongside a lack of a survival or quality of life benefit calls into question the widespread use of the procedure.

Pulmonary Metastasectomy in Colorectal Cancer: updated analysis of 93 randomized patients - control survival is much better than previously assumed

AIM

Lung metastases from colorectal cancer are resected in selected patients in the belief that this confers a significant survival advantage. It is generally assumed that the 5-year survival of these patients would be near zero without metastasectomy. We tested the clinical effectiveness of this practice in Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC), a randomized, controlled noninferiority trial.

METHOD

Multidisciplinary teams in 14 hospitals recruited patients with resectable lung metastases into a two-arm trial. Randomization was remote and stratified according to site, with minimization for age, sex, primary cancer stage, interval since primary resection, prior liver involvement, number of metastases and carcinoembryonic antigen level. The trial management group was blind to patient allocation until after intention-to-treat analysis.

RESULTS

From 2010 to 2016, 93 participants were randomized. These patients were 35-86 years of age and had between one and six lung metastases at a median of 2.7 years after colorectal cancer resection; 29% had prior liver metastasectomy. The patient groups were well matched and the characteristics of these groups were similar to those of observational studies. The median survival after metastasectomy was 3.5 (95% CI: 3.1-6.6) years compared with 3.8 (95% CI: 3.1-4.6) years for controls. The estimated unadjusted hazard ratio for death within 5 years, comparing the metastasectomy group with the control group, was 0.93 (95% CI: 0.56-1.56). Use of chemotherapy or local ablation was infrequent and similar in each group.

CONCLUSION

Patients in the control group (who did not undergo lung metastasectomy) have better survival than is assumed. Survival in the metastasectomy group is comparable with the many single-arm follow-up studies. The groups were well matched with features similar to those reported in case series.

Evaluating prophylactic heparin in ambulatory patients with solid tumours: a systematic review and individual participant data meta-analysis

BACKGROUND

Study-level meta-analyses provide high-certainty evidence that heparin reduces the risk of symptomatic venous thromboembolism for patients with cancer; however, whether the benefits and harms associated with heparin differ by cancer type is unclear. This individual participant data meta-analysis of randomised controlled trials examines the effect of heparin on survival, venous thromboembolism, and bleeding in patients with cancer in general and by type.

METHODS

In this systematic review and meta-analysis we searched MEDLINE, Embase, and The Cochrane Library for randomised controlled trials comparing parenteral anticoagulants with placebo or standard care in ambulatory patients with solid tumours and no indication for anticoagulation published from the inception of each database to January 14, 2017, and updated it on May 14, 2020, without language restrictions. We calculated the effect of parenteral anticoagulant administration on all-cause mortality, venous thromboembolism occurrence, and bleeding related outcomes through multivariable hierarchical models with patient-level variables as fixed effects and a categorical trial variable as a random effect, adjusting for age, cancer type, and metastatic status. Interaction terms were tested to investigate effects in predefined subgroups. This study is registered with PROSPERO, CRD42013003526.

FINDINGS

We obtained individual participant data from 14 of 20 eligible randomised controlled trials (8278 [79%] of 10 431 participants; 4139 included in the low-molecular-weight heparin group and 4139 in the control group). Meta-analysis showed an adjusted relative risk (RR) of mortality at 1 year of 0·99 (95% CI 0·93-1·06) and a hazard ratio of 1·01 (95% CI 0·96-1·07). The number of patients with venous thromboembolic events was 158 (4·0%) of 3958 with available data in the low-molecular-weight heparin group compared with 279 (7·1%) of 3957 in the control group. Major bleeding events occurred in 71 (1·7%) of 4139 patients in the control population and 88 (2·1%) in the low-molecular-weight heparin group, and minor bleeding events in 478 (12·1%) of 3945 patients with available data in the control group and 652 (16·6%) of 3937 patients in the low-molecular-weight heparin group. The adjusted RR was 0·58 (95% CI 0·47-0·71) for venous thromboembolism, 1·27 (0·92-1·74) for major bleeding, and 1·34 (1·19-1·51) for minor bleeding. Prespecified subgroup analysis of venous thromboembolism occurrence by cancer type identified the most certain benefit from heparin treatment in patients with lung cancer (RR 0·59 [95% CI 0·42-0·81]), which dominated the overall reduction in venous thromboembolism. Certainty of the evidence for the outcomes ranged from moderate to high.

INTERPRETATION

Low-molecular-weight heparin reduces risk of venous thromboembolism without increasing risk of major bleeding compared with placebo or standard care in patients with solid tumours, but it does not improve survival.

FUNDING

Canadian Institutes of Health Research.

The myth of pulmonary metastasectomy

Pulmonary metastasectomy is widely and increasingly practiced in the belief that this intervention can cure patients with colorectal cancer, and that without it few survive 5 years. No good evidence exists supporting such convictions, indeed recent trial results challenge them. What evidence underpins this acceptance of illusory truths or misconceptions?

The Khorana score for prediction of venous thromboembolism in cancer patients: An individual patient data meta-analysis

BACKGROUND

Oncology guidelines suggest using the Khorana score to select ambulatory cancer patients receiving chemotherapy for primary venous thromboembolism (VTE) prevention, but its performance in different cancers remains uncertain.

OBJECTIVE

To examine the performance of the Khorana score in assessing 6-month VTE risk, and the efficacy and safety of low-molecular-weight heparin (LMWH) among high-risk Khorana score patients.

METHODS

This individual patient data meta-analysis evaluated (ultra)-LMWH in patients with solid cancer using data from seven randomized controlled trials.

RESULTS

A total of 3293 patients from the control groups with an available Khorana score had lung (n = 1913; 58%), colorectal (n = 452; 14%), pancreatic (n = 264; 8%), gastric (n = 201; 6%), ovarian (n = 184; 56%), breast (n = 164; 5%), brain (n = 84; 3%), or bladder cancer (n = 31; 1%). The 6-month VTE incidence was 9.8% among high-risk Khorana score patients and 6.4% among low-to-intermediate-risk patients (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1-2.2). The dichotomous Khorana score performed differently in lung cancer patients (OR 1.1; 95% CI, 0.72-1.7) than in the group with other cancer types (OR 3.2; 95% CI, 1.8-5.6; Pinteraction  = .002). Among high-risk patients, LMWH decreased the risk of VTE by 64% compared with controls (OR 0.36; 95% CI, 0.22-0.58), without increasing the risk of major bleeding (OR 1.1; 95% CI, 0.59-2.1).

CONCLUSION

The Khorana score was unable to stratify patients with lung cancer based on their VTE risk. Among those with other cancer types, a high-risk score was associated with a three-fold increased risk of VTE compared with a low-to-intermediate risk score. Thromboprophylaxis was effective and safe in patients with a high-risk Khorana score.

Obtaining and managing data sets for individual participant data meta-analysis: scoping review and practical guide

BACKGROUND

Shifts in data sharing policy have increased researchers' access to individual participant data (IPD) from clinical studies. Simultaneously the number of IPD meta-analyses (IPDMAs) is increasing. However, rates of data retrieval have not improved. Our goal was to describe the challenges of retrieving IPD for an IPDMA and provide practical guidance on obtaining and managing datasets based on a review of the literature and practical examples and observations.

METHODS

We systematically searched MEDLINE, Embase, and the Cochrane Library, until January 2019, to identify publications focused on strategies to obtain IPD. In addition, we searched pharmaceutical websites and contacted industry organizations for supplemental information pertaining to recent advances in industry policy and practice. Finally, we documented setbacks and solutions encountered while completing a comprehensive IPDMA and drew on previous experiences related to seeking and using IPD.

RESULTS

Our scoping review identified 16 articles directly relevant for the conduct of IPDMAs. We present short descriptions of these articles alongside overviews of IPD sharing policies and procedures of pharmaceutical companies which display certification of Principles for Responsible Clinical Trial Data Sharing via Pharmaceutical Research and Manufacturers of America or European Federation of Pharmaceutical Industries and Associations websites. Advances in data sharing policy and practice affected the way in which data is requested, obtained, stored and analyzed. For our IPDMA it took 6.5 years to collect and analyze relevant IPD and navigate additional administrative barriers. Delays in obtaining data were largely due to challenges in communication with study sponsors, frequent changes in data sharing policies of study sponsors, and the requirement for a diverse skillset related to research, administrative, statistical and legal issues.

CONCLUSIONS

Knowledge of current data sharing practices and platforms as well as anticipation of necessary tasks and potential obstacles may reduce time and resources required for obtaining and managing data for an IPDMA. Sufficient project funding and timeline flexibility are pre-requisites for successful collection and analysis of IPD. IPDMA researchers must acknowledge the additional and unexpected responsibility they are placing on corresponding study authors or data sharing administrators and should offer assistance in readying data for sharing.

Pulmonary Metastasectomy versus Continued Active Monitoring in Colorectal Cancer (PulMiCC): a multicentre randomised clinical trial

BACKGROUND

Lung metastasectomy in the treatment of advanced colorectal cancer has been widely adopted without good evidence of survival or palliative benefit. We aimed to test its effectiveness in a randomised controlled trial (RCT).

METHODS

Multidisciplinary teams in 13 hospitals recruited participants with potentially resectable lung metastases to a multicentre, two-arm RCT comparing active monitoring with or without metastasectomy. Other local or systemic treatments were decided by the local team. Randomisation was remote and stratified by site with minimisation for age, sex, primary cancer stage, interval since primary resection, prior liver involvement, the number of metastases, and carcinoembryonic antigen level. The central Trial Management Group were blind to patient allocation until completion of the analysis. Analysis was on intention to treat with a margin for non-inferiority of 10%.

RESULTS

Between December 2010 and December 2016, 65 participants were randomised. Characteristics were well-matched in the two arms and similar to those in reported studies: age 35 to 86 years (interquartile range (IQR) 60 to 74); primary resection IQR 16 to 35 months previously; stage at resection T1, 2 or 3 in 3, 8 and 46; N1 or N2 in 31 and 26; unknown in 8. Lung metastases 1 to 5 (median 2); 16/65 had previous liver metastases; carcinoembryonic antigen normal in 55/65. There were no other interventions in the first 6 months, no crossovers from control to treatment, and no treatment-related deaths or major adverse events. The Hazard ratio for death within 5 years, comparing metastasectomy with control, was 0.82 (95%CI 0.43, 1.56).

CONCLUSIONS

Because of poor and worsening recruitment, the study was stopped. The small number of participants in the trial (N = 65) precludes a conclusive answer to the research question given the large overlap in the confidence intervals in the proportions still alive at all time points. A widely held belief is that the 5-year absolute survival benefit with metastasectomy is about 35%: 40% after metastasectomy compared to < 5% in controls. The estimated survival in this study was 38% (23-62%) for metastasectomy patients and 29% (16-52%) in the well-matched controls. That is the new and important finding of this RCT.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT01106261. Registered on 19 April 2010.