At American Society Of Clinical Oncology Research Articles

Improving tolerability of pembrolizumab with weight based dosing: A meta-analysis.

2639 Background: Pembrolizumab, a PD-1 immune checkpoint inhibitor (ICI), has demonstrated significant clinical activity in various cancers. Despite a favorable toxicity profile, discontinuation due to adverse events including immune related adverse events (irAE) has been reported. We conducted a meta-analysis of published clinical trials to evaluate the tolerability of pembrolizumab in cancer patients. Methods: A systematic review was conducted of relevant studies from the databases of PubMed and abstracts presented at American Society of Clinical Oncology (ASCO) from June 2015 until September 2020. Eligible studies included prospective clinical trials that reported a discontinuation rate due to adverse effects. Incidence, relative risk and 95% confidence intervals (CI) were calculated by employing fixed or random effects models. Results: A total of 6,380 patients with a variety of hematologic and solid malignancies from 20 studies of pembrolizumab were included for analysis. The overall rate of pembrolizumab discontinuation due to adverse events was 8.2% (95% CI: 6.4-10.4%). The discontinuation rate of pembrolizumab was not significantly lower than the chemotherapy controls, with RR of 0.84 (95% CI: 0.58-1.12, p = 0.33). However, the discontinuation rate of pembrolizumab was significantly higher compared to placebo control with RR of 2.20 (95% CI: 1.36-3.54, p < 0.001), and significantly lower compared to ipilimumab with RR of 0.58 (95% CI: 0.34-0.99, p = 0.04) respectively. The discontinuation rate varied widely among different tumor types with the lowest rate of 0.8% (95% CI: 0.2-3%) in gastric cancer, and the highest of 13.5% (95% CI: 10.8-16.8%) in head and neck squamous cell carcinoma. Interestingly, the discontinuation rate varied with pembrolizumab dosing, with the fixed dosing of 200mg being 9.2% (95% CI: 6.9-12%) and the weight-based dosing being 6.5% (95% CI: 4.8-8.8%). The weight-based dosing was associated with a significantly lower discontinuation rate compared to controls with RR of 0.62 (95% CI: 0.47-0.81, p < 0.0001), while the fixed dosing had similar discontinuation rate with RR of 1.03 (95% CI: 0.89-1.20, p = 0.67). Conclusions: The tolerability of pembrolizumab may be comparable to chemotherapy in cancer patients and may vary with its dosing. Future studies are warranted to evaluate the impact of different dosing.

A pooled analysis of molecularly targeted agents for treatment of metastatic oesophago-gastric cancer in elderly patients

IntroductionThe aim of the present study was to assess the efficacy of molecularly targeted agents (MTAs) in the treatment of elderly patients with metastatic oesophago-gastric cancer (mOGC).Material and methodsWe systematically searched electronic databases and abstracts presented at American Society of Clinical Oncology (ASCO) meetings up to January 31, 2017. Hazard ratios (HRs) were used to estimate overall survival (OS) and progression-free survival (PFS). Subgroup analysis and publication bias were also evaluated. All statistical analysis was conducted using Comprehensive Meta Analysis software (Version 2.0).ResultsA total of 2,149 elderly patients with mOGC from thirteen trials were included. Compared to non-MTA-containing regimens, OS was significantly improved in the MTA-containing regimens (HR = 0.86, 95% CI: 0.75–0.99, p = 0.037), but not for PFS (HR = 1.05, 95% CI: 0.85–1.30, p = 0.67). In addition, subgroup analysis indicated that MTA-containing regimens as second-line therapy in elderly mOGC patients significantly improved PFS (HR = 0.58; 95% CI: 0.39–0.85, p = 0.005) and OS (HR = 0.82, 95% CI: 0.70–0.96, p = 0.016), but did not significantly improve PFS (HR = 1.36; 95% CI: 1.06–1.76, p = 0.017) and OS (HR = 0.98, 95% CI: 0.77–1.27, p = 0.90) for MTA-containing regimens as first-line therapy in these patients. No publication bias was detected by Begg’s and Egger’s tests for OS and PFS.ConclusionsOur results indicate that the MTA-containing therapies significantly improve OS but not for PFS in elderly mOGC patients. Sub-group analysis shows that improved efficacy is only observed in the second-line setting and not in the first-line setting. Our findings support the use of angiogenesis as second-line treatment for elderly mOGC patients.

Abstract P5-22-13: Representation of surgical breast research at an interdisciplinary oncology conference

Abstract Background: The treatment of breast cancer requires an interdisciplinary approach, involving the fields of surgery, radiation oncology, medical oncology, pathology and radiology. The roles of various specialties may differ in the local versus metastatic setting. Despite the importance of collaborative care, significant disparities remain in federal funding of research among different medical specialties. The purpose of this analysis is to evaluate the representation of the surgical specialty at an interdisciplinary oncology research conference. Methods: All electronically available abstracts in the breast cancer local, regional, adjuvant or breast cancer metastatic categories at American Society of Clinical Oncology (ASCO) 2017 annual meeting were reviewed. All abstracts containing the word “breast” in the title of other relevant categories were also included. These categories included developmental therapeutics, patient and survivor care, brain metastases, cancer prevention/hereditary genetics/epidemiology, tumor biology, health services/clinical informatics/quality of care. Only abstracts in these categories that were presented via poster or oral presentation at the annual meeting were included. The medical discipline, gender, and country of institution were recorded for each first and last author. Country of institution was recorded based on abstract reported affiliation. Gender and medical discipline were recorded based on information from academic and industry profiles available online. Results: A total of 301 breast cancer posters (n = 276) and oral abstracts (n = 25) were presented at ASCO 2017. The majority of first (56.8%) and last (56.1%) authorships were from institutions in the United States. Geographic distribution of surgical first authors was as follows: 50.0% United States, 13.9% Europe and 36.1% Asia. While medical oncology represented the majority of first (59.5%) and final authorships (61.8%), surgery was underrepresented at 12.0% of first and 9.0% of final authors. When only non-metastatic breast cancer related abstracts were included (n = 142) surgical representation improved for both first (18.3%) and final (14.1%) authorship. While low in comparison to medical oncology, representation for the field of surgery was better than that of radiation oncology (2.3% first and 2.0% last authors), pathology (2.7% first and 3.3% last authors), and radiology (1.7% both first and last authors). In the entire cohort, female researchers were well represented as first authors (50.8%), but less often as final authors (41.9%). Representation of female surgeons was variable based on authorship: 61.1% of surgical first authors were female, but only 37% of surgical final authors were women. Conclusions: The treatment of breast cancer requires a multidisciplinary approach. However, despite the collaborative nature of care, researchers in the field of surgery were less likely to present scholarly activity at ASCO 2017. This is likely multifactorial, and warrants further research to identify barriers and facilitators of surgical participation in the conduct and reporting of breast cancer surgical research. Citation Format: Shuford RA, Dulaney CR, Wallace A. Representation of surgical breast research at an interdisciplinary oncology conference [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-22-13.

The role of angiogenesis inhibitors in the treatment of elderly patients with advanced non-small-cell lung cancer: A meta-analysis of eleven randomized controlled trials.

Data on the role of angiogenesis inhibitors (AIs) in the treatment of elderly patients with advanced non-small-cell lung cancer (NSCLC) remains limited. We aimed to assess the overall efficacy of AIs-containing regimens in the treatment of advanced NSCLC in this setting. Databases from PubMed, Web of Science, and abstracts presented at American Society of Clinical Oncology (ASCO) meeting up to October 31, 2014 were searched to identify relevant studies. Eligible studies included prospective randomized controlled trials (RCTs) evaluating therapies with or without AIs in elderly patients with advanced NSCLC. The endpoints were overall survival (OS) and progression-free survival (PFS). Statistical analyses were conducted by using random effects models and 95% confidence intervals (CIs) were calculated. A total of 3,709 elderly patients with advanced NSCLC from 11 RCTs were identified for analysis. The pooled results demonstrated that there was a clinical benefit in PFS for AIs-containing regimens (hazard ratio (HR) 0.88, 95%CI: 0.78-1.00, P = 0.053) when compared to non-AIs-containing regimens, but not for OS (HR 0.99, 95%CI: 0.90-1.10, P = 0.89). On subgroup analysis, similar results were found based on treatment line. No publication bias was detected by Begg's and Egger's tests for OS. In elderly patients with advanced NSCLC, AIs-containing therapies offer a clinical benefit in PFS but for OS. With present available data from RCTs, we are still unable to clearly set the role of specific AIs in the treatment of advanced NSCLC in this setting.

Incidence and risk of severe infections associated with aflibercept in cancer patients: a systematic review and meta-analysis.

Aflibercept is an engineered humanized vascular endothelial growth factor (VEGF)-targeted agent. Severe infections are serious adverse event associated with aflibercept. However, the contribution of aflibercept to infection is still unknown. We thus conducted this meta-analysis to investigate the overall incidence and risk of developing severe infections in cancer patients treated with aflibercept. Electronic databases including PubMed, Embase and abstracts presented at American Society of Clinical Oncology (ASCO) and European Society of Medical Oncology (ESMO) meeting were searched. Eligible studies were phase II and III prospective clinical trials of aflibercept in cancer patients with toxicity profile on infections. Summary incidences, relative risk (RR), odds ratio (OR) and 95% confidence intervals (95% CIs) were calculated by using either random effects or fixed effect models according to the heterogeneity of included studies. A total of 4310 patients with a variety of solid tumours from 10 prospective clinical trials were included in the meta-analysis. The incidence of high grade infections associated with aflibercept was 7.3% (95% CI 4.3, 12.0%), with a mortality of 2.2% (95% CI 1.5, 3.1%). In addition, patients treated with aflibercept had a significantly increased risk of developing high grade (RR 1.87, 95% CI 1.52, 2.30; P < 0.001) and fatal (OR 2.16, 95% CI 1.14, 4.11; P = 0.018) infections. No evidence of publication bias was observed. Furthermore, the risk of infections with aflibercept was substantially higher than bevacizumab. Aflibercept is associated with a significant increased risk of developing severe infections in patients with solid tumours. Frequent clinical monitoring and appropriate management for infections should be emphasized during aflibercept treatment.

Soft tissue sarcomas &amp; GIST Insights into subtype-specific therapy concepts: Highlights from ASCO meeting 2015

Sarcomas are a rare and heterogeneous group of mesenchymal malignancies that have historically been challenging in diagnosis and treatment. In soft tissue sarcomas (STS), the recognition of different histological subtypes has made a dramatic conceptual change leading to histotype-driven targeted therapies. In gastrointestinal stromal tumors (GIST), the most important advance in the past decade was the demonstration that tyrosine kinase inhibitors (TKIs) can durably control disease and lead to remarkable treatment responses. The advent of TKIs has unquestionably changed the overall survival of patients with GIST, not only in the advanced-disease setting but also in individuals with high-risk disease. This review covers the latest clinical study highlights for STS and GIST presented at American Society of Clinical Oncology (ASCO) 2015 meeting, demonstrating the constant progress from conventional chemotherapy to histology-driven therapy approaches.

The impact of histological types on the efficacy of angiogenesis inhibitors in the treatment of advanced NSCLC: a meta-analysis of randomized controlled trials.

PurposeWe aimed at assessing the overall efficacy of angiogenesis inhibitor (AI)-containing regimens in the treatment of advanced non-small-cell lung cancer (NSCLC) according to histological types.MethodsStudies from PubMed and Web of Science, and abstracts presented at American Society of Clinical Oncology (ASCO) meeting up to October 31, 2014 were searched to identify relevant studies. Eligible studies included prospective randomized controlled trials (RCTs) evaluating AIs in advanced NSCLC with survival data according to patients’ histologies. The endpoints were overall survival (OS) and progression-free survival (PFS). Statistical analyses were conducted by using either random effects or fixed effect models according to the heterogeneity of included studies.ResultsA total of 10,035 patients with advanced NSCLC from 13 RCTs were identified for analysis. The pooled results demonstrated that AI-containing regimens significantly improved the PFS (HR, 0.84, 95% confidence interval (CI): 0.78–0.91, P<0.001) and OS (HR, 0.92, 95% CI: 0.85–0.99, P=0.017) in lung adenocarcinoma when compared to non-AI-containing regimens. Additionally, there was a significantly improved PFS (HR, 0.87, 95% CI: 0.77–0.98, P=0.027) for AI-containing regimens in squamous cell lung carcinoma, but it did not translated into OS benefit (HR, 1.02, 95% CI: 0.92–1.15, P=0.68). For NSCLC patients with other histological types, the use of AIs did not significantly improve PFS (HR, 0.90, 95% CI: 0.75–1.09, P=0.27) and OS (HR, 0.90, 95% CI: 0.76–1.08, P=0.19).ConclusionThe findings of this study suggest that the addition of AIs to the treatment therapies for patients with lung adenocarcinoma offers improved survival benefits. Prospective clinical trials investigating the role of AIs in this setting are recommended.

Negative results of METLung study: an opportunity to better understand the role of MET pathway in advanced NSCLC.

The negative results of the global METLung phase III trial recently presented at American Society of Clinical Oncology (ASCO) were clearly unexpected (1). The trial assessed the impact on overall survival (OS) of adding onartuzumab, a monovalent monoclonal antibody against mesenchymal-epithelial transition (MET) factor receptor tyrosine kinase (RTK), to erlotinib in second or third-line therapy of advanced non-small cell lung cancer (NSCLC) patients with MET overexpression. There was a strong rationale behind this phase III trial: dysregulation of MET signaling in cancer is responsible for cell proliferation, cell cycle progression, cell dissociation, motility, spreading and invasion, overexpression of MET is linked to a worse prognosis for both early and late stages of NSCLC, and crosstalk with other RTKs including EGFR can lead to synergistic activation of downstream pathways. Moreover, amplification of MET seems to be involved in a significant proportion of patients with EGFR mutations developing acquired resistance to EGFR inhibitors.

Risk of gastrointestinal perforation in cancer patients treated with aflibercept: a systematic review and meta-analysis.

Gastrointestinal (GI) perforation is a serious adverse event associated with aflibercept, a novel vascular endothelial growth factor (VEGF)-targeted agent currently approved as second-line treatment for previously treated metastatic colorectal cancer, but the incidence and risk of GI perforation associated with aflibercept has not been well determined. We thus conducted this meta-analysis to investigate the overall incidence and risk of developing GI perforation associated with aflibercept. Databases from PubMed, Web of Science, and abstracts presented at American Society of Clinical Oncology (ASCO) and European Society of Medical Oncology (ESMO) meeting up to January, 2014 were searched to identify relevant studies. Eligible studies included prospective phase II and III trials evaluating aflibercept in cancer patients with adequate data on GI perforation. Statistical analyses were conducted to calculate the summary incidence, odds ratio, and 95% confidence intervals (CIs) by using either random effects or fixed effect models according to the heterogeneity of included studies. A total of 4,101 patients with a variety of solid tumors from eight clinical trials were included in our analysis. The incidence of GI perforation associated with aflibercept was 1.9% (95%CI, 1.0-3.8%), with a mortality of 10.8% (95%CI, 4.1-25.5%). In addition, patients treated with aflibercept had a significantly increased risk of developing all-grade (OR 3.76; 95%CI, 1.94-7.25; p < 0.001) and high-grade GI (OR 4.14; 95%CI; 2.12-8.06; p < 0.001) perforation compared with patients treated with control medication. No evidence of publication bias was observed. The use of aflibercept is associated with a significantly increased risk of GI perforation compared to controls.

Comparison of the Efficacy and Safety of S-1-Based and Capecitabine-Based Regimens in Gastrointestinal Cancer: A Meta-Analysis

PurposeOral fluoropyrimidine (S-1, capecitabine) has been considered as an important part of various regimens. We aimed to evaluate the efficacy and safety of S-1-based therapy versus capecitabine -based therapy in gastrointestinal cancers.MethodsEligible studies were identified from Pubmed, EMBASE. Additionally, abstracts presented at American Society of Clinical Oncology (ASCO) conferences held between 2000 and 2013 were searched to identify relevant clinical trials. The outcome included overall survival (OS), progression-free survival (PFS), overall response rate (ORR), disease control rate (DCR) and advent events.ResultsA total of 6 studies (4 RCTs and 2 retrospective analysis studies) containing 790 participants were included in this meta-analysis, including 401 patients in the S-1-based group and 389 patients in the capecitabine-based group. Results of our meta-analysis indicated that S-1-based and capecitabine-based regimens showed very similar efficacy in terms of PFS (HR 0.92, 95% CI 0.78–1.09, P = 0.360), OS (HR 1.01, 95% CI 0.84–1.21, P = 0.949), ORR (HR 1.04, 95% CI 0.87–1.25, P = 0.683) and DCR (HR 1.02, 95% CI 0.94–1.10, P = 0.639). There was also no significant difference in toxicity between regimens other than mild more hand–foot syndrome in capecitabine-based regimens.ConclusionBoth the S-1-based and capecitabine-based regimens are equally active and well tolerated, and have the potential of backbone chemotherapy regimen in further studies of gastrointestinal cancers.

Risk of anti-EGFR monoclonal antibody-related skin rash: an up-to-date meta-analysis of 25 randomized controlled trials

Purpose:To assess the risk of severe skin rash in cancer patients treated with anti-epidermal growth factor receptor (EGFR)-monoclonal antibodies (MoAbs).Methods:Databases from PubMed, Web of Science, and abstracts presented at American Society of Clinical Oncology (ASCO) meeting up to 31 June 2013 were searched to identify relevant studies. Eligible studies included prospective randomized controlled trials (RCTs) evaluating MoAbs in cancer patients with adequate data on skin rash and/or acne-like skin rash.Results:A total of 14 270 patients from 25 RCTs were included. The overall incidences of all-grade and high-grade rash were, respectively, as follows: skin rash – 55·4 and 10·5%, and acne-like skin rash – 71·9 and 13·3%. Patients who received MoAbs significantly increased the risk of developing all-grade and high-grade skin rash and acne-like skin rash. Meta-regression indicated that the odds ratio (OR) of high-grade skin rash tended to be higher in the study in which the MoAbs treatment was longer. Additionally, similar results were observed in prespecified subgroup analysis.Conclusions:In patients with advanced solid tumors, EGFR-MoAbs are associated with an increased risk of developing skin rash and acne-like skin rash, and the risk tends to be associated with EGFR-MoAbs treatment duration. Adequate monitoring and early intervention are recommended to prevent decreased quality of life (QoL) and inconsistent dosing.

Upper gastrointestinal cancer: POST ASCO 2013

Overall survival of patients suffering from upper gastrointestinal (GI) cancer is still poor. Most of the patients are diagnosed in advanced stages. But even in patients with operable disease, the recurrence rates, especially of gastric and pancreatic neoplasias, are still very high. Much effort has therefore been put in the development of palliative and curative therapeutic concepts. The aim of this article is to summarize the most important publications presented at American Society of Clinical Oncology (ASCO) 2013 concerning gastric and pancreatic cancer with the main focus on relevance for clinical practice.

Correlation Between Financial Relationships With Commercial Interests and Research Prominence at an Oncology Meeting

Little is known about the effects of financial relationships between biomedical researchers and industry (financial conflicts of interest [FCOIs]) on research prominence. We examined the prevalence of FCOIs in oncology and associations between FCOIs and research prominence among abstracts presented at American Society of Clinical Oncology (ASCO) annual meetings. We analyzed 20,718 abstracts presented at ASCO meetings in 2006 and 2008 to 2011. Measures included the following: financial relationships, peer review score (PRS), and meeting placement prominence (descending order of prominence: plenary session, clinical science symposium, oral presentation, poster discussion, general posters, and publish only). Of 20,718 abstracts, 36% reported at least one author with an FCOI. The proportion of abstracts with any FCOI increased from 33% in 2006 to 38% in 2011 (P < .001). Abstracts with FCOIs had significantly higher meeting prominence compared with publish only and general poster abstracts. The odds ratios compared with general posters were 7.3 for plenary session, 2.2 for clinical science symposium, 1.9 for oral presentation, and 1.7 for poster discussion (P < .001). Abstracts with FCOIs had significantly better PRSs compared with those without FCOIs. For all abstracts, PRS was 2.76 (95% CI, 2.75 to 2.77) with FCOIs compared with 3.01 (95% CI, 3.001 to 3.02) without FCOIs (P < .001). Omitting publish-only abstracts, PRS was 2.62 (95% CI, 2.61 to 2.63) with FCOIs compared with 2.73 without FCOIs (95% CI, 2.71 to 2.73). Abstracts with FCOIs had more prominent meeting placement and better PRSs. FCOIs were reported more frequently by year, suggesting an increasing influence of industry on cancer research, greater disclosure, or both.

S-1-based therapy versus 5-FU-based therapy in advanced gastric cancer: a meta-analysis

We set out to evaluate the efficacy and safety of S-1-based therapy versus fluorouracil (5-FU)-based therapy in advanced gastric cancer (AGC). Eligible studies were identified from Pubmed, EMBASE, and Cochrane Library. Additionally, abstracts presented at American Society of Clinical Oncology (ASCO) conferences held between January 2000 and November 2009 were searched to identify relevant clinical trials. The outcome included overall survival (OS), overall response rate (ORR), and grade 3/4 advent events. Four randomized controlled trials (one full text and three abstracts) with 2,115 participants in AGC were identified in our analysis(1,065 patients were in the S-1-based group, 1,050 patients were in the 5-FU-based group). Meta-analysis showed there was significant OS benefit in favor of S-1-based therapy (hazard ratio [HR]=0.87, 95% confidence interval [CI]: 0.79 to 0.96). Pooled estimate for ORR showed no significant difference between S-1-based group and 5-FU-based group (OR=1.25, 95%CI: 0.31 to 5.09). Lower incidence of grade 3/4 neutropenia was observed in patients with S-1-based therapy (OR=0.33, 95%CI: 0.25 to 0.44). With regard to grade 3/4 anemia (OR=1.20, 95%CI: 0.74 to 1.96), leucopenia (OR=1.09, 95%CI: 0.43 to 2.74), stomatitis (OR=2.65, 95%CI: 0.12 to 58.89), diarrhea (OR=0.53, 95% CI: 0.00 to 229.10), nausea (OR=1.36, 95%CI: 0.68 to 2.72), and treatment-related deaths (OR=1.84, 95%CI: 0.95 to 3.54), equivalent frequencies were found between groups. S-1-based therapy significantly improved OS in relation to 5-FU-based therapy. ORR and safety profile were considerable between two groups. These results needed to be confirmed by high-quality trials and further studies in the West.

Consistency of Phase III Clinical Trial Abstracts Presented at an Annual Meeting of the American Society of Clinical Oncology Compared With Their Subsequent Full-Text Publications

This study aimed to determine the consistency of phase III clinical trial abstracts presented at American Society of Clinical Oncology (ASCO) Annual Meetings compared with their subsequent full-text publications. We identified abstracts describing phase III clinical trials of chemotherapy, chemoradiotherapy, immunotherapy, and hormone therapy presented at the 36th ASCO Annual Meeting in May 2000. We searched MEDLINE and PubMed for all corresponding publications. Data were extracted from the abstracts and publications that met our inclusion criteria. A total of 192 abstracts were identified. Seventy-four abstracts met our inclusion criteria. Six years after the 2000 ASCO Meeting, 74% of abstracts had corresponding publications. The primary end point was stated in 34% of abstracts and 100% of published papers. The primary end point result differed by more than 5% between the abstract and publication in 42% of comparisons. The statistical significance of the primary end point and study conclusions were consistent between abstracts and subsequent publications in 89% and 91% of the comparisons, respectively. Abstracts selected as plenary or oral presentations were significantly more likely to be published. No factors predicted consistency for primary end point significance and overall conclusion between ASCO abstracts and their journal publications. When carefully selected, ASCO Annual Meeting abstracts of phase III trials consistently reflect final published results, but some differences were observed that warrant caution in using abstract results to shape treatment decisions before full publication.

Statistical Power of Negative Randomized Controlled Trials Presented at American Society for Clinical Oncology Annual Meetings

To investigate the prevalence of underpowered randomized controlled trials (RCTs) presented at American Society of Clinical Oncology (ASCO) annual meetings. We surveyed all two-arm phase III RCTs presented at ASCO annual meetings from 1995 to 2003 for which negative results were obtained. Post hoc calculations were performed using a power of 80% and an alpha level of .05 (two sided) to determine sample sizes required to detect small, medium, and large effect sizes. For studies reporting a proportion or time-to-event as primary end point, effect size was expressed as an odds ratio (OR) or hazard ratio (HR), respectively, with a small effect size defined as OR/HR >or= 1.3, medium effect size defined as OR/HR >or= 1.5, and large effect size defined as OR/HR >or= 2.0. Logistic regression was used to identify factors associated with lack of statistical power. Of 423 negative RCTs for which post hoc sample size calculations could be performed, 45 (10.6%), 138 (32.6%), and 233 (55.1%) had adequate sample size to detect small, medium, and large effect sizes, respectively. Only 35 negative RCTs (7.1%) reported a reason for inadequate sample size. In a multivariable model, studies that were presented at oral sessions (P = .0038), multicenter studies supported by a cooperative group (P < .0001), and studies with time to event as primary outcome (P < .0001) were more likely to have adequate sample size. More than half of negative RCTs presented at ASCO annual meetings do not have an adequate sample to detect a medium-size treatment effect.