Augmenting control arms with real-world data for cancer trials: Hybrid control arm methods and considerations.

Background: Hybrid controlled trials with real-world data (RWD), where the control arm is composed of both trial and real-world patients, could facilitate research when the feasibility of randomized controlled trials (RCTs) is challenging and single-arm trials would provide insufficient information. Methods: We propose a frequentist two-step borrowing method to construct hybrid control arms. We use parameters informed by a completed randomized trial in metastatic triple-negative breast cancer to simulate the operating characteristics of dynamic and static borrowing methods, highlighting key trade-offs and analytic decisions in the design of hybrid studies. Results: Simulated data were generated under varying residual-bias assumptions (no bias: HRRWD = 1) and experimental treatment effects (target trial scenario: HRExp = 0.78). Under the target scenario with no residual bias, all borrowing methods achieved the desired 88% power, an improvement over the reference model (74% power) that does not borrow information externally. The effective number of external events tended to decrease with higher bias between RWD and RCT (i.e. HRRWD away from 1), and with weaker experimental treatment effects (i.e. HRExp closer to 1). All dynamic borrowing methods illustrated (but not the static power prior) cap the maximum Type 1 error over the residual-bias range considered. Our two-step model achieved comparable results for power, type 1 error, and effective number of external events borrowed compared to other borrowing methodologies. Conclusion: By pairing high-quality external data with rigorous simulations, researchers have the potential to design hybrid controlled trials that better meet the needs of patients and drug development.

Enhancing Radioiodine Incorporation in BRAF-Mutant, Radioiodine-Refractory Thyroid Cancers with Vemurafenib and the Anti-ErbB3 Monoclonal Antibody CDX-3379: Results of a Pilot Clinical Trial.

Background: Oncogenic activation of mitogen-activated protein kinase (MAPK) signaling is associated with radioiodine refractory (RAIR) thyroid cancer. Preclinical models suggest that activation of the receptor tyrosine kinase erbB-3 (HER3) mitigates the MAPK pathway inhibition achieved by BRAF inhibitors in BRAFV600E mutant thyroid cancers. We hypothesized that combined inhibition of BRAF and HER3 using vemurafenib and the human monoclonal antibody CDX-3379, respectively, would potently inhibit MAPK activation and restore radioactive iodine (RAI) avidity in patients with BRAF-mutant RAIR thyroid cancer. Methods: Patients with BRAFV600E RAIR thyroid cancer were evaluated by thyrogen-stimulated iodine-124 (124I) positron emission tomography-computed tomography (PET/CT) at baseline and after 5 weeks of treatment with oral vemurafenib 960 mg twice daily alone for 1 week, followed by vemurafenib in combination with 1000 mg of intravenous CDX-3379 every 2 weeks. Patients with adequate 124I uptake on the second PET/CT then received therapeutic radioactive iodine (131I) with vemurafenb+CDX-3379. All therapy was discontinued two days later. Treatment response was monitored by serum thyroglobulin measurements and imaging. The primary endpoints were safety and tolerability of vemurafenib+CDX-3379, as well as the proportion of patients after vemurafenb+CDX-3379 therapy with enhanced RAI incorporation warranting therapeutic 131I. Results: Seven patients were enrolled; six were evaluable for the primary endpoints. No grade 3 or 4 toxicities related to CDX-3379 were observed. Five patients had increased RAI uptake after treatment; in 4 patients this increased uptake warranted therapeutic 131I. At 6 months, 2 patients achieved partial response after 131I and 2 progression of disease. Next-generation sequencing of 5 patients showed that all had co-occurring telomerase reverse transcriptase promoter alterations. A deleterious mutation in the SWItch/Sucrose Non-Fermentable (SWI/SNF) gene ARID2 was discovered in the patient without enhanced RAI avidity after therapy and an RAI-resistant tumor from another patient that was sampled off-study. Conclusions: The endpoints for success were met, providing preliminary evidence of vemurafenib+CDX-3379 safety and efficacy for enhancing RAI uptake. Preclinical data and genomic profiling in this small cohort suggest SWI/SNF gene mutations should be investigated as potential markers of resistance to redifferentiation strategies. Further evaluation of vemurafenib+CDX-3379 as a redifferentiation therapy in a larger trial is warranted (ClinicalTrials.gov: NCT02456701).

The experience of financial toxicity among advanced melanoma patients treated with immunotherapy.

Purpose To measure financial toxicity and explore its association with quality of life (QOL) in an emerging population of survivors: advanced melanoma patients treated with immunotherapy. Design Cross-sectional survey and medical record review. Sample 106 survivors (39% response). Median time since start of immunotherapy was 36.4 months (range: 14.2-133.9). Methods The Comprehensive Score for Financial Toxicity measured financial toxicity, and the EORTC-QLQ30 assessed QOL and functioning across five domains. Data were collected online, by phone, or in clinic. Findings: Younger patients (<65 years) reported higher financial toxicity (p < .001) than older patients. Controlling for age, financial toxicity was correlated with QOL (p < .001), financial difficulties (p < .001), and EORTC-QLQ30 functioning subscales. Conclusions Given the demonstrated association between financial toxicity and QOL, our study highlights the importance of addressing financial toxicity, particularly among patients receiving high-cost treatments. Implications for Psychosocial Providers: Providers should educate patients and their caregivers about cost-management techniques, link them with available resources, and provide psychosocial counseling to alleviate related distress.

Using electronic health record data to identify comparator populations for comparative effectiveness research.

Electronic health records (EHRs) can define real world patient populations with high levels of clinical specificity, potentially addressing some of the shortcomings of other types of real world data (RWD) when informing decisions about the comparative effectiveness of medical technologies. An important but under-recognized concern for EHR-derived RWD, however, is that the rich clinical data permits creation of very homogenous subpopulations from the larger group of eligible patients, thereby reducing the representativeness of the cohort relative to clinical practice. In this article, we discuss the tradeoffs between choosing clinical specificity versus representativeness in population sampling for comparative effectiveness research. Using EHR-derived RWD, we provide an example in non-small cell lung cancer to illustrate the concepts, showing wide variation in outcomes among potential comparator cohorts. We close with several recommendations for selecting comparator populations from EHRs that address the balance between matching clinical guidelines and capturing practice variability in comparative effectiveness research.

Letting the GENIE Out of Its Bottle: Examining the Potential of Real-World Clinicogenomic Data.

In this issue, Smyth and colleagues investigate the natural history of AKT1-mutant metastatic breast cancer using the AACR Project GENIE, a novel research platform comprised of real-world, clinicogenomic data. A rare subset of tumors, AKT1-mutant breast cancers demonstrated similar clinical and demographic characteristics and overall survival as AKT1-wild-type tumors, but a longer duration of therapy on mTOR inhibitors.See related article by Smyth et al., p. 526.

Quality of life in long-term survivors of advanced melanoma treated with checkpoint inhibitors.

BACKGROUND: Immune checkpoint inhibitors (CIs) have revolutionized treatment of advanced melanoma, leading to an emerging population of long-term survivors. Survivors' quality of life (QOL) and symptom burden are poorly understood. We set out to evaluate symptom burden and QOL in patients with advanced melanoma alive more than 1 year after initiating CI therapy. METHODS: Cross-sectional surveys, accompanied by chart review of patients with advanced melanoma treated with CIs at Memorial Sloan Kettering Cancer Center, completed therapy, and were alive >1 year after treatment initiation. Surveys were administered between February and August 2018. Surveys included: European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30, EuroQOL, items from Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events and Fatigue Severity Scale. RESULTS: We included 90 patients. The most common CI regimens were ipilimumab plus nivolumab (53%) and pembrolizumab (41%); most patients (71%) were not treated in clinical trials. Median time from CI therapy initiation was 40 months and from last dose was 28 months. Fatigue was reported by 28%, with higher fatigue scores in women than men; 12% reported difficulty sleeping. Aching joints (17%) and muscles (12%) were fairly common. Level of functioning was generally high. Overall QOL was excellent though 40% reported 'some or moderate' problems with anxiety/depression and 31% with pain/discomfort. CONCLUSIONS: After CI therapy, long-surviving advanced melanoma patients commonly report fatigue but otherwise have moderate symptom burden and good QOL. Ensuring appropriate symptom management will optimize clinical outcomes for these patients.

A Phase 1b Study of Cetuximab and BYL719 (Alpelisib) Concurrent with Intensity Modulated Radiation Therapy in Stage III-IVB Head and Neck Squamous Cell Carcinoma.

PURPOSE: Activation of the PI3K/mTOR signaling pathway is common in head and neck squamous cell carcinoma (HNSCC). BYL719 is an α-specific PI3K inhibitor that is synergistic and efficacious when combined with cetuximab, a Food and Drug Administration-approved radiosensitizing agent in the treatment of HNSCC. The agent independently has been shown to enhance radiosensitivity. This study evaluates the addition of BYL719 to cetuximab and radiation in the treatment of locally advanced HNSCC. METHODS AND MATERIALS: This is a single-institution, phase 1 study. Patients with American Joint Committee on Cancer seventh edition stage III to IVB HNSCC received standard cetuximab (400 mg/m2 intravenous loading dose) before intensity modulated radiation therapy (IMRT) followed by 250 mg/m2 weekly infusions during IMRT. BYL719 was given orally during IMRT in 3 dose levels: (1) 200 mg/d, (2) 250 mg/d, or (3) 300 mg/d in a standard 3 + 3 dose-escalation design. RESULTS: Eleven patients were evaluable. Dose level 2 was the maximum tolerated dose for BYL719. Two patients on dose level 3 had dose-limiting toxicities of oral mucositis that required a dose reduction of BYL719. One patient on dose level 2 had a dose-limiting toxicity of nausea that led to withdrawal of on-study treatment. Related grade 3 or higher adverse events consisted of decreased lymphocyte count, oral mucositis, dysphagia, hyperglycemia, maculopapular rash, and palmar-plantar erythrodysesthesia syndrome. All 11 patients had a complete response on posttreatment imaging, and 10 remain disease free. Of the 8 patients with mutational analysis, 1 had an activating PIK3CA mutation associated with a rapid response on serial intratreatment magnetic resonance imaging scans. CONCLUSIONS: The recommended phase 2 dose of BYL719 is 250 mg/d in combination with cetuximab and IMRT in patients with locally advanced HNSCC. Further evaluation of the addition of BYL719 to the platinum-sparing regimen of cetuximab and IMRT in the treatment of locally advanced HNSCC is warranted.

First-line immune checkpoint inhibitor use in cisplatin-eligible patients with advanced urothelial carcinoma: a secular trend analysis.

Aim: Standard first-line treatment of advanced urothelial cell carcinoma involves cisplatin-based chemotherapy, with carboplatin or immune checkpoint inhibitor therapy (ICI) reserved for cisplatin-ineligible individuals. Methods: Using a large de-identified electronic health record-derived database of patients with advanced urothelial cell carcinoma in the USA, we examined trends in utilization of first-line systemic therapies in cisplatin-eligible patients from 1 January 2015 to 31 March 2018. Results: Among 1181 cisplatin-eligible patients, the quarterly proportion who received first-line ICI increased from 1 to 42% (ptrend <0.001), while the proportion who received cisplatin-based chemotherapy decreased from 53 to 33% (ptrend = 0.018). Patients receiving ICI were older than those receiving cisplatin (median age: 75 vs 68). Conclusion: Our analysis suggests rising off-label ICI use in cisplatin-eligible individuals, potentially because of ICI's favorable toxicity profile.

Phase 2 study of vascular endothelial growth factor trap for the treatment of metastatic thyroid cancer.

BACKGROUND: Several multitargeted tyrosine kinase inhibitors (TKIs) have demonstrated activity in patients with thyroid cancer that is refractory to radioactive iodine (RAI). The antitumor effect is attributed at least in part to the ability of these TKIs to inhibit angiogenesis in these vascular tumors. Vascular endothelial growth factor (VEGF) Trap (VT) is a recombinantly produced fusion protein consisting solely of human sequences for VEGF receptors 1 and 2 extracellular domains and human immunoglobulin 1. Evaluating VT in patients with thyroid cancer is reasonable considering the activity observed with TKIs targeting VEGF. METHODS: The current study was a single-institution, phase 2, Simon 2-stage design (21 to >41 patients) study based on the objective response rate and/or 6-month progression-free survival as the primary endpoints. Eligible patients were required to have progressive, RAI-refractory and/or [18 F]fludeoxyglucose-avid, recurrent and/or metastatic, nonmedullary, nonanaplastic thyroid cancer; disease that was measurable using Response Evaluation Criteria In Solid Tumors (RECIST) criteria; and adequate organ and bone marrow function. VT at a dose of 4 mg/kg intravenously was administered every 14 days. RESULTS: A total of 40 patients were included in the analysis. Of these patients, 24 had papillary thyroid cancer, 2 had follicular thyroid cancer, and 11 had Hurthle cell thyroid cancer. The final 3 tumors were classified as poorly differentiated. There were no complete and/or partial responses noted; 34 patients achieved stable disease and 6 patients experienced disease progression as their best response. Of the 34 patients with stable disease, 16 remained on the study for >6 months and 6 patients remained on the study for >12 months. The median duration on treatment was 4.1 months (range, 0.6-30.8 months). CONCLUSIONS: Unlike TKIs, which have shown responses in this setting, to the authors' knowledge there have been no responses observed with the use of single-agent VT to date. It does not appear to be a promising drug for the treatment of patients with thyroid cancer.

Automating Treatment Summary Development Using Electronic Billing Information: A Pilot Study of Survivors of Head and Neck Cancer.

PURPOSE: Although the provision of a treatment summary (TS) is a quality indicator in oncology, routine delivery of TSs remains challenging. Automatic TS generation could facilitate use, but data on accuracy are lacking in complex cancers such as head and neck cancer (HNC). We developed and evaluated an electronic platform to automate TS generation for HNC. METHODS: The algorithms autopopulated TSs using data from billing records and an institutional cancer registry. A nurse practitioner used the medical record to verify the accuracy of the information and made corrections electronically. Inaccurate and missing data were considered errors. We described and investigated reasons for errors in the automatically generated TSs. RESULTS: We enrolled a heterogeneous population of 43 survivors of HNC. Using billing data, the information on primary site, lymph node status, radiation, and chemotherapy use was accurate in 93%, 95%, 93%, and 95% of patients, respectively. Billing data captured surgery accurately in 77% of patients; once an omitted billing code was identified, accuracy increased to 98%. Chemotherapies were captured in 90% of patients. Using the cancer registry, month and year of diagnosis were accurate in 91% of cases; stage was accurate in 28% of cases. Reprogramming the algorithm to ascertain clinical stage when pathologic stage was unavailable resulted in 100% accuracy. The algorithms inconsistently identified radiation receipt and treating physicians from billing data. CONCLUSION: It is feasible to automatically and accurately generate most components of TSs for HNC using billing and cancer registry data, although clinical review is necessary in some cases.

Vemurafenib Redifferentiation of BRAF Mutant, RAI-Refractory Thyroid Cancers.

CONTEXT: BRAFV600E mutant thyroid cancers are often refractory to radioiodine (RAI). OBJECTIVES: To investigate the utility and molecular underpinnings of enhancing lesional iodide uptake with the BRAF inhibitor vemurafenib in patients with RAI-refractory (RAIR). DESIGN: This was a pilot trial that enrolled from June 2014 to January 2016. SETTING: Academic cancer center. PATIENTS: Patients with RAIR, BRAF mutant thyroid cancer. INTERVENTION: Patients underwent thyrotropin-stimulated iodine-124 (124I) positron emission tomography scans before and after ~4 weeks of vemurafenib. Those with increased RAI concentration exceeding a predefined lesional dosimetry threshold (124I responders) were treated with iodine-131 (131I). Response was evaluated with imaging and serum thyroglobulin. Three patients underwent research biopsies to evaluate the impact of vemurafenib on mitogen-activated protein kinase (MAPK) signaling and thyroid differentiation. MAIN OUTCOME MEASURE: The proportion of patients in whom vemurafenib increased RAI incorporation to warrant 131I. RESULTS: Twelve BRAF mutant patients were enrolled; 10 were evaluable. Four patients were 124I responders on vemurafenib and treated with 131I, resulting in tumor regressions at 6 months. Analysis of research tumor biopsies demonstrated that vemurafenib inhibition of the MAPK pathway was associated with increased thyroid gene expression and RAI uptake. The mean pretreatment serum thyroglobulin value was higher among 124I responders than among nonresponders (30.6 vs 1.0 ng/mL; P = 0.0048). CONCLUSIONS: Vemurafenib restores RAI uptake and efficacy in a subset of BRAF mutant RAIR patients, probably by upregulating thyroid-specific gene expression via MAPK pathway inhibition. Higher baseline thyroglobulin values among responders suggest that tumor differentiation status may be a predictor of vemurafenib benefit.

Long-term quality of life in older patients with HPV-related oropharyngeal cancer.

BACKGROUND: We explored if age affects quality of life (QOL) in survivors of locally advanced human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (SCC). METHODS: In a cross-sectional survey of 185 patients, at least 12 months from radiation, we evaluated generic (EuroQOL-5D questionnaire [EQ-5D]) and head and neck specific (European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Head and Neck 35-questions [EORTC-QLQ-H&N35]) QOL questionnaires and compared differences between younger (<65) and older (≥65) patients. RESULTS: The median age was 57.0 years (range 25-77 years), and 31 patients (16.8%) were ≥65 years old. There was no significant difference in EQ-5D global QOL scores by age (P = .53). Patients ≥65 years reported more immobility (P < .01), problems with social eating (P < .0001), and coughing (P < .01). Patients ≥65 years were not more likely to ever require a gastrostomy (P = .24) but were more likely to remain gastrostomy-dependent at the time of the survey (P = .02). CONCLUSION: Despite similar generic QOL, older survivors may have more mobility problems and issues with social eating compared with younger survivors deserving of further evaluation.

OncoKB: A Precision Oncology Knowledge Base.

PURPOSE: With prospective clinical sequencing of tumors emerging as a mainstay in cancer care, there is an urgent need for a clinical support tool that distills the clinical implications associated with specific mutation events into a standardized and easily interpretable format. To this end, we developed OncoKB, an expert-guided precision oncology knowledge base. METHODS: OncoKB annotates the biological and oncogenic effect and the prognostic and predictive significance of somatic molecular alterations. Potential treatment implications are stratified by the level of evidence that a specific molecular alteration is predictive of drug response based on US Food and Drug Administration (FDA) labeling, National Comprehensive Cancer Network (NCCN) guidelines, disease-focused expert group recommendations and the scientific literature. RESULTS: To date, over 3000 unique mutations, fusions, and copy number alterations in 418 cancer-associated genes have been annotated. To test the utility of OncoKB, we annotated all genomic events in 5983 primary tumor samples in 19 cancer types. Forty-one percent of samples harbored at least one potentially actionable alteration, of which 7.5% were predictive of clinical benefit from a standard treatment. OncoKB annotations are available through a public web resource (http://oncokb.org/) and are also incorporated into the cBioPortal for Cancer Genomics to facilitate the interpretation of genomic alterations by physicians and researchers. CONCLUSION: OncoKB, a comprehensive and curated precision oncology knowledge base, offers oncologists detailed, evidence-based information about individual somatic mutations and structural alterations present in patient tumors with the goal of supporting optimal treatment decisions.

Phase 2 study evaluating the combination of sorafenib and temsirolimus in the treatment of radioactive iodine-refractory thyroid cancer.

BACKGROUND: Patients with recurrent and/or metastatic, radioactive iodine-refractory thyroid carcinoma have limited treatment options. Sorafenib, an oral kinase inhibitor, is approved by the US Food and Drug Administration for the treatment of radioactive iodine-refractory thyroid carcinoma, although it demonstrated low response rates (12.2%) as a single agent in the first-line setting. The objective of the current study was to determine whether adding the mammalian target of rapamycin inhibitor temsirolimus to sorafenib could improve on these results. METHODS: In this single-institution, phase 2 study, 36 patients with metastatic, radioactive iodine-refractory thyroid carcinoma of follicular origin received treatment with the combination of oral sorafenib (200 mg twice daily) and intravenous temsirolimus (25 mg weekly). The receipt of prior systemic treatment with cytotoxic chemotherapy and targeted therapy, including sorafenib, was permitted. The primary endpoint was the radiographic response rate. RESULTS: The best response was a partial response in 8 patients (22%), stable disease in 21 (58%), and progressive disease in 1 (3%). Six patients were not evaluable for a response. Patients who had received any prior systemic treatment had a response rate of 10% compared with 38% of those who had not received prior systemic treatment. One of 2 patients with anaplastic thyroid cancer had an objective response. The progression-free survival rate at 1 year was 30.5%. The most common grade 3 and 4 toxicities associated with sorafenib and temsirolimus included hyperglycemia, fatigue, anemia, and oral mucositis. CONCLUSIONS: Sorafenib and temsirolimus appear to be an active combination in patients with radioactive iodine-refractory thyroid carcinoma, especially in patients who received no prior treatment compared with historic data from single-agent sorafenib. Activity is also observed in patients who previously received sorafenib. This regimen warrants further investigation. Cancer 2017;123:4114-4121. © 2017 American Cancer Society.

Variation in use of postoperative chemoradiation following surgery for T1 and T2 oropharyngeal squamous cell carcinoma; National Cancer Database.

BACKGROUND AND OBJECTIVES: Primary surgical treatment of patients with early T-classification (T1-T2) oropharyngeal squamous cell carcinoma (OPSCC) has increased. We sought to determine how often these patients receive postoperative chemoradiation (CRT). METHODS: Patients with T1-T2 OPSCC in the National Cancer Database who underwent primary surgery were evaluated for receipt of postoperative CRT. Postoperative CRT use was examined among patients with high risk factors (positive margins and/or extracapsular spread [ECS]), intermediate risk factors (negative margins, no ECS, and either pT3-4 and/or N2-N3), and no apparent risk factors. RESULTS: Of 4833 patients with T1-T2 OPSCC who underwent primary surgery, 43% had high risk pathologic factors, of whom only 63% received postoperative CRT. Another 31% had no apparent risk factors, of whom 16% nonetheless received postoperative CRT. On multivariable analysis, in addition to tumor and demographic factors, patients treated at community hospitals were more likely to receive postoperative CRT (O.R. 1.41 C.I. 1.18-1.87, P = 0.001). CONCLUSIONS: Variation in postoperative CRT use indicates a lack of consensus and/or knowledge about its benefits and indications. Usage of postoperative CRT regardless of pathologic risk factors suggests an area where future efforts at implementation of best practices may be targeted.

Overuse of Health Care Services in the Management of Cancer: A Systematic Review.

BACKGROUND: Overuse, the provision of health services for which harms outweigh the benefits, results in suboptimal patient care and may contribute to the rising costs of cancer care. We performed a systematic review of the evidence on overuse in oncology. METHODS: We searched Medline, EMBASE, the Cochrane Library, Web of Science, SCOPUS databases, and 2 grey literature sources, for articles published between December 1, 2011 and March 10, 2017. We included publications from December 2011 to evaluate the literature since the inception of the ABIM Foundation's Choosing Wisely initiative in 2012. We included original research articles quantifying overuse of any medical service in patients with a cancer diagnosis when utilizing an acceptable standard to define care appropriateness, excluding studies of cancer screening. One of 4 investigator reviewed titles and abstracts and 2 of 4 reviewed each full-text article and extracted data. Methodology used PRISMA guidelines. RESULTS: We identified 59 articles measuring overuse of 154 services related to imaging, procedures, and therapeutics in cancer management. The majority of studies addressed adult or geriatric patients (98%) and focused on US populations (76%); the most studied services were diagnostic imaging in low-risk prostate and breast cancer. Few studies evaluated active cancer therapeutics or interventions aimed at reducing overuse. Rates of overuse varied widely among services and among studies of the same service. CONCLUSIONS: Despite recent attention to overuse in cancer, evidence identifying areas of overuse remains limited. Broader investigation, including assessment of active cancer treatment, is critical for identifying improvement targets to optimize value in cancer care.

Quality of Cancer Surveillance Clinical Practice Guidelines: Specificity and Consistency of Recommendations.

Importance: Primary care clinicians, who are increasingly responsible for caring for the growing population of cancer survivors, may be unfamiliar with appropriate cancer surveillance strategies. Clinical practice guidelines can inform cancer follow-up care and surveillance testing. Vague recommendations and inconsistencies among guidelines can lead to overuse and underuse of health care resources and have a negative impact on cost and quality of survivorship care. Objective: To examine the specificity and consistency of recommendations for surveillance after active treatment across cancer guidelines. Design, Setting, and Participants: Retrospective cross-sectional analysis of national cancer guidelines from North America and Europe published since 2010 addressing posttreatment care for survivors of the 9 most common cancers. We categorized surveillance modalities into history and physical examinations, tumor markers, diagnostic procedures (eg, colonoscopy), and imaging. Within each guideline, we classified individual recommendations into 5 categories: (1) risk-based recommendation, (2) recommendation for surveillance, (3) addressed but no clear recommendation, (4) recommendation against surveillance, or (5) cases in which surveillance was not addressed. We reviewed each surveillance recommendation for frequency and a stop date, evaluated consistency among guidelines, and analyzed associations between the organizations proposing the guidelines and recommendation characteristics. Main Outcomes and Measures: Description of guideline recommendations for cancer surveillance. Results: We identified 41 guidelines published between January 1, 2010, and March 1, 2016. Eighty-five percent of guidelines (35) were from professional organizations. Ambiguous recommendations (ie, modality not discussed or discussed without a clear recommendation) were present in 83% of guidelines (34), and 44% (18) recommended against at least 1 test. European guidelines were more likely than North American guidelines to contain ambiguous recommendations (100% vs 68%; P < .01). Recommendations commonly specified testing frequency (from 88% [14 of 16] for tumor markers to 92% [24 of 26] for procedures and/or imaging) but infrequently provided a definitive stop time. Cross-sectional imaging recommendations varied among guidelines for each cancer. For example, among breast cancer guidelines, surveillance computed tomographic scans were recommended against in 2, discussed without a clear recommendation in 1, and not addressed in 3 guidelines. Conclusions and Relevance: Guidelines addressing the care of cancer survivors have low specificity and consistency. As guidelines continue to be revised, developers should clarify recommendations with simple, nonambiguous, definitive language for or against the use of specific tests to optimize care quality and resource utilization.