David W Cescon

The Princess Margaret Hospital, Toronto, Ontario, Canada

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Publications (14)159.83 Total impact

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    ABSTRACT: Hormone receptor positive breast cancer is characterized by the potential for disease recurrence many years after initial diagnosis. Endocrine therapy has been shown to reduce the risk of such recurrence, but the optimal duration of endocrine therapy remains unclear. We conducted a systematic review and meta-analysis to quantify the benefits and harms of extended adjuvant tamoxifen (>5 years of therapy) compared with adjuvant tamoxifen (5 years of therapy). Odds ratios (ORs) and 95% confidence intervals (CIs) were computed for disease recurrence, death and adverse events. Subgroup analyses by timing of recurrence and baseline lymph node and menopause status were carried. Five trials comprising 21,554 patients were included. Extended adjuvant tamoxifen was not associated with a significant reduction in the risk of recurrence (OR:0.89, 95% CI 0.76-1.05, p = 0.17). There was no association between extended adjuvant tamoxifen and all-cause death (OR:0.99, 95% CI 0.84-1.16, p = 0.88). There was an apparent reduction in risk of recurrence occurring after completion of extended adjuvant tamoxifen with little evidence of effect during therapy, however, this difference was not significant (p for difference 0.10). Subgroup analysis suggested that a greater effect size among lymph node positive patients compared with those who are lymph node negative (NNT: 25 vs. 49). There was no apparent difference in the effect between pre- and post-menopausal patients. Endometrial carcinoma was substantially more frequent with extended adjuvant tamoxifen (OR:2.06, 95% CI 1.65-2.58, p<0.001, number needed to harm:89). In unselected patients, extended adjuvant tamoxifen is not associated with a significant reduction in recurrence, or a reduction in all-cause death. Patients with lymph node positive breast cancer may derive some benefit. Reduction in the risk of recurrence appears to occur only after completion of extended adjuvant therapy.
    PLoS ONE 01/2014; 9(2):e88238. · 3.53 Impact Factor
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    ABSTRACT: BACKGROUND AND AIMS: Although gastroesophageal reflux disease (GERD) is a risk factor for esophageal adenocarcinoma (EAC), some patients develop EAC in the absence of GERD. A putative mechanism of reflux-induced tumorigenesis involves disruptions in the p53 pathway. We assessed the interaction of GERD and p53 pathway polymorphisms on EAC prognosis. METHODS: In a prospective cohort of 358 EAC patients, clinical data (including GERD history and survival) were collected. Germline DNA was genotyped for MDM2 T309G and p53 Arg72Pro. Cox proportional hazards models were used to determine adjusted hazard ratios (AHR) for associations between genotype, GERD, and genotype-GERD interactions with survival. RESULTS: Compared with other genotypes, MDM2 G/G (median overall survival 21 versus 30 months; p<0.001) and p53 Pro/Pro (12 versus 30 months; p=0.004) were associated with shorter survival. When analyzed by GERD, MDM2 G/G was associated with shorter survival in patients without GERD (AHR 3.4, 95% C.I. 2.0-6.0), but not in patients with GERD (AHR 1.1 (0.7-1.8)); the MDM2-GERD interaction was significant (p=0.003). A similar trend was seen for p53 Pro/Pro (AHRs 2.5 without GERD versus 1.4 with GERD). Combined analysis of at-risk variants (MDM2 G or p53 Pro), revealed each additional at-risk variant was associated with shorter survival in patients without GERD (AHR 1.6), but not with GERD (AHR 1.0). CONCLUSIONS: MDM2 G/G and the combination of MDM2 G and p53 Pro were negative prognostic factors for EAC patients without GERD, but not for those with GERD. There may be biological differences between GERD positive and GERD negative EAC.
    Journal of Gastroenterology and Hepatology 06/2013; · 3.33 Impact Factor
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    ABSTRACT: Lung cancer is the leading global cause of cancer-related mortality. Interindividual variability in treatment response and cancer outcomes has focused attention on genetic polymorphisms as prognostic markers. We evaluated the overall contribution of candidate polymorphism association studies to our current understanding of the genetic predictors of lung cancer outcomes. We examined the results of 90 studies that evaluated associations between genetic polymorphisms and lung cancer outcomes published between January 1990 and May 2009. A total of 170 genetic variations in 90 studies were identified. Overall survival was a primary outcome in 81% of the studies and toxicity in 19%. Candidate polymorphisms in the DNA repair/synthesis pathway were the most frequently studied. Strong evidence in large-scale confirmatory studies of any single polymorphism was lacking. Polymorphisms of EGFR, XRCC1, and ERCC1 were associated with pharmacogenetic outcomes, whereas polymorphisms of MDM2, p53, and GSTM1 were associated with prognostic outcomes. All remaining polymorphisms had results lacking or failing replication testing. Heterogeneity in study populations, incomplete reporting of important population or study characteristics, inadequate power, and inconsistencies in methodology were common. Although the quality of existing studies involving the candidate polymorphism approach is highly variable, a small set of candidate polymorphisms was identified as potential biomarkers of clinical or pharmacogenetic outcome and would benefit from further replication testing. Newer approaches including haplotype tagging, pathway, genome-wide association, and combination methods with validative approaches may facilitate a more accurate prediction of lung cancer outcomes by genetic variation.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 02/2011; 6(2):296-304. · 4.55 Impact Factor
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    ABSTRACT: Phase III randomized clinical trials (RCTs) have become larger and are powered to detect small absolute benefits. Temporal changes in absolute benefits of experimental medical therapies reported in RCTs are unknown. We identified all RCTs with sample size > or =200 evaluating experimental medical therapies for breast and colorectal cancer published from 1975 to 2007. We assessed changes over three decades in absolute differences in time-to-event end points between experimental and control arms by (i) the usual method (i.e. at one point) and (ii) as the area between time-to-event curves up to a predefined time. We identified 236 eligible RCTs of which 57% (N = 135) evaluated adjuvant treatments. Experimental treatments became more often compared with active treatments (48% versus 59% versus 81%; P < 0.0001). Median absolute benefits of experimental adjuvant treatments decreased but outcomes in control arms improved with time. For RCTs evaluating metastatic disease, there were no changes in absolute benefit over time but incremental monthly costs of new approved treatments increased with time by 100-fold (P < 0.0001). In RCTs of breast and colorectal cancer, new effective adjuvant treatments show decreasing absolute benefit, while new treatments of metastatic disease show unchanging levels of benefit at rapidly escalating costs.
    Annals of Oncology 11/2009; 21(7):1411-8. · 7.38 Impact Factor
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    ABSTRACT: To assess the frequency, implications, and factors associated with reporting nonfinal analyses (NFAs) of randomized controlled trials (RCTs) as abstract publications. We identified 138 consecutive reports of RCTs testing systemic therapy for lymphoma, breast, colorectal, or non-small-cell lung cancer published in six major journals between 2000 and 2004. We then searched proceedings of seven major cancer meetings, 1990 to 2004, for abstracts related to these publications which presented efficacy results. Articles and abstracts were compared for discordance in sample size, median follow-up, results, and conclusions. Abstracts were evaluated for statements explicitly noting or implying that results were not final. Factors associated with discordance were assessed by uni- and multivariate analyses. We identified 303 related abstracts; 197 were eligible. In 86 abstracts (44%), results were stated or implied to be NFA; this was explicitly stated in 41 (21%). The NFAs included 12 where accrual was ongoing. Discordance with article was found in 124 abstracts (63%) and was more common with NFAs (67 of 86 [78%] v 57 of 111 [51%]; P = .0001). When compared with articles, authors' conclusions were substantively different in 17 abstracts (10%). Factors most associated with data discordance were lymphoma trial (odds ratio [OR], 3.8; 95% CI, 1.5 to 10.8), cooperative group trial (OR, 2.8; 95% CI, 1.4 to 5.6), and presentation of a NFA (OR, 2.9; 95% CI, 1.5 to 5.8). Meeting abstracts often include NFAs and are frequently discordant with subsequent article publication.
    Journal of Clinical Oncology 08/2009; 27(24):3938-44. · 18.04 Impact Factor
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    ABSTRACT: This study aimed to evaluate the prognostic significance of two functional single nucleotide polymorphisms (SNP) in the p53 pathway (p53 Arg72Pro and MDM2 T309G) in patients with esophageal cancer, and to determine the importance of histologic subtype in the SNP-outcome relationships. A cohort of 371 patients with esophageal carcinoma enrolled in Boston, USA from 1999 to 2004 were genotyped for the p53 and MDM2 SNPs. Associations between genotypes and overall survival (OS; the primary outcome) and progression-free survival (PFS) were assessed using the Kaplan-Meier method. Cox proportional hazard models, adjusted for age, stage, performance status, and smoking were developed. Interaction analyses were done for histology (adenocarcinoma versus squamous cell carcinoma). At the median follow-up of 33 months, median survival (MS) and PFS were 29.1 and 15.7 months, respectively. p53 Pro/Pro was strongly associated with shorter survival in the entire cohort (MS of 11.8 versus 29.1 months, P < 0.0001; adjusted hazard ratio for death, 2.05; 95% confidence interval, 1.30-3.24; P = 0.002 for Pro/Pro versus Arg/Arg). MDM2 G/G was associated with markedly reduced survival in squamous cell carcinoma (MS of 10.3 versus 49.4 months; adjusted hazard ratio for death, 7.9; 95% confidence interval, 2.4-26.0; P = 0.0007 for G/G versus T/T) but not in adenocarcinoma (SNP-histology interaction P = 0.004). In a large prospective cohort, p53 Arg72Pro Pro/Pro was associated with a 2-fold increased risk of death in all esophageal cancers, whereas MDM2 T309G G/G was associated with a 7-fold increased risk of death in squamous cell carcinoma.
    Clinical Cancer Research 05/2009; 15(9):3103-9. · 7.84 Impact Factor
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    ABSTRACT: p53 Arg72Pro, MDM2 T309G, and CCND1 G870A are functional single-nucleotide polymorphisms (SNPs) in key genes that regulate apoptosis and cell cycle. Variant genotypes of these SNPs have been associated with increased risk and earlier age of onset in some cancers. We investigated the association of these SNPs with susceptibility to esophageal adenocarcinoma in a large, North American case-control study. Three hundred and twelve cases and 454 cancer-free controls recruited in Boston, USA were genotyped for each of the three SNPs, and demographic and clinical data were collected. Genotype frequencies for each of the three SNPs did not deviate from the Hardy-Weinberg equilibrium, and did not differ between cases and controls. Odds ratios (OR), adjusted for clinical risk factors, for the homozygous variant genotypes were 0.99 (95% confidence interval [CI] 0.57-1.72) for p53 Pro/Pro, 0.81 (95% CI 0.52-1.28) for MDM2 G/G, and 0.97 (95% CI 0.64-1.49) for CCND1 A/A. The analysis was adequately powered (80%) to detect ORs of 1.37, 1.35, and 1.34 for each SNP, respectively. In contrast to the results of smaller published studies, no association between p53 Arg72Pro, MDM2 T309G, and CCND1 G870A SNPs and susceptibility to esophageal adenocarcinoma, age of onset, or stage of disease at diagnosis was detected.
    Diseases of the Esophagus 04/2009; 23(1):36-9. · 1.64 Impact Factor
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    David W Cescon, David N Juurlink
    Canadian Medical Association Journal 02/2009; 180(2):251. · 6.47 Impact Factor
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    ABSTRACT: A patient presented with a small-bowel obstruction associated with signs and symptoms of botulism. Fecal cultures were positive for viable Clostridium botulinum. This case emphasizes the importance of a broad differential diagnosis and doing a complete examination to account for all signs and symptoms.
    Canadian Medical Association Journal 11/2008; 179(9):927-9. · 6.47 Impact Factor
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    ABSTRACT: The randomized controlled trial (RCT) is the gold standard for establishing new therapies in clinical oncology. Here we document changes with time in design, sponsorship, and outcomes of oncology RCTs. Reports of RCTs evaluating systemic therapy for breast, colorectal (CRC), and non-small-cell lung cancer (NSCLC) published 1975 to 2004 in six major journals were reviewed. Two authors abstracted data regarding trial design, results, and conclusions. Conclusions of authors were graded using a 7-point Likert scale. For each study the effect size for the primary end point was converted to a summary measure. A total of 321 eligible RCTs were included (48% breast, 24% CRC, 28% NSCLC). Over time, the number and size of RCTs increased considerably. For-profit/mixed sponsorship increased substantially during the study period (4% to 57%; P < .001). There was increasing use of time-to-event measures (39% to 78%) and decreasing use of response rate (54% to 14%) as primary end point (P < .001). Effect size remained stable over the study period. Authors have become more likely to strongly endorse the experimental arm (P = .017). A significant P value for the primary end point and industry sponsorship were each independently associated with endorsement of the experimental agent (odds ratio [OR] = 19.6, 95% CI, 8.9 to 43.1, and OR = 3.5, 95% CI, 1.6 to 7.5, respectively). RCTs in oncology have become larger and are more likely to be sponsored by industry. Authors of modern RCTs are more likely to strongly endorse novel therapies. For-profit sponsorship and statistically significant results are independently associated with endorsement of the experimental arm.
    Journal of Clinical Oncology 11/2008; 26(33):5458-64. · 18.04 Impact Factor
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    Journal of Clinical Oncology 06/2008; 26(13):2214-5. · 18.04 Impact Factor
  • David W Cescon, Edward Etchells
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    ABSTRACT: Preventable adverse drug events (ADEs) generate an estimated $2 billion in direct hospital costs each year and are a substantial source of morbidity and mortality.1 The 2 processes from which preventable ADEs most commonly arise are medication prescribing and administration. A physician order for penicillin for a patient with a known penicillin allergy is an example of the former, whereas the latter is illustrated by the erroneous administration of 100 units of insulin when 10 were ordered. There has been considerable attention devoted to reducing prescribing error with systematic solutions such as computerized physician order entry, electronic decision support, and pharmacist presence during physician rounds. None of these solutions, however, reduces medication administration errors, which account for 34% of preventable ADEs.2
    JAMA The Journal of the American Medical Association 06/2008; 299(18):2200-2. · 29.98 Impact Factor
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    ABSTRACT: Head and neck cancer (HNC) patients have variable prognoses even within the same clinical stage and while receiving similar treatments. The number of studies of genetic polymorphisms as prognostic factors of HNC outcomes is growing. Candidate polymorphisms have been evaluated in DNA repair, cell cycle, xenobiotic metabolism, and growth factor pathways. Polymorphisms of XRCC1, FGFR, and CCND1 have been consistently associated with HNC survival in at least two studies, whereas most of the other polymorphisms have either conflicting data or were from single studies. Heterogeneity and lack of description of patient populations and lack of accounting for multiple comparisons were common problems in a significant proportion of studies. Despite a large number of exploratory studies, large replication studies in well-characterized HNC populations are warranted.
    Cancer Epidemiology Biomarkers &amp Prevention 04/2008; 17(3):490-9. · 4.56 Impact Factor
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    ABSTRACT: Severe acute respiratory syndrome (SARS) is an emerging infectious disease that first manifested in humans in China in November 2002 and has subsequently spread worldwide. To describe the clinical characteristics and short-term outcomes of SARS in the first large group of patients in North America; to describe how these patients were treated and the variables associated with poor outcome. Retrospective case series involving 144 adult patients admitted to 10 academic and community hospitals in the greater Toronto, Ontario, area between March 7 and April 10, 2003, with a diagnosis of suspected or probable SARS. Patients were included if they had fever, a known exposure to SARS, and respiratory symptoms or infiltrates observed on chest radiograph. Patients were excluded if an alternative diagnosis was determined. Location of exposure to SARS; features of the history, physical examination, and laboratory tests at admission to the hospital; and 21-day outcomes such as death or intensive care unit (ICU) admission with or without mechanical ventilation. Of the 144 patients, 111 (77%) were exposed to SARS in the hospital setting. Features of the clinical examination most commonly found in these patients at admission were self-reported fever (99%), documented elevated temperature (85%), nonproductive cough (69%), myalgia (49%), and dyspnea (42%). Common laboratory features included elevated lactate dehydrogenase (87%), hypocalcemia (60%), and lymphopenia (54%). Only 2% of patients had rhinorrhea. A total of 126 patients (88%) were treated with ribavirin, although its use was associated with significant toxicity, including hemolysis (in 76%) and decrease in hemoglobin of 2 g/dL (in 49%). Twenty-nine patients (20%) were admitted to the ICU with or without mechanical ventilation, and 8 patients died (21-day mortality, 6.5%; 95% confidence interval [CI], 1.9%-11.8%). Multivariable analysis showed that the presence of diabetes (relative risk [RR], 3.1; 95% CI, 1.4-7.2; P =.01) or other comorbid conditions (RR, 2.5; 95% CI, 1.1-5.8; P =.03) were independently associated with poor outcome (death, ICU admission, or mechanical ventilation). The majority of cases in the SARS outbreak in the greater Toronto area were related to hospital exposure. In the event that contact history becomes unreliable, several features of the clinical presentation will be useful in raising the suspicion of SARS. Although SARS is associated with significant morbidity and mortality, especially in patients with diabetes or other comorbid conditions, the vast majority (93.5%) of patients in our cohort survived.
    JAMA The Journal of the American Medical Association 07/2003; 289(21):2801-9. · 29.98 Impact Factor

Publication Stats

599 Citations
159.83 Total Impact Points

Institutions

  • 2011–2013
    • The Princess Margaret Hospital
      Toronto, Ontario, Canada
  • 2008–2009
    • University of Toronto
      • Department of Medicine
      Toronto, Ontario, Canada
    • McMaster University
      Hamilton, Ontario, Canada