Kimberly S. Peairs

Long-term All-Cause Mortality in Cancer Patients With Preexisting Diabetes Mellitus: A Systematic Review and Meta-analysis

CONTEXT Diabetes mellitus appears to be a risk factor for some cancers, but the effect of preexisting diabetes on all-cause mortality in newly diagnosed cancer patients is less clear. OBJECTIVE To perform a systematic review and meta-analysis comparing overall survival in cancer patients with and without preexisting diabetes. DATA SOURCES We searched MEDLINE and EMBASE through May 15, 2008, including references of qualifying articles. STUDY SELECTION English-language, original investigations in humans with at least 3 months of follow-up were included. Titles, abstracts, and articles were reviewed by at least 2 independent readers. Of 7858 titles identified in our original search, 48 articles met our criteria. DATA EXTRACTION One reviewer performed a full abstraction and other reviewers verified accuracy. We contacted authors and obtained additional information for 3 articles with insufficient reported data. RESULTS Studies reporting cumulative survival rates were summarized qualitatively. Studies reporting Cox proportional hazard ratios (HRs) or Poisson relative risks were combined in a meta-analysis. A random-effects model meta-analysis of 23 articles showed that diabetes was associated with an increased mortality HR of 1.41 (95% confidence interval [CI], 1.28-1.55) compared with normoglycemic individuals across all cancer types. Subgroup analyses by type of cancer showed increased risk for cancers of the endometrium (HR, 1.76; 95% CI, 1.34-2.31), breast (HR, 1.61; 95% CI, 1.46-1.78), and colorectum (HR, 1.32; 95% CI, 1.24-1.41). CONCLUSIONS Patients diagnosed with cancer who have preexisting diabetes are at increased risk for long-term, all-cause mortality compared with those without diabetes.

Diabetes Mellitus and Breast Cancer Outcomes: A Systematic Review and Meta-Analysis

PURPOSE The goal of this study was to perform a systematic review and meta-analysis to examine the effect of pre-existing diabetes on breast cancer-related outcomes. METHODS We searched EMBASE and MEDLINE databases from inception through July 1, 2009, using search terms related to diabetes mellitus, cancer, and prognostic outcome. Studies were included if they reported a prognostic outcome by diabetes status, evaluated a cancer population, and contained original data published in the English language. We performed a meta-analysis of pre-existing diabetes and its effect on all-cause mortality in patients with breast cancer and qualitatively summarized other prognostic outcomes. RESULTS Of 8,828 titles identified, eight articles met inclusion/exclusion criteria and described outcomes in patients with breast cancer and diabetes. Pre-existing diabetes was significantly associated with all-cause mortality in six of seven studies. In a meta-analysis, patients with breast cancer and diabetes had a significantly higher all-cause mortality risk (pooled hazard ratio [HR], 1.49; 95% CI, 1.35 to 1.65) compared with their nondiabetic counterparts. Three of four studies found pre-existing diabetes to be associated with more advanced stage at presentation. Diabetes was also associated with altered regimens for breast cancer treatment and increased toxicity from chemotherapy. CONCLUSION Compared with their nondiabetic counterparts, patients with breast cancer and pre-existing diabetes have a greater risk of death and tend to present at later stages and receive altered treatment regimens. Studies are needed to investigate pathophysiologic interactions between diabetes and breast cancer and determine whether improvements in diabetes care can reduce mortality in patients with breast cancer.

Postoperative Mortality in Cancer Patients With Preexisting Diabetes Systematic review and meta-analysis

OBJECTIVE Diabetes appears to increase risk for some cancers, but the association between preexisting diabetes and postoperative mortality in cancer patients is less clear. Our objective was to systematically review postoperative mortality in cancer patients with and without preexisting diabetes and summarize results using meta-analysis. RSEARCH DESIGN AND METHODS We searched the Medical Literature Analysis and Retrieval System Online (MEDLINE) and Excerpta Medica Database (EMBASE) for articles published on or before 1 July 2009, including references of qualifying articles. We included English language investigations of short-term postoperative mortality after initial cancer treatment. Titles, abstracts, and articles were reviewed by at least two independent readers. Study population and design, results, and quality components were abstracted with standard protocols by one reviewer and checked for accuracy by additional reviewers. RESULTS Of 8,828 titles identified in our original search, 20 articles met inclusion criteria for qualitative systematic review. Of these, 15 reported sufficient information to be combined in meta-analysis. Preexisting diabetes was associated with increased odds of postoperative mortality across all cancer types (OR = 1.85 [95% CI 1.40–2.45]). The risk associated with preexisting diabetes was attenuated but remained significant when we restricted the meta-analysis to models that controlled for confounders (1.51 [1.13–2.02]) or when we accounted for publication bias using the trim and fill method (1.52 [1.13–2.04]). CONCLUSIONS Compared with their nondiabetic counterparts, cancer patients with preexisting diabetes are ∼50% more likely to die after surgery. Future research should investigate physiologic pathways to mortality risk and determine whether improvements in perioperative diabetes care can reduce postoperative mortality.

Colorectal cancer outcomes, recurrence, and complications in persons with and without diabetes mellitus: a systematic review and meta-analysis.

BackgroundDiabetes mellitus increases the risk of incident colorectal cancer, but it is less clear if pre-existing diabetes mellitus influences mortality outcomes, recurrence risk, and/or treatment-related complications in persons with colorectal cancer.MethodsWe performed a systematic review and meta-analysis comparing colorectal cancer mortality outcomes, cancer recurrence, and treatment-related complications in persons with and without diabetes mellitus. We searched MEDLINE and EMBASE through October 1, 2008, including hand-searching references of qualifying articles. We included studies in English that evaluated diabetes mellitus and cancer treatment outcomes, prognosis, and/or mortality. The initial search identified 8,208 titles, of which 15 articles met inclusion criteria. Each article was abstracted by one author using a standardized form and re-reviewed by another author for accuracy. Authors graded quality based on pre-determined criteria.ResultsWe found significantly increased short-term perioperative mortality in persons with diabetes mellitus. In the meta-analysis of long-term mortality, persons with diabetes mellitus had a 32% increase in all-cause mortality compared to those without diabetes mellitus (95% CI: 1.24, 1.41). Although data on other outcomes are limited, available studies suggest that pre-existing diabetes mellitus predicts increased risk of some post-operative complications as well as 5-year cancer recurrence. In contrast, there is little evidence that diabetes confers increased risk for long-term cancer-specific mortality.ConclusionsPatients with colorectal cancer and pre-existing diabetes mellitus have an increased risk of short- and long-term mortality. Future research should determine whether improvements in prevention and treatment of diabetes mellitus will improve outcomes for colorectal cancer patients.

Does pre-existing diabetes affect prostate cancer prognosis? A systematic review.

To summarize the influence of pre-existing diabetes on mortality and morbidity in men with prostate cancer. We searched MEDLINE and EMBASE from inception through 1 October 2008. Search terms were related to diabetes, cancer and prognosis. Studies were included if they reported an original data analysis of prostate cancer prognosis, compared outcomes between men with and without diabetes and were in English. Titles, abstracts and articles were reviewed independently by two authors. Conflicts were settled by consensus or third review. We abstracted data on study design, analytic methods, outcomes and quality. We summarized mortality and morbidity outcomes qualitatively and conducted a preliminary meta-analysis to quantify the risk of long-term (>3 months), overall mortality. In total, 11 articles were included in the review. Overall, one of four studies found increased prostate cancer mortality, one of two studies found increased nonprostate cancer mortality and one study found increased 30-day mortality. Data from four studies could be included in a preliminary meta-analysis for long-term, overall mortality and produced a pooled hazard ratio of 1.57 (95% CI: 1.12–2.20). Diabetes was also associated with receiving radiation therapy, complication rates, recurrence and treatment failure. Our analysis suggests that pre-existing diabetes affects the treatment and outcomes of men with prostate cancer.

Does Metformin Reduce Cancer Risks? Methodologic Considerations

The substantial burden of cancer and diabetes and the association between the two conditions has been a motivation for researchers to look for targeted strategies that can simultaneously affect both diseases and reduce their overlapping burden. In the absence of randomized clinical trials, researchers have taken advantage of the availability and richness of administrative databases and electronic medical records to investigate the effects of drugs on cancer risk among diabetic individuals. The majority of these studies suggest that metformin could potentially reduce cancer risk. However, the validity of this purported reduction in cancer risk is limited by several methodological flaws either in the study design or in the analysis. Whether metformin use decreases cancer risk relies heavily on the availability of valid data sources with complete information on confounders, accurate assessment of drug use, appropriate study design, and robust analytical techniques. The majority of the observational studies assessing the association between metformin and cancer risk suffer from methodological shortcomings and efforts to address these issues have been incomplete. Future investigations on the association between metformin and cancer risk should clearly address the methodological issues due to confounding by indication, prevalent user bias, and time-related biases. Although the proposed strategies do not guarantee a bias-free estimate for the association between metformin and cancer, they will reduce synthesis of and reporting of erroneous results.

Screening for colorectal cancer

This review will comprise a general overview of colorectal cancer (CRC) screening. We will cover the impact of CRC, CRC risk factors, screening modalities, and guideline recommendations for screening in average-risk and high-risk individuals. Based on this data, we will summarize our approach to CRC screening.

Screening for breast cancer

This review will give a general overview of the impact of breast cancer, as well as breast cancer risk factors, identification of high-risk groups, screening modalities, and guidelines for screening average-risk and high-risk individuals, including a case discussion of the primary care providers approach to screening.

Screening for prostate cancer

This review comprises a general overview of the impact and risk factors for prostate cancer. Evidenced-based professional society prostate cancer screening guideline recommendations are reviewed, and our approach to a case is presented.

Coordination of care in breast cancer survivors: an overview.

The number of breast cancer survivors in the United States is increasing. With longer survival, there has been an increase in the complexity and duration of posttreatment care. Multidisciplinary care teams are needed to participate across the broad spectrum of issues that breast cancer survivors face. In this setting, the need for well-established patterns of communication between care providers is increasingly apparent. We have created a multidisciplinary approach to the management of breast cancer survivors to improve communication and education between providers and patients. This approach could be extended to the care and management of survivors of other types of cancer.