Research methods: Systematic reviews and meta-analysis in geriatric oncology
Cancer is largely a disease of aging with increasing incidence with age for most malignancies and the majority of cancer patients diagnosed after age 65. At the same time, aging is associated with a progressive increase in the number of major medical comorbid conditions that may complicate the disease course and increase treatment-related complications and their adverse consequences. Unfortunately, age restrictions in clinical trials have led to limited data on the special characteristics, comorbidities, and outcomes of older patients with cancer. Geriatric Oncology has emerged as a subdiscipline within oncology with a focus on clinical management and research related to cancer in the older patient. Topics in Geriatric Oncology studied in randomized or nonrandomized clinical studies including those captured in systematic evidence reviews and meta-analyses cover a broad range of subjects related to cancer in the elderly. In this chapter, the basic methodology for conducting high quality systematic reviews and evidence summaries including meta-analyses is summarized. Such studies range across areas of prevention and screening, diagnosis and staging, functional assessment including comprehensive geriatric assessment, cancer treatment, supportive care, and survivorship and end-of-life. Systematic reviews start with defining the specific question and then establishing the relevant clinical setting including the target patient population or problem, the exposure, prognostic factor or intervention, any relevant comparison(s), and clinically important outcomes. Subsequently, a rigorous explicit and transparent process of identifying, appraising, and selecting or excluding the relevant evidence is undertaken. The resulting evidence from the systematic review may then be summarized descriptively or, when appropriate, in the form of a formal meta-analysis. Later in the chapter, a summary of reported systematic reviews and/or metaanalyses related to Geriatric Oncology over the past two decades is presented and summarized. Finally, available tools for the conduct, analysis, quality appraisal, and reporting of systematic reviews and meta-analyses are provided for the reader interested in a better understanding of such systematic evidence reviews.
