Purpose: Patients with cancer experience acute and chronic symptoms caused by their underlying disease or by the treatment. While numerous studies have examined the impact of various treatments on symptoms experienced by cancer patients, there are inconsistencies regarding the symptoms measured and reported in treatment trials. This article presents a systematic review of the research literature of the prevalence and severity of symptoms in patients undergoing cancer treatment.

Methods: A systematic search for studies of persons receiving active cancer treatment was performed with the search terms of "multiple symptoms" and "cancer" for studies involving patients over the age of 18 years and published in English during the years 2001 to 2011. Search outputs were reviewed independently by seven authors, resulting in the synthesis of 21 studies meeting criteria for generation of an Evidence Table reporting symptom prevalence and severity ratings.

Results: Data were extracted from 21 multi-national studies to develop a pooled sample of 4,067 cancer patients in whom the prevalence and severity of individual symptoms was reported. In total, the pooled sample across the 21 studies was comprised of 62% female, with a mean age of 58 years (range 18 to 97 years). A majority (62%) of these studies assessed symptoms in homogeneous samples with respect to tumor site (predominantly breast and lung cancer), while 38% of the included studies utilized samples with mixed diagnoses and treatment regimens. Eighteen instruments and structured interviews were including those measuring single symptoms, multi-symptom inventories, and single symptom items drawn from HRQOL or health status measures. The MD Anderson Symptom Inventory was the most commonly used instrument in the studies analyzed (n = 9 studies; 43%), while the Functional Assessment of Cancer Therapy, Hospital Anxiety and Depression Subscale, Medical Outcomes Survey Short Form-36, and Symptom Distress Scale were each employed in two studies. Forty-seven symptoms were identified across the 21 studies which were then categorized into 17 logical groupings. Symptom prevalence and severity were calculated across the entire cohort and also based upon sample sizes in which the symptoms were measured providing the ability to rank symptoms.

Conclusions: Symptoms are prevalent and severe among patients with cancer. Therefore, any clinical study seeking to evaluate the impact of treatment on patients should consider including measurement of symptoms. This study demonstrates that a discrete set of symptoms is common across cancer types. This set may serve as the basis for defining a "core" set of symptoms to be recommended for elicitation across cancer clinical trials, particularly among patients with advanced disease.