Braun et al. BMC Cancer 2011, 11:353 http://www.biomedcentral.com/1471-2407/11/353 instruments which can be broadly classified into generic and targeted [28]. Generic QoL instruments tend to ask questions general enough for broad applicability, includ- ing for use among individuals in good health. On the other hand, targeted measures may focus on specific symptoms that are common to a particular cancer or to its treatment. There is no “gold standard” cancer QoL questionnaire available and the choice of selecting a QoL questionnaire for a particular study is governed for the most part by the research goals of that study. The positive relationship between QoL and survival as described above has not been universally observed in the literature, with some studies founding no asso- ciation between QoL and survival [29-31]. As a result, there is no unanimity on the prognostic role of QoL in cancer. These conflicting and inconsistent results in the literature could perhaps reflect the different meth- odologies used to analyze the data (as an example by selecting different cut off values for variables), different patient populations investigated, different QoL ques- tionnaires used, or alternatively, different selection of covariates to be included in the regression analysis [32]. Moreover, it is currently unclear why QoL may be prognostic, and it has been hypothesized that, in patients with micrometastatic disease, there is produc- tion of tumor factors that affect general health and that patients perceive this and report it in terms of poor QoL before it is clinically or radiologically appar- ent [33]. Therefore, preclinical progression of disease after curative treatment may be associated with wor- sening of QoL, which may be assessed with self- reported QoL measures [33]. It is possible that QoL presumably captures those aspects of disease severity that may not be apparent in the observer-rated perfor- mance status or tumor burden [34]. In the light of the above, we investigated whether QoL can predict survi- val in non-small cell lung cancer patients treated at a community hospital comprehensive cancer center. Methods Study Sample We examined 1194 histologically confirmed non-small cell lung cancer patients treated at Cancer Treatment Centers of America® (CTCA) at Midwestern (MRMC) and Southwestern (SRMC) Regional Medical Centers between Jan 2001 and Dec 2008. None of these patients had received any treatment at our hospitals when con- tacted to participate in this investigation. The inclusion criteria for participation in this study were a histological diagnosis of lung cancer and the ability to read English. Patients with all stages of lung cancer were eligible for the study. Patients were excluded if they were unable to give informed consent or were unable to understand or cooperate with study conditions. Page 2 of 9 A trained clinical coordinator was responsible for determining eligibility, describing the study, and obtain- ing informed consent. All patients were assured that refusal to participate would not affect their future care in any way. Patients who chose to participate were pre- sented with the questionnaire at their initial visit and instructed to return their completed questionnaires to the clinical coordinator within 24 hours; thus, patients completed questionnaires prior to receiving therapy at our facility. Data were systematically collected and entered in an excel spreadsheet which was maintained by the Office of Clinical Research. Several quality checks were performed from time to time to ensure complete- ness and accuracy of data. QoL data used in this study is part of a long-term prospective database on QoL in cancer patients treated at CTCA. Additional patient data recorded for this study were gender, age at presentation (current age), stage of dis- ease at diagnosis and prior treatment history. The only follow-up information required was the date of death or the date of last contact/last known to be alive. This study was approved by the Institutional Review Boards at MRMC and SRMC. QoL Assessment QoL was assessed using European Organization for the Research and Treatment of Cancer Core Quality of Life Questionnaire (QLQ-C30), which emphasizes a patient’s capacity to fulfill the activities of daily living. The QLQ- C30 is a 30-item cancer specific questionnaire that incorporates five functioning scales (physical, role, cog- nition, emotional, and social), nine symptom scales (fati- gue, pain, and nausea/vomiting, dyspnea, insomnia, loss of appetite, constipation, diarrhea, financial problems), and a global health status/QoL scale. The raw scores are linearly transformed to give standard scores in the range of 0-100 for each of the functioning and symptom scales. Higher scores in the global and functioning scales and lower scores in the symptom scales indicate better QoL. A difference of 5-10 points in the scores repre- sents a small change, 10-20 points a moderate change and greater than 20 points a large clinically significant change from the patient’s perspective [35]. This instru- ment has been judged to be reliable and valid as a result of extensive testing in a wide range of clinical cancer populations [36-38]. Prespecified Baseline Clinical Factors Baseline clinical factors that were assessed for prognos- tic significance were gender, current age, stage of disease at diagnosis and prior treatment history. Stage at diag- nosis was categorized into two groups consisting of locoregional (stages I-III) and metastatic (stage IV) dis- ease. The prior treatment history variable categorized