Relationship between quality of life and clinical status in patients with gastrointestinal cancer

Background: previous studies with patients having cancer have shown that quality of life scores depend on the clinical stage of the disease (the more advanced the disease, the worst quality of life). Methods: in a prospective study we studied 317 patients with gastric or colorectal cancer attending the Instituto Nacional de Cancerologia between 2010 and 2011; the patients completed the EORTC QLQ-C30 before receiving treatment. This instrument measures quality of life in 15 domains. Scores of each domain were compared according to tumor stage. Differential Item Functioning was measured across neoplasm staging and tumor localization. Results: 145 patients (45.7%) were diagnosed with colorectal cancer. According to clinical staging, differences in quality of life scores were observed in 4 of 15 domains (physical and social functioning, anorexia). Most of the differences in quality of life domains depended on tumor localization (patients with colorectal cancer had the highest scores in quality of life) and sex (women reported better scores). These differences seemed to be independent of item properties. The construct was more adequately measured with items that explore the construct using a general approach. Conclusion: in this group of patients with colorectal and gastric cancer quality of life scores were more related with tumor localization than with clinical stage.