Cancer patients' quality of life over the disease course: lessons from the real world.

We examined the correlates of the Quality of Life Index (QLI) in three samples of cancer patients: newly diagnosed (N = 397), recipients of chemotherapy (N = 194), and terminal (N = 2046). The relative importance of physical, emotional, social, and disease symptom characteristics in predicting the QLI was compared across samples. Despite differences in data collection approaches (telephone, personal interview, or paper and pencil) and differences in patient characteristics, the QLI was a robust construct with its central organizing principle being physical functioning. In all samples, functioning, symptoms, depression, and social support were significant predictors of the QLI, while age and cancer type were only minimally related. The QLI significantly differentiated between patients at different disease phases and measured more than physiological functioning. However analyses suggested that the dominant factor constraining the range of human psychosocial functioning was physical condition.