The objective of the current study was twofold: (a) to determine whether subgroups of breast cancer patients could be identified on the basis of their distinct trajectory or pattern of fatigue following treatment for early stage cancer using growth mixture modeling and (b) to examine whether the subgroups could be distinguished on the basis of a cognitive-behavioral model. Growth mixture modeling and a prospective longitudinal design were used to examine the course of fatigue after treatment for early stage breast cancer. Women (n = 261; mean age = 55.2 years) provided fatigue ratings for 6 months following treatment. A low-fatigue group (n = 85) and a high-fatigue group (n = 176) were extracted. Women who were not married, had a lower income, had a higher body mass index, engaged in greater fatigue catastrophizing, and were lower in exercise participation were more likely to be in the high-fatigue group. Only body mass index and catastrophizing remained significant predictors in multivariate analysis. Findings suggest considerable heterogeneity in the experience of fatigue following treatment and support the utility of a cognitive-behavioral model in predicting the course of posttreatment fatigue.
Keywordsfatigue; breast cancer; catastrophizing; exercise; growth mixture modeling Fatigue is one of the most common symptoms reported by women undergoing chemotherapy or radiotherapy for breast cancer and may persist for months and even years following treatment (Andrykowski, Curran, & Lightner, 1998;Bower et al., 2006;Broeckel, Jacobsen, Horton, Balducci, & Lyman, 1998;Jacobsen & Stein, 1999 2002). Evidence for the persistence of fatigue comes primarily from studies comparing breast cancer patients with age-matched women with no history of cancer (Andrykowski et al., 1998;Broeckel et al., 1998;Hann et al., 1998) and with published norms (Bower et al., 2000). On the basis of the research to date, however, it is difficult to draw definitive conclusions about fatigue persistence. This is because of the cross-sectional nature of most previous studies and because the length of time between treatment completion and the assessment of fatigue has varied greatly across previous studies. An additional issue concerns the fact that most studies consider only fatigue scores in the aggregate and do not examine whether there are subgroups of patients who differ in their experience of fatigue after treatment completion. This approach of using aggregate (i.e., group mean) scores may mask meaningful differences among subgroups of patients in the severity, course, and predictors of fatigue. For example, it may be the case that some patients report a reduction in fatigue as time since treatment increases, whereas others report worsening of fatigue; consequently, the overall trajectory of fatigue for the group as a whole would not appear to change.A study of fatigue in breast cancer patients by Bower et al. (2000) partly addressed this issue. In this study, women diagnosed with breast cancer an average of 35 months previously w...