Latent class piecewise linear trajectory modelling for short-term cognition responses after chemotherapy for breast cancer patients

This paper investigates the impact of chemotherapy on cognitive function of breast cancer patients and whether this response is homogeneous for all patients. Latent class piecewise linear trajectory (growth) models were employed to describe changes and identify subgroups in three Auditory Verbal Learning Test measures (learning, immediate retention and delayed recall) in 130 breast cancer patients taken at three time periods: before chemotherapy and 1 and 6 months post-chemotherapy. Two distinct subgroups of women exhibiting different patterns of response were identified for learning and delayed recall and three for immediate retention. The groups differed in level (intercept) at 1 month post-chemotherapy and patterns of decline and recovery. Binomial and multinomial logistic regressions on the latent classes found that age, initial National Adult Reading Test (NART)-predicted IQ, stage of cancer and the initial Functional Assessment of Cancer Therapy-Breast subscale (or subsets thereof) to be significant predictors of classes.