Conclusions
Metabonomics identifies excess energy expenditure pathways perturbed during chemotherapy for breast cancer, and establishes a significant association between serum lactate, body fat, and substantive weight gain during chemotherapy.
Purpose
Weight gain in women receiving chemotherapy for breast cancer is associated with a higher risk of recurrence but its mechanisms are poorly understood. Experimental design: To investigate this, we assessed the metabolic, cytokine, and appetite-related peptide alterations during adjuvant chemotherapy for early breast cancer in postmenopausal women, and correlated these with body mass measurements. Specifically, we performed global metabolic profiling using (1)H-nuclear magnetic resonance spectroscopy of sequential sera, examined ghrelin immunoreactivity, RIAs for GLP-1 and peptide YY, and electrochemiluminescent cytokine analyses (tumor necrosis factor-alpha and interleukin-6) on sequential samples.
Results
In those who gained >1.5 kg, several metabolite levels were positively associated with weight gain, specifically lactate, which was 63.5% greater in patients with increased body weight during chemotherapy compared with those with no weight gain (P < 0.01; the prespecified primary end point). A strong correlation (r = 0.7, P < 0.001) was detected between the rate of weight change and serum lactate levels, and on average, lactate levels exhibited the greatest metabolic response to chemotherapy, increasing by up to 75%. Normalized levels of peptide YY were also observed to be elevated in patients not gaining weight posttreatment (+30% compared with -7% for the weight gain group; P < 10(-4)). Baseline lactate, alanine, and body fat were all prognostic for weight gain (area under the receiver operator characteristic curves, >0.77; P < 0.05). No associations were observed between any other parameter and weight gain, including cytokine levels. Conclusions: Metabonomics identifies excess energy expenditure pathways perturbed during chemotherapy for breast cancer, and establishes a significant association between serum lactate, body fat, and substantive weight gain during chemotherapy.