Fatigue, weight gain, lethargy and amenorrhea in breast cancer patients on chemotherapy: Is subclinical hypothyroidism the culprit?

N Kumar PhD RD^a, KA Allen MA RD^b, D Riccardi MPH RD^b, BB Bercu MD^c, A Cantor PhD^a, S Minton, DO ^d, L Balducci MD^d, PB Jacobsen PhD^e

^aDepartment of, Cancer Control, Tampa, Florida, United States, ^bNutrition, ^cPediatrics & Pharmacology & Therapeutics, ^dMedical Oncology, ^ePsychosocial & Palliative Care; H. Lee Moffitt Cancer Center & Research Institute, University of South Florida, University of South Florida College of Medicine, Tampa, Florida, United States

AIM: The purpose of this study was to prospectively observe the relative contribution of nutritional intake, physical activity, body composition, steroid hormones, thyroid function, and fatigue on changes in body weight in breast cancer patients, receiving adjuvant chemotherapy. METHODS: This was a prospective observational research design where 198 consecutive breast cancer patients receiving adjuvant chemotherapy were monitored from start to end and 6 months post therapy on changes in anthropometics, fatigue, nutritional intake, physical activity, thyroid and steroid hormones. RESULTS: We observed a weight gain over >5 lbs in 22.2% of this patient population with a significant and progressive gain of 6.7 lbs (P<0.0001) at six months. Ninety four percent of all patients reported fatigue and 56% of patients reported lowered physical activity. A significant reduction in serum free and total estradiol (P<0.0001) was observed indicative of reduction in ovarian function with 86% amenorrehic at the end of treatment. A significant reduction in mean serum triiodothyronine uptake levels (P <0.05), in addition to a significant increase in TBG (P<0.0001) from baseline to end of chemotherapy, was observed. Changes in fatigue frequency and serum sex-hormone binding globulin (SHBG) were variables significantly predictive of weight gain (P<0.0001). CONCLUSIONS: Adjuvant therapy including cytotoxic agents may influence thyroid function in breast cancer patients contributing to and progressively worsening symptoms such as weight gain, amenorrhea, fatigue and lowered physical activity in this population. The present study indicates the value of screening breast cancer patients for thyroid function at diagnosis and as therapy progresses.

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 793 (Dietary Influences).