BODY-COMPOSITION MEASUREMENTS USING DXA AND OTHER TECHNIQUES IN TAMOXIFEN-TREATED PATIENTS

Tamoxifen is an anti-oestrogenic drug which is widely used in the trea tment of patients with breast cancer. There is increasing interest in using the drug both for benign breast disease and as a chemo-preventat ive agent of the drug in women at high risk of breast cancer. Despite the fact that the acute side-effects of the drug are few, its agonisti c and antagonistic oestrogenic effects are not fully known and may hav e some undesirable effects for patients treated with the drug for seve ral years. A number of studies carried out recently indicate a varying degree of change in bone mineral content following treatment with tam oxifen. These studies concentrated mainly on bone mineral density meas urements only and non of them reported the effects of tamoxifen on lea n body mass and fat mass. In this study we measured lean body mass and fat mass in tamoxifen-treated females and a comparison group to deter mine the difference between the two groups. Twenty-six women receiving tamoxifen (20 mg/d) have participated in this study. The control grou p comprised 31 healthy women of a similar age. Total body bone mineral (TBBM) was measured using a dual-energy X-ray absorptiometry (DXA) (H ologic INV., Waltham, U.S.A.). Similarly, regional and total body soft tissue (lean and fat tissue) were measured using the DXA system. In a ddition to DXA measurements, percentage body fat (%BF) was measured us ing total body potassium counting (TBK), skinfold anthropometry (SF), infrared interactance (IR) and bioelectric impedance analysis (BIA). R esults from DXA alone showed that there were no significant difference s between the two groups for TBBM, regional and total body lean tissue mass. However, there was a significant difference between the two gro ups (P < 0.05) for %BF measurement. Similarly there was a significant difference between the two groups (P < 0.05) for %BF measured by other body composition techniques. Although;there is no other research repo rted on the effects of tamoxifen on %BF, this retrospective study indi cates that tamoxifen may lead to increase in fact content in women who are subjected to this treatment. We conclude that this observation is probably related to the agonistic oestrogenic effect of Tamoxifen on body fat. To our knowledge this deleterious effect has not been report ed before and it should be taken into considerable when comprising dif ferent types of-anti-oestrogenic drugs. Furthermore, patients should b e warned about this side-effect when they are prescribed Tamoxifen the rapy. (C) 1998 Elsevier Science Ltd. All rights reserved.