The Breast (2006) 15, 456–460 THE BREAST SHORT REPORT The effects of tamoxifen on radiation-induced pulmonary fibrosis in Wistar albino rats: Results of an experimental study Nuran Senel Bese a,Ã , Cenk Umay a , Sukru Yildirim b , Sennur Ilvan c , Ahmet Dirican d , Seda Salar e , Tuncay Altug f , Ahmet Ober a a Department of Radiation Oncology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey b Department of Pathology, GATA Haydarpasa Training Hospital, Istanbul, Turkey c Department of Pathology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey d Department of Biostatistics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey e Cerrahpasa Medical Biology School, Istanbul University, Istanbul, Turkey f Department of Experimental Animal Breeding and Research Laboratory, Cerrahpasa Medical School, Istanbul University Received 24 November 2004; received in revised form 24 March 2005; accepted 13 April 2005 Summary This study was performed to evaluate the effects of tamoxifen on pulmonary fibrosis, given concurrently with or after irradiation in Wistar albino rats. Twenty-one female Wistar albino rats were randomized into three groups. The first group (Group A) had tamoxifen, which was started after the completion of irradiation. The second group (Group B) had tamoxifen concomitant with irradiation. The third group (Group C) had only thoracic irradiation and did not receive tamoxifen. Whole lungs were irradiated to a total dose of 30 Gy in ten fractions with Co60. Tamoxifen was continued until the animals were sacrificed 16 weeks after the start of irradiation. As an end point the percentage of lung with fibrosis for each rat was quantified with image analysis of histological sections of the lung. Groups were compared using the one-way ANOVA method and Bonferroni post hoc test. The mean percentage values of fibrosis were 10.03 for Group A, 36.81 for Group B, and 3.87 for group C (Po0:001). When the percentages of fibrosis were compared for each group, the difference was statistically significant between Group A and Group B (Po0:001) and between Group B and Group C (Po0:001). Concomitant use of tamoxifen appears to increase radiation-induced pulmonary fibrosis and it seems more convenient to delay tamoxifen until the completion of irradiation. & 2005 Elsevier Ltd. All rights reserved. ARTICLE IN PRESS www.elsevier.com/locate/breast KEYWORDS Pulmonary fibrosis; Tamoxifen; Irradiation; Rats 0960-9776/$ - see front matter & 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.breast.2005.04.016 Ã Corresponding author. Tutuncu Mehmet Efendi Caddesi, Dr. Rıfat Pasa Sok, Goztepe Konutları 19/2, Goztepe 34730, Istanbul, Turkey. Tel.: +902164781915 or +905324680705; fax: +90 2124143097. E-mail addresses: nuranbese@superonline.com, bese@tnn.net (N.S. Bese).