MULTIFOCAL ERG IN PATIENTS TREATED WITH LOW DOSAGE TAMOXIFEN

Abstract

Abstract: : Purpose: Tamoxifen, an antiestrogen, has been used as an effective therapeutic agent in the treatment of breast cancer. This drug can cause ocular toxic effects in high dosage. The purpose of this study is to investigate central retinal toxicity by multifocal electroretinography (mfERG) in patients treated with low–dosage tamoxifen (20mg/day) for breast cancer. Methods: mfERGs were recorded from 103 retinal locations within the central 25^o with VERIS Science^TM 4.9 Imaging System. Participants were 46 asymptomatic females with BCVA≥0.1 logMAR and no fundus abnormalities assigned in 3 groups: Tamoxifen – 21 patients (39–65 years, mean 49.8± 6.5; median=49.0), treated with low dosage tamoxifen for breast cancer from 1 to 55 months (23.0±14.3; median =26.0 months); Breast Cancer Control – 10 patients (30–76 years, mean 49.6±14.8; median=49.5) with previously diagnosed for breast cancer who have not received tamoxifen as treatment until ERG testing; Normal Control – 15 normal volunteers (30–71 years, mean 47.7±12.9, median=45.2). Parameters of response densities (nV/deg²) and implicit times (ms) for N1 and P1 components of the first order kernel were determined and statistically analyzed (one–way ANOVA). Results: Mean N1–P1 response densities (RD), N1 and P1 implicit times (IT) for retinal eccentricities at 0º, 5^o, 10^o, 15^o, 20^o, e 25^o were, respectively – Tamoxifen: RD – 52.5±15.8; 30.6±10.3; 22.4±7.8; 19.3±7.2; 16.3±6.0; 17.1±6.6; IT N1 – 15.1±1.8; 14.7±1.0; 13.2±1.3; 12.9±1.9; 13.3±1.7; 13.4±0.8; IT P1 – 30.1±2.4; 27.7±4.0; 27.8±3.1; 27.2±3.4; 27.1±3.3; 27.4±3.1; Breast Cancer Control: RD 51,1±15.5; 31.4±10.9; 22.1±8.1; 18.0±6.3; 15.3±4.4; 15.3±4.2; IT N1 – 15.6±1.9; 15.2±1.0; 13.2±0.9; 14.2±2.6; 14.7±2.5; 14.1±1.7; IT P1 – 30.1±1.8; 29.4±2.1; 29.1±3.8; 28.9±4.1; 29.8±3.5; 29.5±3.2. Norma Control: RD – 64.6±15.9; 37.1±9.1; 28.0±7.8; 23.6±6.5; 19.9±5.2; 20.4±5.3; IT N1 – 15.1±1.6; 15.3±1.1; 13.4±0.7; 13.0±0.5; 13.5±0.7; 13.7±0.8; IT P1 – 28.0±1.5; 27.7±1.0; 26.4±1.0; 25.6±1.0; 25.8±1.0; 25.9±0.8. Response densities and implicit times were comparable for the 3 groups. Conclusions: Low–dosage tamoxifen showed no central retinotoxic effect in patients with breast cancer. These results confirm and extend our previous results of no widespread retinal toxicity assessed by full–field ERG in the same patients (Berezovsky et al, ARVO 2003).

Keywords: electroretinography: clinical • drug toxicity/drug effects • electrophysiology: clinical