Tamoxifen and Ocular Toxicity
March 1, 1999
Tamoxifen and Ocular Toxicity
Abstract & Commentary
Synopsis: A cross-sectional study of women taking tamoxifen found no evidence of vision-threatening ocular toxicity.
Source: Gorin MB, et al. Am J Opthalmol 1998;125: 493-501.
A group of ophthalmologists from many medical centers conducted a cross-sectional study of 303 women with breast cancer currently taking tamoxifen. Subjective information was collected regarding vision, and testing was performed for visual acuity and color vision. In addition, each participant received a full ophthalmic examination. There was no evidence of any decrease in visual function associated with tamoxifen, except for an increased color confusion. Most importantly, there were no differences detected in corneal opacities comparing tamoxifen users with nonusers. However, the tamoxifen-treated group had greater prevalence of intraretinal crystals and posterior subcapsular opacities. Gorin and associates believe this latter finding is potentially troublesome, and women receiving tamoxifen should have a baseline ophthalmic evaluation within the first year of therapy.
Comment By Leon Speroff, MD
In the American Tamoxifen Prevention Trial, there was a statistically significant 1.6-fold increase in cataracts.1 For this reason, I was pleased to see a well done major effort reported by ophthalmologists. Opacity changes in the eye that are drug-related are a very serious concern since they are not reversible. I find this report to be somewhat, but not wholly, reassuring.
The findings with color confusion may not be a problem. Color confusion is important because disturbances in color perception are recognized as early indications of optical dysfunction associated with diabetes, maculopathy, and optic nerve problems. When patients with these conditions were excluded, the significance was reduced.
Although no definite evidence of an increase in opacities was detected, the prevalence of posterior subcapsular opacities could be a prelude to cataract formation. Therefore, Gorin et al ended their generally negative report with a cautionary warning. They advised ophthalmologic evaluation of patients using tamoxifen.
The American Tamoxifen Prevention Trial was unblinded because there were 49% fewer cases of invasive breast cancer and 50% fewer cases of noninvasive breast cancer in the tamoxifen-treated arm of the study. These results lead me to recommend tamoxifen prophylaxis (20 mg daily for 5 years) for those women who are diagnosed with ductal carcinoma-in-situ of the breast or who have atypical hyperplasia in a breast biopsy (especially if a positive family history of breast cancer is also present). For others who seek tamoxifen preventive treatment, because of the side effects of endometrial cancer, venous thrombosis, and possible cataracts (and a basic reluctance to base clinical practice on the outcome of one study), I advise that the final answers are not in, and that clinical trial results from long-term follow-up will be necessary before fully informed decision making is possible.
Because of the gynecologic problems associated with tamoxifen, I recommend the following program for monitoring women during long-term tamoxifen treatment:
All women: Careful pelvic examination every six months to detect the emergence of endometriosis, ovarian cysts, and uterine leiomyomata.
Postmenopausal women: Annual measurement of endometrial thickness by transvaginal ultrasonography. Endometrial biopsy of all women with a two-layer thickness of 5 mm or greater. Saline instillation (sonohysterography) when appearance is not totally benign.
Premenopausal women: Periodic assessment for ovulation; if ovulatory, no further intervention is necessary; however, contraceptive counseling should not be ignored.
If anovulatory, an annual endometrial aspiration biopsy; interpretation of endometrial thickness measurements by ultrasonography is uncertain in premenopausal women.
Reference
1. Fischer B, Constantino JP, Wikerham DL, et al. J Natl Cancer Inst 1998;90:1371-1388.
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