Most people know that the standard treatments for breast cancer, namely chemotherapy and radiation, often come with side effects such as nausea, fatigue, skin irritation, infertility, and trouble sleeping. But the list of potential cancer treatment side effects is so long that many of them often get overlooked.
Eye problems are one of those side effects that may not seem very important to patients who have bigger problems on their plates, such as surviving. But after they’ve been declared cancer-free, vision-related side effects may be more important. Certain cancer treatments can cause everything from dry eye to retinopathy…and cataracts.
What treatments cause cataracts?
Certain chemotherapy drugs, such as 5-fluorouracil (5-FU) and methotrexate, can have ocular side effects, and experts are beginning to suspect aromatase inhibitors of causing eye issues as well, specifically dry eye, retinal hemorrhage, and “floaters” in the eyes. But the big offender is tamoxifen, a selective estrogen modulator drug often used to treat hormone receptor-positive breast cancers.
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Tamoxifen and cataracts
Researchers have known for years that tamoxifen causes eye-related side effects, from dry eye and irritation, from retinopathy to macular edema. And, of course, cataracts.
When tamoxifen blocks the estrogen receptors in the eye, it changes the estrogen activity in the eye, which could result in changes to visual processing and the lacrimal and meibomian glands that protect the eye’s surface. The drug may just be doing its job, but it appears to increase the risk of posterior subcapsular cataracts by 400 percent while it’s at it.
What is my risk level?
Tamoxifen is particularly dangerous because it’s a treatment often continued even after the cancer has been eradicated in the hopes of reducing the risk of recurrence. Some patients will take this drug for five to 10 years. Other women, who are at a high risk of breast cancer incidence, may be placed on tamoxifen despite never having had breast cancer at all.
However, tamoxifen is less risky than it used to be, as most patients are only prescribed about 20 mg or less of the medication now, as opposed to numbers like 150 mg years ago. Even so, many experts advise against taking tamoxifen for more than five years.