WASHINGTON, February 20, 2014 — Researchers have discovered that the antidepressant paroxetine, sold under the name brand Paxil, can cause breast cancer.
City of Hope National Medical Center in Duarte, California has discovered that Paxil can disrupt the hormonal balance and lead to the development of certain types of breast cancer.
Hormone positive breast cancer is the most common type of the disease, accounting for about 70 percent of the diagnosed cases each year.
Patients who have a history of hormone positive cancer are prescribed a strict hormone-reducing regime including medications to deplete virtually all sex hormones produced naturally in the body, modified diet to reduce intake of foods that spike hormone such as soy products, and sometimes even additional surgery.
Research has shown that if a patient has a history of one type of cancer, such as hormone positive, future cancers will be of the same variety.
Keeping the estrogen and progesterone levels low in these survivors is the best defense against new cancers growing or developing.
The discovery that Paxil has an effect on estrogen in the body is particularly disturbing since almost a quarter of women being treated for breast cancer suffer from depression. Treatment for these women often involves prescribed antidepressants known as selective serotonin reuptake inhibitors, such as Paxil.
Also, last summer, the Food and Drug Administration approved a low dose form of paroxetine, under the name Brisdelle, to be prescribed as a non-hormonal treatment for hot flashes and menopausal symptoms.
Fifty percent of women under 35 who have chemotherapy go into menopause from the treatment as do 80 percent of women 35 – 44 and nearly 100 percent of women over the age of 45.
Since women who have a history of hormone positive breast cancer cannot take any hormone replacement to relieve their often severe and sudden menopause symptoms, they are prescribed what are believed to be non-hormonal options.
The discovery explains questions some in the cancer community have been asking for years. A 2010 study found that Canadian women who were taking Paxil were more likely to die from breast cancer than women who were on other antidepressants.
At the opposite end of the spectrum, the City of Hope research also found that two antifungal medications, biconazole and oxyconazole, inhibit the action of aromatase, where androgens are converted into estrogen.
Anyone who has questions about their use of Paxil, should contact their doctor for more complete answers.