A new study suggests that hormone drugs might boost ovarian cancer risk by as much as 40 percent.

University of Oxford professor Richard Peto confides, “For women who take HRT for five years from around age 50, there will be about one extra ovarian cancer for every 1,000 users, and one extra ovarian cancer death for every 1,700 users.”

The researchers said: “The increased risk may well be largely or wholly causal; if it is, women who use hormone therapy for five years from around age 50 have about one extra ovarian cancer per 1,000 users and, if its prognosis is typical, about one extra ovarian cancer death per 1,700 users.”
The researchers continue, “The findings that ovarian cancer risk is greatest in current users of hormone therapy, falls after use ceases, and varies by tumour type, strongly suggest a causal relationship – ie: that among otherwise similar women, use of hormone therapy increases the probability of developing the two most common types of ovarian cancer, and hence ovarian cancer as a whole.”

Furthermore, the researchers go on to say, “At present, the WHO, European, and US guidelines about hormone therapy do not mention ovarian cancer, and the UK guidelines – which are due to be revised – state only that risk may be increased with long-term use.”

Finally, the researchers conclude, “The definite risk of ovarian cancer that is observed even with less than five years of use starting at around age 50 is directly relevant to current patterns of hormone therapy use, and hence directly relevant to medical advice, personal choices, and the current efforts to revise UK and worldwide guidelines.”