Ovaries or not: is your only choice one between ovarian cancer and surgical menopause?

While most of us have the time to be fairly well convinced of our need (or not) for a hysterectomy, doctors often don't bring up the question of the future of our ovaries till we get down to the final pre-op appointment and signing the operative permit. In fact, it may never be discussed at all but just lumped in with the other indigestible terminology in the permit itself. Women who ask about keeping their ovaries when they are not aware of any particular disease affecting them have been told things like "most ovaries fail within three years and the rate for ovarian cancer is well over 50% in those that do fail" (actual post from our discussion forum) or simply "you'll require another separate operation once they go bad later." As the woman whose doctor is quoted above went on to say, "I have not researched those statistics but I would not want to take any chances."

Most of us don't want to take any chances, either, but this is a case where we need to do some thinking of our own. Dorie, over on HysterList's blog, has spelled out the basic situation pretty succinctly: many doctors see no need for hormones in menopause and don't acknowledge that post-menopausal ovaries contribute to health, but unless you would consider having a separate surgery to remove your healthy ovaries to reduce your risk of cancer, it's worth giving some though to why you're so anxious to go for a "two-fer."

But we were a little alarmed at the stats that poster passed along from her doctor and decided to do a little extra research on the risks and benefits.

First of all, the ovarian function rate is better expressed as: 50% of the women who retain ovaries at the time of a hyst experience natural menopause (with some variable degree of continued hormonal support) within the following five years. That's quite a bit different from this particular doctor's figure, and we can only wonder at the population pool he practices within if his experience deviates so radically from what research has shown.

The question of cancer is a more complex one, since that is not the only risk we face. Balanced risk management is trickier, but more realistic if we are talking overall survival: cancer is not necessarily what we are going to die from and in fact is statistically less likely to kill us than a number of other things. Let's look at what we could find in the research.

The main issue is the balance between the risks of ovarian cancer as compared to other disorders that relate to lower levels of estrogen:
For women at average risk of ovarian cancer, heart disease, osteoporosis, breast cancer and stroke, the probability of survival to age 80 after hysterectomy at ages 50 to 54 ranged from 62 percent for those who kept their ovaries but didn't take estrogen, to 53 percent for those who had their ovaries removed but didn't take estrogen. 
Keeping the ovaries without estrogen therapy reduced the percent of women dying by age 80 of heart disease from 15 percent to 7 percent, and those dying of hip fractures from nearly 5 percent to 3 percent. 

The reductions in those two diseases, Parker said, far outweigh the increase in ovarian cancer deaths by age 80. (source)
And from another, stating the numbers more graphically:
For a hypothetical cohort of 10,000 women undergoing hysterectomy who chose oophorectomy between the ages of 50 and 54 without estrogen therapy, our analyses predict that, by the time they reach age 80, 838 more women will have died from CHD than in a similar cohort of women who chose ovarian preservation; 158 more will have died from hip fracture; 47 fewer women will have died from ovarian cancer. In the base case analyses, oophorectomy in women ages 50–54 leads to an overall excess mortality of 858 per 10,000 women subjected to surgery. (source)
In fact, the incidence of ovarian cancer seems to reduced by the hyst:
The incidence rate of ovarian cancer was 0.27 per 1000 person-years in the group that had undergone hysterectomy and 0.34 per 1000 person-years in the general population (age-standardised). The extrapolated lifetime risk of developing ovarian cancer was 2.1% after hysterectomy and 2.7% in the general population. (source)
The opinion of gynecologist/researcher William H. Parker, M.D. in his book A Gynecologist's Second Opinion brings the estrogen back into the situation:
Thus, the risk of a woman developing ovarian cancer after hysterectomy is probably closer to 1 in 300 rather than 1 in 80 for women who have not had a hysterectomy. The benefit of removing ovaries for ovarian cancer prevention has been overstated in the medical literature and is, therefore, misunderstood by most physicians. 
Significantly, the ovaries produce hormones long after menopause. Estrogen continues to be produced in small amounts, about 25 percent of normal pre-menopausal levels. Blood levels of estrogen in some post-menopausal women are equivalent to the levels attained by low-dose estrogen patches used for estrogen replacement in menopause. (source)
Even the North American Menopause Society, which doesn't advocate the use of HRT for more than a few months, states in their position "Women Undergoing Hysterectomy Before Age 65 Derive Survival Benefit From Ovarian Conservation":
after menopause, the ovaries continue to produce significant amounts of testosterone and androstenedione, which are converted to estrogen peripherally. Although younger women with BRCA1 or BRCA2 mutations who have significant risk for breast or ovarian cancer may derive a survival benefit from oophorectomy, women at average risk for these cancers experience increased risk of osteoporotic fracture and coronary heart disease. The study found that women younger than age 65 clearly benefit from ovarian conservation, and at no age is there a clear benefit from oophorectomy. (source)
If low estrogen raises risk for other problems, what does HRT use do for ovarian cancer risk? One older study, which was based on higher doses than currently used, found:
Ovarian cancer risk was associated with use of hormone replacement therapy both for women who had had a hysterectomy and for those who had not. Among those who had had a hysterectomy before entering the study, the risk increased by a significant 8% with each year of estrogen-only use, and 20 or more years of use was associated with a tripling of risk (rate ratio, 3.4). Women who had used only combined hormone replacement therapy did not have a significantly higher risk of ovarian cancer than women who had never used replacement hormones; however, only 18 such women developed ovarian cancer, so the analysis was limited. The duration of use of this type of therapy (which averaged only 5.6 years among long-term users) was not significantly associated with the risk of ovarian cancer. Women who switched from estrogen-only to combined hormone therapy had a marginal increase in risk of ovarian cancer, which the researchers hypothesize reflected their prior use of estrogen-only therapy. Commenting on the findings, the investigators observe that many women who had used estrogen-only formulations were likely exposed to higher daily doses of hormone than are used today; the study could not determine the independent effects of dose and duration. Therefore, they conclude that it remains uncertain if long-term use of lower doses of estrogen is associated with an elevated risk of ovarian cancer. (source)
On the other hand, for those who develop ovarian cancer, the logic is inarguable that they would presumably not have done so had they had their ovaries removed. The reason for that qualifying "presumably" is that existing cancer at the time of surgery may subsequently develop elsewhere despite ovarian removal.
The literature has recorded elective oophorectomy rates of between 50% and 66% in women 40-64 years of age undergoing hysterectomy. Data from the Centers for Disease Control and Prevention collected between 1988 and 1993 concur that ovarian retention occurs in approximately 40-50% of patients undergoing hysterectomy at 40 years of age or older. It has been suggested that, in the United States, approximately 1,000 cases of ovarian cancer can be prevented if prophylactic oophorectomy is practiced in all women older than 40 years of age who undergo hysterectomy. This assumes an annual incidence of 24,000 new ovarian cancer cases and does not take into account the incidence of peritoneal carcinoma. The dilemma for the patient and the clinician is whether the estimated number of cancer cases prevented is worth the number of oophorectomies performed (approximately 300,000). The benefit of prophylactic oophorectomy may be offset by the consequence of estrogen loss early in life. (source, now no longer available)
In one study that is a literature review of previous work, the authors could not find that the retention of ovaries was more of a liability than an asset:
I asked how often do women get ovarian cancer? And is there any relationship between a non cancer condition in the uterus, and the likelihood of subsequently developing ovarian cancer? Dr. Garcia had been taught that there was evidence to suggest that women were better off having healthy ovaries removed while a surgeon had easy access to them during a hysterectomy. 
We decided to investigate and our search of published papers led us to conclude that the "evidence" had been based on a grammatical error. The literature had been misquoted.
Our research further suggested that the studies recommending ovariectomy were erroneous. We concluded that the ovary does contribute to the hormonal well-being of women past their reproductive years and should be left intact especially during hysterectomy if possible. (source)
Elsewhere in the above discussion they go on to explain:
For example, Annegers et al. Reported a 5 % prior hysterectomy rate in ovarian cancer patients, compared with a 23% hysterectomy rate in age-matched women who had not undergone prior ovariectomy. Two other studies published in the 1950s showed a similarly low 4% and 4.5%30 rate of prior hysterectomy among the ovarian cancer patients. Unfortunately, even though these data are quiet clear in showing that hysterectomy in ovarian cancer patients is disproportionately lower, misleading logic has been applied for the reverse conclusion, i.e., that ovaries should be removed at hysterectomy. This incorrect conclusion has been widely cited and, thereby, a false premise perpetuate. 
Another line of investigation also supports the safety of retaining the ovaries at hysterectomy. Prospective rates of ovarian cancer in ovaries retained after hysterectomy also support the absence of a risk. A cohort study following 900 hysterectomized women for 20 years showed an overall rate of subsequent ovarian cancer at 0.2% in the sample. The women who had both ovaries preserved showed a much lower rate (0.01%) of subsequent cancer than those who had only one ovary preserved (0.3%). (source)
And we could go on, or you can, using a simple google search. What this all indicates, however, is that risks continue to need to be considered not in isolation but as part of an individual's total risk profile. That ovarian removal does not protect from cancer in high risk individuals or in those cases where complexity of anatomy/scarring or surgeon incompetance promotes retention of some ovarian tissue fragments is well demonstrated. That ovarian removal increases the risk of other problems associated with higher levels of mortality is also demonstrated. Use of HRT adds another layer of individualized risk. There is no risk-free option and no single option is without its associated risks. While the fears that cancer raises in us, especially ovarian cancer, are real, whether or not we choose to make them the driving force in our decision is a personal decision regardless of whether that decision is driven by fear or research and statistics. Those who are seeking a broader evaluation of risks and benefits of either option for their ovaries, however, would be better served by looking at (and perhaps getting specialized medical evaluation of) their personal risk factors in order to make a reasoned, nuanced choice. Because no matter what your doctor may tell you, "most" women who have a hyst and retain their ovaries don't go on to develop ovarian cancer.