Shelley Tworoger, PhD, Moffitt Cancer Center’s Associate Center Director of Population Science, talks about the possible correlation between following an aspirin regime and the risk of ovarian cancer.
Interview conducted by Ivanhoe Broadcast News in October 2018.
This research that you’ve done is pretty big, can you elaborate a little on it?
Tworoger: We’ve had a long interest in trying to understand what inflammatory factors might increase risk of ovarian cancer and multiple studies showed that higher inflammatory markers in the blood were associated with higher risk of ovarian cancer. So we wanted to think about ways we might be able to offset that effect which is why we looked at aspirin. There have been multiple studies looking at aspirin in ovarian cancer in the past with somewhat conflicting results and we were able to do some things that were new compared to prior studies. One was looking at baby aspirin or low dose aspirin versus regular dose aspirin. That’s where we saw the really striking findings. Ultimately we found taking low dose aspirin regularly was associated with a lower risk of ovarian cancer but taking regular dose aspirin, three hundred twenty five milligrams, was not associated with a low risk of ovarian cancer.
What impact do you think this research will have?
Tworoger: My hope is that it’s going to spur some additional research to do a couple of things. The first is to identify women who might most benefit from taking aspirin to reduce risk of ovarian cancer. Another is to understand the mechanisms by which aspirin may influence ovarian cancer, because that may help us find better ways to prevent ovarian cancer. Most importantly, in the short term though I hope that this opens up conversation for women to talk to their doctor about aspirin for prevention of cardiovascular disease and colon cancer. Those are things that we know aspirin reduces the risk and there are recommended guidelines especially for cardiovascular disease. So I hope that this gives women an opportunity to have a conversation with their doctors about whether taking aspirin is right for them.
At this point would you recommend taking aspirin to someone who could be at high risk for ovarian cancer?
Tworoger: At this point I wouldn’t recommend people take aspirin to prevent ovarian cancer explicitly. However, if it’s recommended or appropriate for them to take it for cardiovascular disease prevention or potentially colorectal cancer prevention then I think it would be appropriate. But keep your eyes open for future research because I think ultimately this could become part of a larger conversation about aspirin use in healthy individuals.
What other research would be needed before a doctor can feel comfortable making a recommendation?
Tworoger: Well one thing we need to do is understand why aspirin is altering ovarian cancer to make sure that it’s really a causal association; that aspirin is actually changing things that are stopping ovarian cancer from progressing. There’s research that can look at how aspirin may affect different factors related to ovarian tumors and we have research in that area that will be coming out soon, as well as looking at some other factors that aspirin affects. For example, aspirin affects prostaglandins, which are inflammatory hormones in the body, and prevents them from being formed. So we might want to look at whether prostaglandins themselves are directly related to ovarian cancer. An early study that was just published suggests that might not be the mechanism. In ovarian cancer patients, platelets appear to be important in ovarian cancer progression and aspirin can reduce platelets, so we might want to look at how platelets are related to ovarian cancer. The other main area of research is using our population-based studies and pooling a bunch of them together so that we have a really large sample size that will allow us to look at different populations, such as women who are at high risk, say because they have a family history of ovarian cancer, to see if aspirin is particularly protective for them. So we could target prevention of women who are at high risk.
It was a twenty three percent …
Tworoger: It was a twenty three percent reduction in risk.
Okay.
Tworoger: We have another study that came out a couple of months ago in JNCI where we actually pulled together data from thirteen different studies around the world. Unfortunately in that study we didn’t have very much data on aspirin dose, but we did find that daily aspirin was associated with a lower risk. That study had several thousand ovarian cancer patients. The current study has about probably around a thousand patients. What we hope to do is get more data from those studies that asked about dose and we can combine it all together and have this very large dataset with many thousands of cases.
When the average person hears a twenty percent decrease they might jump on taking aspirin every day. Do you think that’s too early to do that?
Tworoger: I do think it’s too early to recommend that women take aspirin to prevent ovarian cancer. We don’t know for sure that aspirin prevents ovarian cancer yet and we don’t know which women could benefit. What’s the risk benefit ratio, as taking aspirin has some potential side effects. Some individual for example have GI or gastrointestinal bleeding from aspirin and that’s why these recommendations are carefully vetted. That said, there are existing recommendations for women to take a low dose aspirin for cardiovascular disease from age fifty to seventy. Any woman who is in that age range should talk to their doctor about that. And that of course is the age range in which women are at the most likely to get ovarian cancer. So if we can sort of loop people in by talking about cardiovascular disease we might have a secondary benefit of helping prevent ovarian cancer along the way.
In your years of research this something that you’re obviously proud of …
Tworoger: Yeah, I feel really lucky to have such amazing collaborators because the data in our study has been collected starting in nineteen seventy-six. That was when I was much younger, so I am really lucky to be able to leverage the legacy of many investigators over a long period of time. I feel very lucky to have had the opportunity to collaborate on that study, the Nurse’s Health Study, because of my interest in ovarian cancer and some challenges in studying ovarian cancer and because it’s a rarer female cancer than breast cancer. I’ve worked with collaborators, like I said, from all over the world to develop this large consortium called the Ovarian Cancer Cohort Consortium where we are trying to expand our research by leveraging really great research that has gone on all over the world and use that for a new purpose to understand and help women reduce their risk of getting ovarian cancer.
Is there anything right now that a woman can do to prevent ovarian cancer at this point that you know of? Is there anything out there?
Tworoger: Well that’s a complex answer so I’ll kind of break it up in to two parts. At this point there are no official recommendations for women who are at normal risk to reduce their risk of ovarian cancer. Now there are a couple of exceptions to that. Women who have certain genetic mutations, I’m sure you’ve heard of BRCA mutations as that’s often in the media. Angelina Jolie recently had her ovaries removed a few years back because she was at high risk from this particular genetic mutation. So for women with those genetic mutations they should consult with a gynecologic oncologist to discuss having their ovaries and their fallopian tubes removed, which largely reduces your risk of ovarian cancer quite significantly by about eighty five to ninety percent. We don’t want to recommend for an average risk woman to just have her ovaries removed for ovarian cancer prevention and that is because unfortunately having your ovaries removed can cause other health problems, such as increasing your risk of heart disease, which is as you know is an important health condition for women. But there are some things that we do know lower risk of ovarian cancer, we just don’t want to recommend them on a population scale yet. For example, oral contraceptives are associated with a lower risk of ovarian cancer. A lot of women may choose to take oral contraceptives for other reasons, but because they can have some side effects we don’t want to just recommend that all women take oral contraceptives.
That’s birth control, does that cause breast cancer or …
Tworoger: Yeah, certain birth control pills may increase risk of breast cancer while you are on them but that seems to go away once you stop. Obviously birth control pills are also associated with certain cardiovascular events like strokes and blood clots; for some women it’s okay and other women it’s not. There has also been a push and some recommendations by the Society of Gynecologic Oncology and other similar groups to have women consider having their fallopian tubes removed as an alternate to when they either are considering having their tubes tied, that’s called tubal ligation, or when they’re having their uterus removed and if they have some other reason that they need to have their uterus removed. You might say why your fallopian tubes, that doesn’t make sense. Well it turns out that we think some ovarian cancers actually arise from cells in the fallopian tube not from cells on the ovary, they just end up growing on the ovary. So for a long time we thought they were ovarian cancers but now we’re pretty sure that some of what we call ovarian cancers are really from the fallopian tube cells. There is a lot of research in this area to determine the long-term safety of having your tubes removed, either when you have hysterectomy or in place of tubal ligation. More and more evidence is suggesting that it may be a promising approach for some women undergoing those procedures.
So removing the fallopian tubes, the oral contraceptive and …
Tworoger: Yeah, and for very high-risk women, because of genetics, having their ovaries and their fallopian tubes completely removed after they’re done with child bearing.
That’s where we’re at right now.
Tworoger: That is where we’re at.
Do you think the aspirin recommendation would be like a couple of years from now, maybe it won’t even end up being a recommendation?
Tworoger: I think it’s a little hard to say. I mean of course we’re probably never going to be able to do a randomized trial of aspirin and ovarian cancer because it would just be too expensive. But I think we can probably incorporate that as part of the discussion for talking about taking aspirin for reducing risk of other chronic diseases. So that is my goal in our upcoming research is to move towards having this be part of a bigger conversation about the potential benefits of taking aspirin.
END OF INTERVIEW
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