Prevention in Focus: Modifiable Risk Factors for Ovarian Cancer

In this episode, Sabrina sits down with Dr. Jennifer Ritonja, a scientist in the Department of Population Health Sciences at the BC Cancer and epidemiologist specializing in modifiable risk factors for women’s cancers. Together, they explore what life-course research tells us about physical activity, body fatness, vitamin D, and the realistic potential of lifestyle-based prevention for ovarian cancer. Does timing matter? Is being active at one stage of adulthood enough? And how do we distinguish between what’s truly modifiable versus what’s simply associated? This conversation dives into the science behind prevention — and the methodological challenges of identifying meaningful risk factors across decades of life. 🎧 Listen now wherever you get your podcasts.

#CancerEpidemiology #OvarianCancer #PreventionScience #WomensHealth #LifeCourseEpidemiology #PublicHealthResearch

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Transcript

00:00:02 Intro 

Thanks for listening to the GOSH Podcast, the Gynecologic Oncology Sharing Hub. We share real, evidence-based discussions on gynecologic cancers featuring stories from patients, survivors, researchers, and clinicians. Our podcast is produced and recorded on traditional unceded territories of the Musqueam, Squamish, and Tsleil-Waututh Nations. It is produced by the Gynecologic Cancer Initiative, a BC-wide effort to advance research and care for gynecologic cancers. 

00:00:35 Sabrina 

Alright. Hello everyone and welcome back to another episode of the GOSH Podcast. My name is Sabrina and I will be your host today we are joined by Dr. Jennifer Ritonja, a scientist in the Department of Population Health Sciences at the BC Cancer Research Institute in Vancouver, British Columbia. She's an epidemiologist by training, and her research program specializes in identifying modifiable risk factors that can be used to prevent cancer in women. Recently, her work has explored lifestyle factors across the life course, such as physical activity and body fatness and how they affect the development of ovarian cancer. And her current work examines breast density changes in relation to breast cancer risk. Welcome to the podcast, Dr. Ritonja. 

00:01:25 Jennifer 

Yeah, thanks for having me. 

00:01:27 Sabrina 

How are you doing today? 

00:01:29 Jennifer 

Good. I'm not originally from Vancouver, so I feel like the winters here are a little different for me, but I'm actually quite enjoying it because coming from Montreal, it's very, very cold there this time of year. 

00:01:42 Sabrina 

Yes, the temperate weather is certainly a nice change. 

00:01:46 Jennifer 

Yeah, exactly. 

00:01:48 Sabrina 

Okay, well, let's get right into it. So in your research on ovarian cancer risk, which period of adulthood did physical activity appear to matter most? And how did you identify the timing as being important? 

00:02:04 Jennifer 

Yeah, so I'd like to begin by sharing that this research comes from my postdoctoral fellowship, which was done with Dr. Anita Kushik at McGill University in Montreal. And so she was really the dragon horse force behind these research ideas, as well as the funding. And I had the opportunity to really carry out the work under her guidance. So with that in mind, so overall studies previously looking at physical activity and ovarian cancer risk were pretty inconsistent, unlike maybe for other cancer types where physical activity has been more strongly seen as a protective factor. And so we really wanted to look at the relationship more closely and saw that overall women who had more physical activity levels had a lower risk of ovarian cancer. So what was especially interesting was that when that activity occurred, it seemed to really matter the most. So in our study, physical activity in mid-adulthood, which we'd say would be between the ages of 30 to 49, really stood out as maybe being a potentially important period. And so we did this using an approach that compares the importance of these activities across these different life stages, instead of just measuring it maybe once later in life, which is what most previous studies have done. And, you know, thinking about the fact that cancer can take decades to develop, it's really important whether we're considering exposures at this right time period. And our research suggests that being active earlier in adulthood may be particularly important. And that makes these findings especially informative. 

00:03:39 Sabrina 

Very interesting. And how did you define and measure physical activity across adulthood in your studies? And were there any limitations to capturing activity over such long time spans? 

00:03:52 Jennifer 

So physical activity can actually mean a lot of different things. But when people hear that term, they usually think about exercise. So, whether you're running, biking, or going to the gym. And in research, we call this moderate to vigorous activity, which basically means that anything that gets your heart rate up. So this is a really activity that we focus on because that is the strongest evidence for relationship and for having benefits across, for different cancers as well as for other chronic diseases. But it's also important to mention that we didn't just look at, this exercise alone. We wanted to include these moderate to vigorous physical activities for, you know, what we do during jobs, commuting, and especially for women among what they do for housework and childcare. And this really turned out to be crucial in our study. So among our group of participants, we found that over 60% of their total physical activity that they would do across their lifetime was really coming from housework and childcare. So thinking about what other studies had done and where they really only looked at exercise, you realize you're missing a large part of a woman's daily movements. And that might help explain why some of these past findings have been pretty inconsistent. So, of course, there are limitations. Asking people to remember their activity across their whole adult life isn't perfect. And to improve accuracy, we tried to link it to these activity changes to major life events. So, you know, how things might change when they were having children or retiring. And we tried to use some expert assessment to help us estimate some of the physical activity, for example, for jobs and commuting. But misremembering is pretty inevitable. But we really think that the strength of our studies that we captured a much more complete picture of physical activity across adulthood than most previous research. 

00:05:49 Sabrina 

Very interesting. I like I really like the idea of I'm thinking about beyond just what we think about as exercise typically, which is very important for women. So thank you for sharing that. Did you find your findings suggested that maintaining physical activity consistently over time was more important than being active at, say, just a single period of time during adulthood? 

00:06:13 Jennifer 

So our analyses were kind of designed to look at both possibilities, you know, whether being active consistently over time matters, or whether activity at one particular stage of adulthood is especially important. And what we found is a bit more nuanced. So this middle adulthood period, roughly between ages 30 to 49, seems to be a particularly important window. And in research terms, we'd call this kind of a sensitive period, meaning that physical activity during this time appears to have a stronger influence on ovarian cancer risk than maybe at other ages. So that said, that doesn't mean that, activity at other times doesn't matter. And it really still does. And so the practical message really is to stay physically active whenever you can. And there might be, at least for ovarian cancer, some particular attention that needs to be, you know, paid to looking at staying active during middle life. 

00:07:08 Sabrina 

Okay, thank you for clarifying that nuance. And so from a biological perspective, what mechanisms might be able to explain how physical activity could influence ovarian cancer development, particularly across different life stages? So we don't know for certain. There are several biological pathways that could help explain how physical activity lowers the risk of ovarian cancer. So unlike for other risk factors that we know, such as birth control, which reduces ovarian cancer risk mainly through reducing the number of times a woman ovulates, physical activity likely works through birth different mechanisms. We know that from other cancer research that being physically active can reduce chronic inflammation, strengthen immune function, and influence hormone levels. And so all of this could be important for cancer development. So as for why middle adulthood might be more important, that part isn't entirely clear. So one possibility is that physical activity during this time helps prevent cancer from developing in the first place. Another is that it might  actually slow or stop the growth of these early carcinogenic effects that happen, maybe earlier in adulthood, maybe whether it's during peer review or during early adulthood at this age 20 to 29 period. But really, we don't know. So at this point, we don't have a definitive answer, but understanding these biological mechanisms and especially how they might differ across adulthood is really an important next step for future research. 

00:08:43 Sabrina 

Okay, very interesting. And how does body fatness fit into this relationship? So that's also something you looked at in this study. Did it sort of act more as a confounder, a mediator, or a modifier of the association between physical activity and ovarian cancer? 

00:09:01 Jennifer 

So we know from past research that body fatness is probably an important part of the relationship. In our paper specifically, we didn't look at body fatness and exactly, you know, like how it modified the risk for looking at physical activity in ovarian cancer. But in previous work, we've shown that higher body fatness is probably a strong risk factor for ovarian cancer. And we kind of used a similar methodology where we're trying to figure out a different, you know, what important time period there might be. And we found that it might be really important during this early adulthood period. So a little bit earlier than what we're seeing for physical activity. So in our, you know, physical activity study though, we mainly thought of body fatness as a mediator, meaning that it, you know, would lie along this pathway of leading from physical activity to ovarian cancer risk. We know from a lot of existing evidence that physical activity plays a major role in shaping body fatness over time. So we didn't want to adjust for it because it could actually remove away part of this effect that we're trying to understand. And so based on prior research, it also seems likely that, you know, sure, maybe body fatness could act as a confounder. In other words, that differences in body fatness alone, you know, maybe could that explain, you know, whether someone's more physically active or not? That seems less likely of a scenario, but That said, this is a pretty complex and dynamic relationship. So we can think that physical activity and then, body fat is probably influence each other over time and influence, in different ways for different people and across, different stages of life. So it makes it really challenging to fully disentangle, these individual effects. 

00:10:46 Sabrina  

Okay, yeah. I hadn't even thought about all the different ways that it really could be related to physical activity. So thank you for explaining that. So another factor often discussed in cancer prevention is vitamin D. In your work, what did studying vitamin D reveal about the challenges of identifying truly modifiable risk factors for ovarian cancer? 

00:11:11 Jennifer 

So in our work, we found that higher vitamin D levels appear to be associated with a lower risk of ovarian cancer. And, you know, studying vitamin D actually really is a good factor to look at when you're trying to highlight how challenging it can be sometimes to examine these modifiable risk factors. So, you know, vitamin D isn't really just one exposure. It comes from sunlight, diet, and the supplements that we take. And, you know, measuring these separately doesn't, wouldn't, you know, fully capture someone's overall vitamin D status across their life. And ideally, you'd want to measure vitamin D directly in the blood. But when we think about, these long-term population-based studies, it's really rare, even with these studies that do, you know, multiple blood samples across time, that they have enough repeated blood samples to look at it across the lifetime or across these decades. So to address this, we've kind of wanted to do it, a bit differently. So we use existing evidence to build this model that can basically predict or estimate a woman's vitamin D level in their blood. And they were able to do it for year over year across adulthood. And then we're able to relate these patterns that we saw to how this might affect ovarian cancer risk. And so the fact that when we saw, like looking across our whole adult life period and averaging that out, that we saw a protective association, when many actually previous studies didn't, suggests that probably the timing and this long-term exposure might be important. And similar approaches, especially these ones that measured it close to diagnosis, are probably missing an important part of the story. So more broadly, this actually probably helps explain why public health often sees these conflicting headlines about whether something like vitamin D is good or bad with cancer. Lifestyle factors are complex. And just thinking of this one factor of loan that's setting them, you might see different relationships based on how you're looking at them across this life course is really important. And understanding this better is essential for drawing these kind of clear conclusions. 

00:13:20 Sabrina 

Fantastic. Yeah, I think that's such a good thing to remind research of and researchers of and really highlight these modifiable risk factors and how they are hard to study. So looking ahead, what do you identify as the most important next step for advancing life course research on ovarian cancer risk? And it can be methodologically or conceptually. 

00:13:45 Jennifer 

So I think one of the most important next steps is really recognizing that many ovarian cancer risk factors they might matter at different life points across the life course. And so, rather than assuming that their effects are the same at all ages, we have to start thinking about how these effects might be different. And so if, we only measured exposures at a single time point, we're really missing these critical windows potentially when risks may be shaped most strongly. So life course approach really allows us to look at how these changes and things like, behavior, biology, and also social roles, which is kind of what we saw with physical activity, how that across adulthood could work together to influence risk. Methodologically, this means, you know, improving how we can capture long-term patterns. So both for lifestyle factors, thinking about, physical activity or body fatness like we had done, but also for other exposures. So looking at maybe hormonal factors, metabolic health or inflammation. And conceptually, I think it really pushes the field towards thinking more about timing, not just whether, you know, black or white, whether an exposure matters. And that shift is really important if we wanted to move from identifying risk factors to, being better at developing these effective age-appropriate interventions and prevention strategies for ovarian cancer. 

00:15:09 Sabrina 

Fantastic. Well, thank you so much for joining us on the podcast today, taking time out of your very busy life. I think our audience will learn lots from this episode. 

00:15:19 Jennifer 

Yeah, thanks for having me. 

00:15:21 Outro 

Thanks for joining us on the GOSH Podcast. To learn more about the Gynecologic Cancer Initiative and our podcast, make sure to check out our website at gynecancerinitiative.ca.