Lorelei Mucci: Thank you so much. Delighted to be here today.
Zachary Klaassen: Well, this is really interesting because we were just talking before we hit record about how much diet, and risk factors of men with prostate cancer are risks of chronic diseases of other things that are probably going to lead to mortality. So maybe just by way of background, what got you interested in this study? Why is it important to think about diet, prostate cancer, especially men on systemic therapy for prostate cancer?
Lorelei Mucci: Yeah, no, I think this is a fantastic question. There's right now over three and a half million men in the United States living after a prostate cancer diagnosis. And as you mentioned, there's a lot of shared risk factors for prostate cancer such as low physical activity, excess body weight, smoking that are also associated with other chronic diseases. So we were interested in at that, can we give evidence-based recommendations about the optimal dietary patterns that are not only potentially going to improve cancer mortality, but really overall mortality and survivorship for patients?
Zachary Klaassen: No, absolutely. And I spent a lot of time talking about cardiovascular disease and diet in my clinic, and I think it all wraps up into that story. So to get into the design of your study, just take some time to lay out what the population was, how you define some of these diets you guys looked at. What was the study design?
Lorelei Mucci: Yeah, sure. So I have been involved in a study called the Health Professionals Follow-Up Study. We're actually celebrating the 40th anniversary of this study. So these are all male health professionals, dentists, optometrists, veterinarians. The reason we picked them is because one, we thought they'd be able to provide high-quality information about their health and that they'd want to be a part of a study over the long-term. And in fact, on our last questionnaire, these men are now in their 80s, 90s, even some in the hundreds, 90% of them completed these biennial questionnaires we send them. So that's the cohort that we were looking at. And in this cohort of 50,000 individuals, actually almost 9,000 have been diagnosed with prostate cancer at some point during the follow-up.
And the other thing about this population is we actually have data collected on these individuals both before and after their cancer diagnosis. So we can really look at things like, if I change my diet, does that improve outcomes?
Zachary Klaassen: Sure.
Lorelei Mucci: And what about what they were doing before? So we actually, for this study, we looked at 6,000 men with prostate cancer. They were diagnosed between 1986 and 2016. And then we've also been prospectively following individuals for mortality. And so we were able to look at not only overall mortality, but looking at death from cardiovascular disease, other cancers, respiratory diseases, et cetera. So that was sort of the study design. And on average, we followed men for at least up to 35 years, but on average about 12, 14 years.
Zachary Klaassen: Awesome. And I know that you looked at several different types of diets. How did you define that? How did you pull that out of the data?
Lorelei Mucci: Yeah, so we focused in on five different dietary patterns that we hypothesized might benefit mortality outcomes. And these were mainly based on studies in patients without cancer. So looking at individuals with just a range of health outcomes. So we focused on five. The first was the Alternative Healthy Eating Index, which was developed to optimize lower risk of chronic diseases more broadly, a Mediterranean style diet, which people may have heard about, which was a pattern of eating that in Mediterranean, they have healthy aging longevity, so it's thought to potentially lower the risk of other diseases. Diabetes, the DASH diet, a diet that was optimized to reduce diabetes risk. And then two other dietary patterns that were actually developed based on biomarkers. So one was the anti-insulinemic diet. So this are food items that lower insulin levels, and then an anti-inflammatory diet that lowered biomarkers of inflammation. So those were the five dietary patterns that we looked at.
Zachary Klaassen: That's great. And just a treasure trove of data to be able to compare diets even before diagnosis to after. I mean, I can't think of another database that has that information. So there's a lot of great results here. Maybe just pull out what you think are the key results for our listeners.
Lorelei Mucci: Yeah, sure. So I think when we looked at overall mortality, there were three dietary patterns that really kind of stood up. The first was this Alternative Healthy Eating Index. So men who were consuming, the top 20th percentile of this healthy dietary pattern had about a 25% lower risk of death overall. Also, this Mediterranean style diet was associated with about a 20% reduced risk. So those were from overall mortality. But I think what was really interesting to see were the benefits of these dietary patterns, specifically for lowering the risk of death from other cancers. So not prostate cancer specifically, but colorectal cancer, other types of cancers. So really substantial, about 30 to 40% reduction of death from other cancers. So those were some of the real highlights. The other thing I think that was really interesting to see was a number of these dietary patterns. I think the message is it's never too late to start eating a healthy diet.
Zachary Klaassen: Yes.
Lorelei Mucci: So we found that compared to individuals who perhaps weren't eating a healthy diet before their diagnosis, if they changed their diet to one that was more healthy, whether it was the Mediterranean style diet, and anti-insulinemic diet, we really saw strong benefits for reduction in mortality.
Zachary Klaassen: No, that's fantastic. And I think it's a great message because patients often want to try to control something in this whole process. If they have localized disease or on active surveillance, "Doc, what can I do to help?" You can eat a healthy diet. I mean, we knew that, but this data really sort of shows that you're decreasing the risk of overall mortality, other cancers, as you mentioned. I think this is really important information.
Lorelei Mucci: Yeah. And I think the other message is that there's many paths to a healthy diet. So they have some core themes. These diets are high in plant-based foods. So whole fruits, vegetables, whole grains, legumes, and nuts, healthy sources of protein. There's some differences. So for example, the Mediterranean diet really emphasizes fish and seafood, and olive oil as its component. But I think the key thing is that there's many healthy style diets, and some foods to avoid such as red meats and saturated fats, for example. So I think there's commonalities in these dietary patterns too.
Zachary Klaassen: Absolutely. I think just to hit on one of the things you mentioned in your limitations, this is a healthcare professional, obviously a litle higher socioeconomic status probably, obviously concerned about their health. I mean, they have this great track record of filling out these surveys. How does this information maybe translate to some lower socioeconomic status areas, whether that be different cities, different parts of the country, other countries in general? How would you message that?
Lorelei Mucci: Yeah, no, I think that's a really great question. So first of all, our Health Professionals Follow-Up Study participants actually live in all 50 states. They live in very rural areas to all the way up to urban areas, and they were diagnosed with all different types of prostate cancer. We included both localized, locally advanced, and then some patients who had metastatic disease. So when you look at it that way, we really are looking at breadth of patients. But as you said, these were individuals who are health professionals, so they had higher education, attained education. So there's both a benefit of that. It controls for some residual confounding that might be due to higher socioeconomic status. But as you said, there are some limitations.
These men are pretty healthy, lots of exercise, lots of healthy diet, and the types of foods that, for example, let's say in the Southeast part of the United States where we have very high mortality from prostate cancer, there's different dietary patterns than some of these [inaudible 00:09:00] you might see. So I think it is important to look at other populations, but I think just to emphasize these individuals are, as I said, from all over the United States, all sorts of different types, and all sorts of healthcare systems where they were treated as well.
Zachary Klaassen: That's very helpful. I think that's a good point. Just as a very high-level take-home point, what can people take from this study to their clinic either later today, tomorrow, this week? What should their message be to their patients?
Lorelei Mucci: Yeah, no, I think that's a great point. I think one is it's never too late to start eating a healthy diet. Secondly, find, I think, the healthy foods that you enjoy eating. So whether it's vegetables, whole grains, different types of... You don't have to avoid red meat, for example, altogether, but maybe limit its consumption, limit consumption of sugar-sweetened beverages, for example, and think about ways that you can, I think, maintain diet. So I think one of the recommendations also is find foods not only for yourself, but that your family ate, because I think the more you can enjoy food, healthy foods, I think the more likely you are to be able to sustain a healthier diet.
Zachary Klaassen: Absolutely. Lorelei, congratulations on the great work, again. This paper was published and JNCI recently will tag the citation to our conversation. Thank you so much for joining us.
Lorelei Mucci: Thank you so much.