Lifestyle factors and prostate cancer: Expert insights

Keep reading for Dr. Phull’s insights on weight management, supplements, and diet. 

The following question and responses have been lightly edited for grammatical purposes.

1) What lifestyle changes and habits can patients focus on to help manage prostate cancer risk and support their overall treatment?

If you go on the internet, there’s going to be a ton of data. Some of it’s mixed, some of it makes sense, and some of it doesn’t. The number-one thing I tell most patients is that moderation is key. What’s within your control to modify is also key.

For example, even today, there are a lot of patients who still smoke. That is a huge risk factor for any sort of cancer. I have patients on treatment who are still smoking. They may be cutting down and trying to quit, and it’s not necessarily their fault. I think it’s an addiction and it merits resources, which we provide. Stopping smoking is within someone’s control. Even if you don’t have prostate cancer or aren’t at risk for it, smoking still greatly increases the risk of other issues, including lung disease unrelated to cancer.

Obesity or being overweight is usually within someone’s control, or there are things that can be done, especially in today’s “Ozempic era.” There are many medicines that can be given, and for some, bariatric surgery can be an option if diet alone isn’t enough. To me, smoking and weight management are two of the biggest modifiable risk factors.

Then we go into risk factors where we talk about, “Oh, what supplements can I take? Or what should I avoid?” The number one question I get asked is, “I stopped eating all sugar. How come my cancer is growing?” It’s not as simple as that. It’s not as simple as a high sugar diet feeding your tumor cell, and that’s why it’s progressing, or vice versa. It’s not that simplistic. I tell people, “Eat in moderation.” 

I don’t necessarily want to endorse this, but there’s mixed data on dairy intake. We don’t know if it’s hormones in the dairy, including cows that are injected with growth factors to produce more milk, [which could] increase prostate cancer risk. There’s some data that lycopene, especially in cooked tomatoes, decreases your risk of getting advanced prostate cancer. These are very difficult correlations. Remember, they’re correlations. You can’t do a control trial where you watch the milk intake of a person throughout their lives, watch every bottle of milk and cow that they got it from, know the hormones the animal had, and try to say there’s cause and effect. It’s correlations. So no, you shouldn’t stop taking dairy, and no, you shouldn’t eat an all-tomato diet. I don’t think that’ll do very much. 

Some other thoughts: vitamins like vitamin E and selenium. People used to prescribe this all the time. About 20 years ago, it was thought you had to do that. Now it’s been cast into doubt from mixed data, so we actually don’t know if those supplements do anything overall. Here’s the other thing breast cancer patients tell me, “Soy and phytoestrogens in soy can promote breast cancer. Can’t it also promote prostate cancer?” The thought is, it could. We don’t know 100%. Does that mean don’t eat any products with soy, which is in almost every food product we eat? No, I think, again, in moderation. I don’t think it should be that harmful, but we have very mixed data. 

Going back to supplements. There is one supplement, that’s not really a supplement, that’s marketed to men as an energy aid, helping them gain back muscle and vitality. That, of course, is testosterone. It’s not wrong for someone who is low on testosterone, as they age, to get testosterone supplementation under the guidance of a physician. However, it’s often touted as a supplement you can buy online without a doctor’s prescription or any sort of monitoring. It’s thought that excessive testosterone use, especially if you have prostate cancer, can feed the cancer because the backbone of treatment is androgen deprivation. So the opposite of that is giving those hormones, which is testosterone. What’s sinister about this industry, in my opinion, is that these are not always written out in boldface letters, such as testosterone. “Do not take if you have prostate cancer.” It’s often written off as vitality or energy for men and on the back where it says side effects, it says, “Ask your doctor.” Rather than listing the ingredients and the risks: just ask your doctor. 

We talked about the risks of medicine and they have a package insert or a radio commercial where they talk extremely fast at the end where you’re like, “Whoa.” Why do they do that? It’s because it’s studied in a systematic, evidence-based manner. When I see a supplement or medicine and the back label says, “Nothing can go wrong, but go talk to your doctor.” That tells me there’s a problem that’s not been studied. That’s one big thing I tell patients: be aware. 

I have a lot of patients who just bring in these bottles of stuff they’re taking, and they go one by one and say, “What do you think of this one? What do you think of this one?” A lot of them, I don’t even know. If you want to be scientific, take one at a time. If you add five pills plus your prostate cancer treatment and then you have a side effect, we don’t know what caused what and if it was an interaction with one of them. One of the biggest mistakes some patients make is that they give up on the treatment that’s actually working in favor of herbal medicines or alternatives. I’m not against alternative medicine, but what I’m saying is there are confounding variables there. 

2) There was an article circulating about pomegranate extract and its potential to lower or slow PSA rise. Have you heard about that, and what are your thoughts?

I’ve read these over and over. I know they’re sold as supplements, and there is some data on this, whether it’s pomegranate juice or pills. I always tell patients: if you’re going to use a supplement, why not use it in its natural form? For example, turmeric is one of the most widely discussed supplements among patients. My thought is, why not sprinkle turmeric into your food as a dietary flavor rather than taking it as a pill? We don’t always know exactly what’s in these extracts or how they behave in the body.

As for pomegranate extract, as far as I know, there was a meta-analysis published five to seven years ago. But again, meta-analyses like that are correlative; they combine different trials with different patients, indications, and variables, which is an invalid scientific approach. In general, I believe that all of these placebo control trials didn’t necessarily show a major improvement in survival or any sort of improvement, whether it’s done pre-cancer and as a neoadjuvant approach or metastatic cancer.

Sometimes trials are very reassuring, and then they go to a clinical trial with humans and they fail. They may even go up to monkeys and succeed, but fail when they go to humans. Pharmaceutical companies spend a lot on research and development because they can have a blockbuster drug that seems to be doing [well] under the microscope and then fail during a large phase III trial. That trial is a worldwide and multi-center and it fails, and now you’ve lost billions of dollars.  But that’s the right way to do science, rather than just throwing out extracts of things and saying, “Oh, we have historical data or narratives from patients, case, control, studies, or observations.” These have a lot of confounders.

The next thing I always discuss with patients is “What’s the harm or risk?” If there’s almost no risk and a patient says, “I want to start pomegranate extract,” I’m not going to say, “No, absolutely not.” Instead, I’ll say, “Okay, let’s do it thoughtfully.” I’ll ask to see exactly what they’re taking, recommend starting at the lowest possible dose, and we’ll monitor them closely over a few months. If it seems to help, wonderful. Maybe it’s something worth doing a trial. It’s really hard to give promising, evidence-based data to patients on something like pomegranate extract alone.

I’d say in general, supplements should be supplementing your standard medical care, not replacing it. If anything, do it in addition to the textbook approach. I just don’t think we know enough. That’s just the limitation of how we’re able to do science on supplemental products, but I’m glad that more of these are being incorporated into trials and formal studies.

To view the full recording of Dr. Phull’s Ask the Expert webinar, click here.