Transcription:
Obesity and Cancer Risk

Melanie Cole (Host):  Multiple studies have shown correlations between obesity and a risk of cancer recurrence. My guest today is Dr. Misagh Karimi. He’s a staff physician specializing in hematology/oncology at City of Hope. Welcome to the show, Dr. Karimi. Tell us a little bit about how obesity affects cancer risk and what you’re seeing in the country today as we have this obesity epidemic going on.

Dr. Misagh Karimi (Guest):  Thank you for having me. I think obesity is an epidemic in this country. There have been multiple studies that have been done, epidemiological studies and also studies that look at the patients who have had cured early- stage cancers that have links to obesity with either recurrence, risk of a cancer or incidence of having a new primary cancer. Look at multiple studies that have been done in colorectal cancer, in breast cancer, which are two of the most common types of neoplastic diseases in this country and you see a direct correlation with obesity with people who have a higher body mass index having a higher chance of developing those cancers. But also if you look at other types of less common cancers such as the esophageal, pancreatic, and also looking at gallbladder and urinary bladder cancers also have been shown to have increased risk of disease with a higher body mass index. 

Melanie:  With certain cancers, Dr. Karimi, when you mentioned breast cancer and colorectal cancer and we linked that and looked at obesity, where is that link? Colorectal would seem to make sense because maybe it means that you’re eating a lot of junk and your colon gets filled up with that, but what about breast cancer or esophageal cancer, stomach cancer, how are these related to obesity? 

Dr. Karimi:  Looking at the breast cancer, if you look at the risk factors that have been studied in the past and have been shown to be important in increasing the chance of developing breast cancer, hormones seem to have a major play. Estrogen replacement has been linked very well to developing breast cancer with very large women studies that was eventually finalized about 10 to 15 years ago. If you look at estrogen, basically synthesis in the body after menopause, it’s linked to peripheral adipose tissue: The higher the content of adipose tissue or the fat tissue in the body, the higher chance of having a high level of estrogen and estrogen-like compounds in the body. That’s one way of linking the risk of developing breast cancer in the patients who have higher body mass index. But that doesn’t stop there. There are a lot of other issues that come up. Having a higher body mass index in general also is linked to lower exercise and perhaps not very healthy eating that also affects your immune system. If you want to think of this, perhaps in all of us, we develop one type of cancer or another on a regular basis. Our immune system keeps these under check, finds these cancer cells and removes them from the system. Now, if your immune system is not working very well, then we run to this problem that some of these go unchecked and eventually develop into advanced disease that the body cannot take care of any longer. So it is a constellation; I mean we look at several things. It’s really healthy habits, living habits, that all come together and one part is the obesity. 

Melanie:  Here’s the big question, Dr. Karimi. If you lose the weight, does that then decrease your risk of developing these specific cancers? Because I imagine that when you’re overweight, you worry about diabetes and heart disease, but you don’t always think about that link between obesity and cancer. If you lose the weight and you lose that body mass index, then are you decreasing your risk of cancer or is it already there? 

Dr. Karimi:  That’s an excellent question. We discuss this all the time. I discuss this all the time with my patients who have had early stage of cancer, for example, breast cancer, and we see them in follow-up. I do try to make this point every time I see my patients that it’s very, very important to try to follow some rules. We have studies that show reduction of body mass index of obesity would reduce the chance of developing a primary cancer that may be hard to show. These are again epidemiologic studies, very hard to perform a study that will actually do this and have an adequate control for it. But we have plenty of data in women who have had the cancer and have been followed afterwards. In other words, let’s say women who’ve had breast cancer early-stage disease have been cured with surgery, chemotherapy, radiation hormonal blockage and so on. Then they are randomized to either a healthy diet, if you want to call it, the prudent diet, Mediterranean diet, regular exercise; versus the other group, the control group that was left to continue their lifestyle as before. There is very good data that these patients had a much lower chance of recurrence of their breast cancer. Interestingly the study did not try to promote weight loss, but on average, women did have significant weight loss when they were on the experimental group that were followed closely by dietitian and encouraged to exercise and so forth. There is an indirect correlation, at least in this study, that weight loss by itself reduces chance of recurrence. There is no question that a healthy diet and exercise also adds to that.  

Melanie:  In just the last few minutes, give your best advice in what people can do to prevent obesity and their increased cancer risk and why they should come to City of Hope for their care.

Dr. Karimi:  That’s a very tall order, but that’s also an excellent question. I think there are several things that fit into this. We talk about diet. We talk about exercise. I think we need to also talk about how much time we’ve spent sleeping at night. I think these are all important. People who in general sleep less, a fewer hours on average, tend to have more problems with obesity, with high blood pressure. It is a really healthy lifestyle that’s important to discuss. When we talk about exercising, generally most of the studies have shown that daily routine is recommended. Not to do two to three times a week, but try to do that on a regular basis, on a daily basis, to do an aerobic type of exercise. When we talk about diet, in general, it’s recommended to have a higher amount of fruits and vegetable intake and less amount of dietary protein that are basically originated from meat, especially red meat. So protein that comes from plant-based food is also recommended to be more beneficial, perhaps more legumes, more not in those general categories, and less red meat, and less dairy product.Again, finally, just the practice of trying to live a stress-free life as much as possible and getting enough sleep at night.

Melanie:  It’s great information and these are such important points and such interesting topic. Thank you so much, doctor.  You are listening to City of Hope Radio. For more information, you can go to cityofhope.org. That’s cityofhope.org. This is Melanie Cole. Thanks so much for listening.