Bariatric Surgery Substantially Lowers Risk of Obesity-Related Cancers

Podcast Transcript

Dale Shepard, MD, PhD: Cancer Advances, a Cleveland Clinic podcast for medical professionals, exploring the latest innovative research and clinical advances in the field of oncology. Thank you for joining us for another episode of Cancer Advances. I'm your host, Dr. Dale Shepard, a medical oncologist here at Cleveland Clinic overseeing our Taussig phase I and Sarcoma programs. Today, I'm happy to be joined by Dr. Ali Aminian, Director of Cleveland Clinic's Bariatric and Metabolic Institute. Dr. Aminian is here today to talk to us about the impact of bariatric surgery on the risk of obesity-related cancers. Welcome.

Ali Aminian, MD: Thank you, Dr. Shepard. Thanks for the invitation.

Dale Shepard, MD, PhD: Absolutely. Maybe just give us an idea, what's your general role here at Cleveland Clinic?

Ali Aminian, MD: I'm a bariatric surgeon and Director of Bariatric and Metabolic Institute at the Cleveland Clinic Main Campus.

Dale Shepard, MD, PhD: Excellent. We're going to talk about the link between bariatric surgery and obesity-related cancers. There's a lot of people that might be listening in that we just give a background. When we talk about obesity-related cancers, what kind of cancers are we primarily talking about?

Ali Aminian, MD: First of all, we should know that after smoking, obesity is the second most common preventable risk factor for cancer. By 2030, only seven years from now, one out of two Americans will have obesity, one out of four will have severe obesity. These are unbelievable predictions. And it's estimated that with the wider spread of obesity worldwide, obesity will be the most common preventable risk factor for cancer globally and in the United States. The link between obesity and at least 13 different type of cancers have been established. Those will include breast cancer, endometrial cancer, liver cancer, thyroid cancer, esophageal cancer, and many other cancers.

Dale Shepard, MD, PhD: So really, a lot of very common cancers that really could be prevented. Again, just to set the stage here, when we talk about obesity-related, how are we defining obesity?

Ali Aminian, MD: There are different classifications for obesity, but the simplest way to classify obesity is anybody who has body mass index over 30. There are different stages of obesity. BMI or between 30 to 35 is defined as stage I obesity or mild obesity, 35 to 40 is moderate obesity or stage II, and above 40 is defined as severe obesity.

Dale Shepard, MD, PhD: So just roughly speaking, what percentage of the American population would fit that criteria of obesity of BMI over 30?

Ali Aminian, MD: Currently, over a hundred million people in the United States are fitting in that criteria, but as I briefly explained, by seven years from now in 2030, one out of two American will have obesity.

Dale Shepard, MD, PhD: Wow.

Ali Aminian, MD: Which is extremely high.

Dale Shepard, MD, PhD: That's extremely high, particularly when it's linked to so many cases of cancer. Tell me a little bit about the study that you participated in and that link between obesity and cancer, specifically bariatric surgery.

Ali Aminian, MD: Well, we knew that obesity increases the risk of cancer, at least those 13 type of cancer that we just discussed. But we wanted to find out whether that risk was reversible with significant weight loss or not. So that was our research question. It was not about bariatric surgery itself, it was about the weight loss, but we focus on bariatric surgery because that's the most effective way to help patient with obesity lose weight. In terms of the study, details of the study, we enroll near 5,000 patients with obesity who underwent bariatric surgery at the Cleveland Clinic between 2004 and 2017. Those patients were carefully matched with near 25,000 patient with obesity who did not undergo bariatric surgery. So in total, we had near 30,000 patients who were followed over 17 years.

Dale Shepard, MD, PhD: So that's a really large group.

Ali Aminian, MD: It was really large group with a good follow-up time.

Dale Shepard, MD, PhD: When we think of the control group, were those patients who were also trying to lose weight but by methods other than bariatric surgery?

Ali Aminian, MD: Some of them, yes. Some of them tried non-surgical methods to lose weight and some of them chose just lifestyle modifications. That's correct.

Dale Shepard, MD, PhD: I guess just for everyone to understand what we're talking about with bariatric surgery, can you give us a little bit of an overview of what bariatric surgery is about and types of surgeries and how effective that usually is?

Ali Aminian, MD: Sure. Bariatric surgery or metabolic surgery or weight loss surgery are procedures that help patient to lose large amount of weight. These procedures are usually done with the minimally invasive approach with laparoscopy or robot. Takes about two hours to do the procedure. We do procedure through five or six small incisions and go inside the abdomen and do the procedure. The two most common surgeries currently are either sleeve gastrectomy or gastric bypass. Takes about, as I said, two hours to do the procedure. In the sleeve, we remove about 80 percent, 85 percent of the stomach and take that part out. The stomach inside the body looks like a football. After surgery, going to look like a banana, narrow tubular stomach. For a gastric bypass, we don't remove anything. We reroute the stomach. We cut the stomach on the top part and then we bring a loop of small intestine and connect to that top part of the stomach.

When patient take food, foods go through the esophagus to that small pouch that we create on the top part of the stomach and then it will be diverted into the small intestine. We bypass about 90 percent, 95 percent of the stomach. Patient usually stay in hospital one night after the surgery. Recovery is about two or three weeks. Risk of having complication is about 3 percent. Out of 100 patients, three may develop complications. It significantly improves quality of life and obesity-related comorbidities. Patient usually lose about one-third of their body weight. If the patient is 300 pounds before surgery, they typically lose around 80, 90, 100 pounds after surgery and they are able to keep their weight off for a long period of time. So that's brief explanation of bariatric surgery.

Dale Shepard, MD, PhD: And between those two procedures, are they similar in terms of weight loss and the ability to keep the weight off?

Ali Aminian, MD: Sleeve gastrectomy is a bit safer than the gastric bypass. Risk is about 2 percent, 3 percent after the sleeve, maybe 3 percent, 4 percent after the gastric bypass. 1 percent or 2 percent less risk with the sleeve than the bypass. Bypass is more powerful tool. Patient usually lose 10, 15, 20, 25 pounds more with a gastric bypass compared with the sleeve. They're able to keep the weight off for a longer period of time with the bypass than the sleeve. It's more durable. It has a stronger effect on diabetes and cardiovascular risk reduction. So overall, the sleeve is a bit safer, gastric bypass is a bit more effective.

Dale Shepard, MD, PhD: All right. When I look at the study that you conducted, what were the primary results?

Ali Aminian, MD: Obviously, surgical patients, as expected, lost large amount of weight over the time and kept the weight off for a very long period of time. That led to a 32 percent low risk of developing cancer and 48 percent low risk of dying from cancer in the surgical patients compared with the patient who didn't undergo weight-loss surgery. As you see, the magnitude of effect was very large. 32 percent low risk of developing cancer was extremely large and was surprising to us. The findings were consistent in the subgroups. Whether patients were male or female, young or old, Black or white, the cancer risk reduction after bariatric surgery was consistent and observed on all these subgroups. Another interesting finding was of those dependent response. We found that the greater weight loss in the surgical group, the lower the risk of developing cancer.

Dale Shepard, MD, PhD: Were there any particular types of cancer that were impacted more than others?

Ali Aminian, MD: That's correct. Before the study from the available literature, we knew that among all cancer types, endometrial cancer has the strongest association with obesity. Our findings confirmed that. Our study found that endometrial cancer had the largest cancer risk reduction after bariatric surgery. Actually, the risk of developing endometrial cancer was 53 percent lower in the bariatric surgery group compared with the control group. The second cancer on that list after endometrial cancer was postmenopausal breast cancer.

Dale Shepard, MD, PhD: With the results of such a dramatic decrease in the rate of cancer, the mortality-related to cancer, is this something that's likely to become more widely utilized? I guess the question would be, why isn't this more widely adopted?

Ali Aminian, MD: That's a good question and hard to answer. You know that obesity is the root cause of numerous devastating medical conditions, not just about the cancer. It can increase the risk of diabetes, cardiovascular disease, nephropathy, fatty liver disease, and it increase the risk of mortality overall. It shorten the lifespan. The good news here is that health consequences of obesity are reversible. If we help patient to lose substantial weight and keep the weight off for a long period of time, we can reverse or prevent health consequences of obesity to some extent. We show that with that cancer study that we just discussed. We had showed that before with diabetes, cardiovascular disease, nephropathy, fatty liver and other health consequences of obesity. We just need to help our patients to lose large amount of weight. To get to that point, we need real treatment for obesity. Just asking patient to eat less and exercise more probably not going to work.

They need powerful tools to help them to lose large amount of weight. For the purpose of the cancer risk reduction, the current guidelines recommend weight loss. Our findings support those guidelines, but again, in patient with obesity, instead of focusing on lifestyle modification, only effective and durable treatment such as bariatric surgery are required for cancer prevention. I think the misconception here is that many patients and many healthcare providers think that obesity is the patient choice. If the patient decide to eat less and exercise more, we don't have obesity problem. But that's not the case. If the solution was that simple, we wouldn't reach to that obesity epidemic in this country that by seven years from now, half of this population will suffer from obesity.

Dale Shepard, MD, PhD: There seems to be an increased use of some medical therapies for weight loss as well. How might that change the landscape and the use of bariatric surgery?

Ali Aminian, MD: That's a really good question. We are in exciting time in terms of obesity management. Having this new medications available, the landscape of obesity treatment going to change in the next few years. Then we have those powerful tool in our toolbox to help patients. Hopefully, we are going to see very similar results in terms of the cancer risk reduction that we have seen with the bariatric surgery in this study. So obviously, we cannot offer bariatric surgery to a hundred million people with obesity who live in the United States, but when we have effective medical treatment for obesity, that can be widely offered to large number of patients. As we discussed, this study and the other studies have shown that health consequences of obesity can be reversed, so hopefully, we can reduce the burden of health consequences of obesity on some of these patients.

Dale Shepard, MD, PhD: Are there any significant barriers from insurance coverage or anything like that that block the use of bariatric surgery for weight loss?

Ali Aminian, MD: Yeah, there are significant barrier on the insurance side, on the payer side. Some insurance companies cover bariatric surgery and some don't. Sometimes they cover only one surgery per patient lifetime. Obesity is a chronic disease. Like any other medical problems, sometimes we need to go up the ladder and augment the treatment. For example, you have a patient with heart disease. You start with lifestyle modification, then you put the patient on medication. Sometimes patient needs the coronary angiography and stent placement. Sometimes patient needs a CABG, sometimes need to redo CABG. All those tools are available for cardiologists to take care of patient with heart disease, but the treatment for obesity in terms of the coverage is limited and patient don't have access to bariatric surgery, so the coverage is not universal. That's even worse for the new medications. The new medications that are really effective in helping patient to lose 10 percent, 15 percent, 20 percent of their body weight and they came to market the past few years are not covered by most payers at this moment and that's really sad.

Dale Shepard, DM, PhD: It is sad. You've very, very thoroughly discussed all of the health consequences of obesity and not doing things that could be preventive is unfortunate. Do you think the trial we discussed here and some of these others might help push the public policy, the health policy to improve coverage?

Ali Aminian, MD: Yeah, I hope so. We have seen the trend over the past two decades. We are in much better state now compared to 10 years ago or 20 years ago, so hopefully in the next few years, we going to be in much better state. Because it's going to help patients and it's going to help the payers too. It's very cost-effective intervention because instead of prescribing patients three diabetes medication and two blood pressure medications and putting the patient at risk to develop fatty liver disease and nephropathy and cancer, you take care of obesity, which is the root cause of all of these medical problems and you can substantially decrease the risk of those health consequences. That can be cost saving in the long run. If the insurance companies and payer look at that in this way, it can be both lifesaving and cost saving. Hopefully, it's going to get better in the next few years.

Dale Shepard, MD, PhD: I guess just from a surgical side, originally, primarily procedures were gastric bypass and now there's sleeve gastrectomy. As you know, they're fast procedures and short length of stay and low side effect or adverse effects from the surgery procedures. Is there anything new coming along from a procedural standpoint that might change things on a surgical side?

Ali Aminian, MD: Yeah. There are newer procedures that are even less invasive or technically simpler than the gastric bypass to do. We should wait to see the long-term results of those procedures. The Roux-en-Y gastric bypass, which is a gold standard procedure, has been around for 60 years now. To do the Roux-en-Y gastric bypass, we have to create two connections, two anastomosis, but there are at least two different new procedures that we create only one connection between the stomach and the small intestine, so the surgical procedure itself is faster, recovery is comparable, and there seems like going to be less with those new procedures. But we don't have the long-term data of those, so hopefully in the next few years, we are going to collect those data to show the safety and efficacy of those new procedures in long run. But the field is evolving.

Dale Shepard, MD, PhD: Excellent. Well, this is certainly an incredibly important topic and I appreciate your insight. Thanks for being with us.

Ali Aminian, MD: Thanks again for taking time to have that discussion about the role or consequences of obesity and importance of weight loss on medical comorbidities associated with obesity, including the cancer risk. Really appreciate it. Thanks so much, Dale.

Dale Shepard, MD, PhD: To make a direct online referral to our Taussig Cancer Institute, complete our online cancer patient referral form by visiting clevelandclinic.org/cancerpatientreferrals. You'll receive confirmation once the appointment is scheduled.

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