HOUSTON, June 23 — Obese women had a 42% reduction in cancer risk following bariatric surgery, data from a Swedish study showed.

• Explain to patients that surgery for obesity may reduce the risk of cancer in women.
• Point out that the data came from a study that was not designed to determine the effect of bariatric surgery on cancer incidence.

Neither the magnitude of weight loss nor change in energy intake could explain the finding, Lars Sjostrom, MD, of the University of Gothenburg, Sweden, and colleagues reported in the June 24 issue of The Lancet Oncology.

Obesity surgery did not affect cancer risk in men, a finding consistent with previous reports, they said.

“The current exploratory report on cancer further underlines the favorable effects of bariatric surgery, particularly in women,” the authors concluded. “The intriguing but unproven possibility that the beneficial effects of bariatric surgery on cancer are mediated by mechanisms other than weight loss or reduced energy intake needs to be further explored.”

Rising body mass index (BMI) increases the risk of a variety of cancers. In the U.S., where a third of adults are obese, 14% of cancer deaths in men and 20% in women may result from overweight and obesity, “making it the largest avoidable cause of cancer with the exception of smoking,” the authors said.

Intentional weight loss might reduce cancer morbidity and mortality, particularly in women, but the evidence is limited, they continued.

The Swedish Obesity Subjects (SOS) study was the first prospective, controlled intervention study to investigate the effects of long-term weight loss on disease incidence and mortality.

As previously reported, the trial showed that bariatric surgery reduced overall mortality risk compared with conventional obesity management. (See Missing Link Found: Bariatric Surgery Reduces Mortality)

Dr. Sjostrom and colleagues analyzed SOS data to determine whether bariatric surgery influenced cancer incidence.

The analysis included 2,010 obese patients who had bariatric surgery and 2,037 matched obese control patients. Women accounted for 71% of the SOS patient population. The trial began in 1987 and had a median follow-up of 10.9 years.

Baseline weight averaged 113 to 114 kg (about 250 lbs) in women and 128 to 130 kg (about 285 lbs) in men, and BMI averaged about 40 for all patients. Bariatric surgery resulted in a 10-year sustained mean weight reduction of 19.9 kg (44 lbs), whereas participants in the control group gained 1.3 kg (about 3 lbs).

Overall, cancer risk was 33% lower in the surgery group (HR 0.67, 95% CI 0.53 to 0.85, P=0.0009).

The difference was attributable to a 42% risk reduction in women who had surgery (HR 0.58, 95% CI 0.44 to 0.77, P=0.0001).

Cancer incidence was virtually identical among men in the surgery and control groups (HR 0.97).

The between-group difference remained statistically significant after exclusion of cancers diagnosed during the first three years of observation. A multivariable analysis that controlled for sex, age, BMI, menopausal status, diabetes, and smoking yielded a hazard ratio of 0.70 in favor of surgery, including 0.58 in women.

The type of surgery influenced subsequent cancer risk in women but not men. Banding reduced cancer risk in women by 46% (P=0.026) and vertical banded gastroplasty by 56% (P=0.0012). Gastric bypass did not reduce cancer risk in women or overall.

The results add to evidence of a cancer-prevention effect of bariatric surgery reported in three recently reported prospective cohort studies, all of which showed significant reductions in cancer risk following surgery (Surg Obes Relat Dis 2008; 4: 691-95, Obesity 2009; 17: 796-802, J Am Coll Surg 2009; 208:1093-98).

“Taken together the studies provide the strongest evidence yet that weight reduction in obese individuals in association with subsequent reduction in cancer incidence strengthen the cause for causality between adiposity and cancer,” Andrew G. Renehan, MD, of the University of Manchester, England, said in an accompanying commentary.

He pointed out that “the absence of effect in men might simply reflect small sample numbers. For women, the greatest cancer-prevention effects from weight reduction are likely to be for postmenopausal breast and endometrial cancers, two hormone-sensitive malignancies, the effects of which might manifest within a decade.”

But, Dr. Renehan noted, that the effects of weight reversal might take much longer to become apparent for obesity-related cancers that are more common in men — such as colon, rectal, and kidney cancers.

“As the obesity epidemic shows few signs of abating, the incidences of obesity-related cancers may rise,” he added. “However, the establishment that the development of these cancers is reversible brings about an encouraging new paradigm in cancer prevention.”

The SOS trial received support from Hoffmann-La Roche, AstraZeneca, and Cederroths. Dr. Sjostrom reported relationships with Hoffmann-La Roche, AstraZeneca, Cederroths, sanofi-aventis, Ethicon, Biovitrum, BMS, GlaxoSmithKline , Johnson and Johnson, Lenimen, Merck, Novo Nordisk, and Servier. Co-author Bjorn Carlsson is an employee of AstraZeneca. Co-authors Ingmar Naslund, Anna-Karin Lindroos, David Sjostrom, Jan Karlsson, Kaj Stenlof, Jarl Torgerson, and Lena M. S. Carlsson reported one or more competing interests. Dr. Renehan reported no potential conflicts of interest.

Primary source: The Lancet Oncology

Source reference:
Sjostrom L, et al “Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial” Lancet Oncol 2009; DOI: 10.1016/S1470-2045(09)70159-7.

Additional source: The Lancet Oncology

Source reference:
Renehan AG “Bariatric surgery, weight reduction, and cancer prevention” Lancet Oncol 2009; DOI: 10.1016/S1470-2045(09)70170-6.

Related Article(s):

• Missing Link Found: Bariatric Surgery Reduces Mortality

In the fruit fly’s developing brain, stem cells called neuroblasts normally divide to create one self-renewing neuroblast and one cell that has a different fate. But neuroblast growth can sometimes spin out of control and become a brain tumor.

Researchers at Duke-NUS Graduate Medical School in Singapore have found a tumor-suppressing protein in the fly’s brain, with a counterpart in mammals, that can apparently prevent brain tumors from forming.

“Our data explicitly show that the fruitfly protein PP2A (protein phosphatase 2A) suppresses brain tumor formation and controls the balance of self-renewal and differentiation of neural stem cells,” said Hongyan Wang, Ph.D, assistant professor of neuroscience and behavioral disorders, and senior author of a paper published online in the journal Development.

“Given that mechanisms for stem cell division in flies and mammals are likely to be similar, our study on fly PP2A may provide useful insights for certain types of human brain tumors and possibly in a wide variety of cancers,” Wang said.

By studying flies that had a PP2A mutation, the researchers learned that flies with missing or abnormally expressed PP2A had ten times the amount of stem cell growth in their larval brains. The flies’ neural stem cells did not become neurons (nerve cells) in the brain, the types of cells needed for normal function. Instead, they effectively grew into a tumor mass.

Dr. Wang’s previous work had identified a protein kinase called Polo as a tumor suppressor. Because phosphatases like PP2A usually have the opposite biochemical function to kinase, the scientists predicted that PP2A would stop the tumor suppressor Polo and allow for unchecked cell growth. “We were very surprised when we found that PP2A also suppressed tumors,” Wang said.

Follow-up experiments showed that PP2A is important for regulating Polo kinase function, and showed that these two critical brain tumor suppressors work together to control neural stem cell divisions.

“Our discovery suggests that PP2A and Polo, both of which are crucial brain tumor-suppressors and cell cycle regulators, can function in the same pathway to regulate stem cell self-renewal and tumor development,” Wang said. The research team plans to uncover novel proteins in this pathway by learning which protein functions between PP2A and Polo during the neural stem cell division process.

Notes>

Other authors include Cheng Wang (lead author) and David Virshup at Duke-NUS Graduate Medical School; Kai Chen Chang and Fengwei Yu, Temasek Life Sciences Laboratory in Singapore; Gregory Somers, Department of Anatomy and Cell Biology, University of Melbourne, Australia; and Beng Ti Ang and Carol Tang at the National Neuroscience Institute. The study was supported by Duke-NUS funding and by the Singapore Millennium Foundation.

Source:
Mary Jane Gore
Duke University Medical Center

Cancer the word resonates in people’s nightmares and strikes fear in the hearts of millions. Can there be a positive side amidst the panic, anxiety and hopeless feelings that often accompany the word? The answer is yes according to Dr. Patricia Mumby, associate professor Loyola University Chicago Stritch School of Medicine Psychiatry and Behavioral Neurosciences Department and director of Loyola Cardinal Bernadine Cancer Center Psychosocial Oncology Service.

“When we first ask people to find something good about having cancer they pause and give us a puzzled look, but a majority of cancer survivors and patients can find positives. The longer it’s been since their diagnosis the more positives they can find,” said Mumby. “It’s amazing to watch as they look for benefits. They mentally make a shift and start to have a broader perspective. People who can find positives early on often have less anxiety overall.”

Though research is preliminary, staff at the Loyola University Health System Cardinal Bernadine Cancer Center have discovered that finding benefits and positives in the cancer experience may improve a patient’s quality of life and relationships with others. They appear to have a greater appreciation for life, deeper spirituality and often find changes in their life values. It can also build self-esteem and self-confidence.

“People who are going through cancer treatments have to face challenges head-on and when they are able to master them and move forward, that builds self-esteem. Coping and adapting to life stresses builds self-confidence,” said Mumby.

Another commonly found positive is that people who are being treated for cancer improve their health behaviors, often making them healthier then they were before their diagnosis.

“Some of the behaviors people have prior to their cancer treatment may put them at risk for recurrence, secondary types of cancer or other health issues. Cancer can be a scary wake-up call causing people to change many of their unhealthy behaviors and may help them to realize the importance of taking care of themselves,” said Mumby.

According to Mumby a recent study of health outcomes and quality of life of breast cancer survivors at Loyola showed that 49 percent of women in the study smoked prior to their diagnosis. Following treatment only 9 percent continued the habit.

“We would of course like the number to be zero, but the decrease in smoking among these women was significant and a very positive thing,” said Mumby.

Initially the benefit-finding process can be difficult as patients work through their anxiety, try to adjust to all the changes and cope with the idea that their lives will never be the same. Over time they begin to see that good has come out the difficult journey. Many find that they have a healthier perspective on relationships. Some have significant life, career or education changes.

Silvia Durkin, a Schaumburg, Ill., resident, wife and mother of two, was the picture in the dictionary of self-sacrifice. She was always thinking of others, sometimes to the detriment of herself. When a lump in her breast turned out to be cancer her life was turned inside out.

“When I found out I had cancer it was like an explosion that shook me to the core. I didn’t know where to go or what do. I like to be in control, but when the diagnosis was cancer I thought I had lost control of my own body and that was really difficult,” said Durkin. “But it was what I needed to get me out of my ingrained habits. Though I’d always been active and a healthy eater I started to break out of my old habits and learn more about different types of exercise and eating a variety of foods. When I met with Dr. Mumby she encouraged me to start doing something for myself.”

That something was Pilates and yoga classes. Durkin found she really enjoyed them and was a star pupil. Now, cancer free, Silvia has become a Pilates instructor at the studio at the request of the owner.

“I would never have even considered taking classes let alone being an instructor before I had cancer. We get so boxed into our lives that it sometimes takes a kick in the butt to get us out,” said Durkin.

She’s also found that it has encouraged her to help others in a healthier way and that she hopes her experience will give someone else facing a similar situation hope.

“This really made me reach into myself and take a look at the big picture. Good things and bad things happen and we need to find positives in every bump in the road,” said Durkin.

“People need time to process their experience. Benefit-finding helps people contemplate and reflect over the whole experience and put things into perspective: this is where I was and this is where I am now,” said Mumby.

This is especially true for cancer survivors like Durkin.

“The transition into long-term cancer survivor has received little attention, but with 12 million cancer survivors and the number continuing to grow these issues will become more and more important,” said Mumby. “Having had cancer will always be a part of their lives, but the question is where do they go from here? Benefit-finding helps them look at the experience and to see how far they’ve come and to take pride in that. It also shows them life is still out there and there is more for them to do.”

Source: Loyola University Health System