Saturday, March 10, 2012

Obesity as Risk Factor for Pancreatic Cancer

Being obese will un-doubtfully increase the risk for a wide variety of health and medical problems. People that are overweight and obese during early adulthood have a greater risk of contracting pancreatic cancer at a younger age, and obesity at an older age is associated with a lower rate of survival from pancreatic cancer.

What is Obesity?

Obesity is increasingly being recognized as a risk factor not only for cancer development, but also for worse outcomes after cancer treatment. Links between obesity and endometrial cancer, postmenopausal breast cancer, and colorectal cancer are well established, but the effects of obesity appear to extend to several other types of cancer as well, including pancreatic cancer.

A commonly used (though imperfect) measure of body size is the body mass index (BMI). BMI involves a comparison of weight to height (weight in kilograms divided by height in meters squared). A BMI between 18.5 and 24.9 is generally considered healthy, a BMI between 25 and 29.9 is considered overweight, and a BMI of 30 or higher is considered obese.

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PanScan Study, 2010

While multiple previous studies have shown the obesity is a substantial risk factor for breast and colon cancers, a recent study by Arsian and colleagues from the Pancreatic Cancer Cohort Consortium (PanScan) suggests that obesity is also contributes to the pancreatic cancer risk factors.

Using a nested case-control design that included 2170 cases and 2209 control subjects, the PanScan study found a positive 33% higher risk for pancreatic cancer in individuals with the highest compared to the lowest BMI quartile. This relationship was found both in men and women.

When the researchers looked at abdominal obesity, the risk for pancreatic cancer in women in the highest quartile of waist circumference was almost twice that of women in the lowest quartile. These findings certainly provide strong support for a positive association between BMI and pancreatic cancer risk and suggest that centralized fat distribution may increase pancreatic cancer risk, especially in women.

Given the observation that one of the most impressive impacts of bariatric surgery is an almost 60% reduction in cancer mortality, prevention of weight gain or successful weight management may certainly go a long way in reducing the risk of dying of this horrible disease.

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US National Cancer Institute, 2008

The study, by researchers at the U.S. National Cancer Institute, found that men and women who were severely obese were 45 percent more likely than normal-weight adults to develop pancreatic cancer over five years. Abdominal obesity, in particular, was linked to a higher risk of the disease among women.

Researches offered the explanation on the fact by establishing the logical link from obesity to pancreatic cancer through type 2 diabetes. In type 2 diabetes, the body loses its sensitivity to the blood sugar-regulating hormone insulin, which is produced by the pancreas; this leads to persistently high levels of insulin in the body. Insulin has growth-promoting effects, and it's thought that too much of the hormone may encourage pancreatic tumor cells to grow and spread.

Dr. Rachael Stolzenberg-Solomon, leading the study, reported: "Our results, as well as those of others, may have important implications for cancer prevention particularly related to the avoidance of obesity".

The findings are based on data collected from more than 300,000 U.S. adults who were cancer-free and between the ages of 50 and 71 at the outset. Over roughly five years, 654 developed pancreatic cancer. In general, the risk of the cancer climbed in tandem with body mass index, a measure of weight in relation to height. Severely obese study participants were at greatest risk. Among women, the odds of developing pancreatic cancer also increased along with waist size.

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Sweden's Karolinska Institute, 2008

The specific risk of pancreatic cancer for women as factor of being overweight has been investigated by Juhua Luo of Sweden's Karolinska Institute and colleagues. "We found that the risk of developing pancreatic cancer was significantly raised in obese postmenopausal women who carry most of their excess weight around the stomach," Dr. Luo said in a statement. "Obesity is a growing and largely preventable problem, so it's important that women are aware of this major increase in risk."

As part of a large study known as the Women's Health Initiative, Luo and colleagues followed more than 138,000 menopausal women in the United States for more than seven years to investigate the links between obesity and pancreatic cancer. They found that 251 women developed the disease, and of these, 78 had the highest waist-to-hip ratios. After factoring in other risk factors, this was 70 percent more than the 34 women with the lowest excess stomach weight who got pancreatic cancer.

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University of Texas, 2008

While positive correlation between obesity and risk of pancreatic cancer development has been validated by multiple studies, the research, performed by Donghui Li, PhD, from the University of Texas MD Anderson Cancer Center in Houston, has allowed to look on this fact from slightly different perspective, offering the novel finding that putting on excess weight in the teenage years is particularly risky.

The researchers conducted a case–control study of 841 patients and 754 matched controls, and investigated the association between pancreatic cancer risk and excess body weight across an individual's life span. They found a significant association between pancreatic cancer risk and being overweight between the ages of 14 and 39 years, and being obese from 20 to 49 years. "Notably, the strongest association between obesity and pancreatic cancer was seen in those who were overweight or obese from the ages of 30 to 39 years," they reported.

"The increased risk of pancreatic cancer with weight gain leveled off for gains after the ages of 40 to 49 years," they add. "The stronger association of the disease with weight gain in earlier adulthood, as opposed to later adulthood, might be explained by the longer duration of exposure to cumulative excessive body fat in the earlier gainers," Dr. Li and colleagues suggest.

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