Q&A: Pancreatic Cancer and Obesity

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Recent research at M. D. Anderson shows that obesity is a risk factor for pancreatic cancer, and being overweight may play a role in the outcomes of people who develop the disease.

Donghui Li, Ph.D., professor in M. D. Anderson's Department of Gastrointestinal Medical Oncology and the study's senior author, answers questions about this landmark investigation.

What inspired you to do this study?
We know obesity is a risk factor for pancreatic cancer, but few studies have looked at body mass index (BMI) throughout a patient's lifetime rather than just when they are adults or the year they are diagnosed. We wanted to show the relationship between BMI and the risk of developing pancreatic cancer across a patient's life span and determine if being overweight in a specific time period raised that risk.

Also, we were curious about the links among BMI, cancer occurrence and overall survival.
Why is this study important?

Pancreatic cancer is one of the most dangerous types of cancer. It's the fourth leading cause of cancer death in men and women in this country. Median survival is less than 10 months, and the five-year survival rate is less than 5%.

Obesity and smoking are known risk factors for the disease, and while smoking is on the decline, obesity is increasing.

This study helps us understand the cause-and-effect relationship between obesity and pancreatic cancer, and we hope it will help identify high-risk people and specific ways to prevent them from getting the disease.

What were the research methods?
First, we enrolled 1,595 people:
•    841 pancreatic cancer patients treated at M. D. Anderson from 2004 to 2008
•    754 cancer-free people

We interviewed each person about his or her:
•    Smoking history
•    Family cancer history
•    Alcohol use
•    Medical history

Participants were asked to recall their height and body weights at 14 and 19 years old; in their 20s, 30s, 40s, 50s, 60s and 70s; and the year prior to their pancreatic cancer diagnoses or enrollment in the study.

We then calculated each person's BMI during each decade and compared the healthy patients with the pancreatic cancer patients.

Among the cancer patients, we also looked at the average age of diagnosis and the overall survival time, then compared those to their BMIs.

What were the results?
As we suspected, the research confirmed an association between obesity and pancreatic cancer.

People who were obese when they were young had a higher risk of developing pancreatic cancer than those who became overweight later in life.
For example, people who became overweight:
•    Between 14 and 19 years old had 100% increased risk
•    In their 20s had 65% increased risk
•    In their 30 had 27% increased risk

The risk of developing the disease diminished for those who gained excess weight in their 40s and later in life.

Also, we found an association between excess weight and earlier onset of pancreatic cancer. Median age at diagnosis was 64 for those at normal weight, compared to 61 and 59 for overweight and obese patients respectively.

Obesity later in life, especially within a year before a patient's cancer diagnosis, reduced overall survival time.

Did these results surprise you?
It was surprising that overweight and obese pancreatic cancer patients were diagnosed at a younger age. This underscores the impact of obesity on loss of life, especially in productive years.

What do these results mean for pancreatic cancer?
Obesity is a risk factor that can be controlled. This study shows that we should try hard to help people control their weight at an early age to reduce the risk of pancreatic cancer.

What's next?
We need to further investigate the links among obesity, pancreatic cancer and poor outcome, looking at insulin resistance as a possible mechanism.

We also will research factors, such as heredity, diet and others, that might affect the relationship between excess body weight and the disease. One day, we hope to develop ways to prevent this dangerous cancer and detect it earlier.

Related article:
After Pancreatic Cancer, 'Southern Style' Gets A Healthy Makeover

M. D. Anderson resources:

Pancreatic Cancer (M. D. Anderson)

M. D. Anderson Study Finds Even Stronger Relationship Between High Body Mass Index,
Pancreatic Cancer
(M. D. Anderson News Release)

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