Posted online October 21, 2013 on www.jco.org.
A large, long-term follow-up study showed that people who were overweight or obese years before their pancreatic cancer diagnosis tend to have more advanced stage at diagnosis and shorter survival. Prior research had suggested that having a higher body mass index (BMI) increases one’s risk of developing pancreatic cancer. This is the first prospective study to demonstrate that BMI also affects outcomes after diagnosis.
Interestingly, BMI had the strongest impact on survival for patients who had been overweight roughly two decades before their diagnosis. The finding suggests that maintaining a healthy weight throughout one’s lifetime is important in improving survival after diagnosis. One possible explanation for this finding is that obesity triggers molecular changes in pancreatic tumors over time, and these cancer-related changes may be different in healthy-weight people compared to overweight people.
Researchers evaluated the association between patients’ BMI in 1986 with survival after diagnosis of pancreatic cancer. This study assessed 902 cases of pancreatic adenocarcinoma that were diagnosed during a 24-year period. The median survival by cancer stage was 16 months for those with localized disease, 8 months for locally advanced disease and 3 months for metastatic disease. Obese patients (BMI greater than or equal to 35 kg/m2) lived two to three months less on average than healthy-weight patients (BMI less than 25 kg/m2), even after controlling for differences in other factors linked to pancreatic cancer survival (age, gender, smoking status, disease stage). Patients with a higher BMI were also more likely to be diagnosed with advanced disease – 72% of obese patients had metastatic disease at diagnosis compared to 59% of healthy-weight patients.
What This Means for Patients
Pancreatic cancer is the fourth leading cause of cancer-related death in the United States. Most patients with pancreatic adenocarcinoma survive less than a year after their diagnosis.
While the findings of this study will not affect the way patients are treated today, they provide a lead to investigate molecular pathways that may be responsible for the survival difference between obese and healthy-weight patients. In the future, that research may bring new and improved approaches for treatment of pancreatic cancer.
Obesity is an ongoing and growing public health problem in the United States, linked to chronic illnesses such as heart disease and diabetes. We are becoming more and more aware that obesity is also associated with various forms of cancer. Scientists predict that obesity will soon become the leading preventable cause of cancer. This study adds to the mounting evidence for the role of weight control not only in reducing the risk of developing cancer but also in improving outcomes after a cancer diagnosis.
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