The evidence is mounting that obesity plays a role in many chronic diseases, including cancer. In fact, some scientists suggest that obesity will become the leading preventable cause of cancer in the near future. But how does weight impact cancer survival?
A recent study found that patients who were obese before being diagnosed with pancreatic cancer did not live as long as patients with a healthy weight.
The association was greatest for individuals who had been obese up to 20 years before their diagnosis.
This study adds to the growing understanding of the vital importance of maintaining a healthy weight throughout life.
Brian M. Wolpin, MD, MPH, an assistant professor of medicine at Dana-Farber Cancer Institute and Harvard Medical School in Boston, MA, was the senior author of this study.
A number of earlier studies have demonstrated that a high body mass index (BMI) is linked to increased risks of developing pancreatic cancer, a particularly lethal cancer that overtakes most patients in the first year.
Scientists have theorized this link may be due to changes that obesity causes in the body’s metabolism, along with chronic inflammation that can accompany obesity.
This study used the data from two large research efforts to look at BMI and pancreatic cancer survival.
The researchers analyzed data from the Nurses’ Health Study (NHS) and Health Professionals Follow-Up Study (HPFS). The NHS began in 1976 with 121,700 female registered nurses, ages 30 to 55 years, while the HPFS began in 1986 and included 51,529 men.
Participants completed biennial surveys about their lifestyle and medical history.
The current study relied on data collected through 2010 from the NHS and HPFS.
During the study period, 902 participants were diagnosed with pancreatic cancer — 561 participants from NHS and 341 from HPFS.
The researchers discovered that patients with an average, healthy weight BMI of 25 lived two to three months longer than obese patients with a BMI of 30 or more.
BMI is a measure height to weight, and is used to determine whether a person is normal weight, overweight or obese.
A BMI of less than 18.5 is considered underweight, between 18.5 and 25 is considered normal weight, between 25 and 30 is overweight, and 30 or greater is considered obese.
Patients who had been obese 18 to 20 years prior to their pancreatic cancer diagnosis had the strongest association with poorer survival.
Obese patients lived an average of five months after diagnosis.
This obesity/survival association was seen even after adjusting for other factors such as age, gender, race/ethnicity, smoking status and disease stage.
The analysis also revealed that obese patients were more likely to be diagnosed with metastatic (has spread to other organs) pancreatic cancer than normal weight patients.
The researchers saw that 72 percent of obese patients had metastatic cancer, compared with 59 percent of normal weight patients.
“Higher prediagnostic BMI was associated with statistically significantly decreased survival among patients with pancreatic cancer from two large prospective cohorts,” the authors of this study concluded.
Further study is needed to explore the biological links between obesity and cancer, the authors suggested.
This study was published October 21 in the Journal of Clinical Oncology.
The research was funded in part by a 2009 Conquer Cancer Foundation of ASCO Career Development Award to Brian Wolpin.
No conflicts of interest were reported.