Obese patients with a body mass index (BMI) of more than 35 appear more likely to have cancer that has spread to their lymph nodes, lower rates of survival and higher rates of recurrence following surgery for pancreatic cancer, according to a report in the March issue of Archives of Surgery, one of the JAMA/Archives journals.
Obesity rates have dramatically increased in the United States over the past 20 years, according to background information in the article. "In many obesity-related diseases and malignant neoplasms [cancerous tumors], an increased prevalence of pancreatic cancer has been reported in numerous epidemiologic and cohort studies focusing on obese patients," the authors write. "Further, obesity has been associated with decreased survival in patients with pancreatic adenocarcinoma, although the mechanism remains unknown."
Jason B. Fleming, M.D., of The University of Texas M. D. Anderson Cancer Center, Houston, and colleagues studied 285 consecutive patients who underwent pancreatic resection (removal of some or all of the pancreas) to treat pancreatic cancer between 1999 and 2006. Data about surgery, patient BMI and outcomes were obtained from the institutional database and electronic medical records.
A total of 152 patients (53 percent) died during a median (midpoint) of 16 months of follow-up. Patients with a BMI higher than 35 survived a median of 13.2 months, compared with 27.4 months for those with a BMI of less than 23. At the last follow-up, 15 of 20 patients (75 percent) with a BMI of more than 35 had died, compared with 137 of 265 patients (52 percent) with a BMI of 35 or less.
"We identified a subset of obese patients (BMI greater than 35) who were at 12-fold risk of lymph node metastasis compared with non-obese patients (BMI of 35 or less). The estimated disease-free and overall survival rates were decreased in the obese patients, and the risk of cancer recurrence and death after pancreatectomy [removal of the pancreas] was nearly twice that in non-obese patients," the authors write. "Cancer recurrence was observed in 95 percent (19 of 20) of patients in the group with a BMI of more than 35 vs. 61 percent (161 of 264) of all other patients."
Previous studies have shown an association between a BMI of more than 35 and an increased risk of death from pancreatic cancer, the authors note. "Our findings extend these observations to those patients who undergo surgery to treat pancreatic cancer and suggest that obesity is a host factor affecting tumor biology independent of the difficulties (patient- and treatment-related) involved in delivering oncologic care in obese patients. Future investigations should include a search for systemic or tumor biomarkers in this group of patients that could provide additional insight."