Long-Term Diabetes Shortens Pancreatic Cancer Survival

Pancreatic cancer patients with long-standing diabetes have poorer survival than those without diabetes, according to an analysis from longitudinal cohort studies. Recent-onset diabetes, however, appeared to have no impact on pancreatic cancer survival.

Survival after pancreatic cancer diagnosis is generally poor, with most patients in the United States surviving less than 12 months. “Aside from disease stage, few prognostic factors have been well characterized,” wrote researchers led by Brian M. Wolpin, MD, MPH, of Dana-Farber Cancer Institute in Boston, in the Journal of Clinical Oncology. Earlier work has shown some connections between pancreatic cancer and diabetes, including many studies showing an increased risk of the malignancy among those with long-standing diabetes (usually defined as diabetes for more than 3 to 5 years).

To determine how that relationship extends to those diagnosed with pancreatic cancer, the researchers analyzed data from two longitudinal cohort studies and then validated the findings in a prospective clinic-based study of pancreatic cancer.

The study included a total of 1,006 patients diagnosed with pancreatic cancer between 1986 and 2010 in the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS). The validation cohort included 386 patients from a clinic-based case series at Dana-Farber Cancer Institute.

The hazard ratio (HR) for death in the NHS and HPFS cohort was 1.40 (95% CI, 1.15-1.69; P < .001) for patients with long-standing diabetes (at least 4 years) compared to those without diabetes. The median survival for long-term diabetics was 3 months, and 5 months for non-diabetics. The researchers performed an adjustment to reduce confounding by various comorbidities, and the results did not differ.

In the prospective validation cohort, the HR for death was 1.53 (95% CI, 1.07-2.20; P = .02) for long-term diabetes. The median survival in this cohort was 9 months for those with diabetes and 13 months for those without. In both cohorts, the HR for death among those with short-term diabetes was non-significant compared with patients without diabetes. The authors noted that there seemed to be some reduced survival among long-term diabetics receiving oral hypoglycemics or insulin compared with non-diabetics.

“Our results suggest that the chronic consequences of diabetes affect survival after diagnosis of pancreatic cancer,” the authors wrote. “A potential explanation for this finding is that the milieu of chronic glucose intolerance has an impact on the genetic architecture of the developing tumor, rendering it more aggressive and leading to shorter patient survival.” Long-term diabetes, of course, also leads to non-malignancy-related complications including kidney and heart failure, which could affect intensity of cancer treatment and patient survival. Aside from the clinical considerations, the authors concluded that clinical trials of pancreatic cancer should account for diabetes status and duration.