The onset of diabetes or the rapid deterioration of existing diabetes may be an early signal for pancreatic cancer for some patients, according to the results of a study (abstract 540) presented at the European Cancer Congress 2017.
The study, conducted in Belgium and Italy, showed that one-half of all cases of pancreatic cancer were diagnosed within 1 year of patients being diagnosed with type 2 diabetes and being given their first prescription for the disease.
“Doctors and their diabetic patients should be aware that the onset of diabetes or rapidly deteriorating diabetes could be the first sign of hidden pancreatic cancer, and steps should be taken to investigate it,” Alice Koechlin, from the International Prevention Research Institute in Lyon, France, said in a press release.
According to the researchers, type 2 diabetes is a known risk factor for pancreatic cancer. They hypothesized that starting or changing a pharmacologic treatment for the disease could be an early sign of pancreatic cancer.
Koechlin and colleagues used prescription data from the Inter Mutualist Agency data repositories in Belgium and from the region of Lombardy, Italy to identify patients with type 2 diabetes and linked this data with cancer registries in both countries. In Belgium, they identified 368,377 patients, including 885 with pancreatic cancer. In Italy, they identified 456,311 patients, including 1,872 with pancreatic cancer.
One in four pancreatic cancers in Belgium were diagnosed within 90 days of a first prescription of any type 2 diabetes therapy. Similarly, 18% of cases in Lombardy were diagnosed within the first 90 days. Fifty-percent of pancreatic cancers were diagnosed within the first year; however, after 1 year, the proportion of diagnosed pancreatic cancers decreased.
Compared with those who continued on oral antidiabetes medications, patients had a 3.5-fold greater risk of being diagnosed with pancreatic cancer in the first 3 months after their first prescription for incretins. This risk decreased to a 2.3-fold risk in the next 3 to 6 months, to a 2-fold risk for the next 6 to 12 months, and a 1.7-fold risk after the first year.
The researchers also found that a switch from a non-insulin non-incretin antidiabetes treatment to an incretin-based therapy or to insulin treatment was more rapid in patients who had pancreatic cancer during follow-up compared with patients without pancreatic cancer (P < .001).
The hazard ratio for pancreatic cancer associated with use of insulin after a prescription of a non-insulin non-incretin antidiabetic treatment or incretin was 11.9 (95% CI, 10.4–13.6) in Belgium.
“Our study shows that incretin therapies are often prescribed to patients whose diabetes is caused by a still undiagnosed pancreatic cancer,” Koechlin said. “Because the pancreatic cancer finally becomes symptomatic and is thus diagnosed, it looks like it is the intake of incretin drugs that could be the trigger of the pancreatic cancer, while in reality, it is the pancreatic cancer that causes a deterioration of diabetes, which is followed by the prescription of incretins. This phenomenon is called ‘reverse causation.’ Our study also shows that the reverse causation observed for incretin drugs is also observed for other antidiabetic therapies, in particular for insulin therapy.”