Few families have been as devastated by pancreatic cancer as that of former President Jimmy Carter.

“We started out a long time ago with my father dying of pancreatic cancer,” Mr. Carter said in a telephone interview. “One by one, both my sisters and brother died of pancreatic cancer.”

His mother had it as well.

Mr. Carter said that he and other relatives had given blood for studies aimed at finding genetic abnormalities that might cause the disease and help doctors diagnose it.

For a time, Mr. Carter said, he had CT scans twice a year to look for lesions on his pancreas. His doctors switched to M.R.I. scans, fearing that repeated CT scans involved too much X-ray exposure.