Scientists don’t know exactly what causes most pancreatic cancers, but they have found several risk factors that can make a person more likely to get this disease. Some of these risk factors affect the DNA of cells in the pancreas, which can result in abnormal cell growth and may cause tumors to form.
DNA is the chemical in each cell that carries our genes — the instructions for how our cells function. We look like our parents because they are the source of our DNA. But DNA affects more than the way we look.
Some genes control when our cells grow, divide into new cells, and die. Certain genes that help cells grow, divide, and stay alive are called oncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA mutations (defects) that turn on oncogenes or turn off tumor suppressor genes.
Inherited gene mutations: Certain inherited DNA changes can lead to conditions running in some families that increase the risk of pancreatic cancer.
Acquired gene mutations: Most often, DNA mutations of genes related to cancers of the pancreas occur after you are born, rather than having been inherited. These acquired mutations sometimes result from exposure to cancer-causing chemicals (like those found in tobacco smoke). But often what causes these changes is not known. Many gene changes are probably just random events that sometimes happen inside a cell, without having an outside cause.
Some of the DNA changes often seen in sporadic (non-inherited) cases of pancreatic cancer are the same as those seen in inherited cases, while others are different. For example, many sporadic cases of exocrine pancreatic cancer have changes in the p16 and TP53 genes, which can also be seen in some genetic syndromes. But many pancreatic cancers also have changes in genes such as KRAS, BRAF, and DPC4 (SMAD4), which are not part of inherited syndromes. Other gene changes can also be found in pancreatic cancers, although often it’s not clear what has caused these changes.