Many cases are caused directly by smoking - however the remaining cases seem to baffle the scientific community.
Why is this?
One of the main functions of the pancreas' is to use "..the pancreatic hormones, insulin and glucagon..." to "work together to maintain the proper level of sugar in the blood."
Interesting contributors for this type of cancer, even though causes are not known:
1)Individual over age of 45...the older the higher the risk
2)Diabetes linked (associated)
3)Smoking doubles risk
Other interesting things to note about cancer in general:
"Forty-one thousand (41,000) Americans died of cancer in 1900; a death rate of approximately 64 per 100,000 Americans. The 1990 death rate per 100,000 is nearly three times the 1900 figure." "Let's consider the similarities of 19th century America and countries where cancer is practically non-existent. For the most part, the only countries that have a low incidence of cancer are those countries where the environment is largely unspoiled and where the food is simple and unrefined."
In fact, many previously 'isolated' cultures, as described in the book "Good Calories, Bad Calories" by Gary Taubes are noted to have had virtually 0 incidents of any cancers. These were in cases which thousands of individuals were being cared for by physicians over many years. These cultures ate diets of meat, milk, vegetables and zero sugar or flour.
Taking into account the fact that many of the increased risk factors seem to stem from simply getting older and contracting type II diabetes (insulin resistance), it seems that these simply are links or associations. If simply getting older increased risk of contracting pancreatic cancer, why didn't any Native Americans or Inuits contract it in old age?
Dr. Su's article from a couple of years ago sums up some interesting information regarding carbohydrate's link to pancreatic cancer:
"Gapstur SM et al observed, “…[A]bnormal glucose metabolism may play an important role in the etiology of pancreatic cancer. “  An epidemiological study involving nearly 1.3 million participants in Korea by Jee SH et al found pancreatic cancer was the strongest in association with abnormal fasting hyperglycemia. Interestingly, the cancer incidence, although much smaller, still exists in those participants with a normal fasting blood glucose reading.  Therefore, it is important to point out that hyperglycemia at anytime other than at fasting and/or 2-hour postprandial is a silent killer.  Larsson SC et al concluded, “High consumption of sugar and high-sugar foods may be associated with a greater risk of pancreatic cancer.”  And, Meinhold CL et al observed, “…..[R]ather than being causal, the short-term increase in pancreatic cancer risk associated with high available carbohydrate and low fat intake may be capturing dietary changes associated with subclinical disease.” " 
The case is still out on what actually causes pancreatic cancer, but we do have some things we can do to lessen the likelihood:
1)Keep insulin as low as possible.
2)Keep carbohydrate-laden foods out of your diet.
3)Eat a diet that mimics those populations who were cancer free.
1. The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins Medicine, "Pancreas Function", http://pathology.jhu.edu/pc/BasicOverview3.php
2. Pancreatic Cancer Health Center, WebMD, http://www.webmd.com/cancer/pancreatic-cancer/information-pancreatic-cancer
3. "Are We Overlooking the Obvious in Cancer Prevention?", Dr. Mary Rodio, http://curezone.com/art/read.asp?ID=163&db=1&C0=74
4. Pancreatic Cancer and Carbohydrates, Dr. Robert Su, http://www.carbohydratescankill.com/2747/pancreatic-cancer-carbohydrates