Hi, I just had a look at the article (but couldn't download it for some reason), and it's pretty much what you would expect it to be, and pretty much along the lines of what Drew suggested: just an epidemiological study, and subject to all the weaknesses of such studies.

But first of all, it seems like the surveys were done as responsibly as such things can be done: they had an enormous sample (500,000+) and threw away a fair number of the surveys for good reasons as well. But the problem of misreporting obviously remains. One amusing bit is that they threw out some of the extremes:

We further excluded 9778 subjects who had reported extreme values (ie, more than two interquartile ranges above the 75th percentile or below the 25th percentile on the logarithmic scale) for total energy intake (n = 4205), total fat intake (n = 741), or percent energy from total fat (n = 4832).

I'm guessing those of us paleos who like to get around 70% of our calories from fat wouldn't have made the cut.

Anyhow, back to the point. The surveys were "prospective" in that they were performed before any incidence of pancreatic cancer rather than after (and apparently there was a dearth of information on pancreatic cancer, particularly because it is hard to detect early and has a very high mortality rate). So they looked at a whole bunch of data that had been gathered for other purposes (the "NIH-AARP Diet and Health Study"), and then cross-checked all the participants with other databases that have information on cancer. Better than what had come before, but still just an observational thing.

So they found positive associations between dietary fat and pancreatic cancer: higher rates for higher-fat eaters somewhere on the order of 1.5 to 1 from the highest quintile of fat consumption to the lowest quintile of fat consumption, and they found similar results for saturated fat consumption and animal fat consumption (as opposed to vegetable). This of course doesn't tell us anything. At this point we could say that this is just the "healthy people effect." The people who listen to public health advice (eat less fat) are also the people who are healthy: they eat better otherwise, they exercise more, they eat more fruits and veggies (I hear that this is something non-paleos do to make up for lack of meat consumption, ha ha), and they might be happier and healthier in any number of physical and psychological ways.

But the experimenters controlled for a few other things and still found the positive associations. As it says in the abstract, they controlled for total energy intake, smoking history, body mass index, and diabetes. So if your increased fat intake meant that you were eating more calories then they compared people of equicaloric diets and re-examined the data. (I know it's much more complicated than that, but I'm just learning about the statistics stuff.) They did the same with BMI, diabetes, and smoking. Here's the jargon:

We did not find evidence of effect modification by BMI, self-reported diabetes, or smoking history ( P interaction > .5 in most instances; data not shown).

Data not shown! Anyhow, these first two might spell a little bit of trouble. Adjusting for BMI would seem to eliminate the exercise effect. And adjustment for diabetes might seem to eliminate the sugar/flour effect. That is, it might be difficult to be able to explain increased pancreatic cancer among those with higher fat intake by pointing out that the people with higher fat intake are the same people who exercise less. OK, well, exercise schmexercise. What about diabetes? Since there's such a strong link between sugar/flour and diabetes, this might make it difficult to explain increased pancreatic cancer among those with higher fat intake by suggesting that people with higher fat intake are the same people who eat more sugar and other refined carbohydrates. Trouble?

I would guess it's not trouble enough. I'd bet that if you went back through the data and looked for associations with sugar and refined carbohydrate that you'd find something. (Sounds like a job for Denise Minger! This statistics jargon is impenetrable to me.) There are also so many other health factors, like the aforementioned fruit and veggies. They didn't control for that, and getting all your vitamins and minerals has to be pretty big.

Anyhow, the editorial in the same issue of the journal and even the press release caution against misinterpretation of the results, echoing what the authors themselves say (so I guess we can put even more blame on the press, big surprise):

[The authors] do note, however, that there is insufficient epidemiological and laboratory evidence to confirm the importance of animal fats or even that meat is the important factor, as opposed to other dietary or lifestyle preferences associated with meat consumption.

Well, there we go.