Most pancreatic ductal adenocarcinoma patients who are not on clinical trials will currently receive one of three standard regimens. These regimens have been shown to have different levels of benefit, but with a trade-off for increasing toxicity. The selection between these different regimens is a choice that patient will have to make for themselves, with the advice of their oncologist, depending on their own person priorities.

gemcitabine (Gemzar) - was approved in 1997 and is the gentlest of the three treatments. Average survival for first-line metastatic pancreatic cancer patients receiving gemcitabine is ~6 months. However, the agent is very well tolerated and many patients report actually feeling better on this chemotherapy then without it (improved quality of life). 

gemcitabine + nab-paclitaxel (Gemzar/Abraxane) - this regimen has improved efficacy over gemcitabine but is a bit more toxic. The average overall survival is closer to 9 months for this regimen. It is the typical regiment that is used as a "backbone" in clinical trials of new drugs, meaning that new agents are often tested in combination with this standard treatment. 

5-fluorouracil + irinotecan + oxaliplatin + leukovorin (FOLFIRINOX) - this is the most aggressive regimen, and also the most toxic. The average overall survival is about 11 months for this regimen, but some patients have great difficulty tolerating it. 

A small number of additional agents have been approved in combinations, but are not widely utilized for a variety of reasons.