Karen,
The probability is quite high that the Doxil+Herceptin combo is going to work for you based on the high response rates observed in phase 2 trials in 2006 (52% plus 38% stable disease).
You may also ask your onc if supplementation with omega-3 fish oil pills is indicated based on its benefits in other types of cancers & on this article for pancreas (although not necessarily metastatic, the text is not clear on that):
http://jn.nutrition.org/cgi/content/full/129/6/1120
Fish Oil–Enriched Nutritional Supplement Attenuates Progression of the Acute-Phase Response in Weight-Losing Patients with Advanced Pancreatic Cancer