I understand what you are going through considering I am currently worrying about my own "potential" gallbladder/pancreatitis/pancreatic cancer issue myself. If you are worried, I would definitely consider talking with your doctor. I plan on scheduling an appointment with a gastroenterologist myself. I'ld much rather know than not know, y'know? You're damned either way if you actually do have stage 4 cancer, so you might as well see it coming.

I don't know if this would help ease your fears, but by the time my dad had noticeable enough esophageal pain to be diagnosed with cancer (which by the way, was a constant pain that was bad enough to keep him up at night), he only lived for an additional 8 months, and his condition very rapidly declined. By rapid I mean he became near skeletal from wasting/not eating and he was by no means a small man (he was 5'10'' and approximately 300 lbs. precancer). Considering that this thread was started about 5 months ago, and that was when I assume you started experiencing various cancer-like symptoms, you should be in considerably dire straights by now if you really were dying of any type of stage 4 cancer.

On another not, pain in your sternum when swallowing is actually really common, and I have experienced a few times myself. When anxious, your throat and pharynx constricts, which causes the pain you feel. About the weight loss, unless you are consistently counting calories, you can't be entirely sure that you really are eating enough to maintain your weight (which is about 2000 Calories per day for the average healthy person). And anxiety both enhances your basal metabolism and tends to make people nauseous/reduce their appetite, and so combined could contribute to weight loss. Also, many other things could cause weight loss; benign hormonal imbalances and certain relatively benign gastric issues like celiac, both of which can be tested for with a simple and cheap blood test. Anxiety can also cause swollen lymph nodes.

Hope that you feel better soon!