I cleaned out the kitchen cupboard today and found 5 cans of tuna, dating back to 2007. The cans aren’t bulging or showing any signs of distress, but they are dated 2007.
Are they safe to eat? 
It is impossible to say with any certainty. Nevertheless, unless there was some major defect in the manufacturing process (and then they might be dangerous if new), they should be perfectly safe to eat. IIRC there is some limit to the date you can put, so some put the maximum allowed by law, even though the product will be good for years if not decades beyond that date. Furthermore, sometimes the date is a “sell by” date, and not a “best by,” so it doesn’t tell you when it’s bad.
Short answer: it is up to you to take the risk, but it is highly likely that they are perfectly edible. You checked for bulging, now if it smells bad (fishy is normal) after opening, then toss, otherwise enjoy.
If you don’t find the tuna to be tasty, you can use it for catfish bait. Mix it with bread dough and make it into dough balls.
I’ve used canned tuna and salmon at least 3 years past the date on the can before. I just did the same thing you did, make sure the can isn’t bulging or anything.
I would make a tuna casserole.
Good for crawdad bait as well. Use a churchkey and poke a hole in the can. Put it in your trap. Boil up the critters with a lemon and salt in the water. Enjoy!
I’ve found that expired tuna sometimes gives me diarrhea. But not always. I now put my tuna in the can in the fridge. Some canned foods do react to the acids in the foods. I saw a food documentary recently that had a scientist working on peaches for soldier and astronaut food. Six months the food was good as canning day, but a year later it had become an ugly mush that was still okay to eat, but unappetizing.
When in doubt throw it out.
Forgot to include letting the opened can sit in the sun for a day or two.
This is not medical, legal, or any other kind of professional advice; BUT if the can looks fine, and you open the can and it just smells like tuna, it’s most likely fine. Use it for tuna casserole, tuna salad, or basically anything you’d use new canned tuna for.
Tuna is cheap. If you have doubts, throw it out.
But I would likely use it.
I’m new to the world of canned tuna, but at 50 cents a can, if you’re in doubt and you’re not in dire straits, it’s not worth the psychosomatic tummy ailment you’ll give yourself if you eat it and then start doubting its goodness after the fact.
Mine wasn’t quite as old as yours, but I had some two-year-old tuna in the pantry after my 1.5 year business trip. Heck, I had a lot of two-year-old everything, and it’s been perfectly fine. Cereal, tuna (canned and envelope), catsup, mayo, mustard, broth, etc. Other than the cereal, everything is canned. That means it’s been sterilized and nothing will ever happen to it (aside from potential degredation in quality).
I’ve been eating MRE’s from 2005 for lunch lately. Actually, just parts of MRE’s (there’s a lot of food in them). Same basic idea; they’re “canned” in foil envelopes. (I’m expecting to go on a really, really long business trip soon, before I’ll have a chance to take the MRE’s camping, so lunch is a good way to get rid of them).