In a heavy 10 inch skillet, heat the olive oil over moderate heat for 30 seconds; add the garlic and cook for 30 seconds.
Stir in the tomatoes, oregano, and red pepper flakes.
Bring to a boil, then lower the heat until the mixture barely bubbles; simmer, uncovered, for 7 to 8 minutes or until slightly thickened.
Stir in the tuna, capers, and parsley, and simmer 5 minutes longer.
Meanwhile, cook the linguine according to package directions, omitting the salt; drain well and transfer to a heated bowl.
Pour the tuna sauce over the pasta and toss well.