Or better said still: there seems to be a connection between cancer prevention and the consumption of tomatoes. A lot of tomatoes that is (if it was so easy only to eat a few tomatoes to become cancer free, why people would still have cancer? That wouldn’t make sense).
Unfortunately studies are very poor: you cannot make much money with selling tomatoes, so tomato-cancer research is frowned upon.
The active ingredient is Lycopene which gives the specific red colour to tomatoes. In “house and garden English”: for more Lycopene The redder, the better!
As we all know the red pigment doesn’t get destroyed during cooking (our tomato sauces doesn’t become white…), so all tomato based sauces, purees… contain a high amount of this simple cancer prevention pigment.
Of course make sure you only eat organic food and buy organic tomatoes, otherwise what you gain on cancer prevention you loose in pesticides, hormones and antibiotics. (see also: cancer prevention, what is cancer and Why is cancer still around?)