I'm no conspiracy theorist, but am a cancer survivor, and feel compelled to reply that many forms of cancer have incubation periods [so to speak] approaching 20 years. So your salt is premature.
And mobile phones have existed for 40 years, gsm for almost 30.
Considering the most radiation is outputed during the phone conversations, and most people hold their phone always on the same side of the head (irradiating only that half), detecting an epidemic of mobile phone radiation sicknesses would be easy, if there were any.