Is radiation one of causes of cancer?    ​

Dear Anton,
I'm writing to you from London. This is really a great city with its old cathedrals, churches, palaces and museums . I took some pictures of London. Most of all I enjoyed going on а river trip down the Thames. We saw the Houses of Parliament along the north bank of the Thames. The clock tower of the Houses of Parliament is famous for its big hour bell known as «Big Ben».  We saw the Tower of London near Tower Bridge. 
 We also visited  Buckingham Palace where the Queen lives.  Tonight we are going to the London Eye and Trafalgar Square. By the way, we are lucky with the weather. No rain! The days are warm and sunny. I enjoy doing the sights very much. When I return home come to me to see all the pics. 
See you soon,
Sasha

It was an ordinary day at my workplace, like any other. I came, had coffee and started checking data for a project.
I turned on the radio and tuned to the "Aliens' wave". There was nothing special, I was used to that routine work. My expectations are to meet a creature of another civilization had long gone. But suddenly I heard some strange sounds I had never heard before. I made a bit louder and called my colleagues.
We tried to make out at least a bit, replaying the record again and again, but to no avail. Throughout the whole night we were trying to crack the code. In the morning, the chief told us to go home and relax.
Our job program had been made a secret one, so our building was far from the city, in the fields. When my friend and I had come outside, we saw some impressions in the wheat field. It looked as if a huge machine had passed through them. From satellite pictures it became clear that it was connected with that unknown radio signal. We started our search...