That's not always the case. I recently visited a small town outside of the city of Melbourne, Australia.
This city had a higher cancer rate than Melbourne for the simple fact that mining had created a few nasty sources of contamination.
So I suppose the answer to your question would be that if the country location is reasonably free of sources of contamination/ pollution then the risk of cancer will be lower. But if there are sources of contamination and pollution the risk will increase.
Cities have many sources of pollution and cancer, but also much higher populations. So the risk of cancer may be higher, or it could simply be a reflection on the high population numbers.
It's a very complex issue. And not one that has absolute answers.
The reason behind that is life style. Life style changed in citiea rapidly, Due to change in that the habits of individuales changes (from eating to sleeping). The good eating habits and taking a good sleep is very essentially for human beings. The quality of food we get is also matters. Intake a low quality good at abnormal time is not good for health. The vegetables and fruits we use are full of chemicals (pesticides basically).
This is my opinion thanks.