Does the diet affect the risk of kidney cancer?

Unknown. There are theories that high protein diets are associated with kidney cancer, and that obesity may be a risk factor. There is little, if any, direct evidence linking diet to kidney cancer.
Possibly. Over the past dozen years, there have been studies coming out of central europe, eastern europe and russia that have found an association between ingestion of preserved vegetables, milk products, and red meats. Fresh vegetables seem to be protective against the risk or kidney cancer. Since the study groupsr from a particular area, genetic or other environmental factors may be at play.