-In Incidence Between Rural and Urban Populations In China?
The Entry:
http://en.wikipedia.org/wiki/Benign_prostatic_hyperplasia#Etiology
Thanks John, I Suspect a Mechanical Explanation.
Thanks Paul.
John and Paul, Palliative Things?
Like John, I would suggest diet.
Rural China, by the way, was the scene for part of a massive comparative study, strongly indicating the virtues of a traditional, high-fibre, low animal protein diet.
Seethe "China-Oxford-Cornell Diet and Health Project"; described in:
The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss and Long-term Health
by T. Colin Campbell, Jacob Gould Schurman Professor of Nutritional Biochemistry at Cornell University.

No idea, really, but dietary phytoestrogens might be a good hypothesis to look at.
References :
Like John, I would suggest diet.
Rural China, by the way, was the scene for part of a massive comparative study, strongly indicating the virtues of a traditional, high-fibre, low animal protein diet.
Seethe "China-Oxford-Cornell Diet and Health Project"; described in:
The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss and Long-term Health
by T. Colin Campbell, Jacob Gould Schurman Professor of Nutritional Biochemistry at Cornell University.
References :