WATER VAPOUR THERAPY for PROSTATE conditions The prostate is approximately the size of a walnut and weighs about 10-12 grams. It has five lobes, anterior, posterior, medial and two lateral lobes. The medial and lateral lobes are the most prominent. There are three main conditions that can affect the prostate which are prostatitis, prostatic cancer, and lastly benign prostatic hypertrophy (BPH) which is common in older men.