Your grandfather is have prostatomegaly
which can be either benign or maliganant.He requires evalaution by urologist
for per rectal examination
to asses the consistency of prostrate,Prostrate specific antigen and pelvic USG for post residual urine .Based on that treatment planned.
In some cases drugs (e.g. finasteride
, prazosin, terazosin) can be used to shrink the enlarged prostate
slightly. Most cases require surgery once symptoms develop. The operation can vary from simply dilating the urethra, to scraping away the part of the prostate constricting the urethra by passing a specially shaped knife up it (transurethral resection of prostate (TURP)), or completely removing the gland.Hope this will help you