Hi Jaybee-
Yes 4.9 cubic centimeters is indeed 10% of 49g prostate. Tissue is mostly water, so it's roughly 1g per cc. If the tumour (as you misspell it ) were spherical, it would have a radius of 1.05 cm, which would make for a very small golf ball. In the US, golf balls are twice that radius, but I know that everything is bigger in the US.