Occasionally, testosterone injections are preferred over creams or gels. There are three reasons for this. Firstly injections are prepared from formulations that are much cheaper than creams. Secondly, injecting testosterone is a safer method because creams can potentially cause allergies to the person who comes in contact with the substance. Besides, the injections need to be administered less often than creams which mean you will have to go through the embarrassment and misery less frequently. On the flip side, applying creams will reveal your condition to your partner which is something most people don’t want.
Saturation explains the paradox in this way. At very low levels of T, near the castrate range, prostate growth is very sensitive to changes in T concentration. Thus, severely lowering testosterone will definitely cause prostate cancer to shrink; adding testosterone back will cause the cancer to regrow. However, once we get above the point where the prostate is saturated with testosterone, adding more testosterone will have little, if any, further impact on prostate cancer growth. Experimental studies suggest the concentration at which this saturation occurs is quite low.