That's a pretty controversial question, but let me try to give a reasonable answer. It seems to me that theoretically, you should be able to cure any form of gyne chemically. The best evidence for that is that a large percentage of boys have breast growth during puberty and it resolves itself after a few years. That's why most pediatricians simply assure their patients that it will go away in a few years and typically it does. So that means that there is a mechanism where the body is able to grow and destroy breast tissue by itself. Apparently, however, this mechanism fails some of the time, which is why we're all on this forum.
Here is how it works based on the material I have read. During puberty, sometimes boys will have a hormonal imbalance whereby excess estrogen is being produced or is otherwise elevated in their bodies. This will cause breast tissue to develop, we know this because this happens quite frequently with body builders taking certain kinds of steroids. Breast tissue requires a certain amount of estrogen to grow and a certain amount to sustain itself. We have seen with bodybuilders that if you temporarily deprive your body of estrogen, breast tissue can shrink through a process called apoptosis (cell death).
The trick is manipulating your hormones in the correct way. There are some steroids which will simply eliminate estrogen from your body, but when you stop taking the drug, you get a "rebound" effect, which can cause your estrogen levels to spike and can cause regrowth of breast tissue. So you need to be careful because you can make things even worse.
The other problem is that even men require a certain amount of estrogen for their bodies to function, and decreasing or eliminating estrogen from your body for extended periods of time can cause health problems.
That being said, there are lots of drugs out there (mainly breast cancer drugs) that have been proven in clinical studies to have some effect on gyne. Most need prescriptions, but some you can obtain on the gray market. There is much more evidence that they can work when the glands are still tender, probably in the first year or two on onset. After that, there is much less evidence that you can reverse the process because the glands become fibrous and don't respond as well to chemical stimuli. If you are interested, just google "aromatase inhibitor" and "gynecomastia" or check out pubmed.org, there is lots of information on this.
The problem is that people are typically scared to take drugs without a doctor's supervision and there is not a lot of clinical research in general on gynecomastia, which is a real shame. I really believe that if I could have gotten a prescription for Aromasin or Exemestane when I was 10 or 11 I wouldn't have had to go through all of this. I say this because it actually makes a lot of sense when you think through the cause of this condition, most likely elevated estrogen levels. Get rid of the estrogen in time, and in theory, the breasts should stop growing and go away. It's just that doctors are so ignorant about this condition and for some reason there just aren't a lot of people out there doing research on this on a scale that would get people's attention. Just my rant for the day.