How many people like Mr. Wright have experienced a reduction in their cancer tumors by taking Acai berries?

The number of people that may have experienced a tumor reduction while taking Acai berries is undemonstrated. I don't really know how many anecdotal claims are being made for tumor reduction. What I do know is that to demonstrate that the Acai berry is the cause of tumor reduction in people would require a scientific study that met these criteria:
1. The sample would have to be large enough to be statistically relevant. For normal cancer research this might need to be in the hundreds.
2. The group would have to be randomly divided into at least two groups. One group would get normal treatment such as chemotherapy and a placebo (a pill that looks like the pill with the Acai in it). The second group would get normal chemo plus the Acai in pill form. The pill form is for control of the placebo effect. There cannot be a difference between how people in the control group (the placebo group) are administered the treatment. There might also need to be a third group of people who are randomly assigned to only get the normal chemotherapy and no other treatment.
3. The treatment must be double-blind. This means that neither the doctor administering the treatment nor the patients will know who is getting the placebo pills and who is getting the acai pills. I am using a pill as the example, but the two groups could also both take a special mixed drink that looks the same or something like that. The thing is, they have to both look like they are getting the same treatment so that neither the doctor nor the patients can tell the difference.

Only when such a study is done will we really know whether or not the acai berries do any good. Sometimes, because of the placebo effect, maybe an extra 10% (beyond the normal chemotherapy rates) of people taking the acai will also show tumor reductions. But if an increased 10% or even 9% of people taking the placebo also show tumor reductions, then the experiment will show that acai is no better than a placebo. In effect, what that really shows is that the berry does not have any effect. If the acai group had a 10% increase and the placebo group had only a 2% increase then that might be statistically significant and it would show the effectiveness of the treatment. But what counts as statistically significant depends on the size of the study.

I'm not a doctor, but I did serve on an ethics board that had oversight for cancer research of this kind, so I am very familiar with the process and of what counts as a scientifically valid experiment in cancer research. The problem is that I know of no research that supports the claims that acai berries can actually produce tumor reductions in human beings.

There is some research that demonstrates acai berries can cause leukemia cancers to break down, but that does not mean that it actually does that in humans. One reason for this the that the elements that work in the lab might not have what is called bioavailability. In other words, what works in a petri dish will not necessarily work inside the human body.
http://news.ufl.edu/2006/01/12/berries/

I hope this helps.

The claim that Acai berries reduces cancerous tumors is either "Folklore myth" or has had significant improvement. Suppose Acai was reducing cancerous tumors then you would hear reoccurring stories, about people, with terminal cancer, who after taking Acai had their cancer go into remission. Since Chemotherapy rarely save patients at the terminal stage the conclusion was something changed that caused the cancer to remit. If you see a few random stories of people making the claim that Acai berries helped them then start investigating the story. Correlate real life stories with the source of their cures and draw your own conclusions.

Did you ever watch the movie, "Medicine Man"? The Acai berry claim reminds me somewhat of the story line, in "Medicine Man". The research doctor finds a cure from a berry, but can't identify the element in the berry that caused the cancer to remit. The research doctor knows that his data is good, but can not discover the hidden element.