I think that Pau d'Arco may play a role in some cancers but not quite prominently as proposed.
I think you haven´t read the links to the articles I have provided thoroughly.
Pau d'arco has no proven therapeutic utility. Lapachol, its most celebrated ingredient, has demonstrated some anticancer properties but is too toxic for practical use. In trials with human cancer patients, as soon as effective plasma levels were attained, undesirable side effects were severe enough to require that the drug be stopped. Animal and other laboratory studies have demonstrated that lapachol also possesses antibiotic, antimalarial, and antischistosomal properties, but scientific studies have not been done in humans because of the problem of toxicity [8].
1) Some researches are trying to isolate some compounds found in Pau d'Arco and experiment on them. While only the WHOLE inner lining of the bark only (`phloem`) should be used. It's the balanced mixture of ingredients that makes Pau d'Arco working. Lapachol should not be isolated from the rest of Pau d´Arco.
2) Some testimonials shows that before the cure from cancer, the patient had to undergone some very unpleasant experiences like vomitting and having a fever. So indeed it seems at first that Pau d´Arco is toxic. But after these experiences, if the treatment is continued, the patient will recover quickly and the cancer is gone.
3) Some companies are not selling the right kind of Pau d´Arco. The most common errors could be: it´s not the right kind of tree (but the less potent family) or the whole bark is used instead of the inner lining only. But whether this is still a common practice today is unknown to me.
So again, read
this website thoroughly. Click all the available buttons and read all the pages. Here are some (about eight) testimonials of successful use of Pau d´Arco. Just click on the button `Testimonials` below this webpage.
Though looking a bit funny,
this website also provides some useful information on Pau d´Arco (it´s called Taheebo in this website). There are some interesting testimonials too.
What is important in appliance of Pau d´Arco as a cure against cancer and other illnesses is:
1) The tree has to be of the right kind of family (the red or the purple Lapacho (the colors of their flowers)).
2) The WHOLE inner lining of the bark should be used (but not the heartwood or the bark itself). And not only some `active compounds` should be isolated and used.
3) The tea or capsule is extracted well (read the links provided how to do this).
4) The treatment is applied consistently.