The answer is fairly simple. Company producing zapper could invest in the scientific research. Government organisation who spend millions in finding a cure for cancer and other diseases could invest as well. If zapper was the answer to cancer then why would governments spend millions on chemotherapy ? The claim of parasites causing cancer seems ridiculous. Smoking increases the risk of lung cancer how would parasites play a part here ? Does smoking create parasite friendly environment ? Why governments spends millions in anti-smoking campaigns ?