From the article: However, capsaicin isn't effective if it's eaten, inhaled or injected, and researchers think it will only be effective as a pill attached to another drug that targets cancer cells.
Lots of substances work in a petri dish on isolated cells.
Check out Dr. Thomas Seyfried, who contends that cancer is a metabolic disease.
Primary prevention is two 7-day water fasts each year.
https://www.youtube.com/watch?v=fXWE8vQB0eA
Promising therapies involve ketogenic diet, exogenous ketones and hyperbaric oxygen, as is being tested by Dr. Dominic D’Agostino.
https://www.youtube.com/watch?v=Ntob6Sn06_Q&t=3s