Some research indicates that guanabana, or soursop, has cancer-fighting benefits, including slowing the progression of cancer and helping cancer drugs work better. However, it is toxic and unsafe, causing systemic nerve damage, according to WebMD.
Even though studies have shown guanabana to have anti-cancer effects, no clinical studies have been conducted in humans as of 2015. No evidence has been produced of its efficacy or safety in human use. In laboratory studies it has been shown to kill some types of breast cancer and liver cancer cells that are resistant to specific chemotherapy drugs, reports Cancer Research UK. While the use of guanabana is promoted as a cancer treatment by many Internet web sites, none are supported by reputable scientific cancer organizations.
The lack of clinical trials of guanabana for cancer treatement is due to its toxic effects in humans, states the Cancer Research Centers of America. It can destroy nerve cells in the body, including brain cells. It produces movement disorders similar to the effects of Parkinson's disease, and it may worsen the symptoms of Parkinson's, according to WebMD. A study of Caribbean residents consuming large quantities of graviola, the evergreen tree bearing soursop fruit and from which guanabana is derived, showed that they had a higher probability of developing nerve changes and hallucinations, states Cancer Research UK.