In the paper published in the Journal of Ethnopharmacology, papaya leaf extract has been found to boost the production of key signaling molecules called Th1-type cytokines that suggests potential therapeutic abilities that use the immune system to fight cancers in addition to its direct antitumour effect on various cancers.

Nam Dang M.D, Ph.D., researcher from the University of Florida and colleagues from Japan have documented the dramatic anticancer effect of the humble papaya against a wide range of lab-grown tumors including cancers of lung, breast, pancreas and the cervix. The extract was made of dried papaya leaves and results showed the anticancer effects stronger than when tea was used as a substitute.

The papaya extract did not trigger any toxic effects on normal cells. The results from the study that showed the success of the papaya as an anticancer, without toxicity is also consistent with reports from Indigenous populations in Australia and his native Vietnam, said Dang.

He says, Based on what I have seen and heard in a clinical setting, nobody who takes this extract experiences demonstrable toxicity; it seems like you could take it for a long time - as long as it is effective.

The study also included exposure of 10 different types of cancer cell cultures to 3 strengths of papaya leaf extract and found that growth of tumors in all cultures was slowed down. The research team focused on a cell line for T lymphoma to find out the specific mechanism that had checked the growth of the cultures and results suggested that at least one of the mechanisms used by the papaya extract is triggering cell death.

The study also showed papaya's production of cytokines, particularly Th1-type cytokines that play a key role in regulating the immune system. The findings opened up the possibility of using papaya extract components in immune-associated conditions like autoimmune disease, inflammation and certain cancers.

Bharat B. Aggarwal, Ph.D., researcher of the University of Texas M.D. Anderson Cancer Center in Houston, said that, We have always known that papaya has a lot of interesting things in there. Though the paper has just touched on the superficial aspects of the papaya extract components, he said that it is a good beginning.