Prostaglandin 'Rinse and Swish' Protects Against Radiation Side Effects

Drugs similar to chemicals in the body may help prevent a patientfrom suffering hair loss and other side effects of some cancertreatments but leave tumors completely unprotected, a researcherat Loyola University Medical Center, Chicago, and Edward HinesJr. Veterans Affairs Hospital reported recently.

Laboratory studies indicate that synthetic prostaglandins, similarto substances released naturally by cells in response to injury,fail to interact with cancerous tissue, leaving tumors susceptibleto the full impact of chemotherapy and radiation, Loyola scientistDr. Wayne Hanson told colleagues at the 43rd Annual Meeting ofthe Radiation Research Society in San Jose, California

The finding represents a major step forward in the testing ofprostaglandin medications, specifically misoprostol (Cytotec),to prevent side effects such as hair loss and mouth ulcers inpatients undergoing cancer chemotherapy or radiation treatments,said Hanson, professor of radiation therapy and director of researchin the joint Loyola-Hines radiotherapy department.

Working in conjunction with researchers at The University of TexasM.D. Anderson Cancer Center in Houston, Hanson and Dr. Luka Milas,head of the experimental radiotherapy department at M.D. Anderson,spent approximately 1½ years examining four types of rodenttumors with different characteristics.

Injecting the rodents with a prostaglandin solution prior to treatmentof their tumors shielded the animals from hair loss and otherdamage to healthy cells, while leaving the tumors fully exposedto the radiation, Hanson said.

Protecting Against Stomatitis

Recent clinical trials of 70 patients undergoing radiation forhead and neck cancers, conducted by Hanson and Dr. James Marksat Loyola and Hines, demonstrated that merely rinsing the mouthwith a prostaglandin solution can protect healthy cells surroundingthe tumors and reduce the development of mouth ulcers. All ofthe participating patients had first undergone surgery to removemost of their tumors.

"Patients in the study were asked to 'rinse and swish' theirmouths with a solution in which we had dissolved a tablet of misoprostoland then to spit out the substance. Because we did not tell themto gargle, some of them developed sores at the back of their throats,although their mouths remained ulcer-free," Hanson said.

"Our early concern was that use of a prostaglandin medicationwould not only guard healthy tissue, but afford the tumor protection,as well. However, in our laboratory studies, we determined thatthis does not happen, although we do not know precisely why,"Hanson said.

He hypothesized that the tumor presents a dramatically alteredbiologic environment in which prostaglandins are unable to interactwith cells as they do in normal tissue.

Hanson, who began his prostaglandin research in the early 1980s,is now planning to coordinate a national study in which severalhundred head-and-neck cancer patients will be asked to gargleand swallow a prostaglandin solution that is odorless and colorlessbefore undergoing radiotherapy. The study will involve an estimated50 institutions.

"One of the questions we are trying to answer is how largea dosage of prostaglandins is necessary to protect the patientadequately from harmful side effects of radiation or chemotherapy,"Hanson said.

"We do know from our laboratory studies that when all ofthe cell receptors in healthy tissue are filled with prostaglandins,no further medication is necessary. We are also confident thatan overdose of prostaglandins causes essentially no side effects,other than a bout of diarrhea, perhaps," he stated.

Hanson cautioned that the prostaglandin research is promising,but not necessarily a panacea for all side effects and all formsof cancer treatment.

"We do know prostaglandins protect from hair loss in laboratorystudies and from a sore mouth in patient trials, but we do notknow if they may be effective in preventing other side effectsdue to cancer treatments," Hanson said.

For example, prostaglandin medications are not effective withsome chemotherapeutic drugs, including drugs containing platinum.

"Combining prostaglandins with these platinum drugs can actuallymake the side effects worse," Hanson said.

He emphasized that the use of prostaglandin medications in conjunctionwith cancer therapy remains experimental and is not currentlyavailable to patients.