A non-invasive method based on magnetic resonance imaging (MRI) that could predict the success of chemotherapy on cancer patients and influence treatment regimes for millions of them around the world has been developed at the Weizmann Institute of Science in Rehovot. The animal studies' findings, conducted by Prof. Hadassa Degani and colleagues at the Rehovot institute's biological regulation department, appear Tuesday in the journal Cancer Research. The method they developed for predicting chemotherapy success indicates how easily the drug can be delivered into the tumor. Chemotherapy drugs, given intravenously, are the mainstay of the fight against cancer. But doctors know that, while sometimes these drugs bring about a complete cure, at other times they can be nearly ineffective. Intravenous infusions depend on the bloodstream to transport chemotherapy drugs to where they are needed. Normally, these toxic drugs cross into tissue on the principle of diffusion, making the concentration of material equal inside and outside the tissue. However, in some cancers, even though the material "wants" to disperse evenly, fluids inside the tumor may exert pressure to prevent this from happening. When the internal pressure created by these fluids rises above a certain level, it acts as a barrier that keeps drugs and other materials from entering the tumor. The new Weizmann method can measure, with a non-invasive MRI scan, whether the fluid pressure in cancer tissues is at levels that could render chemotherapy ineffective. Their research was conducted with standard MRI equipment similar to that found in hospitals and clinics. A contrast agent often used in MRI served as a stand-in for chemotherapy drugs, and this material was injected into mice with different cancerous growths. The team verified the connection between the amount of material that found its way into the growth and the pressure of the fluids inside the tumor tissue. The Weizmann team's research, as well as that of other research groups, shows that this relationship can differ from one animal to the next, from one human to the next, and even from one tissue to the next in the same animal. Degani said that, ideally, the fluid pressure inside tumor tissues would be checked using this method before a patient began chemotherapy. If the pressure were discovered to be high, it might be possible to reduce it by various means, such as drugs similar to those for lowering blood pressure. The method, if it proves successful in clinical trials, might have the potential to significantly increase the success rate of chemotherapy.