Tumors partially destroyed with sound don’t come back

Technique pioneered in rats at the University of Michigan could improve outcomes for cancer and neurological conditions. Noninvasive sound technology developed at the University of Michigan breaks down liver tumors in rats, kills cancer cells and spurs the immune system to prevent further spread-an advance that could lead to improved cancer outcomes in humans. By destroying only 50% to 75% of liver tumor volume, the rats' immune systems were able to clear away the rest, with no evidence of recurrence or metastases in more than 80% of animals. "Even if we don't target the entire tumor, we can still cause the tumor to regress and also reduce the risk of future metastasis,” said Zhen Xu , professor of biomedical engineering at U-M and corresponding author of the study in Cancers. Results also showed the treatment stimulated the rats' immune responses, possibly contributing to the eventual regression of the untargeted portion of the tumor and preventing further spread of the cancer. The treatment, called histotripsy, noninvasively focuses ultrasound waves to mechanically destroy target tissue with millimeter precision. The relatively new technique is currently being used in a human liver cancer trial in the United States and Europe.