Current treatment for some forms of cancer did not work as well as researchers had initially hoped. But a new virus-based treatment has shown promising results. Using viruses to treat cancer has long been of interest to medical researchers. One type of virus in particular - oncolytic viruses - can kill tumor cells. But so far, the Food and Drug Administration (FDA) has only approved one of these: a genetically modified form of herpes to treat melanoma. The reason that viruses can target tumors is pretty simple. Cancerous tumors are invisible to the immune system, allowing them to grow and spread. But when the virus enters a cancerous cell and replicates itself, this allows the cancer to be seen, prompting the immune system to treat the disease as a common cold. Melanoma is not the only type of cancer that viruses can affect. Researchers have recently tested similar treatment on brain tumors. A new study has found promising results in the form of bladder cancer. "Current treatment is ineffective and toxic in a proportion of patients, and there is an urgent need for new therapies," says Hardev Pandha, Ph.D., lead study investigator. The researchers gave 15 patients who had been diagnosed with NMIBC at a dose of CVA21 one week before surgery to remove their tumors. The urine samples showed that the virus was able to copy itself and attack and kill cancer cells in the majority of patients. The tissue samples indicated that the virus was only successful in attacking cancerous cells, rather than healthy ones. According to Prof. Pandha, the common cold strain "could help revolutionize treatment for this type of cancer." She notes that the therapy could even "signal a move away from more established treatments such as chemotherapy."