geneva. hot shots, pictures worth a thousand words. a new study could spell new hope for thousands of those suffering with the same form of brain cancer that took the life of the late senator ted kennedy. it involves a new treatment, a type of vaccine that can actually prolong survival. and when the preliminary results were made public in june, the benefits were dramatic. our chief medical correspondent, dr. sanjay gupta, has been following this trial for a while and met with patients and doctors nearly two years ago. >> i heard you also volunteered to do a spinal tap today for us. >> yes. >> reporter: this is karen. she's bracing for another painful procedure. you see, she's got cancer. brain cancer. a killer tumor. >> glioblastoma, this is typically thought of as the worst type of tumor. why? >> oh, because left untreated, the -- the patient succumbs to