malpractice resulting in death

I need some advice. A close famy member of mine was diagnosed with cancer of the throat last September. Stage four. In February we were given an amazing report that he was clear of all cancer. In April he went for his PET scan and a week later was hospitalized. The doctors who were on vacation, didn't get the PET scan until three days later while he was in the hospital. When the doctors finally were available they told us the cancer was everywhere, bones, stomach, lungs...and not to mention a 12cm tumor in his liver. Then a doctor had the audacity to ask if he could do expiermental work but it wouldn't make him better. It doesn't make sense. He passed away six days later. The doctors said that the cancer didnt start as throat cancer and they treated him for the wrong cancer. I would think noy with a 12cm tumor in his liver. if he was diagnosed correctly he would have been given the correct chemo/radiation. Would this be considered malpractice?