Worried Son

Dad was told in march that he had stage 3 rectal cancer doctors told him it was curable . He had 8 months of radiation and chemo. They told him after some tests his tumor didn't shrink much . This week finally had his surgery . It took 8 hours and the doctor said it was the worse one she had done . But they got the tumor and he sadly ended up with a permanat colostmy bag. Today the pathlogist tests came back and they said he had cancer in the margin . Doctor won't say no more until it goes it front of the tumor broad . So I am worried and left wondering for a week . So my question has anyone been threw this before ? Does this mean the cancer spread ? Does it mean the cancer is not curable no more ? Could he still be cured with more chemo or surgery ?