Traumatic Brain Injury and Metastatic Disease

My Sister was "cancer" free from breast cancer four months ago.  She was in a very bad car accident with traumatic brain injury, multiple broken bones, including neck, lumbar and arm, ribs and orbital bone.  During the X-rays they found metastatic disease in her lung, liver and on both adrenal glands.  They say they cannot do any treatment for the cancer until her bones and brain injury are healed.  They say the chemotherapy will inhibit healing.  I am concerned if they wait the cancer will continue to spread.  Does anyone know about chemotherapy and injury healing process?