Challenge of the Week / Basic Science / 08.16.19

Which of the following imparts resistance to radiation therapy in patients with chondrosarcoma?
  • High expression of enzymes involved in DNA damage repair
  • Radiation therapy is thought to work through DNA damage, leading to cell death. Enhanced DNA repair may allow tumor cells to survive radiation therapy, although this is not known to be a significant factor in radiation resistance in chondrosarcoma.

  • Absorption of radiation by the surrounding extracellular matrix
  • The attenuation of the radiation by the extracellular matrix does not appear to play a major role in reducing the efficacy of radiation therapy in chondrosarcoma. Current methods of radiation delivery would be able to overcome such concerns.

  • High production of antioxidants
  • Radiation therapy may result in DNA damage due to free radical production. These free radicals can be minimized by increased antioxidants. However, this mechanism is not known to be responsible for the radioresistance of chondrosarcomas.

  • Slow tumor growth
  • Radiation therapy is most effective in fast growing tumors and rapidly dividing cells. Chondrosarcomas tend to be relatively slow growing, however.