Can you tell me how could certain cancer treatments affect the surrounding environment?

Non specificity: The ideal chemotherapy affects the tumor only and does not affect surrounding tissue. Many chemotherapeutic agents affect surrounding tissue causing diarrhea, drop in RBC and WBC. Radiation can affect surrounding tissue producing inflammation and fibrosis and monoclonals to growth factors affect normal cells also.

Non specificity: One of the problems with chemotherapy and radiation therapy is they are not specific for the lesion being treated. That is, while chemotherapy affects tumor DNA more selectively than normal tissue DNA, it also effects normal cells. Drugs effecting growth factors on cancer also effect same factors on normal cells and RT hits normal adjacent cells. Cyberknife tries to localize area treated/