Veterinary Surgical Oncology. Группа авторов

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Veterinary Surgical Oncology - Группа авторов


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the dose intensity used in companion animals is significantly lower than that used in oncology in human patients, neoadjuvant/perioperative chemotherapy is relatively uncommon, and most patients start chemotherapy 10–14 days post‐surgery. A paucity of information exists in the veterinary literature with most of the data limited to dogs with osteosarcoma treated with either cisplatin or doxorubicin either pre‐operatively for 2–3 cycles or 2–10 days post‐surgery. Neither study reported an increase in post‐operative morbidity (Berg et al. 1995, 1997). On the other hand, survival did not appear to improve with these protocols (Berg et al. 1995, 1997). Therefore, general recommendations are to wait 7–14 days after surgery to begin chemotherapy, especially for more high‐risk procedures such as intestinal resection and anastomosis.

      The use of metronomic (low dose continuous) chemotherapy is becoming more commonplace. As conventional chemotherapy typically involves the use of pulsatile cycles of chemotherapy given at the MTD with long breaks to allow recovery of normal cells from damage, metronomic chemotherapy instead utilizes continuous (typically once daily) administration of chemotherapeutics at a dosage well below the MTD, without prolonged drug‐free breaks. Unlike MTD chemotherapy, where the tumor cells are the primary targets of therapy, metronomic therapy appears to target cells of the tumor microenvironment including the endothelial cells that support and nourish the tumor. The mechanisms of action include direct apoptosis for dividing endothelial cells, suppression of the mobilization of circulating endothelial progenitor cells (CEPs) from the bone marrow, and increasing the production of the body’s own natural angiogenesis inhibitors. Furthermore, metronomic chemotherapy has been shown to have immunomodulatory effect via inhibition and depletion of T‐regulatory (Tregs) lymphocytes, thereby decreasing immune tolerance (Lana et al. 2007; Elmslie et al. 2008; Burton et al. 2011; Tripp et al. 2011; Leach et al. 2012; Biller 2014). Although metronomic therapy is often considered “antiangiogenic,” to date there is no evidence on whether its use has a detrimental effect on wound healing, as the vast majority have reported its use either weeks post‐surgery or in the treatment of bulky disease.

      Radiation Side Effects

Photo depicts mix breed canine with an incompletely resected mast cell tumor on the ventral aspect of the chest, over the sternum.

      Source: pictures courtesy Dr. Susan LaRue.

Photo depicts beagle canine with an incompletely resected soft tissue sarcoma on the lateral aspect of the stifle treated with 18 fractions using a manually calculated plan and parallel opposed beams of 6 mV.

      Source: Pictures courtesy Dr. Susan LaRue.

Photo depicts American Staffordshire with an incompletely resected soft tissue sarcoma of the lip treated with 18 fractions using intensity-modulated radiation therapy.

      Source: Pictures courtesy Dr. Susan LaRue.

Photo depicts late radiation therapy side effects. Image (a) shows a dog with a stage 4 nasal carcinoma prior to radiotherapy. This dog was irradiated using stereotactic radiation therapy (3 fractions of 10 Gy using a CyberKnife radiosurgical system). Image (b) shows the same dog 6 months after irradiation. This image demonstrates the late RT side effect of leukotrichia. Using stereotactic radiation therapy, a minimal amount of healthy tissue surrounding a tumor receives a clinically significant dose of radiation.
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