Felis ISSN 2398-2950

Radiotherapy

Contributor(s): William Brewer Jr, Jo Morris, Susan North

Indications

  • As a single treatment modality for malignant tumors which cannot be controlled by surgery.
  • Combined with surgery for treatment of bulky tumors: usually postoperative, but possible pre-operative (neoadjuvant).
  • Most effective and least toxic when employed as a local treatment when no metastases present.
  • Most useful for tumors of extremities, eg oral cavity, nasal cavity and limbs, or intracranial tumors, eg pituitary, but can be successful adjuvant for tumors in other areas of the body, eg feline injection site sarcomas Feline injection-site associated sarcoma.
  • Combined with chemotherapy for highly metastatic tumors, but risk of potentiation of side-effects with some drugs Chemotherapy: complications.

Principles

General

  • Radiation damages cellular DNA but may also affect other cell components, eg proteins and lipids.
  • Radiation damage is oxygen dependent (often works by free radical formation), hence hypoxic cells are less sensitive.
  • Cell death not necessarily immediate, usually occurs at cell division.
  • Rapidly dividing tissues tend to express radiation damage quickly, within days to weeks.
  • Slowly dividing tissues appear more radio-resistant, expressing radiation damage months to years after therapy.
  • Response of tissue to radiation may also depend on the inherent sensitivities of individual cells.Print off the owner factsheet Cancer treatment - radiotherapy Cancer treatment - radiotherapy to give to your client.

Normal cell/tissue radiosensitivity

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Tumor radiosensitivity

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Achieving therapeutic gain

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Radiation techniques

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Radiation and surgery / chemotherapy

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Further Reading

Publications

Refereed papers
  • Recent references fromPubMed.
  • Sabhlok A & Ayl R (2014)Palliative radiation therapy outcomes for cats with oral squamous cell carcinoma (1999-2005). Vet Radiol Ultrasound55(5), 565-570.
  • Nolan N W et al(2013)Stereotactic body radiation therapy for treatment of injection -site sarcomas in cats: 11 cases (2008-2012). JAVMA243, 526-531PubMed.
  • Parshley D L et al(2011)Abdominal irradiation as a rescue therapy for feline gastrointestinal lymphoma: a retrospective study of 11 cats (2001-2008). J Feline Med Surg13(2), 63-68PubMed.
  • Fidel J et al(2010)Treatment of oral squamous cell carcinoma with accelerated radiation therapy and concomitant carboplatin in cats. JVIM25(3), 504-510PubMed.
  • Williams L E et al(2010)Chemotherapy followed by aabdominal cavity irradiation for feline lymphoblastic lymphoma. Vet Radiol Ultrasound51(6), 681-687PubMed.
  • Eckstein C et al(2009)A retrospective analysis of radiation therapy for the treatment of feline vaccine-associated sarcoma. Vet Comp Oncol7(1), 54-68PubMed.
  • Hammond G M et al(2007)Evaluation of strontium Sr90 for the treatment of superficial squamous cell carcinoma of the nasal planum in cats: 49 cases (1990-2006). JAVMA231(5), 736-741PubMed.
  • Sfiligoi G et al(2007)Response of nineteen cats with nasal lymphoma to radiation therapy and chemotherapy. Vet Radiol Ultrasound48(4), 388-393PubMed.
  • Kaser-Hotz B et al(2002)Radiotherapy of pituitary tumours in five cats. J Small Anim Pract.43(7), 303-307PubMed.
  • LaDue T & Klein M K (2001)Toxicity criteria of the veterinary radiation therapy oncology group. Vet Radiol Ultrasound42(5), 475-476.
  • Goossens M M et al(1998)Cobalt 60 irradiation of pituitary gland tumors in three cats with acromegaly. JAVMA213(3), 374-376PubMed.

Other sources of information

  • LaRue S M & Gordon I K (2013)Radiation Therapy.Chapter 12. In: Small Animal Clinical Oncology. Eds: Withrow S J, Vail D M & Page R L. 5th edn. Elsevier, St Louis. pp 180-197.
  • Pruitt A F & Thrall D E (2011)Principles of radiation therapy.Chapter 8 In: Manual of Canine and Feline Oncology.Eds: Dobson J M & Lascelles B D X. 3rd edn. BSAVA Publications, Cheltenham. pp 80-90.
  • McEntee M C (2006)Veterinary Radiation Therapy: Review and Current State of the Art. JAAHA42, 94-109PubMed.
  • Moore A S (2002)Radiation therapy for the treatment of tumous in small animal companion animals. Vet J164, 176-187PubMed.
  • Harris D et al(1997)Radiation therapy toxicities. Vet Clin North Am Small Anim Pract27(1), 37-46.
  • LaRue S M & Gillette E L (1996)Radiation Therapy.In: Small Animal Clinical Oncology.Eds S J Withrow & E G MacEwen. 2nd edn. Philadelphia: W B Saunders Co. pp 87-98.


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