Dogs with nasal tumors treated with IMRT radiation therapy

While the long-term prognosis for canine sinonasal tumors is poor, radiation therapy has been shown to improve survival times. On the other hand, with no treatment, or if surgery, chemotherapy, immunotherapy or cryosurgery is performed as a sole treatment, the median survival time is 3 to 6 mo, as progressive local invasion of the tumor leads to increasingly severe clinical signs, and owners generally opt for euthanasia. With full-course megavoltage radiation therapy, median survival times ranging from approximately 12 to 16 mo have been reported. Patients that have undergone full course radiation therapy may still continue to show clinical signs related to the tumor (such as nasal discharge or sneezing), although these signs are usually less severe than before treatment. One study found that only 39% of dogs were completely free of clinical signs after radiation .

Radiation generally involves 18–20 fractions (doses), which are given under general anaesthesia Monday to Friday for 3½ to 4 weeks as an out-patient procedure. (ed: sounds stressfull!...)

As with all full-course radiation treatments, acute effects will occur to varying degrees. Potential acute effects include oral mucositis, skin erythema and desquamation, conjunctivitis, and keratoconjunctivitis sicca. Pain is controlled through oral medications such as nonsteroidal anti-inflammatories and opioids, as well as daily local anaesthetic blocks and oral rinses. Acute side effects of radiation usually begin to develop during the 2nd to 3rd week of treatment, are at their worst at 2 wk after finishing treatment, and are generally completely healed by 4 wk post-treatment.

Late effects that may be seen months after radiation if the eyes are within the treatment field include keratoconjunctivitis sicca, keratitis, corneal vascularization, and cataract formation.

Clinical outcome in dogs with nasal tumors treated with intensity-modulated radiation therapy. (THIS IS A NEW WAY)
Hunley DW, Mauldin GN, Shiomitsu K, Mauldin GE.
Source
Ocean State Veterinary Specialists, East Greenwich, Rhode Island 02818, USA.
Abstract on new therapy
Intensity-modulated radiation therapy (IMRT) is a valuable tool in human radiation oncology, but information on its use in veterinary medicine is lacking. In this study, 12 dogs with nasal tumors were treated with IMRT at a median radiation dose of 54 Gy. Patient survival times and frequency and severity of side effects on ocular structures, oral mucosa, and skin were recorded. Eight dogs (67%) had resolution of clinical signs during radiation therapy. Median overall survival time was 446 d with a 50% 1-year (meaning half the dogs lived less than a appx year and half the dogs more) and a 25% 2-year survival rate. Minimal grade 2 or 3 acute skin toxicity, no grade 2 or 3 late skin toxicity, and no grade 2 or 3 toxicity to oral mucosa or the eye opposite the tumor were identified in the dogs treated with IMRT in this study. The ipsilateral eye could not be routinely spared due to its proximity to the tumor.


Long-term outcome of 56 dogs with nasal tumours treated with four doses of radiation at intervals of seven days.
Mellanby RJ, Stevenson RK, Herrtage ME, White RA, Dobson JM.
Source
Queen Veterinary School Hospital, University of Cambridge.
Abstract
A retrospective study was undertaken on 56 dogs treated for nasal tumours by megavoltage radiotherapy with a hypofractionated schedule consisting of four doses of 9 Gy given at intervals of seven days. The dogs were followed until they died or were euthanased. The clinical signs had improved in 53 of the 56 dogs by the end of the treatment schedule. Mild acute radiation side effects were observed in the majority of the dogs but late radiation side effects were rare. Kaplan-Meier survival analysis revealed a median survival time after the final dose of radiation of 212 days. The one- and two-year survival rates were 45 per cent and 15 per cent. Fifty of the dogs were euthanased because the initial clinical signs recurred.
Palliation of clinical signs in 48 dogs with nasal carcinomas treated with coarse-fraction radiation therapy.


Gieger T, Rassnick K, Siegel S, Proulx D, Bergman P, Anderson C, LaDue T, Smith A, Northrup N, Roberts R.
Source
Department of Clinical Sciences, Cornell University Hospital for Animals, CPC Box 31, Tower Road, Ithaca, New York 14853, USA.
Abstract
Data from 48 dogs with nasal carcinomas treated with palliative radiation therapy (PRT) were retrospectively reviewed. Factors potentially influencing resolution of clinical signs and survival after PRT were evaluated. Clinical signs completely resolved in 66% of dogs for a median of 120 days. The overall median survival time was 146 days. Duration of response to PRT was shorter in dogs that had clinical signs for <90 days before PRT. Survival times were shorter in dogs that had partial or no resolution of clinical signs after PRT than in dogs that had complete resolution of clinical signs.
PMID: 18451069  [PubMed - indexed for MEDLINE]
J Vet Intern Med. 2001 May-Jun;15(3):183-9.
Retrospective study of orthovoltage radiation therapy for nasal tumors in 42 dogs.
Northrup NC, Etue SM, Ruslander DM, Rassnick KM, Hutto DL, Bengtson A, Rand W, Moore AS.
Source
Harrington Oncology Program, Tufts University School of Veterinary Medicine, North Grafton, MA, USA. Abstract
Megavoltage radiation therapy currently is the standard of care for dogs with nasal tumors. Some studies report that surgery and adjunctive orthovoltage radiation therapy result in longer control of these tumors than does megavoltage radiation therapy alone. This study reports less effective control of nasal tumors in dogs treated with surgery and orthovoltage radiation than previously observed, supporting the superiority of megavoltage radiation therapy for these tumors. In addition, this study suggests 2 new prognostic indicators for dogs with nasal tumors and describes toxicity associated with surgery and orthovoltage therapy. Forty-two dogs with nasal tumors were treated with surgical cytoreduction and 48 Gy orthovoltage radiation therapy administered in twelve 4-Gy fractions. Median survival was 7.4 months. One- and 2-year survival rates were 37% and 17%, respectively. Dogs with facial deformity had shorter survival than those without deformity (P = .005). Dogs with resolution of clinical signs after treatment had longer survival than those with chronic nasal signs (P = .0001). Acute radiation toxicity was moderate to severe for skin and eye and negligible for oral mucosa. Toxicity healed within 1 month after radiation therapy. Late toxicity was mild, but 70% of evaluable dogs experienced persistent ocular signs. Only 39% of dogs achieved a disease-free period.
PMID: 11380025  [PubMed - indexed for MEDLINE]