Treatment Options for Nasal Tumors Affecting the Maxilla

Tumors of the nasal cavity
The most common tumors of the nasal cavity include adenocarcinoma and sarcoma (osteosarcoma, chondrosarcoma). Work up of a nasal tumor involves CT scan of the head and thorax, +/- rhinoscopy and evaluation of the mandibular and retropharyngeal lymph nodes. It is recommended that clotting function is assessed prior to nasal tumor biopsy. In general, rhinoscopy allows for evaluation of the nasal cavity and biopsy, but the biopsies are smaller than blind biopsies and this carries the risk that they will be nondiagnostic. Blind biopsies can be performed using alligator forceps or by coring the nasal tumor out with the casing from a spinal needle. The CT scan can be used to guide the biopsy, taking care to avoid deep penetration beyond the cribriform plate. Another promising technique that was recently reported involves hydropulsion to dislodge large portions of nasal tumors for diagnosis. (J Am Anim Hosp Assoc 2011)

Surgery was originally considered the treatment of choice for nasal cavity tumors. (Can Vet J 1996; 37: 483- 485) However, with the advent of radiation, this therapeutic option replaced surgery for the treatment of nasal tumors. This is because the survival times were equivalent or improved with radiation alone. Surgery combined with post-operative radiation has not been shown to improve survival times compared to radiation alone. Surgical cytoreduction prior to radiation may even cause the radiation to be less effective because the introduction of air into the nasal cavity may affect the accurate and even delivery of radiation to the entire nasal cavity. There is one study that evaluates post-operative exenteration of the nasal cavity after full-course radiation for nasal tumors. This study showed a significantly increased survival time in dogs that had the combination of radiation and post-radiation surgery, with a median survival time of 1431 days in dogs treated with radiation followed by dorsal rhinotomy for removal of the tumor from the nasal cavity, compared to 591 days in dogs receiving radiation alone. (J Am Vet Med Assoc 2005;227:936–941). Both of these median survival times are longer than most reports of nasal tumor treatment with radiation with and without surgery. Dogs in this study that were treated with radiation and surgery had a high rate of complications, including rhinitis, osteomyelitis, and osteonecrosis. A recent retrospective study at our institution evaluated dogs that had full- course radiation followed by surgical cytoreduction. The median survival time for this study of 16 dogs was 457 days. (K Bowles, personal communication) We did not see the survival benefit that was previously reported for dogs with post-radiation cytoreduction. However, we also did not see a high post-operative complication rate in our study. It is possible that selection bias may be the reason for the difference in survival times noted in these two studies. A prospective study is needed to determine if there is an advantage to treating dogs with full-course radiation followed by surgery compared to radiation alone. However, given that most dogs with nasal cavity tumors succumb to local recurrence, more aggressive local therapy with both modalities is a consideration. At our institution, dogs with nasal cavity tumors treated with full-course radiation will be monitored with CT scan. If there is residual or progressive disease, surgical cytoreduction is recommended.  [...]