GENERAL CONSIDERATIONS


Etiology

•tumors of nasal cavity represent approximately 1% of all tumors in dogs

•etiologic factors include:

•dolichocephalic breeds

•dogs living in an urban environment

•exposure to smoke, indoor kerosene or coal combustion and flea spray

•sex predisposition in dogs: ± male

•medium to large sized dogs are more commonly affected

•median age: 10 years although dogs with sarcomas may present at an earlier age


Pathophysiology

•nasal tumors are malignant in 80% dogs

•60%-75% of malignant tumors in dogs are carcinomas with ADC the most common while others include SCC, undifferentiated carcinoma, TCC, and neuroendocrine tumors

•25%-40% of malignant tumors are sarcomas such as FSA, CSA, OSA, undifferentiated sarcoma, rhabdomyosarcoma, HSA, leiomyosarcoma, myxosarcoma, and malignant fibrous histiocytoma

•nasal LSA is rare in both species, but more common in cats and not associated with FeLV infection

•other round cell tumors include plasmacytoma, transmissible venereal tumor, MCT, and histiocytoma

•other nasal tumors include malignant melanoma and paranasal meningioma



From: Withrow SJ & MacEwen EG (eds): Small Animal Clinical Oncology (3rd ed).

•nasal tumors, regardless of histologic type, are characterized by locally invasive growth

•metastatic rate is low at diagnosis but reported in up to 50% of dogs at necropsy

•metastatic sites include lymph nodes and lungs ± bone reported in 2 dogs

•benign nasal tumors include adenoma, basal cell tumor, fibroma, and neurofibroma

•nasal vestibule is the most common site for feline nasal SCC, malignant melanoma, and basal cell tumor



DIAGNOSIS


General Considerations

•history, clinical signs, survey radiographs, CT, and tissue biopsy

•hematology and clotting profile to exclude bleeding disorders: platelet count, PCV, ACT, PT, and APTT

•lymph node aspirates are positive in 10% and thoracic radiographs are usually normal at presentation

•CSF should be collected if CNS involvement: increased CSF pressure, protein, and rarely cell count are abnormal


Clinical Signs

•intermittent and progressive unilateral epistaxis ± mucopurulent discharge

•other clinical signs: sneezing, reverse sneezing, stertorous respiration, dyspnea, facial deformity, epiphora, and neurologic signs (i.e., seizures, behavioural changes, and obtundation) due to direct invasion of cranial vault

•mean duration of clinical signs prior to presentation is 3 months

•DDx: bleeding diathesis, hypertension, bacterial or fungal rhinitis, and developmental anomalies


Imaging


Survey Radiographs

•nasal radiographs determine extent of disease, presumptive diagnosis, and locate an area for biopsy

•views: lateral, dorsoventral, frontal sinus, open mouth oblique, and open mouth ventrodorsal

•radiographic pattern depends on histologic type, duration, and previous treatment

•mixed pattern of conchal destruction ± increased soft tissue opacity

•opacification of the ipsilateral frontal sinus is often due to impaired sinus drainage, but extension of the neoplastic process into the frontal sinus can also occur

•less defined and more destructive appearance with aggressive nasal tumors

•early neoplasia is difficult to differentiate from rhinitis

•unilateral increase in nasal opacity with attenuation or obliteration of normal conchal pattern is characteristic of early epithelial nasal neoplasia

•radiographic appearance becomes more heterogenous due to progressive conchal destruction with tumor progression and growth

•nasal septum can be deviated or destroyed by neoplastic process, but this is difficult to assess

•peripheral signs of nasal neoplasia includes soft tissue swelling, facial bone destruction, and periosteal new bone formation, and these signs are usually associated with highly aggressive neoplasms


Computed Tomography

•CT is preferred for determination of extent of disease and planning for radiation therapy

•useful for determining extent of disease and involvement of cribriform plate and orbit




Biopsy

•trans-nostril technique preferred for core biopsy although rhinoscopic and open techniques also used

•techniques: punch biopsy, large-bore plastic cannula, curette, or grasping (i.e., melon ball) forceps

•measure from the external nares to the medial canthus to prevent penetration of cribriform plate

•mild resistance is usually discernible when tumor tissue is encountered



From: Withrow SJ & MacEwen EG (eds): Small Animal Clinical Oncology (3rd ed).

•other techniques: nasal wash with fluid retrieval for cytologic examination (usually unrewarding), brush cytology (often non-diagnostic for mesenchymal tumors), and rhinoscopic biopsy (although samples are small and superficial)

•complications: mild to moderate hemorrhage

•hemorrhage is usually self-limiting but carotid ligation is occasionally required


Clinical Staging












TREATMENT


Surgery

•palliative

•nasal neoplasia is usually advanced with bone invasion and critical location adjacent to eyes and brain

•acute and chronic morbidity with dorsal rhinotomy

•no improvement in survival time with surgery compared to conservative management or surgery and radiation therapy compared to radiation therapy alone

•principal indication for surgery is rostral nasal tumors (i.e., nasal planum and vestibule)

•unilateral or bilateral carotid artery ligation may be required to control epistaxis


Chemotherapy and Immunotherapy

•no improvement in survival time

•27% response rate to cisplatin but MST only 20 weeks

•OPLA-cisplatin is a radiation sensitizer and improves survival when used in combination with radiation therapy


Photodynamic Therapy

•photodynamic therapy has been used to treated 1 cat and 3 dogs with nasal tumors using pyropheophorbide-a-hexyl ether as the photosensitizing agent

•photodynamic therapy is well tolerated with no cutaneous sensitization, but facial swelling is common and resolves within 72 hours

•clinical signs are controlled for 2 weeks to > 54 weeks


External Beam Radiation Therapy


General Considerations

•CT is preferred for planning of radiation field and dosing to limit exposure of normal tissue

•role of surgical debulking prior to radiation therapy is unknown

•surgical debulking is required for orthovoltage but optional for cobalt and megavoltage radiation therapy

•surgical debulking after curative-intent radiation therapy significantly improves survival time

•dose: 18 fractions at 3 Gy per fraction for 54 Gy total dose

•accelerated dose: 10 fractions at 4.2 Gy per fraction for 42 Gy total dose


Complications

•oral mucositis, rhinitis, and radiation-induced moist desquamation for 4-8 weeks

•treatment of oral mucositis includes tannic acid, glutamine (1.3 g/m 2 q 8 hrs PO), and benzydamine

•ocular changes (i.e., KCS, corneal ulcers, and cataracts) if eyes included in radiation field and dose > 40 Gy


Brachytherapy

•intracavitary therapy using radioactive isotopes

•potential problems include dose distribution and radiation exposure to personnel



PROGNOSIS


General Considerations

•MST 3-6 months for surgery, chemotherapy, immunotherapy, cryosurgery, and no treatment

•MST 8-23 months for radiation therapy ± surgical debulking, with

•1-year survival rate 37%-81%

•2-year survival rate 10%-48%

•MST 580 days for nasal tumors treated with radiation therapy and OPLA-cisplatin (v 325 days in historical group)

•CSA respond better to radiation therapy than other nasal tumors

•ADC responds better to radiation therapy than SCC or undifferentiated carcinomas

•MST 165 days for non-keratinizing nasal SCC

•solid ADC may have a better prognosis than diffuse ADC


Prognostic Factors

•poor prognostic factors for nasal tumors treated with radiation therapy:

•> 10 years (MST 6.8 months v 10.4 months)

•facial deformity (MST 133 days v 402 days)

•regional lymph node or pulmonary metastasis (MST 109 days v 393 days)

•modified tumor stage II (MST 7.0 months v 17.2 months)

•radiation therapy not included in the treatment protocol (MST 126 days v 424 days)

•radiation total dose > 55 Gy (MST 7.1 months v 10.1 months)

•lack of resolution of clinical signs after radiation therapy (MST 133 days v 476 days)


Type of Radiation Therapy

•megavoltage radiation therapy is preferred for the treatment of nasal tumors in dogs

•cobalt radiation therapy is associated with a significantly worse outcome compared to orthovoltage radiation therapy (MST 7.6 months v 18.0 months)



















 

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Stage

Description

I

Ipsilateral tumor with no or minimal bone destruction

II

Bilateral tumor with moderate bone destruction

III

Bilateral tumor with extranasal extension

Stage

Description

I

Unilateral or bilateral tumor confined to nasal passages without frontal sinus involvement

II

Bilateral tumor extending into frontal sinuses with erosion of any bone of the nasal passage

Authors

Radiation Type

MST

1-Year Surv Rate

2-Year Surv Rate

Thrall & Harvey, JAVMA, 1983

Orthovoltage

23 months

57%

48%

Adams et al, JAVMA, 1987

Orthovoltage

8.1 months

-

-

Evans et al, JAVMA, 1989

Orthovoltage

16.5 months

54%

43%

Northrup et al, JVIM, 2001

Orthovoltage

7.4 months

37%

17%

Adams et al, JAVMA, 1987

Megavoltage

8.1 months

-

-

McEntee et al, Vet Radiol, 1991

Megavoltage

12.8 months

59%

29%

Théon et al, JAVMA, 1993

Megavoltage

12.6 months

60%

25%

Henry et al, JVIM, 1998

Megavoltage

14.1 months

-

-