Tumours of the Nasal Cavity in the Dog

Tumours in this area account for approximately 1% of canine neoplasms and are seen in the older dog (Figure 1). Clinical signs overlap with other intranasal diseases but an intermittent unilateral serosanguinous discharge, epistaxis or mucopurulent discharge in an older dog which may progress to bilateral signs, facial deformity or exophthalmos would be indicative of a likely neoplastic process.

Nasal tumours have a low probability of metastasis with most animals being euthanased due to primary disease.

Figure 1. Types of tumour identified in the nasal cavity.

Treatment of Tumours of the Nasal Cavity in the Dog

Supportive Only

In a review of 139 cases of nasal carcinoma not treated with radiotherapy, surgery, chemotherapy or immunotherapy, the median survival time (MST) was 95 days (range 7-114 days). The prognosis was worse for dogs with epistaxis. In several studies cyclo-oxygenase 2 (COX-2) expression has been evaluated .The majority of nasal carcinomas express COX-2 which is therefore a target for COX-2 inhibitors. Often there is secondary infection and therefore antibiosis as well as pain control should be considered.

Surgery Alone

Most nasal tumours usually involve extensive bone invasion and even with extensive curettage of turbinates the chances of effecting a cure are low. In addition there is a high morbidity associated with these procedures and survival times quoted of 120-180 days are not very much improved on antibiotics and pain relief only.

Radiotherapy Alone (Megavoltage Radiation)

Numerous total dosage and fractionated protocols have given MSTs ranging from 180 to 570 days. Due to the limited number of linear accelerators for veterinary use in the UK, a protocol involving four once-weekly fractions of 8-9 Gy to a total of 32-36 Gy has been used for some years. The MST for this protocol is 278 days (CI 38-386 days). External beam radiation has few side effects and is very well tolerated by animals and is good at controlling epistaxis. The most obvious side effect is that the area treated will become alopecic and the hair regrowth will be white. Occasional mucositis is seen in the oral cavity as it is included in the radiation field and care must be taken to avoid the eyes wherever possible. Advanced imaging such as computed tomography (CT) or magnetic resonance imaging (MRI) prior to radiotherapy is necessary to aid planning.

Chemotherapy Alone

Cisplatin was given to 11 dogs with nasal adenocarcinoma resulting in MST of 140 days (range 56-896 days) and resolution of clinical signs in all dogs but measurable response (as evaluated by radiography) in only 3/11 (27%). Alternating doxorubicin/carboplatin every 3 weeks to a total of 8 doses, together with piroxicam given daily, resulted in CR (Complete Remission) in 4/8 dogs with nasal tumours, PR (Partial Remission) in 2/8 and SD (Stable Disease) in 2/8 with 3/8 dead due to disease 510, 540, 185 days after treatment and 3/8 alive 150, 210, 960 days after treatment.

Multimodality Treatments

 Radiotherapy plus surgery. Megavoltage radiotherapy prior to, or after, surgery has been explored. In one relatively small study radiotherapy after debulking surgery showed no improvement in MST. Preoperative radiotherapy did show some improvement with MST of 48 months but 10/13 dogs had immediate postoperative complications. Orthovoltage ('low energy') radiation can only be carried out after a rhinotomy. Survival times are comparable to megavoltage radiation as sole therapy at worst, with some reports of significantly better median survival times of 23 months and 16.5 months.

 Radiotherapy plus chemosensitisers. Gemcitabine was evaluated but significant toxicity was associated with it, either haematological or tissue damage within the radiation field. A slow-release cisplatin preparation (OPLA-Pt) given in conjunction with radiotherapy gave a MST of 474 days, comparable to radiotherapy alone.

Tumours of the Nasal Cavity in the Cat

Cats are more likely to present with facial deformity, sneezing, snorting or dyspnoea than dogs, with a nasal discharge or epistaxis being a less frequent presenting sign. Tumour types are listed in Figure 2.

Figure 2. Types of tumour identified in the nasal cavity of cats.

 Lymphoma

 Adenocarcinoma

 Squamous cell carcinoma

 Sarcomas (rare)

 Others

 Nasopharyngeal polyps (not a tumour but a differential for a nasopharyngeal mass)

Treatment of Feline Nasal Lymphoma

In one study lymphoma was reported to be the most common cause of nasopharyngeal disease in the cat. Most cats are feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) negative. Interestingly there is a nasal/renal lymphoma link, with cats presenting with nasal lymphoma sometimes developing renal lymphoma. Generally nasal lymphoma cases seem to do quite well with 75% achieving CR. MST of 358 days with COP (Cyclophosphamide, Oncovin, Prednisolone) protocol was reported, although a bigger study reported a range of 14-541 days. Some cats have solitary nasal lymphoma and therefore are candidates for radiotherapy, which is especially useful if the tumours do not seem chemosensitive. Survival times range from 6-69 months. Regular monitoring is very important in this latter group of cats to make sure there is no disease elsewhere. A recent study where 19 cats were given radiotherapy and 6 months of chemotherapy gave a median survival of 955 days.

Treatment of Other Feline Nasal Tumours

Surgery Alone

Surgery alone is not recommended as cats tolerate this procedure poorly and survival times in studies are short.

Radiotherapy Alone (Megavoltage Radiotherapy)

In the UK a protocol similar to the one used for canine intranasal tumours has been used for some years. The MST is 382 days (CI 153-477days). Other protocols reported give a similar MST of about 12 months.

Canine Squamous Cell Carcinoma of the Nasal Planum

Although these tumours are said to have a low metastatic rate but are locally invasive, the author would still recommend fine-needle aspiration (FNA) of the draining lymph nodes and chest radiographs before commencing treatment as we have seen a significant number of dogs with metastatic disease, usually in the lymph nodes, at presentation.

Advanced imaging is vital before embarking on treatment to help delineate the tumour. These tumours in the dog frequently involve the underlying tissues and, because of this, an aggressive surgery (nosectomy) is needed to have any hope to control the lesion. For dogs where clean margins were achieved the prognosis is very good. Nosectomies can be challenging for owners as the cosmetic appearance of dogs is compromised to a varying degree, depending on how radical the surgery has been. These tumours are poorly chemo-/ radiosensitive.

Feline Squamous Cell Carcinoma of the Nasal Planum

This is the most common malignant skin tumour seen in the cat and is usually associated with ultraviolet (UV) light damage. It usually involves the unpigmented, nasal planum of white or partly white cats. The tumour progresses from a superficial area of ulceration covered with a crust which resembles a cat scratch, to a deeper erosive lesion. It has a low metastatic potential to lungs and local lymph nodes. Nevertheless chest radiographs and FNA of drainage lymph nodes are a good idea before embarking on an expensive or lengthy course of treatment.

Treatment

Treatment options depend on the size of the tumour and include surgery, external beam radiotherapy, cryosurgery, photodynamic therapy (PDT) and strontium⁹⁰ plesiotherapy. The more superficial tumours respond well to all therapies but the more infiltrative ones need aggressive surgery (nosectomy) to have any hope of controlling the lesion, although a case series of six cats treated with external beam radiotherapy and intralesional carboplatin reported durable remission times for five of the six. However, the delivery of carboplatin into a lesion rather than intravenously is potentially associated with significant health and safety problems.

In one study of 39 cats with nasal or pinna squamous cell carcinoma treated with surgery median survival was 673 days (range 67-1860 days).

Radiotherapy techniques include:

 Plesiotherapy. Strontium⁹⁰ plesiotherapy gives an estimated 80% chance of no recurrence at 1 year. The beta radiation emitted falls off rapidly over 2-3 mm depth of tissue so the treatment is best for more superficial erosive lesions. Due to this superficial penetration it can be repeated if necessary. It is well tolerated by the cat and cosmetically leaves the area intact apart from localised alopecia.

 Teletherapy using megavoltage radiation has been used giving a 1 year DFI (Disease Free Interval) of 88% for more superficial tumours and 36% for more advanced ones. In a recent study six cats were given once-weekly intralesional carboplatin prior to irradiation. All cats achieved complete remission and this was a durable remission.

Cryotherapy gives mixed results. The major problems with cryotherapy are the deep margins where the cold may not penetrate deep enough to kill the entire tumour or alternatively may destroy underlying cartilage and thus affect the cosmetic appearance of the cat.

PDT is best used on very superficial lesions but has a high (63%) recurrence rate with a median time to recurrence of 21 weeks.

References

1.  Ogilvie G, Moore A. Managing the canine cancer patient. Trenton New Jersey: Veterinary Learning Systems, 2006; 406-411, 628-629

2.  Ogilvie G, Moore A. Feline Oncology. Trenton New Jersey: Veterinary Learning Systems, 2001; 369-373, 412-418

3.  Rassnick KM, Goldkamp CE, et al. Evaluation of factors associated with survival in dogs with untreated nasal carcinomas: 139 cases (1993-2003). Journal of the American Veterinary Medical Association 2006; 229(3): 401-406.