Feline cutaneous squamous cell carcinoma of the nasal planum and the pinnae: 61 cases

Comparison of Three Chemotherapy Protocols With Electrochemotherapy for the Treatment of Feline Cutaneous Squamous Cell Carcinoma

Electrochemotherapy (ECT) with intravenous (IV) and/or intratumoral (IT) bleomycin has shown considerable efficacy in the treatment of non-resectable feline cutaneous squamous cell carcinoma (cSCC), boasting response rates of up to 95%, but other chemotherapy protocols have not yet been investigated. The objective of this prospective multicentre study was to compare the overall response rate (ORR) and progression-free interval (PFI) between cats with cSCC treated with ECT using IT and IV carboplatin (IV + IT), IV carboplatin (IV) or IV bleomycin (IV). A total of 44 cats with unresectable cSCC across three centres were enrolled and treated with ECT using carboplatin IV + IT (n = 10), carboplatin IV (n = 11) or bleomycin IV (n = 23). Treatment response according to RECIST criteria was recorded at 2 and 4 weeks post-treatment, and patients were followed until disease progression and/or death. All three groups were comparable regarding age, sex, weight, and lesion size. Adverse events were generally mild, localised and similar between groups. ORRs were 90.0% (carboplatin IV + IT), 90.9% (carboplatin IV) and 95.6% (bleomycin IV) and were not significantly different (p = 0.79). Median PFI was not reached for carboplatin IV + IT or carboplatin IV and was 566 days for bleomycin IV, with no significant difference between the three groups (p = 0.81). This study suggests that ECT using IV or IV + IT carboplatin is a reasonable alternative therapeutic option for managing cSCC, and further studies are warranted to compare outcomes between treatment protocols.

Description of outcome and adverse events in 21 cats with locally advanced nasal planum squamous cell carcinoma treated with electrochemotherapy

OBJECTIVES

Squamous cell carcinoma (SCC) is the most common tumour in the nasal planum of cats. Surgery has traditionally been the treatment of choice but might not be feasible in locally advanced scenarios. Electrochemotherapy (ECT) has shown good control in superficial tumours, but there is a lack of robust information about efficacy in locally advanced cases. The aim of this study was to assess the safety and efficacy of ECT in the treatment of locally advanced stage nasal planum SCC in cats.

METHODS

The clinical database of a veterinary referral hospital was searched retrospectively for cats diagnosed with a locally advanced nasal planum SCC (T3N0M0 or T4N0M0) that had received ECT. Local response, adverse events and outcome were documented. The data were evaluated by inferential statistics and correlations between response, recurrence, feline immunodeficiency virus/feline leukaemia virus status, number of treatments, voltage and severity of adverse events, with Kaplan-Meier curves and log-rank tests. Statistical significance was set at P <0.05.

RESULTS

In total, 21 cats were enrolled over a 4-year period. Nineteen cats achieved a complete response (CR) and two cats a partial response (PR) for an overall response rate of 100%. Cats achieving a CR had a median disease-free interval of 182 days (range 128-327) and those with a PR had a median progression-free survival of 156.5 days (range 122-191). The median time to progression was not reached. The overall survival was 453 days for a median follow-up of 341 days (range 191-989). Of the cats, 62% had grade 3 or 4 toxicities, but no deaths due to the treatment were documented. Only voltage was correlated with longer survival (P = 0.001).

CONCLUSIONS AND RELEVANCE

ECT appears to be an effective treatment for feline nasal planum SCC and could be considered a first-line therapy for locally advanced cases. Toxicities reported can be severe in the short term and these could be secondary to more invasive lesions and equipment used.

Perineural invasion as a predictor of local recurrence in cats with squamous cell carcinoma treated with electrochemotherapy

Introduction

Squamous cell carcinoma (SCC) is a malignant neoplasm that accounts for approximately 15-25% and 70-80% of all feline cutaneous and oral tumors, respectively. Similar to that in humans, feline SCC can be highly invasive locally; however, its metastasis rate is low. Thus, effective local treatment may be curative for most patients, and includes surgery, electrochemotherapy (ECT), cryosurgery, or a combination of these. However, this neoplasia can manifest more aggressively in some patients, leading to higher recurrence rates. In humans, perineural invasion (PNI) has been described as a relevant tumor dissemination pathway associated with high-risk SCC, resulting in higher recurrence rates, resistance to local treatments, and short survival. However, PNI and its prognostic value have not been described in feline SCC. This study aimed to evaluate the PNI in a feline population with SCC treated with ECT and correlate its presence with the occurrence of local recurrence and other clinical variables.

Methods

Twenty-four cats histopathologically diagnosed with SCC between 2013 and 2021 were retrospectively selected from the medical records of the Oncological Center Vet Cancer (São Paulo, SP, Brazil). The inclusion criteria were ECT as the sole therapy, histopathological evaluation of PNI, and absence of distant metastatic disease.

Results

The complete response rate was 96% (23/24), and PNI was identified in 33% of the cats (8/24, PNI-positive group), whereas 67% were free of this invasion (16/24, PNI-negative group). All PNI-positive cats developed local recurrence, whereas only five PNI-negative cats experienced recurrence. Local recurrence was significantly associated with PNI (p = 0.03).

Discussion

The results of this study are preliminary but promising. The data obtained are the first regarding PNI occurrence in feline SCC and pave the way for further studies, mainly to correlate the PNI with survival data and better define its prognostic value.

Canine squamous cell carcinoma: Electrochemotherapy association with surgery and correlation with overall survival

Squamous cell carcinoma (SCC) is an important malignancy in dogs, due to its incidence and clinical presentation, which can be of locally aggressive single or multiple lesions with a metastatic potential. The objective of this investigation was to evaluate SCC response to treatment, anatomopathological and immunohistochemical characteristics, disease-free interval and overall survival time. 54 dogs with histopathologically diagnosed SCC were included in this study. Their mean age was 9.16 years with a range of 1-14 years. Of the 54 animals in the study, 34 (65.4%) had white skin and white fur coats. There was a significant correlation between fur coat colour and the development of tumours in areas of sun exposure (p = .001). Animals with tumours in areas of the body exposed to the sun had longer overall survival time than animals with tumours in areas not associated with sun exposure (p = .001). Surgery combined with electrochemotherapy (ECT) yielded a survival rate 32% higher than using a surgical approach alone (HR = 0.32, p = .038, IC = 0.11-0.94). ECT, with or without surgery, had an objective response rate of 90.9%. Local lymph node and/or distant site metastasis at diagnosis, or at some point during follow-up, occurred in 34.6% (18/52) of animals. Animals with tumours in sun exposed locations had more aggressive histopathological characteristics but had longer overall survival time. This is probably due to individualised therapeutic treatment with both surgery and ECT.

Feline Oncogenomics: What Do We Know about the Genetics of Cancer in Domestic Cats?

Simple Summary

Cancer is a significant cause of suffering and death in domestic cats. In humans, an understanding of the genetics of different types of cancers has become clinically important for all aspects of patient care and forms the basis for most emerging diagnostics and therapies. The field of ‘oncogenomics’ characterises the alterations of cancer-associated genes that are found in tumours. Such a thorough understanding of the oncogenome of human tumours has only been possible due to a high-quality reference genome and an understanding of the genetic variation that can exist between people. Although a high-quality reference genome for cats has only recently been generated, investigations into understanding the genetics of feline cancers have been underway for many years, using a range of different technologies. This review summarises what is currently known of the genetics of both common and rare types of cancer in domestic cats. Drawing attention to our current understanding of the feline oncogenome will hopefully bring this topic into focus and serve as a springboard for more much-needed research into the genetics of cancer in domestic cats.

Abstract

Cancer is a significant cause of morbidity and mortality in domestic cats. In humans, an understanding of the oncogenome of different cancer types has proven critical and is deeply interwoven into all aspects of patient care, including diagnostics, prognostics and treatments through the application of targeted therapies. Investigations into understanding the genetics of feline cancers started with cytogenetics and was then expanded to studies at a gene-specific level, looking for mutations and expression level changes of genes that are commonly mutated in human cancers. Methylation studies have also been performed and together with a recently generated high-quality reference genome for cats, next-generation sequencing studies are starting to deliver results. This review summarises what is currently known of the genetics of both common and rare cancer types in cats, including lymphomas, mammary tumours, squamous cell carcinomas, soft tissue tumours, mast cell tumours, haemangiosarcomas, pulmonary carcinomas, pancreatic carcinomas and osteosarcomas. Shining a spotlight on our current understanding of the feline oncogenome will hopefully serve as a springboard for more much-needed research into the genetics of cancer in domestic cats.

Pilot study evaluating stereotactic body radiation therapy for feline facial squamous cell carcinomas

OBJECTIVES

The use of stereotactic body radiation therapy (SBRT) has not been assessed in advanced-stage feline solar-induced facial squamous cell carcinomas (SCCs). The objective of this study was to provide preliminary data on the use and safety profile of coarse fractions administered with an SBRT regime to manage advanced-stage feline solar-induced facial SCCs.

METHODS

This retrospective study assessed five cats diagnosed with advanced-stage solar-induced facial SCCs that received SBRT as their primary treatment or, in one cat, following failed surgical intervention. Tumour sites received three fractions totalling 26.25-27 Gy over a 3-5-day period.

RESULTS

All patients developed acute effects following SBRT including alopecia, epilation and erythema. Late effects were mild and included alopecia, variable pigmentation and leukotrichia within radiation fields. All patients were alive at the time of article submission, with overall survival times ranging from 118 to 991 days.

CONCLUSIONS AND RELEVANCE

The results suggest that coarse fractions administered with an SBRT technique is a safe and effective treatment tool for the management of advanced-stage feline solar-induced facial SCCs. These data provide preliminary evidence to support larger, prospective studies evaluating the management of feline facial SCCs with SBRT.

VEGF Expression, Cellular Infiltration, and Intratumoral Collagen Levels after Electroporation-Based Treatment of Dogs with Cutaneous Squamous Cell Carcinoma

Canine cutaneous squamous cell carcinoma (SCC) is the most common type of skin cancer in tropical countries and is generally associated with exposure to solar ultraviolet light. It has a low metastatic rate, and local treatments, such as electrochemotherapy (ECT), promote long-term control or even complete remission. This study aimed to evaluate pre- and post-ECT treatment expression levels of vascular endothelial growth factor (VEGF) and CD31, cellular infiltration, and intratumoral collagen levels in dogs with cutaneous SCC. A prospective nonrandomized clinical study was performed using dogs with spontaneous SCC treated with ECT. Eighteen lesions from 11 dogs were included in the study. The expression levels of VEGF and CD31; cellular infiltration; and intratumoral collagen levels, as determined by Masson’s trichrome staining, were not significantly different from pre-treatment measurements on day 21 (p > 0.05). However, among cellular infiltration, the mixed subtype was correlated with better overall survival time when compared to lymphoplasmacytic and neutrophilic infiltration (p < 0.05). In conclusion, ECT had no effect on VEGF expression, cellular infiltration, or intratumoral collagen levels in dogs with cutaneous SCC at the time of evaluation, suggesting that early and late post-ECT-treatment phases should be considered.

A Retrospective Multicentric Study of Electrochemotherapy in the Treatment of Feline Nasal Planum Squamous Cell Carcinoma

Feline squamous cell carcinoma (SCC) is currently treated with surgery, radiation therapy and electrochemotherapy (ECT). Both the efficacy and/or safety of ECT were evaluated as a sole therapy with bleomycin to treat feline nasal planum SCC (npSCC). Sixty-one cats were enrolled. Local treatment response was evaluated as complete remission (CR), partial remission (PR) or stable disease (SD). Recurrence rate (RR), disease-free interval (DFI) and progression free survival (PFS) were calculated. A six-point scale was used for ECT toxicity. The median tumor size was 1.5 cm. CR was achieved in 65.6% of cases, PR in 31.1% and SD in 3.3%. The overall response rate was 96.7%, RR was 22.5%, median DFI was 136 days, and median PFS was 65.5 days. ECT toxicity was ≤2 in 51% of cats. Tumor recurrence/progression (p = 0.014) and local treatment response (PR: p < 0.001; SD: p < 0.001) influenced survival time. Cats with toxicity >2 showed a higher probability of tumor recurrence/progression. Tumor-related death was higher in cats with PR (p < 0.001) and recurrence/progression (p = 0.002), in ECT treatment with 1 Hz (p = 0.035) and 1200 V/cm (p = 0.011) or 1300 V/cm (p = 0.016). Tumor size influenced local treatment response (p = 0.008) and toxicity (p < 0.001). ECT is an effective treatment for feline npSCCs and should be considered as the first-line procedure for low-stage tumors.

Cutaneous Spindle Cell Squamous Cell Carcinoma in Cats: Clinical, Histological, and Immunohistochemical Study

This study describes the clinical and pathological characteristics of cutaneous spindle cell squamous cell carcinoma (SCSCC) in 18 cats. The average age of the cats was 11.8 ± 2.7 years, and all tumors were located in the facial skin, mainly affecting the pinna (13/18, 72%), followed by the periorbital area (4/18, 22%) and the dorsal muzzle (1/18, 6%). Tumors were composed of fusiform neoplastic cells with moderate atypia arranged in solid sheets or fascicles with foci of squamous differentiation. A panel of antibodies against cytokeratins, vimentin, S-100 protein, NSE, GFAP, Melan A, SMA, desmin, CD18, CD31, and p63 was used to help differentiate SCSCC from other spindle cell malignancies. SCSCCs expressed CK5/6 (17/18, 94%), AE1/AE3 (15/18, 83%), and p63 protein (18/18, 100%), but there was no immunolabeling for CK8/18. A role for sunlight exposure in the pathogenesis of the tumors was suggested by changes indicative of actinic keratosis, the location of the tumors in dorsal areas, and the absence of histomorphologic features of papillomavirus infection. Recurrence was not recorded in 14/18 cases (78%) during a follow-up period of 7 to 25 months. Three of 18 (17%) tumors recurred or led to humane euthanasia due to local progression, and one case (5%) had regional lymph node metastasis. Clinical outcome varied with cutaneous location, mitotic count, and invasion of surgical margins; thus, SCSCCs with a more aggressive behavior were located in the periorbital area (4/4 cases), had ≥14 mitoses in 10 high-power fields (2.37 mm²) (4/4 cases), and showed invasion of surgical margins (3/4 cases).

Comparison of two different doses of bleomycin in electrochemotherapy protocols for feline cutaneous squamous cell carcinoma nonsegregated from ultraviolet light exposure

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin tumors in cats due to chronic exposure to ultraviolet light. Local treatments such as electrochemotherapy (ECT) promote disease control or even complete remission. We hypothesize that cats could benefit from treatments using bleomycin at reduced dosages. A prospective nonrandomized single-blind study evaluated the clinical parameters, site lesion, staging, disease-free interval (DFI) and survival time by comparing the standard dose of bleomycin (15,000 UI/m2) (n = 22) with a reduced dose (10,000 UI/m2) (n = 34) in cats with cSCC that underwent ECT as the sole treatment modality. No statistically significant difference in DFI or overall survival was observed between the 2 groups. A higher DFI was found in cats with a small tumor size (less than 0.33 cm3) compared with that for cats with a large tumor size (P = 0.045). Furthermore, a reduced overall survival time for cats with a higher stage in the standard group SG (T3 and T4) (P = 0.004) was observed when compared to that for cats with a lower stage (T1 and T2). In conclusion, ECT using both doses of bleomycin may achieve the same response rate in terms of the overall response, DFI, and overall survival.

Lip-to-nose flap for reconstruction of the nasal planum after curative intent excision of squamous cell carcinoma in cats: Description of technique and outcome in seven cases

OBJECTIVE

To describe the surgical technique for nasal planum reconstruction with a lip-to-nose flap after curative intent surgical excision of squamous cell carcinoma (SCC) in cats and to report the surgical outcomes.

STUDY DESIGN

Short case series.

ANIMALS

Seven cats with SCC of the lateral (n = 6) or dorsal (n = 1) aspect of the nasal planum.

METHODS

After tumor excision, a mucocutaneous lip-to-nose flap was harvested from the upper lip and transposed to reconstruct the nasal planum. Variables recorded included surgical time, surgical complications, healing complications, flap success rate, and cosmetic and long-term functional outcomes.

RESULTS

Median surgical time was 67.5 minutes (range 49-80), and no intraoperative complications occurred. Postoperatively, six cats developed self-limiting edema of the muzzle, and one cat had nasal discharge for 2 days. No major complications occurred during the healing process, and all cats went on to achieve successful healing of their flap. A small area of partial-thickness necrosis developed at the cranial edge of the flap in three cats and healed spontaneously in all cases within a few days. According to owner satisfaction and periodic clinical assessment, cosmetic and long-term functional of outcomes were considered good in all cats.

CONCLUSION

The lip-to-nose flap allowed for aesthetic and functional reconstruction of the nasal planum after curative intent surgical excision of feline SCC.

CLINICAL SIGNIFICANCE

The lip-to-nose flap is an option for a single-stage reconstruction of the nasal planum following partial nasal planectomy in cats.

Response, disease-free interval and overall survival of cats with nasal planum squamous cell carcinoma treated with a fractionated vs a single-dose protocol of strontium plesiotherapy

OBJECTIVES

The main aim of the study was to establish response, disease-free interval (DFI) and overall survival of cats with nasal planum squamous cell carcinoma (SCC) treated with Sr90 plesiotherapy. A secondary aim was to determine whether a fractionated protocol is more effective than a single-dose protocol in terms of response, DFI and overall survival. The third aim was to evaluate whether we can identify prognostic factors that influence overall survival.

METHODS

This was a retrospective study that included cats with a diagnosis of nasal planum SCC treated with Sr90 plesiotherapy at a single institution.

RESULTS

Seventy-four cats were included in the study. Thirty-two were treated with a fractionated protocol and 42 with a single-dose treatment. Sr90 plesiotherapy was able to induce complete response in 74% of cats with nasal planum SCC. The median DFI was 780 days (95% confidence interval [CI] 383-1177), with 17% of cats experiencing local recurrence. The overall survival for all cats was 1039 days (95% CI 55-1528). The DFI of cats treated with the fractionated Sr90 was significantly longer compared with the single-dose treatment, whereas response and overall survival were not statistically different. Other prognostic factors that influenced the overall survival were early-stage disease, absence of concurrent problems and complete response to the treatment. Acute and long-term toxicity associated with the treatment were minimal and the aesthetic outcome was pleasing in almost all cases.

CONCLUSIONS AND RELEVANCE

Strontium plesiotherapy is a safe and effective treatment of nasal planum SCC in cats.

Evaluation of long-term outcome and prognostic factors of feline squamous cell carcinomas treated with photodynamic therapy using liposomal phosphorylated meta-tetra(hydroxylphenyl)chlorine

OBJECTIVES

The aim of this study was to evaluate the efficacy, long-term outcome and prognostic factors of feline squamous cell carcinoma (SCC) treated with photodynamic therapy (PDT).

METHODS

Cats with histologically verified SCC of the head and neck received an intravenous injection of liposomal phosphorylated meta-tetra(hydroxylphenyl)chlorine (mTHPC) and 4 h later 652 nm light was delivered by a diode laser. One group received ⩽10 J/cm2, the other 20 J/cm2. Tumour response and duration were analysed with stage, tumour diameter, location and treatment intensity as prognostic factors.

RESULTS

In total, 63 lesions in 38 cats underwent treatment with ⩽10 J/cm2 (n = 22) and 20 J/cm2 (n = 41). Overall response rate was 84% (complete remission 61%, partial remission 22%) with a mean progression-free interval of 35 months (median not reached) and a median overall survival time of 40 months (95% confidence interval 33-47). With regard to tumour stage, invasiveness yielded a highly significant worse outcome ( P <0.017). All patients with invasive tumours showed progression at less than 6 months. Larger lesions were associated with inferior control and treatment intensity, and tumour location did not influence response and duration.

CONCLUSIONS AND RELEVANCE

PDT using a systemic photosensitiser leads to excellent long-term tumour control in the majority of cats. However, invasive and large tumours had a clearly inferior outcome, even if treated with the higher-dose intensity. This suggests that advanced lesions are not indications for PDT.

The Advantage of FLASH Radiotherapy Confirmed in Mini-pig and Cat-cancer Patients

PURPOSE

Previous studies using FLASH radiotherapy (RT) in mice showed a marked increase of the differential effect between normal tissue and tumors. To stimulate clinical transfer, we evaluated whether this effect could also occur in higher mammals.

EXPERIMENTAL DESIGN

Pig skin was used to investigate a potential difference in toxicity between irradiation delivered at an ultrahigh dose rate called "FLASH-RT" and irradiation delivered at a conventional dose rate called "Conv-RT." A clinical, phase I, single-dose escalation trial (25-41 Gy) was performed in 6 cat patients with locally advanced T2/T3N0M0 squamous cell carcinoma of the nasal planum to determine the maximal tolerated dose and progression-free survival (PFS) of single-dose FLASH-RT.

RESULTS

Using, respectively, depilation and fibronecrosis as acute and late endpoints, a protective effect of FLASH-RT was observed (≥20% dose-equivalent difference vs. Conv-RT). Three cats experienced no acute toxicity, whereas 3 exhibited moderate/mild transient mucositis, and all cats had depilation. With a median follow-up of 13.5 months, the PFS at 16 months was 84%.

CONCLUSIONS

Our results confirmed the potential advantage of FLASH-RT and provide a strong rationale for further evaluating FLASH-RT in human patients.See related commentary by Harrington, p. 3.

Bilateral Superior Labial Mucosal Transposition Flaps to Correct Stenosis of the Nares Following Bilateral Rostral Maxillectomy Combined with Nasal Planum Resection in a Dog

OBJECTIVE

To describe a technique using labial mucosal flaps to correct stenosis of the nares subsequent to bilateral rostral maxillectomy and nasal planum resection.

STUDY DESIGN

Case report

ANIMALS

Client-owned dog.

METHODS

A 10-year-old, neutered male Golden Retriever developed repeated stenosis of the nares, at first after bilateral rostral maxillectomy and nasal planum resection, and again after revision surgery. Bilateral, superior labial mucosal transposition flaps were created and interpolated between the nasal mucosa and skin after debridement of scar tissue.

RESULTS

The stenosis did not recur after mucosal flap transposition and the dog returned to normal quality of life (last follow-up 25 months postoperative).

CONCLUSION

Single-stage, superior labial mucosal transposition flaps can be used to correct nares stenosis subsequent to previous surgery.

Combined Rostrolateral Rhinotomy for Removal of Rostral Nasal Septum Squamous Cell Carcinoma: Long-Term Outcome in 10 Dogs

OBJECTIVE

To report a surgical technique for combined rostrolateral rhinotomy (vestibulotomy) and long-term outcome for treatment of squamous cell carcinoma (SCC) of the rostral nasal septum in dogs.

STUDY DESIGN

Retrospective case series.

ANIMALS

Medium sized, mixed breed dogs (n = 10), aged 7-12.5 years, with SCC of the rostral nasal septum that did not invade the superficial nasal planum.

METHODS

Disease extent was assessed with computed tomography and tumor resection achieved solely with central nasal planum elevation and lateral rhinotomy. Owners were interviewed 60-2,555 days (median, 548 days) postoperatively to determine outcome and survival time.

RESULTS

Vestibulotomy facilitated full-thickness resection of the nasal septum and tumor mass in 10 dogs and nasal floor resection in 4 dogs. There were no major intraoperative complications and all dogs had an excellent cosmetic outcome. Tumor removal was complete in 8 dogs and incomplete in 2 dogs. There was no recurrence in 6 dogs. Of the 4 dogs with recurrence, 3 had required nasal floor resection at initial surgery.

CONCLUSIONS

A combined rostrolateral rhinotomy technique may be used to achieve complete resection of SCC limited to the nasal septum with acceptable cosmetic results. This technique may not be suitable for tumors extending into the nasal floor.

Electrochemotherapy with intravenous bleomycin injection: an observational study in superficial squamous cell carcinoma in cats

The aim of this study was to evaluate the efficacy and safety of electrochemotherapy (ECT) with bleomycin for treatment of squamous cell carcinoma (SCC) in cats. Between March 2008 and October 2011, 11 cats with 17 superficial SCC nodules in different clinical stages (ranging from Tis to T4), located on nasal planum (6/11), pinnae (3/11) and both locations (2/11), were included in a prospective non-randomised study. Sixteen of 17 SCC nodules were treated with ECT (15/16 with single session and in one case with two sessions); one nodule was surgically removed. Altogether, complete response (CR) was achieved for 81.8% (9/11) cats and 87.5% (14/16) nodules, lasting from 2 months up to longer than 3 years. Only 2/9 cats in which CR was initially observed, had recurrence 2 and 8 months after the ECT procedure. In the remaining two cats with highly infiltrative spread into adjacent tissues, progression of the disease was observed, despite ECT, and both were euthanased 4 and 5 months after the procedure. ECT in cats was well tolerated and no evident local or systemic side effects were observed. The results of this study suggest that ECT is a highly effective and safe method of local tumour control of feline cutaneous SCCs. It should be considered as an alternative treatment option, especially when other treatment approaches are not acceptable by the owners, owing to their invasiveness, mutilation or high cost.

A utilização da radioterapia no tratamento do carcinoma de células escamosas cutâneo felino avançado

Avaliou-se a eficácia da radioterapia no tratamento de felinos portadores de carcinoma de células escamosas cutâneo avançado. Um protocolo de fracionamento padrão de radioterapia foi aplicado em seis gatos portadores de uma ou mais lesões cutâneas de carcinoma de células escamosas, em um total de sete lesões neoplásicas, confirmadas por meio de análise histológica. Uma lesão foi classificada como T2 e seis como T4, segundo o sistema de estadiamento da Organização Mundial de Saúde para tumores epidermais de felinos. Os animais foram submetidos a doze frações radioterápicas de 4 Gy, realizadas três vezes por semana, utilizando-se um equipamento de ortovoltagem. Utilizaram-se energia de 120 Kv, 15mA e filtro 2mm de alumínio, o cone usado foi de 6x8cm, e a distância foco-pele foi de 30cm. As lesões foram acompanhadas durante todo o tratamento radioterápico e 30 e 60 dias após o seu término. Neste estudo, 87% das lesões resultaram em remissão completa, e 13%, em remissão parcial. Os efeitos colaterais do tratamento radioterápico, de acordo com a tabela de critérios de toxicidade aguda da Veterinary Radiation Therapy Oncology Group, foram leves e reversíveis em todos os casos, e incluíram eritema cutâneo, epilação e rinite. Considerou-se a radioterapia segura para felinos com carcinoma de células escamosas cutâneo, levando a efeitos colaterais leves, e pode representar uma boa opção terapêutica.

Cutaneous squamous cell carcinoma in the cat: current understanding and treatment approaches

PRACTICAL RELEVANCE

Squamous cell carcinoma (SCC) is a tumour that commonly involves the skin or oral cavity and is, therefore, an important differential diagnosis for any cutaneous lesion(s), especially any non-healing scabbing lesions on the eyelids, nasal planum or ears of light-coloured cats.

CLINICAL CHALLENGES

Superficial lesions of the nasal planum, discrete small eyelid lesions and lesions on the tips of pinnae are relatively easily treated, but higher stage lesions are more challenging to manage and may compromise the cosmetic appearance of the cat.

AUDIENCE

This review article is aimed at all veterinary practitioners that see cats.

EVIDENCE BASE

The review summarises the peer-reviewed literature relating to our understanding of feline cutaneous SCC. Unfortunately, the literature is limited and in need of updating in areas.

Curettage and diathermy: a treatment for feline nasal planum actinic dysplasia and superficial squamous cell carcinoma

OBJECTIVE

To evaluate curettage and diathermy as a treatment for actinic dysplasia and superficial squamous cell carcinoma of the feline nasal planum.

METHODS

Thirty-four cats clinically assessed to have actinic dysplasia and superficial squamous cell carcinoma involving less than 50% of the nasal planum were treated with a three-cycle curettage and diathermy procedure. Degree of dysplasia, response to treatment, adverse effects, owner perceptions, time to recurrence and proportion disease free at 1 year were evaluated.

RESULTS

Lesions ranged from actinic keratoses to invasive squamous cell carcinoma. A complete response to treatment was obtained in all cats. The median follow-up time was 18 · 2 (IQR: 12 · 0-22 · 8) months. Two cats had a clinical recurrence of lesions at 161 and 192 days after treatment. The probability of remaining disease free after 12 months was 0 · 94 (95% CI: 0 · 85-1 · 0). Median time to recurrence was not reached. The procedure was well tolerated with a good cosmetic outcome and no significant post-operative complications.

CLINICAL SIGNIFICANCE

This study suggests that curettage and diathermy is an effective treatment for feline actinic dysplasia and for superficial squamous cell carcinoma involving less than 50% of the nasal planum. Curettage and diathermy is an easily mastered technique, requiring minimal equipment.

Radiation therapy for feline cutaneous squamous cell carcinoma using a hypofractionated protocol

The objective of this paper was to evaluate the efficacy of a hypofractionated radiation protocol for feline facial squamous cell carcinoma (SCC). Twenty-five histologically confirmed SCCs in 15 cats were treated with four fractions of 7.6-10Gy each, with 1 week intervals. The equipment used was a linear accelerator Clinac 2100 delivering electron beam of 4 or 6MeV, and a bolus of 5 or 10mm was used in all lesions. Of the lesions, 44% were staged as T4, 16% as T3, 8% as T2 and 32% as T1. Of the irradiated lesions, 40% had complete response, 12% had partial response and 48% had no response (NR) to the treatment. For T1 tumors, 62.5% had complete remission. Mean overall survival time was 224 days. Owners requested euthanasia of cats having NR to the treatment. Mean disease free time was 271 days. Side effects observed were skin erythema, epilation, ulceration and conjunctivitis, which were graded according to Veterinary Radiation Therapy Oncology Group (VRTOG) toxicity criteria. Response rates found in this study (52%) were lower when compared to other protocols, probably due to technique differences, such as fractionation schedule, bolus thickness and energy penetration depth. However, the hypofractionated radiation protocol was considered safe for feline facial SCC. Modifications of this protocol are being planned with the objective of improving the cure rates in the future.

Electrochemotherapy for the treatment of squamous cell carcinoma in cats: A preliminary report

Squamous cell carcinomas (SCC) of the skin are commonly described in cats. Reported treatments include surgery, radiation therapy and photodynamic therapy. This preliminary study reports on the management of these lesions combining the local administration of bleomycin (plus hyaluronidase for a more uniform distribution) with permeabilizing biphasic electric pulses. Nine cats with SCC graded T(2)-T(4) were treated over a 5 year period, and each cat received two sessions of electrochemotherapy (ECT) 1 week apart. The side effects of this treatment were minimal and limited to mild erythema of the nose. Seven of the cats (77.7%) had a complete response lasting up to 3 years. ECT seems to be a safe and effective option for the treatment of feline sun-induced squamous cell carcinomas and warrants further investigation.

Apparent clinical resolution of pinnal actinic keratoses and squamous cell carcinoma in a cat using topical imiquimod 5% cream

Imiquimod is a topical immune response modifier and stimulator used in humans to treat a number of cutaneous neoplasms. This case report describes a cat with actinic keratoses and squamous cell carcinoma of the pinnae. The pinnal lesions were treated with topical 5% imiquimod three times per week. Treatment was discontinued after 82 days of therapy. Twelve weeks of topical imiquimod application resulted in clinical resolution of the pinnal lesions. Although no post-treatment biopsies were performed, there was no relapse of the pinnal lesions in 5 months of clinical follow-up. Expected side effects were limited to erythema, crusting, alopecia, and mild discomfort at the sites of application during the first 3 weeks of application. These results suggest that topical imiquimod, although unproven, might be a therapeutic option or adjunct to therapy for cats with actinic keratoses and squamous cell carcinoma, especially those cats for whom surgery and radiation therapy are not an option.

Photodynamic therapy of superficial nasal planum squamous cell carcinomas in cats: 55 cases

BACKGROUND

Squamous cell carcinomas (SCCs) are common skin tumors in cats. We investigated photodynamic therapy (PDT) using the photosensitizing agent 5-aminolaevulinic acid (5-ALA) topically and a high-intensity red light source.

HYPOTHESIS

PDT is a safe and effective treatment for feline SCCs.

ANIMALS

Fifty-five client-owned cats with superficial nasal planum SCCs.

METHODS

Prospective, uncontrolled clinical trial. PDT was performed using topical 5-ALA and light of peak wavelength 635 nm. Adverse effects, response, and tumor control were evaluated.

RESULTS

53/55 (96%) cats responded to therapy, and there was a complete response in 47/55 (85%). Six cats (11%) had a partial response. Of the 47 cats with complete response to a single treatment, 24 recurred (51%), with a median time to recurrence of 157 days (95% confidence interval, 109-205 days). Repeat PDT was performed in 22 cats, and at a median follow-up of 1,146 days, 23 (45%) cats were alive and disease free, 17 (33%) had to be euthanized due to tumor recurrence, and 11 (22%) were euthanized for other reasons. Only transient mild local adverse effects were observed after treatment.

CONCLUSIONS AND CLINICAL IMPORTANCE

PDT using 5-ALA and a red light source was safe, well tolerated, and effective in the treatment of superficial nasal planum SCCs of cats and offers an alternative to conventional therapy. Although initial response rates were high, this treatment did not lead to a durable remission or cure in all cases.

Evaluation of strontium Sr 90 for the treatment of superficial squamous cell carcinoma of the nasal planum in cats: 49 cases (1990-2006)

OBJECTIVE

To determine progression-free and overall survival times of cats with squamous cell carcinoma (SCC) of the nasal planum following treatment with a single fraction of strontium Sr 90 ((90)Sr).

DESIGN

Retrospective case series.

ANIMALS

49 cats with SCC of the nasal planum.

PROCEDURES

Information including FIV infection status, diagnosis of SCC vs SCC in situ (ie, evidence that the tumor did or did not penetrate the epidermal basement membrane, respectively), (90)Sr dose and number of probe applications, treatment-related response and complications, and recurrence of SCC and new lesion development was obtained from medical records. The relationships of these variables with calculated progression-free and overall survival times were assessed.

RESULTS

Of 49 cats that underwent (90)Sr plesiotherapy (median dose, 128 Gy), 48 (98%) had a response to treatment and 43 (88%) had a complete response. Median progression-free and overall survival times were 1,710 and 3,076 days, respectively. Treatment complications were infrequent (4 [8%] cats) and mild. Following treatment, the SCC recurrence rate was 20% (10/49 cats); 16 (33%) cats developed new lesions in other locations. Overall survival time was significantly longer for cats with a complete response to treatment than for those with a partial response. None of the other variables evaluated had a significant effect on progression-free or overall survival time.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment of cats with SCC of the nasal planum with a single fraction of (90)Sr appeared to be effective and well tolerated. Initial response to treatment was predictive of overall survival time.

Squamous cell carcinoma of the nasal planum in cats and dogs

The purpose of this article is to review the therapeutic options available for the treatment of squamous cell carcinoma of the nasal planum in cats and dogs. The techniques of complete and partial nasal planum resection in the cat are described in detail. Surgical treatment offers the greatest chance of cure, although several options are available for early, less invasive lesions.

Metastatic squamous cell carcinoma in a cat

A 7-year-old, spayed female Persian cat was referred for evaluation of progressive paraplegia. The cat was thin, cachectic and paraplegic on presentation. The survey radiographs showed a left caudal pulmonary lesion and lytic skeletal lesions at the right iliac crest and left distal scapula. Due to a poor prognosis for complete recovery, the owner opted for euthanasia. Post-mortem examination revealed bilaterally small and irregular kidneys, lysis of the left iliac crest and left distal scapula and a dilated left ventricular lumen with a thin interventricular septum. Histologically, all the lesions were determined to be squamous cell carcinoma. It appears that the origin or the primary site of the malignancy in this case is pulmonary as cardiac and skeletal tissues are primarily mesenchymal in origin and are less likely to develop a primary epithelial malignancy. To the best of our knowledge, there is no description of cardiac or skeletal metastatic squamous cell carcinoma in a cat.

A retrospective study of (90)Strontium plesiotherapy for feline squamous cell carcinoma of the nasal planum

The responses of 15 cats with histologically (n=14) or cytologically (n=1) confirmed nasal squamous cell carcinoma treated with (90)Strontium plesiotherapy were reviewed retrospectively. Cats were treated such that a total dose of 50Gy was delivered at a depth of 2mm, administered in five fractions over a 10-day period. Of the cats, 11 were stage T(2), three were T(is) and one had only a cytological diagnosis precluding staging. Eleven of the cats achieved complete response (no visible lesion after 6-8 weeks) following the first cycle of therapy, and two cats with partial response achieved complete response with a second cycle of therapy. The remaining two cats achieved partial response following therapy, but further intervention was declined. Euthanasia was performed in these two cats because of progressive disease after 81 and 142 days. Of the 85% of cats that achieved a complete response, there was no recurrence of disease during a follow-up period of 134-2,043 days (median 652 days). In addition to prolonged disease-free survivals, (90)Strontium therapy produced excellent cosmetic results from the owners' perspective. These results demonstrate that superficial squamous cell carcinoma of the feline nasal planum responds excellently to (90)Strontium plesiotherapy, and this form of therapy may offer advantages over other alternatives currently available.

Surgery of the ear and pinna

There are several disease processes of the ear and pinna that warrant surgical intervention. This article reviews surgical anatomy and common surgical procedures of the ear and pinna, including aural hematomas, lateral wall resection, vertical ear canal resection, total ear canal ablation and lateral bulla osteotomy, partial pinna resection, and feline inflammatory polyps. The clinical signs, diagnosis, and surgical treatment along with potential complications for each disease process are discussed.

Inflammatory polyps and aural neoplasia

Although aural neoplasia is a relatively uncommon entity in companion animals, it remains a group of heterogeneous conditions that can have a significant negative impact on quality and duration of life of dogs and cats. Chronic ear disease that responds poorly or partially to empiric therapy should raise the suspicion that an underlying condition, such as neoplasia, may be the perpetrator of inflammation. Early diagnosis followed by appropriate therapy improves the likelihood of disease control and prolonged survival.

Diseases of the ear pinna

In conclusion, there are a wide variety of dermatologic diseases that can affect the ear pinnae. Most of these disorders are manifestations of a generalized dermatosis. Therefore, when pinnal lesions are present, a thorough diagnostic workup is indicated.

Proton irradiation of feline nasal planum squamous cell carcinomas using an accelerated protocol

Fifteen cats were treated for squamous cell carcinoma of the nasal planum using proton beam radiation. The protocol used was accelerated with eight equal fractions given on four consecutive days, with a minimum of six hours between fractions. Total dose of radiation delivered was escalated with nine cats receiving 40.4 CGE (60Co Gy equivalent), and three cats each receiving 42.4 and 44.8 CGE. Complete response to the protocol was 60% (9/15), partial response was 33% (5 of 15), and no response was seen in 6.6% (1 of 15). Tumor control rate at one year was 64% and no cat had tumor recurrence after one year. Median survival was 946 days (+/- 516 days). Side effects were minimal with no severe reactions noted in the early or late period. This protocol offers an effective treatment for squamous cell carcinoma of the feline nasal planum with minimal side effects and may be adaptable to conventional radiation sources particularly when the field size is very small.

Radioactive gold-198 seeds for the treatment of squamous cell carcinoma in the eyelid of a cat

A 19-year-old, speyed, domestic short-hair cat was presented with an eyelid tumour of 3 months duration. Ophthalmic examination revealed a large, raised, ulcerated and bleeding mass affecting the left lower eyelid. The mass was 12 mm x 10 mm in size, extended to the medial canthus and had eroded 10 mm of eyelid margin. Mandibular lymph nodes were not palpably enlarged. A diagnosis of squamous cell carcinoma was confirmed by histologic examination. Due to involvement of more than half the lower eyelid, it was decided that treatment with radioactive gold-198 seeds was appropriate. Nine radioactive gold-198 seeds were implanted, delivering a minimum tumour dose of 65 Gy. Three weeks postoperatively the mass had resolved, with only a small scab remaining. After a further 3 weeks, there was no evidence of the eyelid tumour. Although approximately 7 mm of eyelid margin was absent, this did not cause any clinical signs other than mild conjunctivitis. There was no evidence of the tumour 10 months postoperatively, when the cat was euthanased for unrelated disease.

Photodynamic therapy of feline superficial squamous cell carcinoma using topical 5-aminolaevulinic acid

A study was undertaken to investigate the treatment of superficial squamous cell carcinoma of the nasal planum, pinna and eyelid in cats by photodynamic therapy, using topical 5-aminolaevulinic acid cream, with subsequent exposure to red light of wavelength 635 nm, supplied by a light-emitting diode source. A total of 13 squamous cell carcinomas were treated, including 10 nasal planum lesions, two pinnal lesions and one eyelid lesion. After a single treatment, complete responses were seen in nine out of 10 nasal planum lesions, one out of two pinnal lesions and the eyelid lesion. The overall complete response rate for lesions managed with a single photodynamic therapy treatment was 85 per cent. Seven of the 11 lesions (63.6 per cent) showing a complete response subsequently recurred; the time to recurrence ranged from 19 to 56 weeks (median 21 weeks, mean 26.7 weeks).

Principles of adjunctive radiation therapy

Radiation therapy is becoming increasingly available to the practicing veterinarian. It is important that veterinarians be familiar with mechanisms and biologic effects of radiation used as a therapeutic modality in the treatment of cancer. It is also important that the veterinarian understand oncologic decision making and indications for various modalities including radiation therapy, surgery, and chemotherapy. Surgery and radiation therapy can be particularly complementary in combined therapy to achieve a functional and cosmetic result. This review introduces basic radiation therapy concepts, particularly regarding combination of radiation and surgery in the treatment of cancer in animals.