Squamous Cell Carcinoma In Horse Research Articles

Intralesional interferon alpha-2b as a novel treatment for periocular squamous cell carcinoma in horses.

To determine the safety and efficacy of perilesional human recombinant interferon alpha-2b (IFNα2b) for treatment of periocular squamous cell carcinoma (PSCC) in horses. Eleven horses (12 eyes) with PSCC were enrolled in this prospective clinical study with owner consent. Systemically healthy horses were included in the study following confirmation of PSCC via biopsy. Every two weeks for a maximum of six treatments, horses were sedated and perilesional injection of IFNα2b (10 million IU) was performed. Tumors were measured prior to each injection and at one, three, and 12 months after treatment completion. A greater than 50% reduction in tumor size was considered positive response to treatment (i.e., partial or complete response). Development of anti-IFNα2b antibodies was assessed using serum samples obtained after treatment initiation and compared with treatment responses. Antibody concentrations were analyzed using a mixed model. Statistical significance was considered p < 0.05. Each horse received four to six perilesional injections of IFNα2b. Five of 12 eyes (4/11 horses) responded to treatment. Two of five eyes showed complete resolution of gross PSCC. No systemic adverse effects were seen. Local swelling occurred during treatment protocol in 6/11 horses but resolved without intervention. All horses developed serum anti-IFNα2b antibodies. There was no evidence of statistical difference in antibody concentration between responders and non-responders. Perilesional administration of IFNα2b was found to be well-tolerated in horses with PSCC, and induced tumor regression in 42% of treated eyes. Treatment failure appears unrelated to the development of IFNα2b antibodies.

A subset of equine oral squamous cell carcinomas is associated with Equus caballus papillomavirus 2 infection

The aetiology of oral squamous cell carcinoma (SCC) in horses is unknown, but papillomavirus infection as well as chronic periodontal disease are suspected to play a pathogenic role. In humans, some oropharyngeal cancers develop in association with human papillomaviruses. Equus caballus papillomavirus 2 (EcPV2) is suspected to play a causal role in the development of equine genital SCC. Given that association, we hypothesized that EcPV2 is associated with the development of oral SCC in horses. We performed standard polymerase chain reaction (PCR) and in-situ hybridization (ISH) for EcPV2 on 31 formalin-fixed paraffin-embedded equine oral SCCs (lingual, gingival, palate) and 10 equine non-SCC oral samples. PCR for EcPV2 was positive in 10/31 (32%) oral SCCs while all non-SCC oral samples were negative. Intense hybridization signals for EcPV2 nucleic acid were detected by ISH within neoplastic epithelial cells in 8/31 (26%) oral SCCs but not in the adjacent normal oral mucosa. No hybridization signals were detected within control samples. This study provides additional support for a pathogenic association of EcPV2 in oral SCC in horses.

A multimodal approach to management of ocular surface squamous cell carcinoma in horses

A multimodal approach to management of ocular surface squamous cell carcinoma in horses

Multimodal management of periorbital squamous cell carcinoma in horses with keratectomy, laser ablation and topical mitomycin C

Multimodal management of periorbital squamous cell carcinoma in horses with keratectomy, laser ablation and topical mitomycin C

Additional Evidence for DDB2 T338M as a Genetic Risk Factor for Ocular Squamous Cell Carcinoma in Horses.

Squamous cell carcinoma (SCC) is the most common periocular cancer in horses and the second most common tumor of the horse overall. A missense mutation in damage-specific DNA-binding protein 2 (DDB2, c.1012 C>T, p.Thr338Met) was previously found to be strongly associated with ocular SCC in Haflinger and Belgian horses, explaining 76% of cases across both breeds. To determine if this same variant in DDB2 contributes to risk for ocular SCC in the Arabian, Appaloosa, and Percheron breeds and to determine if the variant contributes to risk for oral or urogenital SCC, histologically confirmed SCC cases were genotyped for the DDB2 variant and associations were investigated. Horses with urogenital SCC that were heterozygous for the DDB2 risk allele were identified in the Appaloosa breed, but a significant association between the DDB2 variant and SCC occurring at any location in this breed was not detected. The risk allele was not identified in Arabians, and no Percherons were homozygous for the risk allele. High-throughput sequencing data from six Haflingers were analyzed to ascertain if any other variant from the previously associated 483 kb locus on ECA12 was more concordant with the SCC phenotype than the DDB2 variant. Sixty polymorphisms were prioritized for evaluation, and no other variant from this locus explained the genetic risk better than the DDB2 allele (P = 3.39 × 10−17, n = 118). These data provide further support of the DDB2 variant contributing to risk for ocular SCC, specifically in the Haflinger and Belgian breeds.

Squamous cell carcinoma on the eyelid of Nigerian albino horse

Squamous cell carcinoma is the most common neoplasia of the skin in horses. An adult albino stallion of Nigerian indigenous (Arewa) breed used for military ceremonial parade was presented with the chief complaints of growth on left side lower eyelid and unilateral epiphora. Tentatively diagnosis of eyelid squamous cell carcinoma was made and managed successfully. Restraint was achieved using chlorpromazine as tranquilizer and physical method with the animal on right lateral recumbency for the surgery. Lidocaine-adrenaline 2% was used for local anaesthesia. The growth was debulked only once and chemotherapeutically treated using vincristine 1 mg for local infiltration once and 2 mg intravenously twice at 3 weeks apart. Tissue sample was preserved in formaldehyde-10% and processed for histopathological examination. Haematological findings pre-treatment were neutropenia, 32% (52 to 70%) and hyperproteinemia, 10.2 g/d L (6.0 to 8.5g/dL) which became neutrophilic leucocytosis 16.1 x 109/L (5.6-12.1 x 109/L) post-treatment. Histopathological findings were focal areas of keratin pearls surrounded by a concentric aggregation of cornified squamous epithelial cells. Massive undifferentiated tumour cells and inflammatory cells at different stages of mitosis were also observed. It was concluded that surgical excision of lesion and vincristine therapy twice at 3 weeks apart only was effective to cure the eyelid squamous cell carcinoma in the horse. It was recommended that surgical excision of growths and vincristine therapy given by intravenous and local infiltration routes should be used in management of eyelid squamous cell carcinoma in albino horses.

A missense mutation in damage-specific DNA binding protein 2 is a genetic risk factor for limbal squamous cell carcinoma in horses.

Squamous cell carcinoma (SCC) is the most common cancer of the equine eye, frequently originating at the limbus, with the potential to invade the cornea, cause visual impairment, and result in loss of the eye. Several breeds of horses have a high occurrence of limbal SCC implicating a genetic basis for limbal SCC predisposition. Pedigree analysis in the Haflinger breed supports a simple recessive mode of inheritance and a genome-wide association study (N = 23) identified a 1.5 Mb locus on ECA12 significantly associated with limbal SCC (Pcorrected = 0.04). Sequencing the most physiologically relevant gene from this locus, damage specific DNA binding protein 2 (DDB2), identified a missense mutation (c.1013 C > T p.Thr338Met) that was strongly associated with limbal SCC (P = 3.41×10-10 ). Genotyping 42 polymorphisms narrowed the ECA12 candidate interval to 483 kb but did not identify another variant that was more strongly associated. DDB2 binds to ultraviolet light damaged DNA and recruits other proteins to perform global genome nucleotide excision repair. Computational modeling predicts this mutation to be deleterious by altering conformation of the β loop involved in photolesion recognition. This DDB2 variant was also detected in two other closely related breeds with reported cases of ocular SCC, the Belgian and the Percheron, suggesting it may also be a SCC risk factor in these breeds. Furthermore, in humans xeroderma pigmentosum complementation group E, a disease characterized by sun sensitivity and increased risk of cutaneous SCC and melanomas, is explained by mutations in DDB2. Cross-species comparison remains to be further evaluated.

Equine Genital Squamous Cell Carcinoma: In Situ Hybridization Identifies a Distinct Subset Containing Equus caballus Papillomavirus 2.

Equus caballus papillomavirus 2 (EcPV2) has been proposed as an etiologic agent for genital squamous cell carcinoma (SCC), the most common malignant tumor of the horse penis. EcPV2 is commonly detected by polymerase chain reaction (PCR) on normal horse genitalia; therefore, unraveling the virus' role in oncogenic transformation requires other methods of detection. In this study, a highly sensitive multiple-probe chromogenic in situ hybridization (ISH) technique was designed to recognize the E6/E7 oncogenes of EcPV2. ISH demonstrated abundant virus within 6 of 13 penile and preputial SCCs, whereas evidence of solar damage was found in 6 cases that were negative for EcPV2 by ISH. The ISH technique is valuable for studies of pathogenesis, since it demonstrates for the first time that the vast majority of neoplastic cells contain virus. Moreover, hybridization was present in all metastases examined, implying stability of E6/E7 expression in these clonal populations of neoplastic cells. This study contributes to the accumulating evidence for a causal role of EcPV2 in a subset of genital SCCs in horses.

Comparative Histopathological Diagnosis of Cutaneous Melanoma by H&amp;E, Special Staining and Immunohistochemical Methods against Cutaneous Squamous Cell Carcinoma in Horse and Bovine

Background: The aim of this study was to compare the role of special staining and to test melanoma associated antigens against paraffin embedded bovine and equine melanomas in order to assess their ability and utility as diagnostic tools for diagnosis and confirmation of the melanomas. Methods: From 1991-2012, 13 cases were reviewed histologically, and each case was found to contain a large focus of melanoma and squamous cell carcinoma (SCC) on the hematoxylin and eosin–stained tissue section. All cases had documented cutaneous melanoma and SCC. Serial 5 μm-thick sections were cut from routine formalinfixed paraffin blocks of 4 case cutaneous SCC (including 2 cases from horses and 2 cases from cattle) and 9 case cutaneous melanomas (including 6 horses cases and 3 cattle cases) from the files of the Department of Pathology have been diagnosed by H&E staining method. For diagnosis confirmation, Fontana-masson silver method, melanin bleaching method and immunohistochemical staining for S-100 protein and HMB45 antigen were applied. Majority of cases encompassed intradermal histologic pattern. Results: In 6 cases out of 9 tumors, both S-100 protein and HMB45 staining methods were positive, whereas there were suspicious results for 3 cases. In all cases, results of Fontana-masson silver and melanin bleaching methods were positive. In 4 cases of squamous cell carcinoma, results of 3 tests were negative. Diagnosis of suspicious melanoma tumor cases must be confirmed or reconfirmed by special staining methods and/or immunohistochemical method. Conclusions: The standard of practice in diagnosing melanoma is to use a panel of antibodies consisting primarily of S-100 protein and HMB-45. For spindle cell and desmoplastic melanomas, however, S-100 protein and HMB-45 should remain within antibody panel since S-100 protein is most sensitive marker for these entities and evidence is lacking that either Melan-A or Mitf are better markers than HMB-45 for recognizing spindle cell melanocytic lesions.

Expression of cyclo‐oxygenases‐1 and ‐2, and microsomal prostaglandin E synthase‐1 in penile and preputial papillomas and squamous cell carcinomas in the horse

Penile and preputial papilloma and squamous cell carcinoma (SCC) are commonly diagnosed in horses. Papillomas have the potential to progress to potentially lethal SCC. Knowledge of pathogenetic mechanisms may help in prevention and definition of treatment targets. Retrospective study using archived material. To determine the expression of cyclo-oxygenase 1 (COX-1), cyclo-oxygenase 2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) in penile and preputial normal tissue, papilloma and SCC in horses, and whether expression of these enzymes is influenced by degree of inflammation and differentiation grade. Tumour differentiation grade, degree of inflammation and COX-1, COX-2 and mPGES-1 expression in 75 formalin-fixed paraffin embedded samples of penile and preputial papilloma and SCC of 68 horses were investigated by histopathology and immunohistochemistry. Inflammation was more prominent in SCC compared with papilloma. No correlation between expression of COX-1 or COX-2 and inflammation was found. Expression of mPGES-1 was weakly correlated with inflammation. Expression of COX-1, COX-2 and mPGES-1 was found in 42.6%, 50.7% and 96.0% of lesions respectively, but less than 1% of cells were immunopositive for COX-1 and COX-2 in 59.4% and 84.2% of cases respectively. Expression of COX-1 was moderately negatively correlated with differentiation grade, COX-2 was not correlated and mPGES-1 was poorly negatively correlated. Expression of COX-1 and COX-2 in penile and preputial SCC in the horse is poor and COX inhibitors may thus be of little value for prevention or treatment. Microsomal PGES-1 is more prominently expressed in well-differentiated tissue compared with poorly differentiated tissue. Further research on the role of mPGES-1 in carcinogenesis is needed to assess its potential use as a treatment target. Knowledge of arachidonic pathway enzyme expression and their role in equine penile and preputial carcinogenesis may help in developing preventive and therapeutic strategies.

Carbon dioxide laser photoablation adjunctive therapy following superficial lamellar keratectomy and bulbar conjunctivectomy for the treatment of corneolimbal squamous cell carcinoma in horses: a review of 24 cases

To determine the complications and nonrecurrence rates following superficial lamellar keratectomy, bulbar conjunctivectomy, and adjunctive carbon dioxide (CO(2)) photoablation for corneolimbal squamous cell carcinoma (SCC) in the horse. Retrospective study. Sample population Twenty-four horses with corneolimbal SCC. Medical records of horses diagnosed with corneolimbal SCC that was surgically excised and where CO(2) photoablation was used as an adjunctive therapy from 2000 to 2007 were reviewed. Signalment, prior therapy, tumor location and size, complications, and recurrence of SCC were recorded. The Thoroughbred was the most commonly (25%) represented breed. Lesions were >10 mm in diameter in 70.8% of cases. Eight horses (33.3%) had neoplastic cells extending to the deep margin of the keratectomy. All horses were available for follow-up for an average ± standard deviation of 40.7 ± 25 months. Four horses (16.7%) developed a recurrence of SCC. Three of these four horses underwent repeat keratectomy and CO(2) photoablation, one each, at 4 months, 1, and 2 years following the initial procedure. One horse underwent enucleation 8 months following the initial procedure. As an adjunctive therapy, CO(2) photoablation was successful in 87.5% of the horses following a single procedure and in a total of 91.7% following a second therapeutic application. CO(2) photoablation appears to be effective as an adjunctive therapy following removal of large corneolimbal SCC in the horse and in cases in which all tumor cells were not excised.

Mitomycin C, with or without surgery, for the treatment of ocular squamous cell carcinoma in horses

Ocular lesions in horses, confirmed as squamous cell carcinoma, were treated topically with mitomycin C. Fourteen horses with confirmed ocular squamous cell carcinoma, three of which were affected bilaterally, were...

Photodynamic therapy for the treatment of periocular squamous cell carcinoma in horses: a pilot study

Local photodynamic therapy (PDT) is a novel cancer therapy in veterinary ophthalmology. A prospective pilot study seeking to demonstrate proof of principle and safety for the treatment of equine periocular squamous cell carcinoma (PSCC) was therefore conducted. We hypothesized that surgical excision with adjunctive local PDT is an effective and safe treatment for equine PSCC. Nine horses (10 eyes) with PSCC were treated with surgical resection, local infiltration of resulting wound beds with 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) and irradiation with 665-nm wavelength diode laser. Regular follow-up ophthalmic examinations were performed. Surgical resection and PDT yielded disease-free intervals of 25-68 months in our study horses as of January, 2008. These results were obtained following a single treatment in seven horses and two treatments in one horse. In one horse, carcinoma in situ developed 2.5 months after partial surgical excision and PDT, requiring local excision under standing sedation. Preliminary results suggest that surgical resection and adjunctive local PDT is a safe and effective novel treatment for PSCC in horses. More research is needed before PDT for the treatment of equine PSCC can be adequately compared with other current modalities. Important to future investigations regarding PDT, tumor recurrence rate, length of hospitalization, number of treatment episodes required to effect tumor remission, and total treatment costs should be examined in a controlled manner. Our present results and experiences suggest that this treatment may be useful in the treatment of equine PSCC.

Cyclooxygenase-2 Immunoreactivity in Equine Ocular Squamous-Cell Carcinoma

Squamous-cell carcinoma (SCC) is the second most common tumor in horses, and 40%-50% may occur in ocular and adnexal structures. Cyclooxygenase (COX)-2 is an inducible enzyme responsible for the production of prostaglandins that control cell growth and the development and progression of cancer. Mechanisms responsible for the initial upregulation of COX-2 in neoplasia are unclear; prolonged sunlight exposure and mutations in the p53 gene may be possibilities. Because the etiopathogenesis of ocular SCC in horses may involve ultraviolet sunlight and p53 mutations, the purpose of this study was to characterize the immunoreactivity of COX-2 in these tumors. Cyclooxygenase-2 expression was found in 6 of 22 (27%) paraffin-embedded equine SCCs. Cyclooxygenase-2 immunoreactivity was associated with the mitotic index (P < 0.001). Strategies to inhibit COX-2 by the use of topical or systemic COX-2 inhibitors might prove to be a safe and economical treatment in some horses with SCC.

Immunohistochemical evaluation of cyclooxygenase expression in corneal squamous cell carcinoma in horses

To evaluate expression of cyclooxygenase (COX)-1 and COX-2 in the cornea, eyelid, and third eyelid of healthy horses and those affected with squamous cell carcinoma (SCC) by use of immunohistochemical techniques. 15 horses with SCC involving ocular tissues and 5 unaffected control horses. SCC-affected tissues were obtained from the cornea (n = 5 horses), eyelid (5), and third eyelid (5). Site-matched control tissues were obtained from 5 horses unaffected with SCC. Tissue sections of affected and control cornea, eyelid, and third eyelid were stained immunohistochemically for COX-1 and COX-2 via standard techniques. Stain uptake was quantified by use of computer-assisted image analysis of digital photomicrographs. Immunoreactivity for both COX-1 and COX-2 was significantly greater in equine corneas with SCC than in control corneas. No significant differences in COX-1 or COX-2 immunoreactivity were detected in eyelid and third-eyelid SCC, compared with site-matched control tissues. Immunoreactivity for COX-1 and COX-2 is high in equine corneal SCC, possibly indicating that COX plays a role in oncogenesis or progression of this tumor type at this site. Pharmacologic inhibition of COX may represent a useful adjunctive treatment for corneal SCC in horses.

Combined keratectomy, strontium‐90 irradiation and permanent bulbar conjunctival grafts for corneolimbal squamous cell carcinomas in horses (1990–2002): 38 horses

The purpose of this study was to evaluate the effectiveness of postoperative beta-irradiation with strontium-90 as an adjunctive treatment to superficial keratectomy and permanent bulbar conjunctival graft for removal of equine corneolimbal squamous cell carcinoma (SCC), in decreasing recurrence rate. The retrospective case study included 38 horses diagnosed and treated for SCC of the eye that involved the limbus and/or cornea. The patients were treated between 1990 and 2002, with strontium-90 irradiation immediately after corneal and conjunctival graft surgery. Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe that was previously treated. The Appaloosa was the most commonly represented breed and horses that had more than one base coat color represented the majority of the cases (53%). The coat colors of white, chestnut/sorrel and gray were the most commonly represented colors of the horses treated. Eight horses (21%) could not be assessed for tumor recurrence due to lack of two or more post-treatment examinations, and another horse was enucleated 6 days postoperatively due to progressive corneal ulceration. Twenty-four horses (63% of the entire study population; 83% of the followed cases) had a mean +/- SD of 1754 +/- 1319 days without tumor recurrence, ranging from 14 days to 5110 days. Five horses (13% of the entire study population; 17% of the assessed horses) had tumor recurrence at a mean +/- SD of 449 +/- 339 days with a range of 29 days to 900 days. For the five recurrences, treatment included local excision (n = 1), enucleation (n = 2), and additional strontium-90 therapy (n = 3). The combination of superficial keratectomy, beta-irradiation and permanent bulbar conjunctival grafts for limbal, corneal or corneolimbal SCC in horses is effective in at least 83% of the horses. Recurrence occurred in about 17% of the horses. Multiple biannual re-examinations are recommended to observe for tumor recurrence.

Amniotic membrane transplantation for corneal surface reconstruction after excision of corneolimbal squamous cell carcinomas in nine horses

The purpose of this study was to evaluate the usefulness and effectiveness of permanent amniotic membrane transplantation as an adjunctive treatment to superficial keratectomy alone or combined with strontium-90 irradiation for treatment of equine corneolimbal squamous cell carcinoma (SCC) to decrease corneal scarring and recurrence rate. The retrospective case study included 11 horses (n = 12 eyes) diagnosed and treated for ocular SCC that involved the limbus and cornea. Nine of those horses (n = 9 eyes) were treated between 2002 and 2006, with superficial lamellar keratectomy alone or combined with strontium-90 irradiation and followed by placement of a permanent amniotic membrane graft in the surgical defect. The level of scarring (i.e. the clarity of the cornea) resulting with the use of amniotic membrane was subjectively compared to cases where a permanent bulbar conjunctival graft was performed following keratectomy combined with strontium-90 irradiation or cryotherapy (n = 3 eyes). Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe. The nine horses that received an amniotic membrane graft after keratectomy alone or combined with irradiation showed a minimal level of scarring in a cornea that regained a greater transparency in comparison to the horses that were treated with a bulbar conjunctival graft. All of the horses that received an amniotic membrane graft had 226 +/- 218 days of follow-up without tumor recurrence (mean +/- SD), ranging from 21 days to 778 days. The combination of superficial keratectomy alone or associated with beta-irradiation and permanent amniotic membrane transplantation is an effective treatment of corneal or corneolimbal SCC in horses. The placement of an amniotic membrane material represents an alternative surgical procedure to bulbar conjunctival grafts, especially if there is a lack of bulbar conjunctiva tissue available after tumor resection or if a particularly large corneal resection is necessary. The amniotic membrane is incorporated into the corneal defect and seems to create noticeably much less scarring than a corneal defect covered by bulbar conjunctiva.

Effects of treatment with and without adjuvant radiation therapy on recurrence of ocular and adnexal squamous cell carcinoma in horses: 157 cases (1985–2002)

To determine the effects of treatment with and without adjuvant radiation therapy on recurrence of ocular and adnexal squamous cell carcinoma (SCC) at specific anatomic locations in horses. Retrospective study. 91 horses. Medical records of horses with histologically confirmed ocular and adnexal SCC evaluated from 1985 to 2002 were reviewed. Sex, breed, age, type of treatment, location, and recurrence of SCC were recorded. Two treatment groups determined by recurrence of SCCs treated with and without adjuvant radiation therapy were established. The anatomic site with the highest recurrence rate was the limbus (junction of the cornea and sclera) or bulbar conjunctiva (477%), independent of treatment group. There was a significant difference in recurrence rates of ocular and adnexal SCCs between the 2 treatment groups, independent of anatomic location. Recurrence rates of SCCs treated with and without adjuvant radiation therapy were 11.9% and 44.1%, respectively. Recurrence rates for SCCs of the eyelid, limbus or bulbar conjunctiva, and cornea treated with adjuvant radiation therapy were significantly different from those for SCCs treated without adjuvant radiation therapy. The most frequently represented anatomic site for ocular and adnexal SCCs was the eyelid (28.7%). Coat color, breed, and the interaction of age and breed had a significant effect on tumor recurrence regardless of treatment type and anatomic location. Results indicated that ocular and adnexal SCCs treated with adjuvant radiation therapy had a significantly lower recurrence rate, compared with SCCs treated without adjuvant radiation therapy, independent of anatomic location.