Efficacy of Different Treatment Modalities for Eye Cancer in Bovines

Neoplasms produce high economic losses by impairing the production, reproduction and working ability of the animals. The incidence is increasing at a rapid pace because of carcinogens, pigmentation, irradiation, hereditary factors, irrational use of pesticides and hormones (Bhume et al., 1992 and Otter et al., 1995). Neoplasms were common in aged animals but can occur at any age with significant morbidity and mortality in case of malignancy.
       
Ocular squamous cell carcinoma (or) cancer eye is considered the most common form of neoplasia affecting cattle and has significant economic importance. Keeping  in view the economic importance the present work was  undertaken to study the clinical, macroscopic, histo pathological and immunohistochemical findings of naturally occurring eye cancer in  cattle  and to compare the efficacy of different treatment methods and to monitor the effect of applied treatments.

The present study was carried out on the clinical cases presented at the college clinic, Veterinary Clinical Complex of Sri Venkateswara Veterinary University, Tirupati and also cases presented to the hospitals in and around Tirupati over a period of one year. The study was conducted on 24 animals with eye cancer and divided into four groups of six animals each. Traumatic, infectious, inflammatory ocular conditions were excluded from the study. Animals with small, localized eye tumors where vision is unaffected were included in group II. Animals with extensive eye tumors with presence or absence of vision were included in group I, III and IV.
       
In group I, surgical excision and enucleation/extirpation was performed as per the standard procedure to remove the squamous cell carcinoma with nerve blocks and sedatives.
       
In group II, animals were subjected to intralesional injection of BCG vaccine (Tubervac, Dheer Healthcare Private Limited, Mumbai) at 0, 14, 35 and 56 days interval. Depending on the size of the tumor 2-4 ml vaccine was injected (Rutten et al., 1991) to saturate the whole tumour.
       
In group III, animals were subjected to surgical excision and autogenous vaccine. Tumour mass was collected from the animal aseptically in PBS on ice until processing according to the method described by the Hunt (1984). The animals were administered with 10 ml of vaccine subcutaneously weekly once for 4 weeks and observed for recurrence if any.
       
In group IV, animals were subjected to surgical excision and mitomycin 0.04% was applied topically (Buss et al., 2010) on alternate weeks for two months as adjunctive therapy.
       
The efficacy of treatment was assessed based on clinical outcome, regression, recurrence of tumour and analyzed. Tissues were collected in 10% formal saline and processed for histopathological and immunohistochemical studies. Alterations in haematological parameters (haemoglobin and packed cell volume) and serum biochemical parameters (alanine amino transferase and aspartate amino transferase) were estimated before and at 15, 30 and 45 days following treatment in all the groups.

The incidence  of  eye  cancer  in  cattle  was  found to be  high in age group  of above 5 years followed by 2-5 years (Rutten et al., 1991). This could be due to the allowing of adult animals to outside leading to exposure to radiation.                              
 
The correlations in the breed wise incidence of eye  cancer in cattle revealed highest incidence of Holstein Friesian crossbred cows followed by Jersey crossbred cows and non-descript cows (Gharagozlou et al., 2007 and Fornazari et al., 2017). The availability of different breeds in a particular geographical location would predispose certain breeds to get affected. The incidence was higher in crossbred animals since crossbred population is high in this area. This shows higher susceptibility of crossbred cattle in comparison with indigenous cattle.
       
The incidence of bovine eye cancer was found to be  high in females (Gharagozlou et al., 2007 and Schulz and Anderson, 2010). The reason might be the female cattle usually under stress factors such as gestation, lactation and progression in age. 
       
In the present study, maximum  number of animals  were  having eye  cancer  on nictitating  membrane, followed  by  lower eyelid (Carvalho et al., 2005 and Kalirajan and  Senthilkumar 2016). However, eye cancer involving lower eyelid and nictitating membrane, eyeball, upper and lower eyelids and medial canthus of the eye were also recorded (Fig 1 and 2) in the present study as reported by Panchbhai et al., (1989) and King et al., (1991). In our study, most  of  the eye cancer in cattle was observed on right  eye followed by left eye (Fornazari et al., 2017).
 

 

       
Clinical symptoms like epiphora, mucopurulent discharges, bleeding from the affected eye and growths of different sizes protruding from the eye were observed in the present study (Gharagozlou et al., 2007, Kalirajan and Senthilkumar, 2016).
       
In our study surgical excision was the more appropriate solution with success rate of 83.33%. Surgical  excision  by exenteration/extirpation of eyeball along with muscles was  the best treatment for bovine ocular squamous cell  carcinoma (Islam et al., 2017).
       
In the present study, animals with small localized eye tumors where vision was not affected were treated with intralesional injection of BCG vaccine at 0, 14, 35, 56 days intervals (Rutten et al., 1991). A decrease in size, drying, shrinkage of eye tumors was observed in all the animals after 4^th injection. There was no recurrence after repeated treatments for a period of 6 months (Rutten et al., 1991 and Radhakrishnan et al., 1999). BCG is a potent stimulator of B and T cells especially the enrichment of natural killer cell activity. These natural killer cells are the major producers of interferons of other cytokines in response to various stimuli. The anti tumor activity of  interferon includes activation and increase in antitumor activity of macrophages,  induction  of increase in killer and natural killer activity and regulation  of expression of histocompatibility antigen in cells thus  increasing the immunity and thereby interrupting the  neoplastic  process  in  benign  precursor  lesion  of  bovine  ocular squamous cell carcinoma (Radhakrishnan et al., 1999).
       
Administration of autogenous vaccine in group III animals caused complete recovery with no recurrence for a period of 6 months, with a success rate of 100%. Panchbhai et al., (1989) and Bhume et al., (1992) observed complete  cure after surgical excision followed by autogenous vaccine  in ocular squamous cell carcinoma in cattle.
       
In our study, group IV animals were subjected to surgical excision and topical mitomycin was applied as adjunctive therapy. There was no recurrence for a period of 6 months with 100% success rate. Rayner and Van (2006) and Buss et al., (2010) treated equine squamous cell carcinoma with topical mitomycin as an adjunctive therapy.
       
In the present study, changes in haemoglobin, PCV, neutrophils, lymphocytes, monocyte values, AST and ALT  values  differ  significantly between  the  groups throughout  the  study (Table 1 and 2).
 

 

       
Confirmatory diagnosis of eye cancer was achieved by histopathological examination of the tumor mass. Histologically, all cases were diagnosed as squamous cell carcinoma (Fig 3) in our study (Azarabad et al., 2011 and Islam et al., 2017).
 

       
Immunohistochemical studies were carried out by using VEGF and EGFR stains.  Vascularendothelial growth factor (VEGF) showed mild immunopositive reaction and epidermal growth factor receptor (EGFR) revealed strong immunopositive reaction against EGFR. Based on the immunohistochemical studies it is evident that all eye cancers recorded were highly proliferative in nature.

On the basis of the observations, it was concluded that  surgical excision is best in animals with large, extensive  eye tumors with impaired vision. If facilities are available  for preparation of autogenous vaccine, surgical excision and autogenous vaccine is best treatment in cattle with eye cancer with or without  vision. For small, localized eye tumors where vision is unaffected, intralesional BCG  injection  can  be suggested. Primary surgical excision has been the mainstay of treatment for bovine ocular squamous cell carcinoma, as it is impossible to exclude invasive  disease on clinical grounds or with impression cytology. Hence, mitomycin, an alkylating agent as asignificant antitumor agent which acts by inhibiting DNA synthesis and produces cell death by apoptosis and necrosis can be used as an adjunctive therapy in treatment  of eye cancer in cattle.
               
The benefits of different treatment modalities depended on nature, type, location and extensiveness of tumor. Early detection and aggressive treatment were essential in the successful management of these tumors. A multimodal treatment approach was recommended with surgery, immunotherapy and chemotherapy in providing 100% disease free interval with increased life expectancy.