the incidence of conjunctival malignancies is rare in india and accounts for less than 1% of all malignancies . the diagnosis of early cancers is a challenge as the symptoms are nonspecific and mimic benign conditions such as pingeucula , pterygium , etc . [ 1 , 2 ] . the most common site of occurrence is in the limbal region . squamous cell carcinomas ( scc ) are more common than basal cell carcinoma ( bcc ) . the main treatment modality for these cancers is excision with adequate margins of 3 - 4 mm . recurrences are high in the range of 33 - 56% in tumors with inadequate margin status and greater depth of invasion with intraocular extension [ 3 , 4 , 5 ] . radiotherapy plays an important role in preventing these local recurrences when used in the adjuvant setting appropriately [ 6 , 7 ] . there are very few studies reporting the outcomes of patients treated with brachytherapy . in this study , we report the local control rates , overall survival , and sequelae of patients treated with strontium-90 ( sr ) source applicator brachytherapy . thirteen patients diagnosed to have conjunctival tumors treated with sr brachytherapy were included in the study . all the patients underwent excision of the tumor prior to referral to our institute ( excisional biopsy in 12 eyes , excision with 1 mm margin clearance in 1 eye , 2 mm margin clearance in 1 eye , and 1 eye with wide excision , in which margin status not commented ) . histopathological review was obtained in all the cases before initiation of therapy . visual acuity and local status of the eye strontium-90 brachytherapy was delivered as an adjuvant following primary tumor excision or after excision of recurrent disease . the indications of radiotherapy were unknown , margin status , close margins of  2 mm , recurrent disease after re - excision , deep invasion , which was mainly stromal invasion , and residual carcinoma in situ . the target volume was determined by pre - excision clinical details , which included pictorial representation . a single field was applied in the area involved with the sr applicator of 12 mm active diameter . the eye gaze was fixed to the opposite side of the treatment area in order to completely visualize the target volume ( figure 1a ) . the hand held applicator was then placed over the target area by the radiation oncologist for the treatment duration , which was calculated based on the source activity and prescribed dose ( figure 1b ) . quality assurance was ensured at every step of the procedure , including strict documentation of individual patient treatment record . c ) kaplan meier curve depicting local control at 5 years strontium-90 , a  emitter with a half - life of 28.9 years was used . the decay process is mainly by yttrium-90 ( y ) emission with maximum  energy of 2.28 mev and average of 0.70 mev , which is useful for treatment . the applicator is concave in shape with a radius of curvature of 10 mm and an active diameter of 12 mm . it has a handle of 15 cm with a bend at 12 cm for better positioning . dose of 30 - 50 gy was delivered with a median of 44 gy in once daily fractionated regimen . dose per fraction of 0.25 - 4 gy was delivered with a median of 4 gy / fraction . acute reactions during and in the immediate postbrachytherapy period was evaluated and appropriate measures taken . patients were followed at 3 monthly intervals for 2 years , followed by 6 monthly intervals till 5 years and annually thereafter . clinical examination of the eye was performed at every follow up and checked for recurrence , conjunctivitis , scarring , and ophthalmological evaluation , which included visual acuity was done annually . when in suspicion for recurrence , the area was excised and histopathology report ( hpr ) reviewed . strontium-90 brachytherapy was delivered as an adjuvant following primary tumor excision or after excision of recurrent disease . the indications of radiotherapy were unknown , margin status , close margins of  2 mm , recurrent disease after re - excision , deep invasion , which was mainly stromal invasion , and residual carcinoma in situ . the target volume was determined by pre - excision clinical details , which included pictorial representation . a single field was applied in the area involved with the sr applicator of 12 mm active diameter . the eye gaze was fixed to the opposite side of the treatment area in order to completely visualize the target volume ( figure 1a ) . the hand held applicator was then placed over the target area by the radiation oncologist for the treatment duration , which was calculated based on the source activity and prescribed dose ( figure 1b ) . quality assurance was ensured at every step of the procedure , including strict documentation of individual patient treatment record . strontium-90 , a  emitter with a half - life of 28.9 years was used . the decay process is mainly by yttrium-90 ( y ) emission with maximum  energy of 2.28 mev and average of 0.70 mev , which is useful for treatment . the applicator is concave in shape with a radius of curvature of 10 mm and an active diameter of 12 mm . it has a handle of 15 cm with a bend at 12 cm for better positioning . dose of 30 - 50 gy was delivered with a median of 44 gy in once daily fractionated regimen . dose per fraction of 0.25 - 4 gy was delivered with a median of 4 gy / fraction . acute reactions during and in the immediate postbrachytherapy period was evaluated and appropriate measures taken . patients were followed at 3 monthly intervals for 2 years , followed by 6 monthly intervals till 5 years and annually thereafter . clinical examination of the eye was performed at every follow up and checked for recurrence , conjunctivitis , scarring , and ophthalmological evaluation , which included visual acuity was done annually . when in suspicion for recurrence , the area was excised and histopathology report ( hpr ) reviewed . the median age at the time of presentation was 47 years ( range : 11 - 71 years ) . one patient had meibomian gland carcinoma , 1 patient had bowenoid actinic keratosis , and 1 patient was diagnosed to have mucosa associated lymphoid tissue lymphoma ( malt lymphoma ) . all patients had undergone local excision prior to referral to our institute with a median time to presentation of 3 weeks after surgery . the most common site of presentation was the limbus ( 7 patients in medial limbal region and 4 in the lateral limbal region ) . three patients had tumor in the nasal conjunctiva and 2 in the temporal conjunctival region . doses were in the range of 30 - 50 gy with dose per fraction varying from 2.5 gy to 4 gy . visual acuity of one patient was 6/18 and 6/6 in 12 patients . fundal examination revealed posterior vitreous detachment in 1 patient with a known history of hypertension . the median time to adjuvant treatment from the date of surgery was 7 weeks ( range : 1 - 26 weeks ) . the total treatment duration ranged from 10 to 29 days with a median of 13 days . gray , scc  squamous cell carcinoma , nhl  non hodgkin 's lymphoma , med limb  medial limbus , lat limb xeroderma pigmentosum the median follow up of all the patients was 51 months ( range of 3 - 139 months ) . median follow up of patients with carcinoma was 64 months ( range of 3 - 139 months ) . one patient received re - irradiation with sr brachytherapy after excision and is locally controlled at last follow up . the local control rates of patients with carcinoma at 5 years was 90.9% ( 95% ci : 51 - 98 ) as shown in figure 1c . tolerance to treatment was good in all the patients , none of them developed  grade ii rtog acute reactions . no significant late sequelae such as cataract , limbal stem cell deficiency , or chronic eye pain were observed in our study . squamous cell carcinomas and lymphomas are the most common non - melanocytic malignant ocular surface tumors . the primary treatment of conjunctival carcinomas include surgical excision . however , the frequency of recurrences are as high as 30% in invasive tumors with negative surgical margins and 50% with positive margins [ 5 , 8 ] . adjuvant therapies like brachytherapy , topical chemotherapy with mitomycin - c or 5-fluorouracil , and immunotherapy have been applied with good local rates [ 9 , 10 , 11 ] . the benefit of one treatment over the other has not been proven , due to small number of patients in reported literature , and would be difficult to prove in view in the absence of prospective randomized studies . male gender has a higher predilection of developing these tumors , which is similar in our study . conjunctival malignancies in the past were seen more commonly in the sixth and seventh decade , however , with increase in hpv epidemic , the age at presentation has decreased [ 12 , 13 ] . in our study , we did not include the prevalence of hpv in these tumors . pathological t size , higher grade , and positive margins showed a significant association with recurrences , and the addition of adjuvant therapies reduced the rate of recurrences likewise in tumors with both positive and negative margins . similarly , in our study , the margin status had no association after the delivery of adjuvant sr brachytherapy . this may be because of the inconsistent association of grade amongst the studies [ 1 , 2 ] . have reported improved disease control in patients with positive margins , recurrent tumors , and localized corneo - scleral invasion with the addition of adjuvant brachytherapy [ 7 , 14 ] . the dose prescriptions have been varied amongst the various reports ranging from 15 gy to 80 gy with a mean of 50 - 56 gy . although there is no definite dose response relationship reported for optimal disease control , kearsley et al . have reported inferior local controls with doses less than 30 gy . we recommend a dose of 50 - 56 gy eqd2 ( / : 10 ) for efficient tumor control . local control rates of 90.9% at 5 years in our current series are similar to that reported in literature ( table 2 ) . lr  local recurrence , scc  squamous cell carcinoma , cis  carcinoma in situ , ep epidermalization , nr  not reported various isotopes such as i , ru , sr , and pd have been used over the years . the advantage of strontium is the high dose rate and reduced treatment times as compared to i and ru , and a long half - life of 28.8 years , thus obviating the need for repeated source replacements . also , the virtue of  emission reduces the chances of corneal ulceration , dry eye as compared to the gamma emitting property of 125i . the percentage depth dose ( pdd ) characteristics of sr sia-6 applicator is such that when normalized to 100% at 2 mm of water , the dose at 3 mm and 4 mm is 60.8% and 28.9% , respectively . for the treatment of surface malignancies , the dose is prescribed at the surface , which reduces the pdd further to 9% and 1% at 3 mm and 5 mm , respectively . electron beam therapy , which is most commonly used for superficial malignancies also are inferior when compared to brachytherapy . this is because even the lowest energy electrons used clinically ( 4 mev ) deposit approximately 50% dose at 1.7 cm , and the dosimetry of electrons in small field sizes is not accurate . the advantages of surface applicators are the fixed geometry and dosimetry in addition to the easy application under direct visual guidance of the radiation oncologist . the shape of the applicator gives gains of treating these conjunctival tumors with ease and comfort to the patient . the toxicity rates have been low in our study with 4 patients developing grade i conjunctival teleangectasie , 1 patient developed localized limbal opacification , and 1 patient had minimal scarring at first follow up , which regressed on subsequent follow ups and has conjunctival congestion only at last follow up . the toxicities are lower in our study as compared to other reported literature ( table 2 ) . the local recurrence rates of patients treated with adequate excision and cryotherapy is around 9% . kim et al . reported recurrence rates of 28% with the use of interferon 2b . the local rates with the use of chemotherapeutic agents such as mitomycin - c and 5-fluorouracil range from 70% to 100% depending on the invasive nature . the major limitation of chemotherapy is the development of limbal stem cell deficiency and hence not extensively used [ 20 , 21 ] . in comparison with other modalities such as chemotherapy and immunotherapy , strontium-90 brachytherapy can be effectively and safely used in invasive conjunctival malignancies as an adjunctive treatment both in primary and recurrent setting with good control rates . though there are emerging reports of proton beam therapy , sr has similar advantages in ocular surface malignancies due to the  emitting property and continues to be of value .
purposethe incidence of conjunctival malignancies is less than 1% . 
 though surgical excision remains the mainstay of treatment , the incidence of positive surgical margins and local recurrence rates are high , which is approximately up to 33% in negative margins and 56% in positive margins . 
 radiotherapy reduces the risk of recurrence in these cases . 
 brachytherapy using  emitters such as strontium-90 ( 90sr ) is an ideal treatment technique for these tumors with the advantage of treating only a few millimeters of tissue while sparing the underlying normal eye . 
 we report the long term outcomes in the form of local control and late sequelae of patients with conjunctival malignancies treated with 90sr applicator brachytherapy.material and methodsduring 1999 - 2013 , 13 patients with conjunctival tumors , treated using 90sr brachytherapy were analyzed . 
 brachytherapy was either in a post - operative adjuvant or in a recurrent setting . 
 local control ( lc ) , disease free survival ( dfs ) , overall survival ( os ) , and late sequelae were evaluated.resultsthe median age at presentation was 47 years ( range : 11 - 71 years ) . 
 thirteen patients with 15 tumors were treated . 
 the commonest histology was squamous cell carcinoma . 
 the median dose was 44 gy over 11 fractions . 
 the median follow up of all the patients was 51 months ( range : 3 - 139 months ) . 
 the median follow up of patients with carcinoma only was 64 months with a lc and dfs of 90.9% at 5 years . 
 none of the patients developed  grade ii radiation therapy oncology group ( rtog ) acute toxicities . 
 one patient developed a focal scar and another developed corneal opacification at the limbus . 
 vision was not impaired in any of the patients.conclusionsstrontium-90 brachytherapy used in early invasive conjunctival malignancies as an adjunct to surgery in primary and recurrent settings , results in optimal disease control and ocular functional outcomes .