Plain language summary
Interventions for squamous cell carcinoma of the conjunctiva in HIV-infected individuals
Conjunctival squamous cell carcinoma, a tumour of the thin membrane that covers the white of the eye, is becoming more common, more aggressive, and affecting more young people, especially women. This pattern is associated with the HIV/AIDS pandemic, exposure to solar radiation, and infection with human papilloma virus (HPV). Various treatment modalities exist, but the recurrence rate is high and the cosmetic outcome of late disease unsightly (Figure 1). Death may occur when the disease spreads to the surrounding structures and the brain. This review was conducted to evaluate the effects of the current interventions. No randomised controlled trials of any interventions for this cancer were found. Current clinical practice appears to be based on case series and case reports. These are weak sources of evidence for the effectiveness of a treatment. Randomised controlled clinical trials are needed.
Interventions utilisées pour un carcinome épidermoïde de la conjonctive chez les personnes infectées par le VIH
Le carcinome épidermoïde de la conjonctive, une tumeur de la fine membrane qui recouvre le blanc de l'œil, devient plus courant et plus agressif, touchant des personnes plus jeunes, en particulier des femmes. Cette affection est associée à la pandémie du VIH/SIDA, l'exposition aux radiations solaires et l'infection provoquée par le virus du papillome humain (VPH). Différentes modalités de traitement existent, mais le taux de récurrence est élevé et le résultat esthétique de la maladie en phase terminale est inesthétique (Figure 1). Le décès peut survenir lorsque la maladie se propage aux structures environnantes et au cerveau. Cette revue a été réalisée pour évaluer les effets des interventions actuelles. Aucun essai contrôlé randomisé des interventions pour ce type de cancer n'a été trouvé. La pratique clinique actuelle semble être basée sur des séries de cas et des rapports de cas. Ce sont des sources de preuves insuffisantes pour justifier de l'efficacité d'un traitement. Il est nécessaire de réaliser des essais cliniques contrôlés randomisés.
Notes de traduction
Traduit par: French Cochrane Centre 1st March, 2013
Traduction financée par: Pour la France : Ministère de la Santé. Pour le Canada : Instituts de recherche en santé du Canada, ministère de la Santé du Québec, Fonds de recherche de Québec-Santé et Institut national d'excellence en santé et en services sociaux.
Squamous cell carcinoma of the conjunctiva (SCC) is the end stage of a spectrum of conditions called ocular surface squamous neoplasia (OSSN). Histologically, OSSN varies from a benign form that includes papilloma, pseudoepitheliomatous hyperplasia and benign hereditary intraepithelial dyskeratosis, through a pre-invasive form called conjunctival intraepithelial neoplasia (CIN) graded as I,II or III depending on depth of involvement and finally the invasive form that includes squamous cell carcinoma and mucoepidermoid carcinoma (Basti 2003). When the dysplastic changes are confined to the basal one third of the epithelium, this is termed CIN I or mild dysplasia, when they extend into the middle third of the epithelium this is termed CIN II or moderated dysplasia and when they extend into the superficial third of the epithelium this is termed CIN III or severe dysplasia. Full thickness dysplasia is also referred to as carcinoma-in-situ (CIS). Invasive squamous cell carcinoma of the conjunctiva refers to the infiltration through the basement membrane to involve the underlying stroma (Basti 2003; Shields 2004). Clinically, these stages may be indistinguishable except by histology.
The tumour may be asymptomatic or present with redness, irritation, severe pain, and visual loss (Tunc 1999). It commonly affects the visible area between the upper and lower eyelids (interpalpebral conjunctiva), usually on the nasal side at the margin of the conjunctiva and the cornea (limbus). This slow-growing tumour can present as a solitary or diffuse growth. Solitary tumours can be nodular or gelatinous and may have a whitish plaque (leukoplakia). The lesion mimics benign conjunctival degenerations such as pterygium and pinguecula. Most cases are unilateral(Cervantes 2002; Chisi 2006).
The morbidity from squamous cell carcinoma of the conjunctiva relates to the effects of the disease and its treatment. It may extend into the eyeball, orbit, regional lymph nodes, surrounding paranasal sinuses and the brain. Death may result from regional or distant metastases, as well as intracranial spread.
The aetiology of SCC has been associated with HIV infection (Ateenyi-Agaba 1995;Waddell 1996), human papilloma virus (HPV) infection (Waddell 1996; Nakamura 1997; Newton 2002), immunosuppression in organ transplant recipients (Macarez 1999), and exposure to ultraviolet B rays of the sun (Ateenyi-Agaba 2004; Ng 2008; ). Chronic conjunctival diseases, such as allergic conjunctivitis and trachoma, have also been implicated (Poole 1999).
The majority of affected persons in Africa are HIV-positive; 71% in Uganda, 86% in Malawi (Waddell 1996) ,70.6% in South Africa (Mahomed 2002) and 75% in Nigeria (Osahon 2011). In a smaller study in Zimbabwe, 12 out of 13 persons with SCC or CIS (92.3%) were HIV-positive (Porges 2003). Many ophthalmologists in Africa now consider SCC in young adults to be a marker for HIV infection. The relationship between SCC and HPV is less clear. Some case-control studies have found an association (Moubayed 2004; de Koning 2008) while some have not (Sen 2007; Guthoff 2009). Among HIV-infected people with SCC, cutaneous types of HPV are detected more frequently than the mucosal types (de Koning 2008; Ateenyi-Agaba 2010). In another Ugandan study, HPV was detected more frequently in the low-grade conjunctival neoplasias than in more advanced disease (Tornesello 2006). Ultraviolet solar radiation causes tissue damange mediated through mutation of the tp53 tumour-suppressor gene and tissue matrix metalloproteinases (Ateenyi-Agaba 2004; Ng 2008).
It is plausible that the aetiology involves an interaction of these factors in a yet to be determined model.
The epidemiology of SCC has transformed in the last few decades. It used to be an uncommon slow-growing tumour found in elderly males (Lee 1997; McKelvie 2002), but in Africa it is becoming more common, more aggressive, and more likely to affect young persons, especially females (Ateenyi-Agaba 1995). This pattern is related to the co-existence of the HIV/AIDS pandemic, high HPV exposure, and solar radiation in the region. The HIV pandemic is mainly centered in Africa. In 2009 22.5 million of the 33.3 million infected people worldwide were living in Africa (UNAIDS 2010). Africa also has the highest prevalence of HPV infection in the world, with an age-adjusted prevalence of 25.6% in women of age 15 to 74 years, followed by South America (14.3%), Asia (8.7%) and Europe (5.2%). (Clifford 2005). The equator bissects the continent and over 75% of the continent is within the tropics with consequent high ambient solar exposure all year round.
The Kampala Cancer Registry in Uganda recorded a six-fold increase in the incidence of conjunctival squamous cell carcinoma, from an average of six per million per year between 1970 and 1988, to 35 per million per year in 1992 (Ateenyi-Agaba 1995).
A study in Australia found that 78.5% of affected persons were elderly males with a mean age of 60 years (Lee 1997). Similarly, in Britain, 77% were males and 69% of them were more than 60 years old (McKelvie 2002). In contrast, a study in Zimbabwe found that 70% of patients were young females with a median age of 35 years (Pola 2003), while in South Africa the mean age was 37 years (Mahomed 2002). In Tanzania the tumour has been observed to be more aggressive than it was previously. The mean length of history on presentation is three months (Poole 1999).
SCC is a common tumour of the ocular surface among adults in Africa. Pola 2003 In Tanzania 45.8% of 168 conjunctival biopsies seen between 1996 and 1997 were squamous cell carcinomas, while 35% were pingueculum or pterygium (Poole 1999).
The prevalence of SCC in a hospital-based HIV-positive population in Kenya was 7.8% (Chisi 2006).
Most cases are diagnosed on clinical impression after a person presents with a growth on the eyeball, which is then excised and sent for histology to get a definitive diagnosis (Shields 1997). Histopathology is the commonest mode of diagnosis in practice. Although regarded as the gold standard, histopathological diagnoses are subject to discordant interpretation (Margo 2002). Cytology has also been used, especially for the follow-up of people treated using chemotherapy or immune therapy to monitor recurrence, since malignant cells are poorly adherent to each other (McKelvie 2001).
Other methods include the use of DNA cytometry to identify tumour-cell regression (Nadjari 1999); immunostaining for certain molecular genetic markers, such as proliferating cells nuclear antigens (PCNA), Ki67 expression, tp53 gene mutations, and argyrophilic nucleolar organiser regions (AgNORs) (Aoki 1998); and toluidine blue staining to mark tumour margins for surgical excision (Kaji 2006).
The treatment of this condition since the pre-HIV era has been simple: surgical excision alone or with additional adjunctive therapy. The main objective of surgical excision is complete removal of the tumour to minimise recurrence (Shields 1997). The resulting surface defect may need reconstruction using amniotic membrane transplantation (Espana 2002; Gunduz 2005) or limbal autografts (Copeland 1990). Adjunctive therapies augment surgical excision. These include cryotherapy, chemotherapy, radiotherapy, immune therapy, and amniotic membrane transplants. They work by killing residual malignant cells at the excision margins or any that may be seeded during excision, although there are also reports of their use as primary therapy (Cerezo 1990; Karp 2001; Barbazetto 2004). Cidofovir, an antiviral active against human papilloma virus, has been described as a primary therapy, and was reported to cause tumour regression (Sherman 2002). It undergoes phosphorylation to active diphosphates independent of viral enzymes, which act as both inhibitors and alternative substrates of viral DNA polymerase, thus inhibiting DNA synthesis (Safrin 2004). A list of these interventions is shown in Table 1.
Table 1. 2 Interventions used in treatment of conjunctival squamous cell carcinoma
|Surgical excision||Alcohol epitheliectomy for the corneal component and partial lamellar scleroconjunctivectomy with 3 to 4mm margins for the conjunctival component. Frozen sections may be used to ensure tumour-free margins. Modified enucleation involves removing the affected conjunctiva with a 4mm margin together with the eyeball. Exenteration involves complete removal of orbital tissue including the periosteum of the bony walls. The eyelids may or may not be spared.||Shields 1997 Shields 2004|
|Cryotherapy||Freeze-thaw-freeze-thaw (double freeze-thaw) applying probe to the excised conjunctival margin.||Peksayar 1989|
- 5 Fluorouracil (5FU) 1% solution
- Mitomycin C 0.02% or 0.04%
|As topical solutions to soak operated site for 2-5 minutes, as subconjunctival injection intra- or post operatively or as eyedrops to be applied post-operatively as follows |
4 times daily for 1-2 weeks or as pulsed therapy giving 4 applications for 4 days repeated every month for 4-6 cycles
4 times daily for 2 weeks then repeat at 4-6 weeks intervals depending on response
|Yeatts 2000 |
|Radiotherapy||- beta irradiation |
- gamma irradiation
- photodynamic therapy
|Cerezo 1990 |
|Amniotic membrane transplants (AMT)||Excise tumour with a 3-4 mm tumour-free margin (so frozen sections needed), apply cryotherapy to the margin then to close the defect suture amniotic membrane with 8/0 vicryl sutures to adjacent conjunctiva and to adjacent cornea using 10/0 nylon sutures with epithelial side facing up.||Gunduz 2005|
|Interferon alpha 2b||Topical drops or intralesion injection||Karp 2001|
|Cidofovir eyedrops 2mg/ml||Applied every 2 hours for 2 weeks then 4 times daily for 2 weeks then 3 times daily for 2 weeks||Sherman 2002|
Cryotherapy kills malignant cells by repeated cycles of freezing and thawing (Peksayar 1989). Chemotherapy involves using a class of drugs called antimetabolites. They act by interfering with the enzymes involved in the intermediary metabolism of replicating cancer cells. An example is 5-Fluorouracil (5-FU) and mitomycin C. The former (5-FU), is a prodrug, which means it is converted to active molecules. One of them, 5- fluoro-2'- deoxyuridine-5'-monophosphate (FdUMP), binds to the enzyme thymidylate synthetase critical for the synthesis of thymidylate, which results in the inhibition of DNA synthesis. Another one, 5-fluorouridine-5'-triphosphate (FUTP) interferes with RNA synthesis (Chu 2004). It is cell-cycle specific and acts in the S phase of the cell cycle. In one study, 1% 5-FU eyedrops were used alone without concurrent surgery or radiotherapy to treat a recurrent tumour (Midena 2000). Mitomycin C is an antibiotic which acts by interfering with the DNA of tumour cells. It undergoes metabolic activation, which generates an alkylating agent that cross-links DNA, making the cell unable to replicate (Chu 2004). It is a cycle-non-specific agent that is most effective in the G1 and S phases. Radiotherapy destroys the DNA and RNA of dividing cells (Goldberg 1963). The source of beta radiation is strontium 90 (Cerezo 1990). Photodynamic therapy combines a drug (called a photosensitizer or photosensitizing agent) with light of a specific wavelength to produce activated oxygen species that promote tumour destruction (Castano 2005). Another treatment option is amniotic membrane transplantation. It is one of the layers of the placenta and is obtained after elective Caesarean section. It has anti-angiogenic, anti-scarring, and anti-inflammatory properties (Hao 2000). Immune therapy for this condition involves the use of interferon alpha. Interferon alpha is part of a group of proteins called cytokines. It has three-pronged action with antiviral and oncostatic effects and also activates natural killer cells, which are cells of the immune system that are able to recognise and destroy tumour cells (Lake 2004). The exact mechanism of action is not known. Cidofovir, an antiviral that is active against human papilloma virus, has been reported to cause regression of this tumour (Sherman 2002). It undergoes phosphorylation to active diphosphates independent of viral enzymes, which act as both inhibitors and alternative substrates of viral DNA polymerase, thus inhibiting DNA synthesis (Safrin 2004).
Advanced disease where the tumour has spread requires removal of the eyeball (modified enucleation) or the entire orbital contents (exenteration) in an attempt to save life (Shields 1991).
Despite therapy, up to 43% of treated patients experience recurrence at variable times (but usually within two years) (Peksayar 1989; Tabin 1997; Yeatts 2000). Simple excision has a higher rate of recurrence. A study in Australia reported 23% (Lee 1997). In the USA, it was 28.5%, but was 7.7% when combined with cryotherapy (Sudesh 2000). In one series of 17 cases treated with mitomycin C eye drops, 15 of them had undergone one to four surgical procedures before the mitomycin C treatment and six (35%) recurred within six months (Frucht-Pery 1997). The efficacies of treatment reported in the literature need to be interpreted cautiously, since some of the treated cases have recurrences from prior surgical excision (Frucht-Pery 1997; Midena 2000). The recurrence rate may be higher in Africa due to late presentation, exposure to solar radiation, and lack of many of the adjunctive therapies. Only cryotherapy and chemotherapy are likely to be found in advanced centres.
It is not clear whether the efficacy of these interventions is different in people with HIV infection. The effect, if any, of highly active antiretroviral therapy (HAART) on this condition is also not clearly known.
Clinical and public health importance of this review
Although the number of people living with HIV infection worldwide seems to have stabilized Africa remains the global epicentre of the AIDS pandemic (UNAIDS 2010). The region also has the highest prevalence of HPV in the world and high solar ultraviolet exposure year-round (Clifford 2005). If this triad of risk factors remains, the number of cases of conjunctival squamous cell carcinoma is expected to remain high. The effect of HPV vaccination in children on OSSN if any will take a long time to determine.
Recurrences still occur after surgical excision. Most of the current adjunctive therapies described are not readily available in low-income countries. They are expensive and inconvenient to use. Cryotherapy requires special probes and canisters of liquid nitrogen gas that need refilling. Amniotic membrane transplantation requires tissue banks to process and preserve the transplant material. Medications for chemotherapy are not widely available, but are probably the easiest to obtain and use in such settings, since they are packed in small vials and do not require stringent storage conditions.
The cosmetic outcome of advanced disease and its treatment is very poor and leaves patients with an empty socket (Figure 1). Patients who undergo orbital exenteration often experience social problems because of their facial disfigurement leading to limited social interaction (Bonanno 2010). Facilities for cosmetic surgery and orbital implants in low-income countries are often unavailable.
With antiretroviral therapy, HIV-infected people can now enjoy an improved physical appearance and quality of life, but unsightly lesions on the face such as those caused by conjunctival squamous cell carcinoma unmask what would otherwise be a 'hidden' HIV infection. This potentially exposes the affected persons to the stigma and discrimination associated with HIV infection.
Effective evidence-based interventions that allow early diagnosis and treatment are therefore needed.
Criteria for considering studies for this review
Types of studies
Randomised controlled trials (RCT).
Types of participants
HIV-positive people with ocular surface squamous neoplasia (OSSN), whose diagnosis of HIV infection is based on either antibody or antigen tests, and whose OSSN is determined by histology, conjunctival impression cytology, or immunostaining.
Types of interventions
Any intervention used for treating OSSN, including the following:
surgical excision, modified enucleation, and exenteration
adjunctive therapies such as cryotherapy, chemotherapy, radiotherapy, amniotic membrane transplants , and immune therapies, such as interferon therapy
different regimens of HAART
combinations of the above
We were interested in trials that compared any of the interventions with another intervention or a placebo, or trials comparing different dosages or regimens of the same intervention.
Types of outcome measures
local control, defined as a tumour-free period of two years
recurrence at six months, then at six-month intervals thereafter until two years after treatment, diagnosed by histopathology, conjunctival impression cytology, or immunostaining
time to recurrence
Search methods for identification of studies
The HIV/AIDS review group search methods were used. We searched electronic databases and abstracts of conference proceedings. There were no language restrictions. The key words used in the search included:
ocular surface squamous neoplasia, squamous cell carcinoma, conjunctiva, carcinoma in situ, conjunctival intraepithelial neoplasia, HIV, AIDS, excision, enucleation, exenteration, chemotherapy, cryotherapy, interferon, immunetherapy, radiotherapy,
A search had been conducted in December 2009 using search terms from the first edition of this review and found no trials. We conducted an updated search beginning January 2010.
The following electronic databases were searched.
1. PubMed - from January 2010 to 27th January 2012
2. EMBASE - from January 2010 to 10th February 2012
3. The Cochrane Library - from January 2010 to 3rd February 2012
We searched the WHO International Clinical Trials Registry Platform (ICTRP) on 10th February 2012 (WHO ICTRP 2012). We also searched the clinical trial register of the US National Institutes of Health (NIH) www.clinicaltrials.gov website (NIH 2012) on 12th February 2012. This database includes trials registered with the US National Eye Institute (NEI) and US National Cancer Institute (NCI).
We searched abstracts of the proceedings of the HIV/AIDS conferences covered in the AIDS Education Global Education System (AEGIS) database (http://www.aegis.com/search).
This search covered all the following conferences which also shows the latest conference abstracts available in the AEGIS database:
1. International AIDS conference by the the International AIDS Society (IAS) upto the conference held from 18th-23rd August 2010
2. International AIDS Society (IAS) HIV Pathogenesis and Treatment upto the 5th conference held from 19th-22nd July 2009
3. International Congress on Drug Therapy in HIV infection upto the 9th meeting on 9th-13th November 2008
4. International Workshops on Adverse Drug Reactions and Lipodystrophy in HIV upto the 11th workshop on 26th-28th October 2009
5. Conference on Retroviruses and Opportunistic Infections (CROI) upto the 15th conference on 3rd-6th February 2008
6. Centers for Disease Control and Prevention (CDC) National HIV Prevention conference upto the meeting on 12th-15th June 2005
7. The International Workshops on HIV Drug Resistance and Treatment Strategies upto the 5th workshop on 4th-8th June 2001
8. British HIV Association (BHIVA) upto the 17th conference held on 6th to 8th April 2011
9. European AIDS Clinical Society upto the 11th conference held on 24th-27th October 2007
10. National HIV/AIDS Update Conference upto the 17th conference on 10th-13th April 2005
We checked the reference lists of all studies identified by the above methods for additional relevant records.
Data collection and analysis
We independently screened the results of the search to select potentially relevant studies and to retrieve the full articles (Table 2). Where there was any uncertainty we obtained the full article. We independently applied the inclusion criteria using a specially designed eligibility form to the potentially relevant studies. No randomised controlled trials met the inclusion criteria.
Table 2. 1 Review methods
| || |
|Study selection||The titles and abstracts of search results are scanned and compared to predetermined selection criteria for studies. Articles written in foreign languages are translated to English. Two authors working independently select trials. The authors are blinded to the trial uthors and institutions by asking the trial search co-ordinator to block this out when sending abstracts. Where there is uncertainty about inclusion, the full text of the article is obtained and read. If additional information is needed about the trial in question, it is categorized as awaiting assessment until this is obtained. If differences arise regarding trial inclusion, they are discussed and if still unresolved, Dr Taryn Young at the South African Cochrane Centre is asked to take a decision.|
|Data extraction||Data are collected and recorded in similar data extraction forms. The following information is extracted; citation details, study eligibility, study quality and study characteristics. The study characteristics include methods, participants, interventions and outcomes.|
|Assessment of methodological quality of included studies||The methodological quality of the included studies is assessed to determine validity. Selection bias is checked by assessing whether the generation of a random allocation sequence and allocation concealment were performed. Randomization is considered adequate if the allocation sequence is generated from a table of random numbers or by computer. Allocation concealment is deemed adequate if undertaken by means of sequentially prenumbered sealed opaque envelopes, a centralised system or prenumbered coded identical containers. In addition, assessment of blinding, losses to follow-up and whether the analysis was by intention-to-treat (ITT) is undertaken. The definition of ITT is the requirement that participants be analyzed in the groups to which they were randomized, regardless of which intervention they actually received.|
|Data analysis||Measures of treatment effect:The effect measures of choice here are relative risk (RR) for dichotomous data and hazard ratio (HR) for time-to-event data with a 95% confidence interval.|
| ||Dichotomous data include: - number of people who experience local control in each comparison group |
- number of people who experience recurrence during the specified time periods in each comparison group
- number of deaths in each comparison group
- number of people who experience adverse events in each comparison group
- number of people who experience local control in each comparison group
- number of people who experience recurrence during the specified time periods in each comparison group
- number of deaths in each comparison group
- number of people who experience adverse events in each comparison group
| ||Time-to-event data include: - time to recurrence|
| ||Dealing with missing data: Participants lost to follow up are censored in the survival analysis.|
| ||Assessment of heterogeneity: To identify statistical heterogeneity we look at the forest plot for overlapping confidence intervals and test it using the Cochrane Q test with a p-value of 0.10. The impact of heterogeneity on the meta-analysis is measured using the I-squared test. If I-squared is greater than 70% we will investigate by checking the trials for data entry errors and looking for existence of subgroups. Subgroup analysis by age, sex, geographical location and diagnostic method will be done. These factors have been shown to influence the occurrence of OSSN and we anticipate that they may also influence treatment effects. If no explanation for heterogeneity is found or its correction is not possible, meta-analysis will not be done.|
| ||Meta-analysis: A fixed-effect model is used for meta-analysis but when there is heterogeneity that cannot be readily explained, a random-effects model is incorporated.|
| ||Sensitivity analysis: We examine how the magnitude of effect differs according to study quality or trial size and also the results of per-protocol analysis with those of intention-to-treat analysis.|
| ||Assessment of reporting bias: Publication bias is assessed by using a funnel plot to look for asymmetry.|
In this review no randomised controlled trials on the effectiveness of interventions against conjunctival squamous cell carcinoma in HIV-infected individuals were identified. No randomised controlled trials were found, even in the HIV-uninfected populations. Current practice is based on the results of interventional case series and case reports (Table 1). The quality of evidence from these study designs ranks low by various systems for grading evidence. It is graded level four by the Oxford Centre for Evidence-Based Medicine (OECBM) recommendations (Phillips 2001) and low-grade by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group (Atkins 2004). According to GRADE, low means that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. These studies are also mainly from western countries, where the participants are usually elderly males, who have a different disease profile from participants in developing countries. They have a less aggressive form of the disease and few are HIV-infected (Ateenyi-Agaba 1995; Waddell 1996; Lee 1997; Poole 1999; Mahomed 2002; McKelvie 2002). We could not explain why there are no trials, but postulate that perhaps it reflects differences in research priorities, since the prevalence of this tumour is low among HIV-infected individuals living in the western world.
There is a need to conduct randomised controlled trials to provide unbiased evidence for the effectiveness of currently used interventions for treating conjunctival squamous cell carcinoma. Ideally, the disease would be studied in its early stages, before it has spread, since in the later stages the treatment is more costly, can only be provided in tertiary care centres, and would tend to be individually tailored depending on the extent of spread. Studies are needed in the setting where the greatest burden of disease is found. The typical setting involves young HIV-infected individuals, mostly females with aggressive disease and HIV co-infections, in the context of high HIV prevalence, high solar exposure, and limited resources.
Investigating the effectiveness of simple surgical excision versus wide excision with or without adjunctive antimetabolite eye drops would be relevant as these are relatively simple interventions that can be easily translated in developing countries. The effect of new health technologies used in the developed world, such as cryotherapy, amniotic membrane transplants, and photodynamic therapy, should also be assessed in RCTs.
Preventive interventions directed against the mutagenic effects of solar ultraviolet B radiation and the oncogenic viruses associated with this disease also need to be identified.
There is also an important implication for diagnostic tests for early disease. Ethical issues that may arise include, for instance, whether participants should be subjected to the application of potentially dangerous cytotoxic antimetabolites as an adjunct to excision biopsy before there is histological confirmation of tumour. Treatment of conjunctival squamous cell carcinomas with topical mitomycin C and/or radiation has been associated with induction of atypical cell changes, such as conjunctival DNA-polyploidy afterward (Cartsburg 2001). More sensitive diagnostic tests, such as cytology or immunostaining, may thus need to be used pre-operatively.
Treatment of opportunistic tumours in HIV/AIDS, such as squamous cell carcinoma of the conjunctiva, is part and parcel of HIV care. Untreated squamous cell carcinoma of the conjunctiva threatens survival. Not paying attention to this disease may compromise the gains from other care availed to affected individuals.