INCIDENCE OF CANCERS OF THE OCULAR SURFACE IN SOUTH CHINA: A POPULATION-BASED STUDY FROM 2005-2018
Published 2023 - 27th ESCRS Winter Meeting
Reference: O61 | Type: Free Paper Submission | DOI: 10.82333/1k2b-7v51
Authors: Tze Wah Dennis Law* 1 , Hok Shing Alex Kan 1 , Allie Lee 1
1Department of Ophthalmology,The University of Hong Kong,Hong Kong,Hong Kong
Purpose
Population-based data on the epidemiology of eye cancers, especially those of the ocular surface, is limited. We aim to fill this knowledge gap by describing the epidemiology of ocular surface cancers in Hong Kong.
Setting
Hong Kong has a population of 7.5 million, predominantly Han Chinese (92%). Data came from the Hong Kong Cancer Registry (HKCaR) which reports all cancer cases locally. It is a member of the International Association of Cancer Registries (IACR). Patient demographics, anatomical site, histology and stage are reported for each case. The 9th Revision of the International Classification of Diseases (ICD-9) was used in coding of the cases.
Methods
This is a retrospective population-based cancer registry data review. All eye cancers diagnosed between 1st January 2005 to 31st December 2018 were retrieved from HKCaR. The following data was obtained: age group (5-year interval), sex, year of diagnosis, primary site of cancer, histological subtype and basis of diagnosis (pathologically confirmed, clinical/radiologically diagnosed or death certificate only).
Eye cancers were identified by the ICD-9 codes from 190.0 to 190.9, which included the eyeball, orbit, lacrimal gland, conjunctiva, cornea, retina, choroid, lacrimal duct, other specified sites of eye and part unspecified. Lymphomas of the eye were searched using the codes 202.2 (nodular lymphoma) and 202.8 (other lymphomas). Additional tumour locations were identified by the following keywords: conjunctiva, cornea, iris, ciliary body, choroid, uvea, sclera, lacrimal and orbit. Eyelid cancers were excluded. Amongst them, cancers of the ocular surface (cornea and conjunctiva) were identified.
The crude incidence, age-specific incidence and age-standardized incidence were calculated. The trend in annual incidence was analyzed using percentage change and Joinpoint. Population data was obtained from the Hong Kong Census and Statistics Department. The WHO 2000 World Standard Population was used to calculate age-standardized incidence.
Results
442 eye cancers were identified over the study period and over 98% of cases were histologically verified. 80 cases (18%) were ocular surface cancers. The average crude incidence rate of cancers of the ocular surface was 0.8 case per million population per year which was rising.
The most common cancers of the ocular surface were lymphoma (77.5%), melanoma (12.5%) and squamous cell carcinoma (8.7%). Sex ratio was about 1:1. Those over 50 were more susceptible.
For eye cancers in general, the age-standardized rate was 4.04 cases per million standard population per year. The orbit and lacrimal systems were more susceptible. Lymphoma (58.4%) was the most common histologically, followed by melanoma (14.5%) and retinoblastoma (12.4%).
Conclusion
Compared to the western population, the most common histological type was lymphoma, while melanoma and ocular surface squamous neoplasia (OSSN) were rare. The findings could inform clinical decision making. Future study shall examine the reason for it.