Latitude and uveal melanoma

The prognostic implication of latitude in uveal melanoma: a nationwide observational cohort study of all patients born in Sweden between 1947 and 1989

BACKGROUND

The incidence of uveal melanoma increases with latitude. In this study, we examine the importance of latitude for uveal melanoma prognosis.

METHODS

All uveal melanoma patients born in Sweden between 1947 and 1990 were included (n = 745). The latitude of patients' birthplaces and home counties at the time of uveal melanoma diagnosis were collected. For all latitudes, data on sunlight and UV intensity parameters, temperature, daytime length variations, and socioeconomic factors were added. The prognostic implication of birthplace latitude and of moving > 1 degree of latitude was examined with multivariate Cox regressions and competing risk analyses.

FINDINGS

There were no significant differences in patient sex, age, tumor size, T-category, or BAP-1 immunoexpression between patients born in the south, central or northern regions of Sweden. Decreasing birthplace latitude was a predictor of uveal melanoma-related mortality in multivariate Cox regression. Patients that were born in southern regions or moved > 1 degree south between birth and diagnosis had higher incidence of uveal melanoma-related mortality in competing risk analysis. The sum of yearly sunshine hours, global sunlight radiation, average daily ultraviolet light intensity, average annual temperature, or net wealth were not predictors of uveal melanoma-related mortality.

INTERPRETATION

Latitude is a prognostic factor in uveal melanoma. This does not seem to be related to variations in patient or tumor characteristics at presentation, in management, in sunlight intensity, in ultraviolet light irradiance, in temperature, or in wealth. Future studies should examine if periodical changes in daylight hours or other factors could explain the prognostic implication.

The Impact of Ultraviolet Radiation on the Aetiology and Development of Uveal Melanoma

Uveal melanoma (UM) is currently classified by the World Health Organisation as a melanoma caused by risk factors other than cumulative solar damage. However, factors relating to ultraviolet radiation (UVR) susceptibility such as light-coloured skin and eyes, propensity to burn, and proximity to the equator, frequently correlate with higher risk of UM. These risk factors echo those of the far more common cutaneous melanoma (CM), which is widely accepted to be caused by excessive UVR exposure, suggesting a role of UVR in the development and progression of a proportion of UM. Indeed, this could mean that countries, such as Australia, with high UVR exposure and the highest incidences of CM would represent a similarly high incidence of UM if UVR exposure is truly involved. Most cases of UM lack the typical genetic mutations that are related to UVR damage, although recent evidence in a small minority of cases has shown otherwise. This review therefore reassesses statistical, environmental, anatomical, and physiological evidence for and against the role of UVR in the aetiology of UM.

Uveal Melanoma in Asians: A Review

Despite limited data, some differences in the clinical profile can be observed in Asian population when compared with presentation of uveal melanoma (UM) in white population. The incidence of UM is higher in Whites than in Asians. For the purpose of comparison with Asian population, data from North America, Europe, and Australia were considered as that of "white" population. The annual incidence of UM has been reported to be 5-6 cases/million in whites. The incidence in different parts of Asia is estimated at 0.2-0.6 per million. The age of presentation is around 40-55 years in Asians, which is younger when compared to that of whites (mean age of 58 years). At presentation, mean basal diameter of tumors in Asians is greater compared to whites but overall, medium-size tumors are most common. Clinical presentation is straightforward in majority of cases with retinal detachment, acute glaucoma, uveitis, cataract, or vitreous hemorrhage as common symptoms. Epithelioid cell-type variant carries the worst prognosis. Management options for choroidal melanoma include transpupillary thermotherapy, plaque radiotherapy, charged particle irradiation, local resection, enucleation, or orbital exenteration. Most commonly used modalities are enucleation and plaque radiotherapy.

Induction of hyperpigmentation and heat shock protein 70 response to the toxicity of methomyl insecticide during the organ development of the Arabian toad, Bufo arabicus (Heyden,1827)

Methomyl (MET) is a carbamate insecticide which is used as a substitute for organophosphorus compounds to protect crops against insects. The present study aims to evaluate the cytoprotection response of pigment cells and heat shock protein 70 (HSP70) after exposure to MET during the tadpole developmental stages of the Arabian toad, Bufo arabicus. Three developmental larval stages of the toad were selected and divided into two groups; Control and MET-exposed (MET-EX) tadpoles (10ppm). MET-EX tadpoles showed an increased number of pigment cells in the liver, kidney, anterior eye chamber, and skin tissues as compared to the control. The glycogen content in the developing liver and muscles (myotomes) of MET-EX tadpoles was decreased as compared to the control. In the MET-EX tadpoles, immunohistochemical staining showed an increase of HSP70 expression in the liver hepatocytes, the nucleated red blood cells (nRBC) in kidney glomeruli, the iridocorneal angle of anterior eye chamber, and the skin as compared to the control. The current study concluded that pigment cells and HSP70 represented a cytoprotecting response against MET insecticide during the organ development of B. arabicas tadpoles. Therefore, MET use should be regularly monitored in the environment to protect animals and human from exposure to this insecticide.

Choroidal melanoma: A short review with an Indian perspective

Choroidal melanoma (CM), the most common intraocular tumor in adults, is still a rarity in Asia. Having a high propensity for metastasis with a poor survival, recognizing it early is essential. Although it has typical clinical features, there are instances of simulating lesions. Fine-needle aspiration biopsy can be a valuable tool not only to confirm our clinical suspicion but also aid in prognosticating it. From days of histopathological prognostic markers, we are moving on to genetic markers which are reliably providing insights, helping us in providing a better care for our patients. Eye preservation has taken an all new important meaning in CM with many centers opting for different modalities of radiation. Herein, we try to provide a short synopsis of CM looking into its epidemiology, clinical features, diagnosis, and management. We also look briefly into the role of fine-needle biopsy in managing CM. Being a tertiary referral ocular center in India, we do come across CM; we have shared the preliminary reports of our analysis of managing CM over a 9-year period.

Descriptive epidemiology of malignant mucosal and uveal melanomas and adnexal skin carcinomas in Europe

This work provides descriptive epidemiological data of malignant mucosal and uveal melanomas and adnexal skin carcinomas in Europe as defined as in the RARECARE project. We analysed 8669 incident cases registered in the period 1995-2002 by 76 population-based cancer registries (CRs), and followed up for vital status to 31st December 2003. Age-standardised incidence to the European standard population was obtained restricting the analysis to 8416 cancer cases collected by 64 not specialised CRs or with information available only for some anatomical sites. Period survival rates at 2000-2002 were estimated on 45 CRs data. Twenty-two CRs which covered the period 1988-2002 were analysed to obtain the 15-year prevalence (1st January 2003 as reference date). Complete prevalence was calculated by using the completeness index method which estimates surviving cases diagnosed prior to 1988 ('unobserved' prevalence). The expected number of new cases per year and of prevalent cases in Europe was then obtained multiplying the crude incidence and complete prevalence rates to the European population at 2008. We estimated 5204 new cases per year (10.5 per million) to occur in Europe, of which 48.7% were melanomas of uvea, 24.8% melanomas of mucosa and 26.5% adnexal carcinomas of the skin. Five-year relative survival was 40.6% and 68.9% for mucosal and uveal melanomas, respectively. Adnexal skin carcinomas showed a good prognosis with a survival of 87.7% 5 years after diagnosis. Northern Europe, United Kingdom (UK) and Ireland showed the highest 5-year survival rate for uveal melanomas (72.6% and 73.4%), while Southern Europe showed the lowest rate (63.7%). More than 50,000 persons with a past diagnosis of one of these rare cancers were estimated to be alive at 2008 in Europe, most of them (58.8%, n=29,676) being patients with uveal melanoma. Due to the good prognosis and high incidence of uveal melanomas, these malignancies are highly represented among the long-term survivors of the studied rare cancer types. Therefore, maximising quality of life is particularly important in treatment of uveal melanoma. As regards mucosal melanomas, the centralisation of treatment to a select number of specialist centres as well as the establishment of expert pathology panels should be promoted. The geographical differences in incidence and survival should be further investigated analysing the centre of treatment, the stage at diagnosis and the treatment.

Ultraviolet-B phototoxicity and hypothetical photomelanomagenesis: intraocular and crystalline lens photoprotection

PURPOSE

Ultraviolet-B (UV-B) radiation can cause phototoxic macular injuries in young people who have been sunbathing but not sungazing and in welders. Welders have a reportedly increased risk of uveal melanoma. We analyze phakic and pseudophakic risks for solar and welding arc UV-B exposure.

DESIGN

Optical radiation measurement, analysis, and perspective.

METHODS

Spectral transmittances were measured for UV-transmitting, UV-blocking, and blue-blocking intraocular lenses (IOLs). The photoprotective performances of crystalline and intraocular lenses were analyzed using relevant epidemiologic and laboratory data and action spectra for acute retinal phototoxicity and melanoma photocarcinogenesis.

RESULTS

Crystalline lens UV-B retinal protection is deficient in children and young adults, increasing their potential susceptibility to acute retinal phototoxicity and hypothetical photomelanomagenesis. UV-B radiation has sufficient energy/photon to induce primary melanomagenic DNA lesions, unlike blue light or UV-A radiation. UV-blocking and blue-blocking IOLs have negligible UV-B transmittance. UV-transmitting IOL transmittance of UV-B radiation is equivalent to that of a 15-year-old crystalline lens.

CONCLUSIONS

If optical radiation exposure is responsible for welders' increased risk of uveal melanoma, then UV-B radiation is the most probable causative agent and spectacle wear is a potential confounding factor in epidemiologic studies of ocular melanoma. Welders under 30 years of age are at greater risk for welding maculopathy than older welders. Children, adults under 30 years of age, and pseudophakic individuals with UV-transmitting IOLs should wear sunglasses in bright environments because of the UV-B window in their crystalline lenses or IOLs.