Increase in the incidence rate of conjunctival melanoma in Australia

The study's authors searched the Australian Cancer Database during the time frame 1982–2014 to identify cases of ocular melanoma. Image credit: ©Who is Danny – stock.adobe.com

The rate of conjunctival melanoma increased in Australia during the period from 1982 to 2014¹; however, the mortality rate remained the same, Australian researchers reported. Aaron B. Beasley, MD, from the School of Medical and Health Sciences, Edith Cowan University, and the Centre for Precision Health, Edith Cowan University, both in Joondalup, Western Australia, Australia, was the first author of the study.

Conjunctival melanoma is a rare form of mucosal melanoma and makes up around 5% to 7% of all ocular melanomas,^2-4 the authors pointed out. However, considering that the incidence of ultraviolet-driven cutaneous melanoma increased over the past few decades,⁵ mostly as a result of improved recognition of in situ cases, the authors wanted to identify any changes in the incidence and mortality of conjunctival melanoma in Australia from 1982 to 2014.

The authors searched the Australian Cancer Database during the stated time frame to identify cases of ocular melanoma. The data from patients with conjunctival melanoma cases were extracted, and the incidence and mortality were analysed.

Dr Beasley and colleagues found that during the study period, 299 cases of conjunctival melanoma were identified. They reported that the age-standardised incidence rate was 0.48 (95% confidence interval [CI] = 0.41 to 0.54) per million per year. The incidence of conjunctival melanoma was higher in women than in men (0.52, 95% CI = 0.42 to 0.62 and 0.42, 95% CI = 0.33 to 0.51, respectively).

However, the incidence rates increased in both genders, ie, +1.46% in men and +1.41% in women (p = 0.023) during the study period.

The investigators reported the mean 5-, 10- and 15-year disease-specific survival rates were stable at 90%, 82%, and 80%, respectively, during the 33-year interval. Age, sex and state showed no significant differences.

Dr Beasley and colleagues concluded, “We found an increase in the rate of conjunctival melanoma diagnoses in Australia from 1982 to 2014. Over the same period, disease survival remained unchanged.”

References

1. Beasley AB, Preen DB, McLenachan S, et al. Incidence and mortality of conjunctival melanoma in Australia (1982 to 2014). Invest Ophthalmol Vis Sci. 2023;64:2. doi: https://doi.org/10.1167/iovs.64.14.2

2. Vajdic CM, Kricker A, Giblin M, et al. Incidence of ocular melanoma in Australia from 1990 to 1998. Int J Cancer. 2003;105:117–122.

3. Isager P, Engholm G, Overgaard J, Storm H. Uveal and conjunctival malignant melanoma in Denmark 1943-97: observed and relative survival of patients followed through 2002. Ophthalmic Epidemiol. 2006;13:85–96.

4. McLaughlin CC, Wu XC, Jemal A, et al. Incidence of noncutaneous melanomas in the U.S. Cancer. 2005;103:1000–1007.

5. Aitken JF, Youlden DR, Baade PD, et al. Generational shift in melanoma incidence and mortality in Queensland, Australia, 1995–2014. Int J Cancer. 2018;142:1528–1535.