Given the high incidence of melanoma in Australia alongside high mortality with later stage disease, we investigated the populations and locations most at risk, to optimise public health activities in areas where intervention is most needed. This study examines trends and identifies significant prognostic factors and potential disparities in incidence, mortality and survival between population groups in Victoria, Queensland and South Australia.
The analysis includes data from the population-based cancer registries of the three states over a twenty-year period (1997–2016). Age-standardized and age-specific incidence rates were calculated, and long-term trends analysed using Joinpoint Regression. Five-year relative survival estimates for the study population were calculated using the cohort method and multivariable flexible parametric survival models were applied for each jurisdiction to calculate adjusted excess mortality hazard ratios for the key characteristics.
There were more males with melanoma than females in all the three states. Over 60% of the cases occurred in the 40–74 years age group. Most melanomas had a Breslow thickness less than or equal to 1.0 mm. For males, Victoria and Queensland had a statistically significant increasing trend whereas in South Australia there was a decreasing trend. For females, the incidence rate trend was stable in Victoria but significantly decreasing in South Australia. In Queensland there was an increasing and statistically significant trend from 2006 to 2016. Across all three states there was a reducing incidence rate in the youngest cohort, stabilizing incidence in the 40–59-year-old age group, and increasing in the oldest cohorts. Five-year relative survival decreased with increasing age and with Breslow thickness across all three jurisdictions. Males had between 43%− 46% excess mortality compared to females in all the three states. There was higher risk with increasing age and Breslow thickness, with the largest risk among the 75 + age group and those with a Breslow thickness of > 4 mm.
It is the first time that data from these three registries has been analysed together in a uniform way, covering more than half of the Australian population. This study compares the epidemiology of melanoma across three states and provides a better understanding of trends and factors affecting outcome for Australians with melanoma. While there has been some improvement in aspects of incidence and mortality, this has not been evenly achieved across Australia.
- • Melanoma incidence in Australia and New Zealand remains one of the highest in the world in both males and females.
- • It is the first time that data from the three state cancer registries has been analysed together in a uniform way, covering more than half of the Australian population.
- • It contributes new information about descriptive patterns and trends of melanoma and survivorship in Australia.
- • This research is important for primary prevention initiatives and targeted melanoma awareness campaigns.
Melanoma accounts for approximately 1.6% of all diagnosed cancers globally and its incidence rate has been steadily increasing over the past 50 years , principally among fair-skinned populations. It is largely preventable with ultraviolet radiation exposure being the most common cause . As such, risk factors include sun exposure, lighter skin colour and geography .
Melanoma rates in Australia increased between 1982 and 2006 and have remained relatively steady since then, with a possible slight decline . Despite the relative stability in the recent past, incidence in Australia and New Zealand remains the highest in the world in both males and females . There are differences in rates among different populations and jurisdictions within Australia, with age standardized rates highest in Queensland (76.2 per 100,000) and lowest in South Australia (37.9 per 100,000) . In Australia, overexposure to ultraviolet radiation (UVR) is the cause of around 95 per cent of melanoma skin cancers . The most likely explanation for the higher incidence rate in Queensland is because it has a more sub-tropical climate than either Victoria or South Australia, with the average maximum UV level in the very high to extreme range throughout spring and summer . There are also differences in the burden of melanoma across the population. Melanoma carries the third highest cancer burden among adults aged 25–64, and males account for two thirds of the melanoma disability associated life-years (DALYs) . Prevention efforts in Australia have been most effective for younger age groups as they have been better able to reduce their exposure earlier in their life course .
The majority of people with melanoma are diagnosed with stage I disease and have 5-year survival rates above 99%. However survival decreases with increasing stage – 74% for stage II, 61% for stage III and 26% for stage IV . Relative survival also decreases with age and is lower among males .
Given the high melanoma incidence in Australia alongside high mortality with later stage disease, there is a need to investigate further the populations and locations most at risk, so as to optimise public health activities in areas where intervention is most needed and most likely to impact the health of individuals. In this paper, we present melanoma data trends from 1997 to 2016 from South Australia, Victoria, and Queensland, which together account for 53% of the Australian population. We present the trends over time, and relative survival rates accounting for demographic factors such as age, sex, area-based socio-economic status, and remoteness as well as Breslow thickness to investigate patient outcomes both within and between the three states.