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Melanoma Treatment
New Zealand's Advancements
In 2024, Our Health Journeys partnered with Saint Kentigern College in Auckland and challenged a number of students to conduct research into an aspect of the medical history of Aotearoa New Zealand. The students, ranging from Years 8-13, produced their research in written, oral, or video format and the top projects were chosen for publication to Our Health Journeys. A new project was published weekly following the completion of the project, until late October 2024.
New Zealand’s Advancements in Melanoma Treatment
Melanoma is a form of skin cancer that occurs when melanocytes, the cells responsible for skin colour, begin to grow uncontrollably. It is a subject of study within the field of pathology. There are four main types of melanomas, with this report focusing on cutaneous melanoma. According to JAMA Dermatology with a database covering 185 countries in 2020, New Zealand was observed to have the highest incidence and mortality rates of melanoma, with the latter being more than five times than in many African and Asian countries. A predominant cause is initially lower levels of ozone over New Zealand, combined with ongoing ozone depletion caused by the release of chlorofluorocarbons from applications such as refrigeration and air conditioning. These substances would otherwise absorb most of the ultraviolet radiation before it reaches the Earth’s surface. The rate of melanoma is further intensified by our high proportion of fair-skinned population and the nation’s love for outdoor sports activities.
Breslow Depth and excision margin
One critical measure in assessing melanoma is the Breslow Depth, which examines how deeply the melanoma has invaded the skin, from its surface to the tumour’s deepest point, providing crucial information for determining subsequent treatments because the severity of melanoma depends on its thickness. Lesions under 1 mm include melanoma in situ and thin invasive tumours (stage 0 and 1), which can be cured with over 95% success through excision — surgical removal of the melanoma cancer cells.
The excision margin, which typically ranging from 0.5 to 2 cm depending on the depth of the melanoma, ensures that surrounding normal tissue containing potentially cancerous cells is removed along with the tumour. Tumours between 1.01 and 4.0 mm are intermediate (stage 2 and 3), posing a risk of metastasis. Lesions over 4.0 mm are high-risk (stage 4), with a lower cure rate. In stage 3 or 4 melanoma, metastasis to the lymph nodes is common and Keytruda can help prevent further spread of melanoma in such cases.
New Zealand’s Health Journey
Dermatology involves the diagnosis, treatment, and prevention of skin diseases, including melanoma. In New Zealand, it was officially recognized as a specialty in 1948 under Dr. P. E. Alison, who later became President of the Dermatology Society. Since then, advancements in the field have continued, including the 1997 establishment of MoleMap, which specialises in digital dermoscopy and skin mapping for detecting skin cancers. Using dermatoscopes that combine magnification and light, MoleMap examines moles in detail, revealing structures beneath the skin's surface that are not visible to the naked eye. This enhances diagnostic accuracy, crucial for the early and effective treatment of melanoma.
Treatment methods — Surgery and Keytruda
In New Zealand, surgery remains the most widely used treatment method. However, the drug pembrolizumab (Keytruda) can enhance the effectiveness of surgery by shrinking tumours before excision, increasing the likelihood of successful surgical removal. Studies have also shown that Keytruda can reduce the recurrence rate of melanoma by 43 percent when observed a year after treatment. Most importantly, Keytruda increases the proportion of patients alive up to two years after treatment.
The ‘Keytruda debate’ was sparked in 2015 and 2016 due to the drug being unfunded by Pharmac NZ, despite this being seen as a breakthrough in cancer treatment and approved by the U.S. Food and Drug Administration. This debate highlighted Pharmac's practice of reallocating saved funds to cover underfunding in other areas of the health sector, instead of allocating them to purchase new drugs like Keytruda, as noted by Annette King, the Cabinet Minister at that time.
Health Minister Jonathan Coleman, however, believed that Pharmac should be the authority on deciding which medicines to fund, including Keytruda, rather than politicians intervening. Coleman remarked that the government made a mistake in 2008 by overriding Pharmac to fund the breast cancer drug Herceptin and this should not be repeated.
In 2019, Keytruda was approved in New Zealand for treating stage three melanoma. This approval can significantly benefit patients and reduce metastatic melanoma.
Preventions
While New Zealand should prioritise melanoma advocacy more broadly, public health initiatives like SunSmart, managed by the Cancer Society of New Zealand, focus on educating and advocating for sun protection strategies in communities. Epidemiological studies emphasise the significant role of ultraviolet B (UVB) radiation in melanoma development, therefore it is crucial to practice suitable protection to reduce the risk. Crucial melanoma preventions include covering skin, seeking shade, applying broad-spectrum sunscreen, and wearing wide-brimmed hats from September to April, especially in New Zealand.
