Melanoma is the sixth most common leading cancer worldwide, and its incidence is continuously rising. In 2018, according to the American Cancer Society, it is estimated that about 91,270 people will be diagnosed with melanoma, and approximately 9,320 people are expected to die of melanoma.
Canine melanoma is a relatively common tumor in dogs. Although melanomas can arise in any dog, the prevalence of this disease is higher in Cocker Spaniel, Poodle, Pekinese, Gordon Setter, Chow Chow, Golden Retriever, mixed-breed dogs, and Dachshund compared to Boxers and German Shepherds where the melanoma frequency is lower.
In humans, melanomas are mostly found in the skin, but they could also occur in other parts of the body, such as in the eyes (ocular melanoma), and the intestines (rarely). Melanoma in dogs can affect different parts of the body such as lips, oral cavity, skin, toes and footpad, being oral melanoma the most aggressive type. In dogs, melanomas occur most often in the oral cavity and less frequently in the skin, eye, the foot pads and nail bed. Melanomas affecting the skin, generally have an overall favorable prognosis, in contrast to most oral and melanomas affecting the toes/nail bed.
While melanoma is highly curable if treated at early stages, the treatment of metastatic melanoma patients has been exceptionally challenging, with abysmal survival rate. Similarly to the poor prognosis of human malignant melanoma patients, the survival time of dogs affected by oral melanomas is short (~ 200 days after diagnosis). The high mortality rate is caused by recurrences (when cancer comes back after treatment), and metastasis (the spread of tumor cells to other parts of the body).
Standard therapies for dogs are the same as in human patients. They mostly consist of surgery, radiotherapy, and/or chemotherapy. For dogs, surgery and radiotherapy are the main treatment options to control the tumor locally. However, the 1-year survival is less than 30% due to metastasis development.
Thanks to the recent advances in research, melanomas are now classified at the molecular level. Accordingly, several specific treatments have been developed and exploited for human melanoma patients’ management. However, after an initial effective response to the treatment, often patients acquire resistance to these therapies and this remains a significant problem. Novel strategies are therefore urgently needed to overcome resistance to therapies.
In the last decades, there is an increasing awareness regarding the problem of cancer in dogs that is becoming a serious challenge as in humans. More and more owners are now demanding advanced care options for their affected dogs. These changes represent an opportunity for the development of innovative therapies that could benefit both canine patients and humans.
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