Each year around 14,000 Australians are diagnosed with melanoma. And approximately 10% of those are diagnosed with metastatic malignant melanoma – cancer that has spread beyond the skin. For decades the prognosis for these advanced cancers was poor, an average of just nine months.
But the last few years have seen dramatic improvements in the life expectancy of Australians diagnosed with metastatic melanoma, thanks to a surge of research and new therapies for the disease. Two areas of particular interest have been gene-targeted drugs and immunotherapy.
Approximately 40% of metastatic melanomas are found to have a relevant mutation in the BRAF gene. This mutation, found in other cancers too, promotes the growth and spread of the tumours.
As Dr Melody Caramins, a Sydney-based Genetic Pathologist, explained;
“We can test the tumour tissue for the BRAF mutation. If a relevant mutation is found then the patient may be eligible for certain drug therapies which inhibit the B-raf protein, therefore slowing or stopping the growth of the cancer.”
T-cells make up part of the immune system and may attack abnormal cells, but they have proteins on the surface called “checkpoints” which can stop the immune system from attacking cancer cells.
Certain types of immunotherapy use checkpoint inhibitors to block these proteins, therefore enabling the T-cells to recognise and destroy cancer cells.
These drugs are used in Australia to fight advanced melanoma and have led to significant improvements in prognosis. However, how effective a drug, or combination of drugs, will be for any one person is still hard to predict.
Ongoing research continues to bring new hope. The latest discovery identified 100 genes in melanoma cells that govern the cancer’s resistance to attacks from T-cells. Inactivating these 100 genes left resistant cancer cells vulnerable to being wiped out by T-cells. This could be a potentially important step in extending the benefit of immunotherapy to more patients.
The improvements in treatment have been huge but they don’t work for everyone. Sometimes doctors will have to try several different therapies to find one that does work, but pathology tests hold a lot of potential for improving this process.
Researchers at the University of Queensland are exploring the potential of tests that would give doctors real time evidence of the effectiveness of particular cancer drugs by detecting circulating cancer DNA in the blood. If effective in a clinical setting, these blood tests would be cheaper, and give doctors feedback sooner, than the current process of relying on scans.
These improvements to treatment and patient outcomes would not have been possible without pathology tests. And as research continues to open doors for even better treatments, pathology will continue to be essential for a long time to come.