Personalised cancer medicine: new genetic tests to aid care
Sources: BBC (melanoma), BBC (prostate cancer), BBC (lung cancer)
News of preliminary research with promise to deliver improved care for lung, skin and prostate cancers has emerged in the last week.
Surgical removal of the prostate gland is used for the more aggressive (metastatic) forms of prostate cancer, but not for the less serious ones as it has significant undesirable side effects, including infertility and dysfunctional erection and urination. However, identifying the most aggressive tumours by current methods (microscopic examination of tissue samples) is not highly accurate, and it is thought that many men who receive surgery will not in fact have needed it. A new test that examines the tumour expression profile of a set of genes may be able to predict more precisely which tumours really are aggressive; whilst the test needs further validation, experts have said it is a potential ‘game-changer’.
A similar genetic profiling approach has recently been trialled for lung cancers and found to aid personalisation of treatment and boost survival rates. German researchers tested lung tumour samples from around 5,000 patients and found that some of those that appeared very similar on microscopic examination actually had quite distinct genetic profiles; when treatment was based on these profiles, prognosis was better than for treatment based on traditional analysis.
Another typically aggressive cancer is melanoma, a form of skin cancer. It is not easy to detect when a melanoma begins to spread to other sites in the body, but rapid treatment is vital to give patients the longest survival times possible. A new blood test for a genetic biomarker (the TFP12 gene product) could identify the presence of metastatic melanoma. This would allow rapid intervention at an early stage, when treatments have the best chance of success. A test incorporating a panel of similar biomarkers associated with malignant melanoma might improve performance, as well as being of potential value in the search for new treatments.
Comment: These three examples show how research is driving moves to more personalised and effective cancer medicine. Because cancer is effectively a genetically-driven disease, arising from the accumulation of mutations that prevent normal controls on cell growth and spread, it is particularly well suited to genomic medicine. However, despite great progress, the field remains in its infancy; as well as developing effective tests to identify tumours as belonging to specific genetically determined sub-types, and developing novel treatments directed at important (driver) mutations in cancer cells, oncologists ideally also need non-invasive methods of monitoring cancers, to detect the emergence of new genetic sub-types of tumour cell that would need new treatments to avoid recurrence.