19 February 2020
Mapping papillary thyroid cancer evolution for improved prognosis
Published online 25 October 2019
A genetic sequencing technique details papillary thyroid cancer evolution and may help individualise treatments.
Tracking the evolution of mutations in tumours can help scientists determine relapse chances and improve therapies. Papillary thyroid cancer (PTC) is often successfully treated, but it is unclear why 10-20% of patients suffer relapse.
Khawla Al-Kuraya at King Faisal Specialist Hospital and Research Center in Saudi Arabia and co-workers used genetic sequencing to explore the path of tumour evolution and mutations in tissue samples taken from 79 PTC patients at their hospital. Six patients were sampled twice: once for the primary tumour and again, following relapse, after surgery to remove the thyroid.
Tumours are naturally genetically diverse, and therefore evolve in different ways. This is the case not just between individuals with the same cancer, but also within tumour tissues in a single patient. Tumour cell evolution can be linear, with the successive growth of dominant clones, or branching, with clone subpopulations (or subclones) diverging from a single ancestor. The fittest, often treatment-resistant subclones are thought to assist relapse.
The researchers found that PTC evolution followed both linear and branching paths across the cohort, and that patients with high levels of subclonal mutations had a significant chance of relapsing.
The researchers say their findings have potential implications for individualising prognosis and highlight the importance of evolutionary development as the engine that drives cancer relapse.
Masoodi, T. et al. Evolution and impact of subclonal mutations in papillary thyroid cancer. Am. J. Hum. Genet. 105, 1–15 (2019).