Predicting disease aggression in small cell lung cancer

This study examined the association between microRNA levels and survival rates in small cell lung cancer.

Small-cell lung cancer accounts for 15-25% of lung cancer cases, and is associated with faster tumor growth and metastasis (spread of the cancer) compared to non small-cell lung cancer. While small-cell lung cancer responds to treatments such as chemotherapy and radiation, relapses are common, and the 5-year survival rate remains at 3%–8%. It is not clear why small-cell lung cancer is so aggressive, but a greater understanding could help to direct new treatments.

MicroRNA are gene expression regulators, meaning that they help define which cells and proteins are created by the body. Therefore microRNAs are involved in the creation of tumor cells and, in non small-cell lung cancer, are associated with tumor progression and patient survival.

The current study explored the role of increased microRNA expression in small-cell lung cancer. In this study, tumor specimens from 82 patients were examined, and levels of 924 different microRNAs were measured. All patients had undergone surgical removal of the tumor and chemotherapy. The average follow-up time was 57.2 months. In that time, 42 patients developed recurrent disease, at an average of 12.3 months after treatment.

Two microRNAs, miR-150 and miR-886-3p, were found at decreased levels in small-cell lung cancer cells compared to normal lung cells. Patients with lower levels of these two microRNAs had shorter average overall survival times (12.6 months) compared to those with higher levels of the microRNAs (overall survival times had not been reached at the end of the study for those patients). Low levels of the microRNAs were also associated with shorter progression-free survival (time before the disease progresses or recurs) and distant metastasis-free survival rates (survival without distant spread of the cancer).

This study concluded that levels of two microRNAs, miR-150 and miR-886-3p, were associated with survival rates in small-cell lung cancer. Patients with lower levels of these microRNAs had worse outcomes than those with higher levels.