Can miR-21 levels predict response to chemo after surgery?

The authors examined whether miR-21 levels are linked to patient survival rates. They also examined whether the levels of miR-21 could predict if patients will benefit from adjuvant therapy.

Colorectal cancer is one of the leading causes of cancer mortality (death from cancer). Adjuvant chemotherapy  (additional therapy that is given after primary treatment) after surgery improves the chance of survival in patients with stage III cancer. For patients with stage II cancer the benefit of adjuvant therapy is not as clear. Many stage II patients would benefit from adjuvant therapy. For others, if the surgery has completely removed the cancer, adjuvant therapy may be unnecessary and could affect patients’ quality of life.

Due to this fact, it would be good to find a biomarker (a measurable indicator of a biologic state or condition) that could predict if adjuvant therapy would be helpful. MiR-21 is an anti-apoptotic factor (it stops the process that normally allows cell to die) and is increased in a number of different cancers. This feature indicates that it may be a useful biomarker.

In this study the authors suggest that miR-21 levels in biopsies (tissue removed from a living body to discover the presence or extent of cancer) could be a useful biomarker for predicting patient outcomes.

Overall 301 patients with stage II or stage III colorectal cancer were included in the study. Biopsy samples were taken from the intestines of each patient to measure miR-21 levels.

The authors found that high levels of miR-21 in biopsies was linked to poor survival of patients with stage II cancer. In Japanese patients, this was also true for those with stage III cancer. There was an average of 3 times the mortality risk in the patients with high miR-21 and adjuvant therapy did not increase the survival rates. However, low miR-21 was associated with good response to adjuvant therapy and improved survival. The chance of survival increased by 62% in patients with low miR-21 who received adjuvant therapy compared to those who did not receive treatment.

The authors concluded that miR-21 is a promising biomarker to identify people with poor survival rates and that the levels of miR-21 may help identify patients who will respond well to adjuvant therapy.