Predicting survival time in colorectal cancer patients treated for lung metastases: what can genes tell us?

This study examined whether genetic mutations (abnormal genes) were linked with shorter survival time in patients with colorectal cancer that has spread to the lungs (lung metastases).

Colorectal cancer is one of the most commonly diagnosed cancers worldwide. The cancer will spread to other organs in nearly 50% of patients with colorectal cancer. The lungs are one of the most common sites for the cancer to spread. Surgery can be used to remove the lung metastases, however, the operation can lead to complications and problems with breathing.

Genetic mutations can lead to the growth and spread of colorectal tumors. Two of the most common mutations are of the KRAS and BRAF genes. Patients with these mutations can have shorter survival time or may not respond to drug treatments. It is not known whether these mutations also lead to shorter survival in colorectal cancer patients treated for lung metastases. 

The authors analyzed medical records of 180 colorectal cancer patients with lung metastases. All patients underwent surgery and their tumor samples were removed and tested for BRAF or KRAS mutations. Survival time after treatment and rate of cancer relapse was also recorded.

Overall, 68 (37.8%) patients had no mutations, 93 (51.7%) had a KRAS mutation and 19 (10.6%) had a BRAF mutation. After 5 years 0% of patients with a BRAF mutation were still alive, while 44% of patients with a KRAS mutation and 100% of patients with no mutation were still alive. The average survival time was 15 months for patients with a BRAF mutation, 55 months for patients with a KRAS mutation and 98 months for patients with no mutations. 

By the end of the study 51.7% of patients had relapsed. The rate of relapse was higher for patients with a BRAF mutation (100%) than for patients with a KRAS mutation (46.2%) or no mutation (45.6%).

The authors concluded that KRAS and BRAF mutations seem to predict worse survival outcome in colorectal cancer patients with lung metastases.

This is a very early study, further studies are needed to ensure the results are widely generalizable.