Can certain factors predict survival in colorectal cancer that has spread to the lungs?

The authors aimed to investigate factors associated with survival when undergoing surgery to remove colorectal cancer metastases in the lungs.

Metastatic colorectal cancer is cancer that has spread from the original site (in the colon or rectum) to distant organs. Chemotherapy can prolong average survival times and this may be further improved in some cases by removing colorectal cancer metastases to the lungs. Different factors associated with the patient and the disease are believed to play an important role in prognosis (disease outlook).

The authors aimed to evaluate factors that may influence the outlook of metastatic colorectal cancer to the lungs following surgery to remove the metastases.

The study evaluated 171 colorectal cancer patients with metastasis to the lungs. 61 patients had their original tumor in the middle/lower rectum, while 95 patients had their original tumor in the upper rectum/colon.  74% of patients had metastasis to one lung, while 26% had metastases to both lungs. After an average follow-up of 35.2 months, 61% of patients had died. Of these, 95% died of progressive colorectal cancer. The average survival after surgery to remove lung metastases was 35.2 months.

The average overall survival of patients who had their metastases completely removed was 39 months compared with 13.9 months where removal was incomplete. For patients with complete removal of lung metastases, the percentage of people who were alive was 88.8% at 1 year, 52.1% at 2 years and 32.9% at 3 years.

Spread of the cancer to the lymph nodes close to the lung occurred in 13.5% of those with cancer spread to one lung and 29.7% of those with cancer spread to both lungs. Compared to those without lymph node involvement  those with lymph node involvement had a shorter average survival. Visceral pleural infiltration (spread of the cancer to the thin membrane surrounding the lungs) was also associated with a shorter average survival.

The site of the original tumor was not found to influence the survival outcomes. However, for patients with cancer in the middle/lower rectum , favourable prognostic factors for survival included complete removal of metastases, no lung lymph node involvement, female gender and lower tumor stage. For patients with cancer in the upper rectum/colon, favourable prognostic factors included complete removal of the metastases and having less than two metastases.

Treatment of metastatic cancer with surgery was associated with significantly increased average survival time (44.5 months) compared to treatment with chemotherapy alone (21.8 months).

The authors concluded that distinct survival prognostic factors exist for patients with spread of colorectal cancer to the lungs from the lower rectum compared to the upper rectum or colon. 

Surgery to remove lung cancer metastases is a technically difficult procedure and complete removal is only possible when the number of metastases is small. This study also involved a small number of participants, larger trials are needed to confirm the surival benefits of surgery.