Certain Colorectal Cancer Survivors Should Be Closely Monitored for Lung Metastases

Colorectal cancer commonly spreads to lungs, but no evidence-based standard exists for post-treatment chest imaging to monitor for lung metastases. Undergoing CT scans too frequently can be costly and come with its own side effects, while too sparse scans — or worse, no scans at all — can potentially allow lung metastases to grow, thereby potentially worsening prognosis.

A recent study sought to remedy this by identifying groups of patients with surgically removed colorectal cancer that are at high risk of developing lung metastases.

“We combined two large databases and found a group of patients who developed spots on their CT scans of their lungs within three months of having had their colorectal cancer resected,” study co-author Dr. Nathaniel Deboever, a general surgery resident and Thoracic and Cardiovascular Surgery Research Fellow at The University of Texas MD Anderson Cancer Center in Houston, said in an interview with CURE®.

Study findings showed that patients who were more likely to have pulmonary (lung) metastases were those who needed chemotherapy or radiotherapy before or after surgery, meaning that the cancer was more advanced, as well as those with a KRAS mutation or those who have a higher percentage of cancerous lymph nodes removed during colorectal surgery.

“So, we thought those patients who develop these spots really early are the patients who should receive imaging early, since they also have those risk factors and characteristics that might (indicate) that they are at a higher risk of having pulmonary metastases,” Deboever said.

Knowing who should undergo chest scans more frequently is important because catching lung metastases early can be key in improving survival outcomes. When caught early, cancer in the lungs can be removed surgically, but if the disease grows too much, it may no longer be removable by surgery.

“We know, without a doubt, that when we can surgically remove these spots, survival outcomes are better than if a patient is not a candidate for surgery. If they need to get radiation or just continue on chemotherapy because they can’t have surgery, their likelihood of becoming disease-free and never having to be on therapy is much less,” study principal investigator and senior author, Dr. Mara Antonoff, Associate Professor in the Department of Thoracic and Cardiovascular Surgery at The University of Texas MD Anderson Cancer Center said in an interview with CURE®.

Antonoff explained that oftentimes patients with metastases in their lungs may not experience symptoms until the disease is far enough along when surgery may no longer be an option.

“Symptoms they might experience include shortness of breath, unexpected weight loss, coughing more frequently, coughing up blood and fatigue,” Antonoff said. “At that point, they’d probably just be getting chemotherapy to prolong their life.”

Looking forward, Deboever mentioned that the research team plans to build a machine learning algorithm that could be helpful in determining which patients should undergo more frequent screening based on their individual risk factors.

“(It would) not only tell us who is at high risk, but also (who are) those lower-risk patients — when should they exactly be imaged in order to capture the most metastases at the right time without giving too many CT scans to too many patients,” Deboever said.

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