More Frequent Chest Imaging May Benefit Colon Cancer Patients: Study

Your follow-up care may include regular physical examinations and medical tests. Follow-up care is especially important in the first 5 years after treatment for colorectal cancer because this is when the risk of recurrence is highest. Recurrence refers to the original cancer coming back after treatment.

One of the most common areas colorectal cancer spreads to is the lungs, affecting up to 18% of patients with the disease. Detecting cancerous nodules in the lung early provides patients with the best outcomes, but there are no evidence-based standards for when and how often to screen colorectal cancer patients with chest CT or PET scans.

"After patients are diagnosed with colorectal cancer, many of them want to better understand what their cancer diagnosis entails in terms of their surveillance and survivorship for the rest of their life, but we currently lack data and uniform guidelines to support how often these patients should be screened with chest imaging," said co-author Dr. Mara Antonoff, associate professor of thoracic and cardiovascular surgery, UT MD Anderson Cancer Center, Houston. "With this study, we sought to develop a strategy that is evidence-based to determine how frequently, at what intervals, and for how long patients at risk of developing lung metastases should undergo imaging of their chest."

Study details

The researchers from MD Anderson Cancer Center performed a retrospective analysis from databases that included both colorectal cancer patients and thoracic cancer patients. They used statistical methods to investigate which clinical characteristics, such as age or genetic factors, correlated most with the risk of developing lung metastases.

• Of 1,600 patients with colorectal cancer, 233 (14.6%) developed pulmonary metastases, with a median time of 15.4 months following colorectal surgery
• The investigators identified age, neoadjuvant or adjuvant systemic therapy (such as chemotherapy or immunotherapy), lymph node ratio, lymphovascular and perineural invasion (high-risk tumor characteristics observed under a microscope), and presence of KRAS gene mutations as risk factors for lung metastases
• Another analysis revealed that patients who required systemic therapy around the time of their surgery for colorectal cancer, who had an elevated lymph node ratio, and a KRAS mutation, were at risk for developing lung metastases within three months of surgery.
• They concluded that patients with these characteristics may benefit from more frequent surveillance with chest CT or PET scans.

KRAS & NRAS mutations in colon cancer

In a previous conversation with SurvivorNet, Dr. Heather Yeo, a colorectal cancer surgeon at Weill Cornell, spoke about the role biomarkers have in treating colon cancer, noting that doctors are tailoring certain treatments to individuals, particularly for patients in need of a second therapy after no responding to initial treatment.

Dr. Heather Yeo explains the role of biomarkers in colon cancer treatment. 

"In colon cancer, we're starting to look more and more at people's biomarkers, so we're starting to actually take the cancers, sequence them, understand where the different mutations are to figure out whether or not someone has a normal gene here or an abnormal gene," Dr. Yeo explained.

Approximately 40-45% of colorectal cancer patients have KRAS mutation in their tumors. This mutation is not hereditary and will not be passed from one generation to another it's completely random. NRAS mutations are much less common, though both KRAS and NRAS are part of the RAS oncogene family.

It's important to know if your tumor is KRAS-mutated because positive KRAS-cancers have poor response to EGFR-inhibitor medications (such as cetuximab or panitumumab), and therefore, shouldn't be treated with those drugs, but rather with conventional chemotherapy lines such as FOLFOX or FOLFIRI, with or without the addition of bevacizumab.

Colorectal cancer

Colon cancer is a type of cancer that affects your large intestine (colon) or the end of your intestine (rectum). Your doctor might call this type of cancer colorectal cancer. It's is one of the most common cancers worldwide. In the United States, 147,000 individuals received a diagnosis of the disease in 2020, and 53,200 died from it.

• Most patients with colorectal cancer are older than 50 years of age at diagnosis.
• Men have a higher risk than do women.

Most colorectal cancers develop from benign polyps (abnormal lumps) through a series of genetic changes that take 10 to 15 years. Polyps are very common: about half of individuals 50 years of age and older have polyps.

Colorectal cancer surgeon Dr. Zuri Murrell explains why doctors look for polyps during colonoscopies.

Detection and removal of colorectal polyps by colonoscopy hinders progression to colorectal cancer. Because only individuals who get a disease can die from it, the reduction of colorectal cancer incidence by adenoma detection and removal through screening leads to reduced mortality associated with colorectal cancer. In addition, screening may detect cancers at an early stage and thereby reduce mortality.

What to Ask Your Doctor

• What screening test(s) do you recommend as part of my follow-up care?
• How often should I have a chest CT scan performed?
• How do I prepare for these tests?

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