By GSN Staff

SAN DIEGO—Colorectal cancer patients with certain clinical characteristics may benefit from more frequent chest imaging to help identify and target cancer that has spread to the lungs, according to new research presented at the American College of Surgeons 2022 Clinical Congress. 

Early detection of cancerous nodules in the lung provides patients with the best outcomes, but there are no evidence-based standards for when and how often to screen these 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 Mara Antonoff, MD, an associate professor of thoracic and cardiovascular surgery at The University of Texas MD Anderson Cancer Center, in Houston, where she also serves as the program director of education. “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.”

Dr. Antonoff and an interdisciplinary team of researchers at MD Anderson collaborated to investigate evidence-based surveillance guidelines for CRC patients who are at risk for developing lung metastases.
Using two institutional cancer databases that included both CRC patients and thoracic cancer patients, the team retrospectively reviewed data from CRC patients who developed lung metastases and those who did not. Patients were grouped according to the development of lung metastases and the timing of their diagnosis. The team used statistical methods to investigate which clinical characteristics, such as age or genetic factors, correlated best with the risk for lung metastases.

Key Findings

     • Of 1,600 patients with CRC, 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 CRC, who had an elevated lymph node ratio, and a KRAS mutation, were at risk for developing lung metastases within three months of surgery.
     • The authors concluded that patients with these characteristics may benefit from more frequent surveillance with chest CT or PET scans.

Nathaniel Deboever, MD, a general surgery resident at UTHealth Houston McGovern Medical School, and lead author of the study, noted that while these risk factors are not necessarily surprising from a clinical perspective, they highlight the need to adequately screen certain CRC patients after surgical treatment. In some cases, removing cancerous lung nodules early on can significantly improve outcomes.

“A concrete clinical application of this research, following validation, is to build evidence-based guidelines affecting chest surveillance in patients with resected colorectal cancer,” Dr. Deboever said. “These guidelines will hopefully allow high-risk patients to undergo radiographic screening in a timely manner, permitting the early diagnosis of pulmonary disease.” 

In future research, the team plans to validate the findings in a separate group of patients, with the hope of formalizing chest surveillance protocols for widespread clinical adoption. Drs. Antonoff and Deboever noted that as CRC research evolves, sensitive blood tests to detect cancer or advanced radiographic screening methods using artificial intelligence may also play an important role in monitoring patients.

“There are many patients who receive cancer care outside of cancer hospitals, so having algorithms, pathways and recommended protocols can be very helpful for providers who care for a lot of different diseases with rapidly changing recommendations,” Dr. Antonoff said. “I think this research is really just the tip of the iceberg.”

This study was funded by the Department of Thoracic and Cardiovascular Surgery at MD Anderson Cancer Center, which included financial support from the Mason Family Philanthropic Research Fund. 

The story is based on a press release.