Association between preoperative respiratory function and postoperative complications in patients with colorectal cancer: a retrospective study
This retrospective study of 1,164 colorectal cancer patients found that preoperative respiratory function, defined by FEV1/FVC ratios, was not significantly associated with the incidence of postoperative pulmonary complications.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
When a surgeon removes a tumor from the colon or rectum, the body faces a significant physical challenge. The abdomen is opened, organs are moved, and the healing process begins. For many patients, this recovery is smooth, but for others, the lungs can struggle to function properly after the operation. These breathing problems, known as postoperative pulmonary complications, are serious. They can lead to pneumonia or a partial collapse of the lung, which in turn can shorten a patient's life and prolong their hospital stay. Because these complications are so dangerous, doctors have long tried to predict who is most at risk before the surgery even begins. A common tool for this prediction is a simple breathing test. In this test, a patient takes a deep breath and blows out as hard and fast as they can. Doctors measure how much air comes out in the first second compared to the total amount of air they can exhale. If this ratio is low, it suggests the airways are narrowed or the lungs are stiff, a condition often seen in smokers or people with chronic lung diseases. It has been widely assumed that patients with these lower scores would be far more likely to develop lung trouble after colorectal cancer surgery, leading many to believe that a poor breathing test result is a clear warning sign to delay or alter the surgical plan.
Researchers at Kanazawa University in Japan set out to test this assumption with a large group of patients. They looked back at the medical records of 1,164 individuals who had undergone surgery for colorectal cancer between 2006 and 2025. Every single one of these patients had taken the breathing test before their operation. The team split the group into two categories: those with normal breathing function and those with low breathing function, using the standard cutoff where the first-second breath is less than seventy percent of the total. They then watched to see who developed pneumonia or lung collapse within thirty days of the surgery. The results were surprising. Despite the common belief that poor lung function predicts bad outcomes, the researchers found no statistical difference in the rate of lung complications between the two groups. Whether a patient had a strong, healthy breath or a weaker one, the likelihood of developing a postoperative lung problem was essentially the same. In fact, when the researchers used advanced statistical methods to match patients with similar backgrounds—such as age, smoking history, and overall health—the result remained unchanged. The low breathing scores did not predict the complications.
Instead of the breathing test, the study pointed to a different factor that truly mattered: the type of surgery performed. The researchers found that patients who underwent open surgery, where a large incision is made to access the abdomen, were significantly more likely to suffer from lung complications than those who had minimally invasive procedures. In open surgery, the large wound causes more pain, which can make it difficult for a patient to take deep breaths or cough effectively. This suppression of normal breathing mechanics appears to be a stronger driver of lung trouble than the patient's pre-existing lung capacity. The study also noted that the overall rate of lung complications in this group was quite low, occurring in only about two percent of patients. This low number means that while the data is strong, the researchers could not completely rule out the possibility that a very rare risk exists that their sample size simply missed. They also acknowledged that their hospital has a strict protocol where patients with lower breathing scores receive extra care, such as consultations with lung specialists and preoperative medication, which might have helped protect them.
The findings suggest that for colorectal cancer surgery, the old rule of thumb—that a poor breathing test automatically means a high risk of lung failure—may not apply. The study does not claim that lung health is irrelevant, but it does argue that the specific measure of how fast a person can blow air out is not the deciding factor for this particular operation. The real danger appears to lie in the surgical approach itself. While the researchers cannot change a patient's lung function, they can choose a surgical method that minimizes pain and keeps the lungs working well. The authors conclude that to be certain about these results, larger studies involving many hospitals are needed. Until then, their work offers a quiet but important correction to medical thinking: for patients facing colorectal cancer surgery, the way the operation is performed may matter more for their lungs than the numbers on their preoperative breathing test.
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