Respiratory Sarcopenia: A New Biomarker for Postoperative Outcomes in NSCLC?
—Could this physical biomarker—sarcopenia--effectively stratify risk in patients with non-small cell lung cancer?
Sarcopenia is emerging as a potential predictor of adverse outcomes for some solid tumors, but could this physical biomarker effectively stratify risk in patients with non-small cell lung cancer (NSCLC)? Despite sarcopenia’s high prevalence among older cancer patients, the generalized muscle disorder remains underrecognized in thoracic oncology, in part due to a lack of consensus across diagnostic criteria. In light of the latest guidance from international professional organizations regarding weak muscle strength and low muscle mass as markers of the condition, a new study proposes a novel diagnostic algorithm for clinical use that encompasses respiratory strength and mass.1 The authors explore whether this holistic assessment of respiratory sarcopenia in the setting of NSCLC could lead to reduced postoperative risk.
Data were drawn from two institutions in Tokyo between 2009 and 2018. (The bi-institutional nature of the study, the authors caution, could potentially reduce its generalizability). Patients who had undergone lobectomy and mediastinal lymph node dissection for NSCLC during this time were identified, 806 of whom were eligible for the study (497 men; median age 69 years).
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Electronic computed tomography (CT) image analysis was used to stratify those in the cohort as having normal status, pre–respiratory sarcopenia—that is, poor peak expiratory flow rate but normal pectoralis muscle index (PMI)—or respiratory sarcopenia. The latter condition was diagnosed based on presence of poor respiratory strength and confirmed with low pectoralis muscle mass. Median duration of follow-up for survival was 5.2 years (range, 3.6-6.4).
Respiratory sarcopenia impacts recovery
Pre–respiratory sarcopenia was identified in 22% of the patients and respiratory sarcopenia was found in 16.1%; the remainder of participants had normal status. When the authors compared short- and long-term outcomes among the three groups, their algorithm successfully predicted risk of postoperative complications, recovery time, and all-cause mortality..
Both pre–respiratory sarcopenia and respiratory sarcopenia were associated with a higher risk of postoperative complications than normal status. In patients with normal status, the risk hovered at 16.4%, whereas it climbed to 22.0% in the pre–respiratory sarcopenia group and reached 30.0% in the respiratory sarcopenia group (P for trend <.001). Risk of prolonged recovery time post-surgery also increased (P for trend <.001) as clinical muscle wasting progressed.
Although pectoralis muscle mass alone has previously been explored as a clinically relevant measure in estimating short-term outcomes in chronic obstructive pulmonary disease and lung cancer, the new study demonstrates that cumulative assessment of respiratory strength and thoracic muscle mass is more powerful for detection of severity of respiratory sarcopenia and prediction of which patients may experience post-surgery complications.
Sarcopenia linked with lower overall survival
In addition, this retrospective study provides important insight about the role of respiratory sarcopenia in patient outcomes. Compared with patients with normal status or pre–respiratory sarcopenia, those with respiratory sarcopenia exhibited worse 5-year overall survival (87.2% vs. 72.9% vs. 62.5%, respectively; P for trend <.001). Pre–respiratory sarcopenia or respiratory sarcopenia also was associated with worse overall survival in patients with stage I to IIIA lung cancer, possibly because preexisting muscle wasting intensifies with severe systemic inflammation.
“This study offers an important reminder to think beyond treating the tumor and consider how overall physical health—especially respiratory muscle function—affects outcomes,” explained author Masaki Anraku, MD, a thoracic surgeon at the Tokyo Metropolitan Institute for Geriatrics and Gerontology and a researcher at the University of Tokyo Graduate School of Medicine.
Respiratory sarcopenia was independently associated with a greater risk of mortality (hazard ratio, 1.83; 95% confidence interval, 1.15-2.89; P =.01). [pg. 1A] Moreover, in patients who had stage I NSCLC specifically, risk of all-cause mortality increased with presence of pre–respiratory or respiratory sarcopenia, even though the cancer played a lesser role in skeletal muscle wasting.
An easy-to-implement algorithm
The study also offers straightforward insight for treating older patients, because respiratory strength and PMI declined with aging (both P for trend <.001). Given that frailty is a known risk factor for older adults with cancer, in that population, accurate diagnosis of sarcopenia can help identify underlying decreased skeletal muscle function and mass and aid in estimation of physiologic reserve.
Patients with pre–respiratory sarcopenia or respiratory sarcopenia who were represented in the new research had worse cancer-specific survival, although the authors point out that this finding may have been influenced by the high percentage of later-stage cancer in the two groups. Still, the datapoint highlights the importance of early lifestyle interventions such as nutrition and exercise to help prevent muscle wasting.
“For older patients, the findings encourage a more holistic approach, emphasizing interventions like tailored exercise programs or physical therapy that are practical and improve quality of life,” said Dr. Anraku. “Our goal is to explore strategies that balance effective care with respect for each patient’s needs.”
The diagnostic algorithm proposed by the authors is simple to implement. Spirometry and chest CT are already performed for NSCLC diagnosis, treatment assessment, and disease surveillance. With recent imaging advances, it has become even easier to visualize the pectoralis muscle on chest CT, making screening and staging of respiratory sarcopenia more approachable.
Dr. Anraku described how these findings can be put into practice: “While tools like CT imaging and spirometry were used in this retrospective study to quantify muscle mass and strength, this research is not about adding complexity to routine practice. Instead, it lays the foundation for looking ahead: exploring how tailored treatments or medical interventions can support patients in a measured, meaningful way, without becoming excessive.” She added: “Especially for older adults, this research aligns with a broader vision of improving quality of life while respecting their dignity and individual circumstances.”
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