Colorectal cancer is one of the most commonly diagnosed malignancies worldwide and a leading cause of cancer-related morbidity and mortality. Its global incidence continues to increase, with a substantial proportion of cases diagnosed at advanced stages, which adversely affects prognosis. Patients diagnosed at an early stage and treated with surgery have significantly better long-term survival outcomes. Five-year survival rates are approximately 90% for stage I disease, decreasing to around 70% in stage II and 60% in stage III, and dropping to as low as 8% in stage IV disease.

Advanced age, family history, and environmental exposures are well-established risk factors for colorectal cancer. In addition, modifiable lifestyle factors-including smoking, physical inactivity, unhealthy dietary patterns, and obesity-have been shown to significantly increase the risk of disease.

Although surgical resection remains the cornerstone of curative treatment in colorectal cancer, long-term outcomes are influenced not only by tumor stage but also by various patient-related factors, including comorbidities, functional capacity, and respiratory reserve. Functional status, which reflects a patient's ability to perform activities of daily living, is a key determinant of postoperative recovery and long-term outcomes. Reduced functional capacity has been associated with poorer long-term survival, diminished quality of life, and increased late morbidity. Therefore, objective preoperative assessment of functional status is considered essential for predicting long-term prognosis.

Respiratory function also plays a critical role, particularly in patients undergoing abdominal surgery. Impaired pulmonary capacity increases the risk of postoperative pulmonary complications, prolongs hospital stay, and may indirectly affect long-term survival. However, studies evaluating the impact of preoperative respiratory parameters on long-term outcomes in patients with colorectal cancer remain limited. Furthermore, comprehensive analyses integrating both functional capacity and respiratory function are scarce in the current literature. Therefore, further investigation in this area is warranted.

The aim of this study is to evaluate the impact of functional status and respiratory parameters on long-term clinical outcomes in patients with colorectal cancer.

H0: There is no statistically significant association between functional status, respiratory parameters, and long-term clinical outcomes in patients with colorectal cancer.

H1: There is a statistically significant association between functional status, respiratory parameters, and long-term clinical outcomes in patients with colorectal cancer.

Inclusion Criteria:

• Age between 18 and 80 years
• Voluntary participation in the study

Exclusion Criteria:

• Presence of musculoskeletal disorders that may prevent completion of the required tests
• Presence of cognitive impairment
• History of psychiatric disease
• History of major surgery

The study population consists of patients aged 18-80 years diagnosed with colorectal cancer and scheduled for surgical treatment. All participants undergo preoperative assessment, including evaluation of functional status and respiratory parameters such as the Six-Minute Walk Test (6MWT) and pulmonary function tests. Patients with conditions that may interfere with test performance, including significant musculoskeletal, cognitive, or psychiatric disorders, as well as those with a history of major surgery, are excluded. Participants are followed longitudinally to assess long-term clinical outcomes.