Conditional survival and cure of patients with colon or rectal cancer: A population-based study

Background: The increasing number of colorectal cancer (CRC) survivors need survival estimates that account for the time already survived. The aim of this population-based study was to determine conditional survival, cure proportions, and time-to-cure (TTC) of patients with colon or rectal cancer. Materials and Methods: All patients with pathologic stage I-III CRC treated with endoscopy or surgery, diagnosed and registered in the Netherlands Cancer Registry between 1995 and 2016, and aged 18 to 99 years were included. Conditional survival was calculated for those diagnosed before and after 2007. Cure proportions were calculated using flexible parametric models. Results: A total of 175,384 patients with pathologic stage I (25%), II (38%), or III disease (37%) were included. Conditional 5-year survival of patients with stage I, II, and III colon cancer having survived 5 years was 98%, 94%, and 92%, respectively. For patients with stage I-III rectal cancer, this was 96%, 89%, and 85%, respectively. Statistical cure in patients with colon cancer was reached directly after diagnosis (stage I) to 6 years (stage III) after diagnosis depending on age, sex, and disease stage. Patients with rectal cancer reached cure 0.5 years after diagnosis (stage I) to 9 years after diagnosis (stage III). In 1995, approximately 42% to 46% of patients with stage III colon or rectal cancer, respectively, were considered cured, whereas in 2016 this percentage increased to 73% to 78%, respectively. Conclusions: The number of patients with CRC reaching cure has increased substantially over the years. This study's results provide valuable insights into trends of CRC patient survival and are important for patients, clinicians, and policymakers.