Colon Cancer Recurrence Risk Nearly Gone After 6 Years, Study Reveals

For patients who received treatment for stage II to III colon cancer, the risk of disease recurrence drops below 0.5% 6 years after surgery and adjuvant therapy, revealed a landmark analysis of over 35,000 patients.¹ This finding offers a clear, evidence-based definition of cure that could transform patient counseling and streamline follow-up care.

This pooled analysis study is published in JAMA Oncology.

“As clinicians, we have the duty, whenever possible, to communicate to patients when they are cured beyond any reasonable doubt, as this knowledge empowers them to fully embrace the recovery status, with significant psychological and societal implications,” wrote the researchers of the study. “Furthermore, our finding enables the safe discontinuation of follow-up after 6 years, leading to an improvement in quality of life and a reduction in health care system costs.”

In 2025, the American Cancer Society estimates there will be about 107,320 new cases of colon cancer and 46,950 cases of rectal cancer in the US, along with an expected 52,900 deaths.² Overall incidence has declined about 1% per year since 2012, largely due to screening and lifestyle changes, but rates are rising by 2.4% annually in adults younger than 50. The lifetime risk of developing colorectal cancer is roughly 1 in 24 for men and 1 in 26 for women. While death rates have fallen steadily among older adults due to earlier detection and improved treatment, mortality in people under 55 has increased by about 1% per year since the mid-2000s.

This study analyzed individual patient-level data from 15 phase 3 randomized clinical trials included in the Adjuvant Colon Cancer Endpoints and International Duration Evaluation of Adjuvant Chemotherapy databases.¹ It included 35,213 patients with stage II to III colon cancer who underwent radical surgery followed by adjuvant chemotherapy, with a median follow-up of at least 6 years. Time to colon cancer–related recurrence was analyzed, with death and second primary cancers treated as competing risks. Additionally, the researchers evaluated prognostic factors, stratified by sex, stage, and tumor characteristics. Adjuvant regimens varied and included fluoropyrimidines alone or in combination with oxaliplatin or biologic agents.

The analysis revealed recurrence risk peaked at 6.4% between months 6 and 12 after surgery and then declined steadily. By year 6, colon cancer–related recurrence fell below 0.5%, meeting the study’s predefined threshold for cure. Recurrence rates remained low through year 10 but showed a slight increase to 2.0% between years 12.5 and 13, driven by data from the MOSAIC trial (NCT00275210). Competing-event analysis revealed that including deaths and second primary cancers inflated recurrence estimates, particularly in older patients. Furthermore, female patients had a significantly lower cumulative incidence of relapse (HR, 0.58; 95% CI, 0.45-0.76; P < .001).

However, the researchers noted several limitations. First, because this study pooled data from 15 trials over two decades with varied treatments and follow-up, it lacked long-term consistency. Second, data beyond 10 years and on second cancers were incomplete, and trial populations may not have reflected real-world diversity. Additionally, although the recurrence threshold was practical, it may have been perceived differently by patients and clinicians.

Despite these limitations, the researchers believe the study highlights a clear timeline when recurrence risk becomes negligible after surgery and adjuvant therapy.

“Our finding gains relevance compared with conditions like breast cancer, where recurrence risk remains above 1% even after 22 years, making it impossible to define a cure using the 0.5% threshold,” wrote the researchers.

References

1. Pastorino A, Liu H, Pederson L, et al. The definition of cure in colon cancer: A pooled analysis of 15 randomized clinical trials. JAMA Oncol. Published October 2, 2025. doi:10.1001/jamaoncol.2025.3760

2. Key statistics for colorectal cancer. American Cancer Society. Updated April 28, 2025. Accessed October 2, 2025. https://www.cancer.org/cancer/types/colon-rectal-cancer/about/key-statistics.html