Delayed Systemic Therapy Following Destructive Local Treatment of Pulmonary Oligometastases After No Evidence of Disease (NED) in Colorectal Cancer.

Colorectal cancer (CRC) is the third most common cancer worldwide. Surgical resection is one of the primary treatment options for CRC; however, postoperative recurrence remains a significant clinical challenge for both the medical community and patients. Postoperative chemotherapy, as an important adjuvant therapy, is widely used in CRC patients aiming to reduce the risk of recurrence. Despite extensive research on the efficacy of postoperative chemotherapy in CRC, the mechanisms of postoperative recurrence, predictive factors, and strategies to enhance chemotherapy effectiveness remain unclear. For colorectal cancer patients who have achieved NED (No Evidence of Disease), the decision to either reinitiate or change the systemic chemotherapy regimen for newly developed pulmonary oligometastases remains controversial. Local treatment options for diagnosing oligometastases include surgery, radiotherapy, and radiofrequency ablation. However, whether systemic treatment should be added after local treatment in patients who have achieved NED remains uncertain , and this issue requires urgent resolution.

Colorectal cancer (CRC) is the third most common cancer worldwide. Surgical resection is a primary treatment option; however, postoperative recurrence remains a significant challenge. Postoperative chemotherapy is commonly used as an adjuvant treatment to reduce recurrence risk, but the mechanisms of recurrence, predictive factors, and strategies to enhance chemotherapy efficacy remain unclear.For CRC patients who have achieved No Evidence of Disease (NED), the decision to reinitiate or modify systemic chemotherapy for newly developed pulmonary oligometastases is still debated. Local treatment options for pulmonary oligometastases include surgery, radiotherapy, and radiofrequency ablation. However, whether systemic therapy should follow local treatment in NED patients is uncertain.This issue is actively debated in multidisciplinary team (MDT) consultations both in our hospital and across the country. Some experts argue that pulmonary oligometastases signify disease progression, requiring systemic treatment, while others suggest that these metastases may not indicate high malignancy and that observation, with possible delayed systemic treatment, could be sufficient.This study will include CRC patients who have achieved NED for at least six months and then develop pulmonary oligometastases, treated exclusively with destructive local therapies (surgery, radiotherapy, or ablation) without systemic therapy. The study will assess the timing of transitioning to the next line of systemic therapy through imaging and ctDNA monitoring.