The clinical dilemma of vanishing lesions after systemic therapy in oligometastatic esophagogastric cancer: a narrative review

Background: Radical local metastasis-directed treatment is increasingly considered in oligometastatic cancer. Disappearance of metastases after systemic therapy (“vanishing lesions”) poses management dilemmas, as invisibility does not prove complete response, but local therapy carries morbidity. Summary: We searched PubMed for studies on vanishing metastases after systemic therapy in esophagogastric cancer. Complete disappearance of all metastases occurred in 1-3% of patients treated with chemotherapy alone and in 5-17% in trials using targeted or immune therapies. Series reported ≥1 vanishing lesion(s) in 8-44% of patients. Definitions relied on CT, without comparison to MRI or PET-CT. Lesion-level pathology was lacking; vanishing sites were not resected. Survival benefits were linked to radiologic complete response, but the impact of locally treating vanishing sites was not studied. Because esophagogastric data are scarce, colorectal metastases were reviewed for context: CT disappearance often overestimated cure, liver MRI frequently altered plans, 33-69% of CT/MRI-negative liver lesions still harbored viability or recurred, and survival was comparable between unresected vs. resected vanishing lesions. Key Messages: Current evidence does not support routine local treatment of vanishing lesions in oligometastatic esophagogastric cancer, although this conclusion is based on a very limited and retrospective evidence base. Imaging besides CT (e.g. MRI, PET-CT) may improve staging. Individualized benefit-risk assessment and studies addressing diagnostic and therapeutic strategies are needed.