Malignancy in mirror image anatomy reveals situs inversus totalis as an anatomic modifier of oncologic care.

BACKGROUND

Situs inversus totalis (SIT) is a rare congenital laterality anomaly characterized by complete mirror-image transposition of the thoracic and abdominal viscera. Although SIT is not a proven cancer-predisposition syndrome, cancer in this setting challenges the spatial assumptions that guide diagnosis, staging, surgery, radiotherapy, and surveillance.

METHODS

We conducted a retrospective, single-center observational study of patients with radiologically confirmed SIT treated at our cancer center between July 2017 and December 2025. Patients with histologically confirmed malignancy were included. Clinical, pathological, imaging, treatment, and follow-up data were extracted from medical records. Overall survival (OS) was summarized descriptively; Kaplan-Meier analysis was used only to visualize survival and censoring patterns.

RESULTS

Among 11 patients with SIT, 6 had histologically confirmed malignancies. Median age was 66.5 years (range, 47-76), and median follow-up was 47.5 months (range, 30-55). Tumors included hepatocellular carcinoma, lung squamous cell carcinoma, lung adenocarcinoma, cervical adenocarcinoma, poorly differentiated abdominal adenocarcinoma, and follicular lymphoma transformed to high-grade B-cell lymphoma. Treatment included surgery, radiotherapy, chemotherapy, immunotherapy, targeted therapy, transarterial chemoembolization, and autologous stem cell transplantation. 4 patients died, and 2 were alive at last contact. Pooled median OS was 50 months and was interpreted only descriptively. Across cases, outcomes reflected tumor type, stage, and molecular features, whereas SIT mainly affected lesion localization, laterality recognition, nodal or vascular mapping, operative orientation, and treatment planning.

CONCLUSIONS

Malignancy in SIT is best understood as cancer within a reversed anatomical coordinate system. Standard oncologic care remains feasible but requires explicit anatomical verification and multidisciplinary planning.