Mapping patterns of para-aortic lymph node recurrence in cervical cancer: a retrospective cohort analysis

Background: To map anatomic patterns of para-aortic lymph node (PALN) recurrence in cervical cancer patients and validate currently available guidelines on PA clinical target volumes (CTV). Methods: Cervical cancer patients who developed PALN recurrence were included. The PALNs were classified as left-lateral para-aortic (LPA), aorto-caval (AC), and right para-caval (RPC). Four PA CTVs were contoured for each patient to validate PALN coverage. CTV_RTOG was contoured based on the Radiation Therapy Oncology Group guideline. CTV_K was contoured as proposed by Keenan et al. CTV_M was contoured by expanding symmetrical margins around the aorta and inferior vena cava of 7 mm up to the T12–L1 interspace. CTV_new was created by modifying CTV_RTOG to obtain better coverage. Results: We identified 92 PALNs in 35 cervical cancer patients. 46.8% of the PALNs were at LPA, 38.0% were at AC, and 15.2% were at RPC areas. CTV_RTOG, CTV_K, and CTV_M covered 87.0%, 88.0%, and 62.0% of all PALNs, respectively. PALN recurrence above the left renal vein was associated with PALN involvement at diagnosis (p = 0.043). Extending upper border to the superior mesenteric artery allowed the CTV_new to cover 96.7% of all PALNs and all nodes in 91.4% of patients. Conclusion: CTV_RTOG and CTV_K encompassed most PALN recurrences. For high-risk patients, such as those having PALN involvement at diagnosis, extending the superior border of CTV from the left renal vein to superior mesenteric artery could be considered.