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.