Distribution patterns of lymph node metastasis in early stage invasive cervical cancer.

The spatial distribution of lymph node (LN) metastasis was analyzed to provide data for an evidence-based approach to radiotherapy field design, particularly for guiding intensity-modulated radiation therapy. A total of 1886 postoperative patients were retrospectively reviewed. Pelvic LNs were classified as common iliac nodes, external iliac nodes, internal iliac nodes/obturator nodes, and deep inguinal nodes. The distribution of LN metastasis in these subgroups was calculated, and the distribution patterns of LN metastasis according to the pathologic types were investigated.We identified 392 eligible patients with LN metastasis. The frequency and number of external iliac node metastasis were higher in the left side in both single subgroup (P < .01) and cosubgroup (P = .04) analyses, whereas few differences were found in other subgroups. Among patients with squamous cell carcinoma, left external iliac node metastasis was observed in 102 (15.13%) patients, whereas right metastasis was observed in 65 (9.64%) patients, and the difference was significant (P < .01).The present results indicated uneven distribution of LN metastasis in the different subgroups, which could help surgeon focus on the dissection of the left subgroups, and help oncologists define margins, refine target volumes for radiation, and improve the accuracy of postoperative radiotherapy especially in patients with squamous cell carcinoma.