Distribution pattern of lymph node metastases and its implication in individualized radiotherapeutic clinical target volume delineation of regional lymph nodes in patients with stage IA to IIA cervical cancer

BACKGROUND To study the distribution pattern of lymph node metastases of stage IA to IIA cervical cancer and to clarify the individualized clinical target volume delineation of regional lymph nodes (CTVn). METHODS A total of 665 cases with International Federation Gynecology and Obstetrics stage IA to IIA cervical cancer who underwent radical hysterectomy and pelvic lymphadenectomy were retrospectively reviewed. The clinicopathological factors related to lymph node metastases were analyzed using logistic regression analysis. RESULTS Pelvic lymph node metastases were found in 168 of 665 patients resulting in a metastasis rate of 25.3%. Binary logistic regression analysis showed that age, lymph vascular space involvement, and deep stromal invasion statistically influenced pelvic lymph node metastases (p = 0.017, < 0.001, < 0.001, respectively). Pathological morphology type, lymph node metastases of the obturator, the external iliac and internal iliac, and the para-aortic had a strong influence on lymph node metastases of the common iliac (p = 0.022, 0.003, < 0.001, 0.009, respectively). Tumor size and lymph node metastases of the common iliac were significantly related to lymph node metastases of the para-aortic (p = 0.045, < 0.001, respectively). Lymph node metastases of the obturator, the external iliac and internal iliac were strongly correlated to lymph node metastases of the circumflex iliac node distal to the external iliac node (CINDEIN; p = 0.027, 0.024, respectively). CONCLUSIONS Factors related to lymph node metastases should be comprehensively considered to design and tailor CTVn for radiotherapy of cervical cancer. Selective regional irradiation including the correlated lymphatic drainage regions should be performed.