Clinical Investigations
Impact of point A asymmetry on local control and survival for low dose-rate (LDR) brachytherapy in cervical cancer

Purpose: To evaluate whether Point A asymmetry in low dose-rate (LDR) brachytherapy is associated with local control (LC), disease-free survival (DFS) and/or overall survival (OS).

Material and methods: A retrospective analysis of disease control and survival outcomes was conducted for patients who underwent LDR brachytherapy for advanced cervical cancer. Institutional protocol entailed concurrent chemothe-rapy and whole pelvis radiotherapy (WPRT) over 5 weeks, followed by placement of Fletcher-Suit tandem and colpostat applicators at weeks 6 and 8. Objective Point A doses, 80-85 Gy, were accomplished by placement of Cesium-137 (Cs-137) sources. Cox proportional hazards regression models were used to assess associations between disease control and survival endpoints with variables of interest.

Results: The records of 50 patients with FIGO stage IB1-IVA cervical cancer undergoing LDR brachytherapy at our institution were identified. Thirty of these patients had asymmetry > 2.5%, and 11 patients had asymmetry > 5%. At a median survivor follow-up of 20.25 months, 15 patients had experienced disease failure (including 5 cervical/vaginal apex only failures and 2 failures encompassing the local site). Right/left dose asymmetry at Point A was associated with statistically significantly inferior LC (p = 0.035) and inferior DFS (p = 0.011) for patients with mean Point A dose of > 80 Gy. Insufficient evidence existed to conclude an association with OS.

Conclusions: LDR brachytherapy may be associated with clinically significant dose asymmetry. The present study demonstrates that patients with Point A asymmetry have a higher risk of failure for DFS and LC.