Understanding hydronephrosis occurrence by an individual-kidney level analysis of all events post-chemoradiotherapy for locally advanced cervical cancer.

Abstract

Purpose: Hydronephrosis is a complex renal abnormality that requires assessment of individual-kidney status at different times for correct interpretation of the mechanism of damage. This study analyzes all hydronephrosis events in women with locally advanced cervical cancer (LACC).

Methods: The status of 449 kidneys from 225 women treated with external beam radiotherapy (EBRT) with concurrent cisplatin and image-guided adaptive brachytherapy (IGABT) were retrospectively reviewed. Hydronephrosis incidence, causes (including radiation-induced hydronephrosis [RIH]), associated factors, and resolution rates were analyzed. Univariable and multivariable analyses were performed at the individual-kidney level, clustered by individual patient.

Results: At baseline, 10.9% (49/449) of the kidneys were affected by hydronephrosis, which resolved in 38.8% (19/49) after RT. During follow-up, new hydronephrosis occurred in 15.8% (71/419) of the kidneys, caused more frequently by cancer recurrence than by RIH (2:1 ratio). The overall RIH incidence per kidney was 5.7% (95% CI, 3.2-8.1) and 7.2% (95% CI, 3.8-10.4) at 3 years and 5 years, respectively. The rates of type A RIH (ureteral stenosis) at 3 years and 5 years were 1.9% (95% CI, 0.5-3.3) and 3.5% (95% CI, 0.8-6.2). Both 3- and 5-year rates of type B RIH (damage to structures other than ureter) were 3.8% [95% CI, 1.7-5.9]. Point A dose (p=0.01; EQD2₃), bladder D_2.0cc (p=0.03; EQD2₃), and CTV_HR volume (p<0.01; cm³) were associated with overall hydronephrosis incidence in the multivariable model. Point A dose was associated with type A RIH (p<0.01) but not with type B (p=0.74). At last follow-up, 19.6% (88/449) of kidneys had unresolved hydronephrosis.

Conclusion: Persistent hydronephrosis is not uncommon after definitive RT for LACC (20%), with RIH being a relevant etiology (5y: 7%). In contrary to type B RIH (damage to other structures), type A (ureteral damage) is usually unilateral, associated with dose to the ipsilateral point A, and its incidence does not plateau over time.