Dose Contribution to the Regional Lymph-Node Metastases and Point B from Intracavity and Interstitial Hybrid Brachytherapy in Locally Advanced Cervical Cancer.

Simple Summary: The research investigates dose distributions to regional lymph-node metastases (RLNMs) in locally advanced cervical cancer (LACC) patients undergoing intracavitary and interstitial hybrid brachytherapy (IC/IS), a subject which has rarely been analyzed. Eleven sequential LACC patients with 38 RLNMs who received 38 IC/IS sessions were analyzed. RLNM dose distributions were assessed based on RLNM positions and ipsilateral interstitial needles, revealing significant differences in RLNM D₉₀ based on whether the position was cranial or caudal of the uterine base and the number of interstitial needles was 0–1 or 2 or more. RLNMs located caudal of the uterine base with two or more ipsilateral interstitial needles received higher brachytherapy doses. The findings suggest that when calculating RLNM dose for external beam boost irradiation, consideration of RLNM position and interstitial needle count is crucial. This research sheds light on optimizing brachytherapy dosage delivery to RLNMs in LACC patients, potentially influencing treatment strategies. Purpose: Analyzing dose distributions to regional lymph-node metastases (RLNMs) in locally advanced cervical cancer (LACC) patients undergoing intracavitary and interstitial hybrid brachytherapy (IC/IS). Methods: Dose distributions of eleven LACC patients with 38 RLNMs, and who received 38 IC/IS sessions were analyzed in EQD₂, considering RLNM positions and ipsilateral interstitial needles; these RLNMs, excepting the para-aortic region, were classified into four groups. Results: RLNMs had a median of two ipsilateral interstitial needles per session. Significant differences were observed in total RLNM D₉₀, depending on whether the position was cranial or caudal of the uterine base (85.5 vs. 378.9 cGy, p < 0.0001), and whether the RLNM D₉₀ was associated with a number of ipsilateral interstitial needles between 0–1 or 2 or more (68.4 vs. 112.2 cGy, p = 0.006) per session. At each session, Group 1 RLNMs (cranial of the uterine base, 0–1 ipsilateral interstitial needle) had a mean D₉₀ of 21.1 cGy; Group 2 (cranial, 2 or more), 73.8; Group 3 (caudal, 0–1), 94.7; and Group 4 (caudal, 2 or more), 136.1. Conclusion: RLNMs located caudal of the uterine base associated with two or more ipsilateral interstitial needles in IC/IS had a higher dose contribution, which should be considered when calculating the RLNMs' dose of external beam boost irradiation. [ABSTRACT FROM AUTHOR]