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

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 EQD, 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 D, depending on whether the position was cranial or caudal of the uterine base (85.5 vs. 378.9 cGy, < 0.0001), and whether the RLNM D was associated with a number of ipsilateral interstitial needles between 0-1 or 2 or more (68.4 vs. 112.2 cGy, = 0.006) per session. At each session, Group 1 RLNMs (cranial of the uterine base, 0-1 ipsilateral interstitial needle) had a mean D 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.