Is single implant and multiple fractions radio-biologically iso-effective for cervical cancer high-dose-rate brachytherapy: Observation from patient cohorts during COVID pandemic.

PURPOSE: To report clinical outcomes of cervical cancer patients treated with single implant and multiple fractions of high-dose-rate brachytherapy (HDR BT).

MATERIALS AND

METHODS

Patients treated with (chemo)radiation followed by single implant with all fractionated HDR BT delivered within 24-36 hours were included. Treatment protocol recommended >70 Gy equivalent doses in 2 Gy (EQD210Gy) at point A for intracavitary BT (ICBT) and >85 Gy EQD210Gy for those receiving interstitial-intracavitary BT (IC-ISBT). Local control, locoregional control and disease-free survival was estimated along with late gastrointestinal (GI) and genitourinary (GU) toxicity.

RESULTS

From 2020-2022, 116 patients were treated with single implant multiple fractions HDR-BT. The median dose to Point A, HRCTV D90, B2cc, R2cc and S2cc was 75.1 (72.4-77.8), 80.2 (76-84), 85.2 (83.1-90.1), 69.1 (65.0-73.9) and 67.9 (61-75.3) Gy for those treated with ICBT. The median dose to high risk clinical target volume D90, Bladder 2cc, Rectum 2cc and Sigmoid 2cc was 83.2 (78.2-88.4), 87.4 (84.2-91), 69.6 (64.1-75) and 68.1 (59.5-77.1) Gy in those with IC-ISBT respectively. The median follow-up was 36 months (2-60 months). The 5-year local control, loco-regional control, disease free survival and overall survival was 89%, 84%, 70.8% and 81.6% respectively. Grade ≥3 GI and GU toxicity were 11.3% and 1.7% respectively. The incidence Grade ≥3 GI was higher in those who received 8-9 Gy in three fractions than 5-7.5 Gy in 3-4 fractions.

CONCLUSION

The abbreviated HDR BT schedule of single implant 3-4 fractions for LACC patients is radiobiological iso-effective for tumor control. There seems to be a fraction size dependence of abbreviated fractionation schedule for severe GI toxicity.