Ultrasound image based high dose rate (HDR) brachytherapy in locally advanced cancer cervix

Abstract

Background: Brachytherapy is an integral component of the definitive treatment of locally advanced cancer cervix. Cervical Brachytherapy has evolved from the time when dose prescription was largely empirical, to the image based conformal brachytherapy advocated by Groupe Europeen de Curie Therapie-European society for therapeutic radiology and oncology (GEC-ESTRO) and American brachytherapy society (ABS). Objectives: To explore the feasibility of transabdominal ultrasound (USG) as an imaging modality for conformal brachytherapy (intracavitary) in locally advanced cancer cervix. Methods: Twenty-five patients with locally advanced cervix cancer (FIGO 2009 IB2 to IIIB) treated with definitive chemoradiation andbrachytherapywereincluded in this study. Two plans were generated for each patient at each brachytherapy session - 1) standard orthogonal X-Ray plan with dose presciption to Point A and 2) plan based on USG imaging and clinical assessment. The two plans were compared with respect to doses received at point A, international commission on radiation units and measurements (ICRU) 38 urinary bladder and rectal points. Actual Brachytherapy doses were prescribed to the USG (and clinically) delineated target and patients followed up to 15 months minimum for assessing local control and late toxicity. Results: USG based planning resulted in statistically significant reduction of doses received at organs at risk (OAR) i.e. ICRU 38 bladder (P < 0.001) and rectal (P = 0.002) points, when compared with the standard X-Ray plans. Disease free status was achieved by 73.68% patients in 15 months. 4 patients had pelvic failure and 1 had both pevic and distant (lung) failure. Two patients developed Grade 1 Bladder toxicity. Three patients had grade 1 and one had Grade 2 Rectal toxicities. Grade 3 and 4 toxicities were not observed. Conclusions: Considering the ease of availability, inexpensiveness, quick and good soft tissue imaging offered by ultrasound, this modality’s potential for conformal brachytherapy should be further explored, especially in limited resource settings and where the disease burden is high.