Feasibility of Interdigitation of Intracavitary High Dose Rate Brachytherapy for Locally Advanced Carcinoma Cervix in the Era of Concurrent Chemoradiation.

Abstract

PURPOSE/OBJECTIVE(S)\nThe detrimental effect of treatment prolongation in patients of cervical cancer receiving radiotherapy alone is well established. However, the impact of overall treatment time (OTT) in patients with locally advanced disease treated with concurrent chemo-radiotherapy and high dose rate brachytherapy (BT) has not been adequately addressed. Aim of the present study (1) assess the feasibility of reducing the OTT to 5 weeks by interdigitating BT with external beam radiotherapy (EBRT) (2) compare loco-regional control and toxicities of interdigitated BT with conventional sequential BT.\n\n\nMATERIALS/METHODS\nThe prospective study involved 40 patients of cancer cervix who met the inclusion and exclusion criteria. They were randomized into study and control arms. All the patients received EBRT (45 Gy/20 fractions over 4 weeks) with concurrent weekly Cisplatin@40mg/m2 and 3 fractions of high dose rate BT (7 Gy/fraction to Point A, interval of 1 week between 2 fractions). Patients in the control arm received BT after a gap of one week following EBRT completion where three fractions of BT were delivered weekly to complete the entire treatment in 7 weeks. In the study arm, BT was initiated on 20th day after 15 fractions of EBRT i.e., 33.75 Gy. These patients received subsequent BT fractions on days 27 and 34 to complete the treatment in 5 weeks. Both the groups were compared in terms of OTT, loco-regional control and normal tissue toxicities.\n\n\nRESULTS\nA total of 36 patients completed the planned treatment. There was significant difference in the OTT in study arm and control arm; 36.7 ± 3 days and 52.5 ± 5 days, respectively (P\u202f=\u202f0.001). The mean biologically equivalent dose (BED10Gy) and Equivalent dose in 2 Gy fractions (EQD2) was also significantly higher in the study arm after appropriate correction for accelerated repopulation (P\u202f=\u202f0.001 for both). However no significant difference was found at nine months follow up in terms of local control, 94.1% patients in the study arm had complete response as compared to 89.5% patients in the control arm (P\u202f=\u202f0.615). The overall rate of toxicity, though numerically higher in study arm, was not statistically significant.\n\n\nCONCLUSION\nA shorter treatment schedule of 5 weeks by interdigitating BT during EBRT appears to be a feasible and radiobiologically superior option to achieve a possibly better local control of disease with acceptable toxicities in comparison to sequential brachytherapy following EBRT. Additionally, patient compliance might be better with shorter treatment duration with fewer drop outs along with decreased health care cost and machine occupancy.\n\n\nAUTHOR DISCLOSURE\nS. Singh: None. U. Shahi: None. L.M. Aggarwal: None. S. Choudhury: None. S. Pal: None. A. Pandey: None.