Objective To evaluate the efficacy and toxicity of primary chemoradiation with image-guided adaptive brachytherapy for locally advanced cervical cancer and to identify predictors of treatment failure and toxicity.

Methods Retrospective analysis of 155 stage IB-IVA cervical cancer patients treated from 2008 to 2016 with chemoradiation and image-guided adaptive brachytherapy. Treatment consisted of external beam radiotherapy (45 – 48.6 Gy in 1.8 – 2 Gy fractions) with concurrent weekly cisplatin (40 mg/m², 5 – 6 cycles) and image-guided adaptive brachytherapy (3−4 × 7 Gy high dose rate) using intracavitary or combined intracavitary-interstitial techniques according to GEC-ESTRO (Group Européen de Curiethérapie and the European Society for Radiotherapy and Oncology) recommendations. Incidences of all outcomes were calculated using Kaplan-Meier’s methodology. Risk factors for treatment failure and toxicity were identified using Cox’s proportional hazards model and the Kruskal-Wallis H-test respectively.

Results Median follow-up was 57 months. Five-year local control was 90.4 %. Five-year para-aortic lymph node metastasis-free and distant metastasis-free survival were 85.3 % and 70.2 % respectively. Tumor size and lymph node metastasis were independent risk factors for treatment failure. Cumulative incidences of severe late bladder, rectal, bowel, and vaginal toxicity were 0.8%, 3.3%, 3.6%, and 1.4% respectively at 5 years of follow-up. Combined intracavitary-interstitial brachytherapy techniques were associated with less vaginal morbidity.

Conclusions Primary chemoradiation with image-guided adaptive brachytherapy for locally advanced cervical cancer is a highly effective local and loco-regional treatment. However, survival is compromised by the occurrence of distant metastasis. Patients with large tumors and nodal involvement at diagnosis are at increased risk and may benefit from intensified treatment. Severe late gastrointestinal and urogenital toxicity is limited and may be further reduced by increasing conformity, using combined intracavitary-interstitial techniques and lowering doses to organs at risk.