Long term results from a prospective database on high dose rate (HDR) interstitial brachytherapy for primary cervical...

Present long-term outcomes in primary cervical cancer treated with external beam and high dose rate interstitial brachytherapy.

High dose rate (HDR) interstitial (IS) brachytherapy (BT) and external beam (EBRT) were administered from 1992 to 2009 to 315 patients who were unsuitable for intracavitary (IC) BT alone. Histology was 89% squamous cell, 8% adenocarcinoma, and 3% adenosquamous. FIGO stage was I-14%, II-47%, III-34%, and IVA-5%. Median tumor size was 6cm. Lymph node metastases were 26% pelvic and 9.5% para-aortic. Treatment planning was 49% 2D and 51% 3D-CT. The mean doses were central EBRT EQD2₁₀ 37.3±4.3Gy (sidewall 49.2±3.6Gy) and HDR EQD2₁₀ 42.3±5.3Gy (nominal 5.4Gy×6 fractions using a mean of 24 catheters and 1 tandem). Total EQD2₁₀ mean target dose was 79.5±5.4Gy. Standardized planned dose constraints were ICRU points or D_0.1cc bladder 80%, rectum 75% and urethra 90% of the HDR dose per fraction. Morbidity assessment was CTCAEv3. Median and mean follow-up were 50 and 61months (3-234).

The 10-year actuarial local control was 87%, regional control 84%, and loco-regional control 77%. Distant metastasis free survival was 66%, cause specific survival 56%, disease free survival 54%, and overall survival 40%. The rates of late grade GU and GI toxicities were 4.8% G3 and 5.4% G4.

Template-guided interstitial can be safely performed to successfully deliver high radiation dose to locally advanced cervix cancer and avoid excessive dose and injury to adjacent vital pelvic organs. We achieved high tumor control with low morbidity in patients who were poor candidates for intracavitary brachytherapy.