Hybrid (CT/MRI based) vs. MRI only based image-guided brachytherapy in cervical cancer: Dosimetry comparisons and clinical outcome

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• 作者：Ee Siang Choong¹ ; ^{ee_siang@hotmail.com" class="auth_mail" title="E-mail the corresponding author} ; ^{eesiangchoong@googlemail.com" class="auth_mail" title="E-mail the corresponding author} ; Peter Bownes² ; Hima Bindu Musunuru¹ ; Sree Rodda¹ ; Carolyn Richardson² ; Bashar Al-Qaisieh² ; Sarah Swift³ ; Jane Orton¹ ; Rachel Cooper¹
• 关键词：Image-guided brachytherapy ; Cervical cancer
• 刊名：Brachytherapy
• 出版年：2016
• 出版时间：January-February 2016
• 年：2016
• 卷：15
• 期：1
• 页码：40-48
• 全文大小：977 K

文摘

Limited access to MRI has restricted implementation of MRI-based image-guided brachytherapy (IGBT) in line with GEC-ESTRO guidelines in many centers. This work reports our experience using an alternative CT/MRI based (hybrid) approach for IGBT, dosimetry comparisons, and its impact on long-term clinical outcome and major toxicity.

Methods and Materials

Seventy-six patients diagnosed with locally advanced cervical cancer between May 2008 and May 2012 treated with IGBT were analyzed. The hybrid approach is the default IGBT approach during this study period. Forty-nine had hybrid approach and 27 patients had “3-fraction conformal MRI” approach (17 within EMBRACE study). Treatment consisted of 48 Gy in 24 fractions of conformally planned external beam radiotherapy with weekly cisplatin followed by three weekly fractions of brachytherapy to high-risk clinical target volume (HR-CTV). All patients have a prebrachytherapy MRI 4 days before treatment and with the applicators in place on Fraction 1. MRI only or CT is used for subsequent fractions. Using image registration techniques and the assumption that the HR-CTV is fixed with respect to the applicator, the HR-CTV from MRI at Fraction 1 is transferred onto subsequent fraction CT image sets for the hybrid approach.

Results

Median follow-up was 41 months (range, 23–71 months). Excellent 3-year local control, overall progression-free survival, and overall survival of 92.6%, 78.8%, and 77.7% were seen with the hybrid approach and 92.2%, 66.3%, and 69.6% with a 3-fraction conformal MRI approach, respectively. Dosimetry achieved and late toxicity rates were comparable in the two groups.

Conclusions

Hybrid IGBT in locally advanced cervical cancer offers an alternative approach when access to MRI restricts implementation of IGBT.