Pinzi Valentina, Landoni Valeria, Cattani Federica, Lazzari Roberta, Jereczek-Fossa Barbara Alicja, Orecchia Roberto
Department of Neurosurgery, Radiotherapy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy.
Laboratory of Medical Physics and Expert System, IRCCS Istituto Nazionale Tumori Regina Elena, 00128 Rome, Italy.
Ecancermedicalscience. 2019 Dec 17;13:993. doi: 10.3332/ecancer.2019.993. eCollection 2019.
The role of radiotherapy and brachytherapy in the management of locally advanced cervical and endometrial cancer is well established. However, in some cases, intracavitary brachytherapy (ICBRT) is not recommended or cannot be carried out. We aimed to investigate whether external-beam irradiation delivered by means of intensity-modulated radiation therapy (IMRT) might replace ICBRT in gynaecological cancer when the standard ICBRT boost delivering cannot be administered for technical or clinical reasons.
Fifteen already delivered treatments for gynaecological cancer patients were analysed. The treatments were performed through 3-dimensional conformal radiotherapy (3D-CRT) to the whole-pelvis up to the dose of 45-50.4 Gy followed by a boost dose administered with ICBRT in high-dose-rate or pulsed-dose-rate modality. For each patient, IMRT plans were elaborated to mimic the ICBRT. We analysed the ICBRT boost versus IMRT boost in terms of dosimetric and radiobiological aspects.
Mean conformity index value calculated on boost volume was 0.73 for ICBRT and 0.97 for IMRT. Mean conformation number was 0.24 for ICBRT boost and 0.78 for IMRT boost. Mean normal tissue complication probability (NTCP) values for 3D-CRT plus ICBRT and for IMRT (pelvis plus boost) were, respectively, 28% and 5% for rectum; 1.5% and 0.1% for urinary bladder and 8.9% and 6.1% for bowel.
Our findings suggest that IMRT may represent a viable alternative in delivering the boost in patients diagnosed with gynaecological cancer not amenable to ICBRT.
放射治疗和近距离放射治疗在局部晚期宫颈癌和子宫内膜癌的治疗中所起的作用已得到充分证实。然而，在某些情况下，腔内近距离放射治疗（ICBRT）并不被推荐或无法实施。我们旨在研究当因技术或临床原因无法进行标准的ICBRT推量照射时，调强放射治疗（IMRT）所提供的外照射是否可替代妇科癌症中的ICBRT。
分析了15例已完成的妇科癌症患者的治疗情况。这些治疗通过三维适形放疗（3D-CRT）对全盆腔进行照射，剂量达45 - 50.4 Gy，随后采用高剂量率或脉冲剂量率方式进行ICBRT推量照射。针对每位患者，制定IMRT计划以模拟ICBRT。我们从剂量学和放射生物学方面分析了ICBRT推量照射与IMRT推量照射的情况。
在推量体积上计算得出的ICBRT平均适形指数值为0.73，IMRT为0.97。ICBRT推量照射的平均构象数为0.24，IMRT推量照射为0.78。3D-CRT联合ICBRT以及IMRT（盆腔加推量）的直肠平均正常组织并发症概率（NTCP）值分别为28%和5%；膀胱分别为1.5%和0.1%；肠道分别为8.9%和6.1%。
我们的研究结果表明，对于诊断为不适合ICBRT的妇科癌症患者，IMRT可能是一种可行的推量照射替代方法。
