16. Cervix cancer - The GEC-ESTRO Handbook of Brachytherapy

Cervix cancer

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THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/09/2023

white cell blood count) and treatment-related factors (technique, dose, OTT, concurrent chemotherapy). More recently, response to initial EBRT (pattern and rate of tumour regression, CTV-T_HR volume at time of BT) has been shown to have a significant impact [4, 5, 64-67]. Several groups have combined these factors into nomograms [64, 68-70] to be used to inform patient counselling. Such factors will be used in future to stratify treatment according to risk (EMBRACE-III). Some of the risk factors that are particularly relevant to BT are discussed in more detail below. 12.1 Impact of dose of irradiation, tumour size and histology The impact of dose of irradiation and tumour size on tumour control in cervical cancer has long been recognised. For example, Perez et al. [60] observed from their retrospective analysis that for

lesions <2 cm, doses of 75 Gy to point A resulted in <10% pelvic failures, whereas in more extensive lesions, even doses of 85 Gy resulted in 30–50% pelvic failures. Within the Retro-EMBRACE and EMBRACE I study [62-63], institutions were permitted to prescribe radiation doses according to their own institutional guidelines. The inter-institution and inter-patient dose variations in Retro-EMBRACE and EMBRACE I have provided a unique opportunity to investigate the dose and volume effects for tumour targets and OAR. There was a significant correlation between local control and dose (Figure 22a [27] and b [67]), volume, and OTT and histology [67] for all target volumes at the time of BT: GTV-T res , CTV-T_HR and CTV-T_IR [27]. A D90% dose of ≥85 Gy to CTV-T_HR delivered in 7 weeks results in a 3-year local control rate of ≥94% in small targets (CTV-T_HR

Figure 22. Local control dose-response curves for (A) stage II and stage III and IVA tumours for CTV-T_HR, GTV-T res and CTV-T_IR (Reprinted from Radiother Oncol 120/3, Tanderup K, Fokdal LU, Sturdza A et al., Effect of tumor dose, volume and overall treatment time on local control after radiochemotherapy including MRI guided brachytherapy of locally advanced cervical cancer, 441-446, 2016, with permission from Elsevier) and (B) D90 of CTV-T HR (<20 cm 3 , 20-40 cm 3 , >40 cm 3 ) for squamous cell carcinoma (blue lines) and adeno- or adenosquamous carcinoma (red lines), dotted lines indicate 95% CI. (Reprinted from J. Clin. Oncol., 41/10, Schmid MP, Lindegaard JC, Mahantshetty U, et al. , Risk Factors for Local Failure Following Chemoradiation and Magnetic Resonance Image Guided Brachytherapy in Locally Advanced Cervical Cancer: Results From the EMBRACE-I Study, 1933-1942, 2023, with permission from Wolter Kluwer).