18. Primary vaginal cancer and vaginal recurrences - The GEC-ESTRO Handbook of Brachytherapy

Primary vaginal cancer and vaginal recurrences

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

and duration of the planned treatment. In addition, use of an intra uterine tandem where there is an intact uterus can help to prevent displacements. In parallel, strategies to detect applicator shifts are necessary which should include at least visual inspection of the outer parts of the applicator before dose delivery related to the situation at treatment planning. Documentation with skin marks and photos can be very helpful. In addition, repeated imaging preferably with the same imaging modality as for treatment planning should be performed in the case of longer lasting treatments (e.g. more than one day) to evaluate the need for re-planning or re-positioning of the applicator [36].

the D90 of the CTV-T HR . However, doses prescribed for vaginal tumours are in general lower, especially in those tumours that are located in the distal part of the vagina. This is because this part of the vagina appears to be more prone to severe toxicity due to the close proximity of the anorectum, urethra and vulva, and the increased risk of mucosal ulceration and obliteration. Consequently, in vaginal tumours, the dose prescribed to the target is dependent on the location. A total D90 dose in the CTV-T HR of 75-85 Gy in EQD2 αβ10 is aimed for. It mirrors the interquartile range (IQR) from the RetroEMBRAVE study (73-85 Gy), reflecting current practice in five European centres [24]. This corresponds well with the guidelines of the ABS from 2012, recommending 70-85 Gy to a CTV, which is dependent on tumour location, extent of disease and response to EBRT [27]. According to the retroEMBRAVE data, a D90 for the CTV-T HR > 80Gy should be considered for large (T2-4) tumours [24]. The ABS recommends limiting the total dose in the lower third of the vagina to 75 Gy [27]. Evidence-based planning aims for GTV-T res and CTV-T IR are not available yet, however based on the concept of cancer cell densities a higher dose could be considered for the GTV-T res and a lower dose for the CTV-T IR with the aim of at least 60 Gy to the D98 according to the target planning aims for CTV-T IR in cervical cancer[33]. In some centres it is common practice to prescribe with brachytherapy additional dose to the adjacent vaginal wall not included in the CTV-T IR for possible multifocal spread. However, it is under debate if this is needed on top of the prescribed EBRT dose, and will be a topic of future prospective studies in which patients are treated according to the GEC-ESTRO and GEC-ESTRO-ABS-CBG recommendations for contouring of vaginal tumours [12, 17]. For the organs at risk the currently used dose constraints for cervical cancer (D2cm 3 rectum < 65-75 Gy, D2cm 3 bladder < 80 90 Gy, and D2cm 3 sigmoid/bowel < 70-75 Gy) are also applied to the treatment of vaginal tumours [33]. Hopefully, upcoming prospective multicentre trials in vaginal cancer will help us to adapt our planning aims and constraints more precisely and comprehensively. Finally, in some specific conditions brachytherapy only can be considered, especially in the case of a very small, superficial tumour or in a re-irradiation setting [31, 34]. Although limited literature is available about the prescribed dose in BT-only setting, an HDR planning aim of 6 x 6-7 Gy prescribed to 3-5 mm tissue depth has been used in the past [31].

12. RESULTS

Data published in the 26th annual FIGO report regarding the outcome of patients with primary vaginal cancer showed a 5-year overall survival of 77%, 52%, 42%, 20% and 13% for FIGO stages I, II, III, IVA and IVB, respectively [37]. These data have not been recently updated. Due to the rarity of the disease, the published results include mainly monocentric, retrospective studies in the era before the use of 3D image-guided adaptive brachytherapy (IGABT). In addition, the ranges of published outcome data are very large and centre dependent. Larger (> 50 patients) 2D-image guided brachytherapy studies report a five-year pelvic control of 74-81% [7]. In comparison, results from the 3D IGABT studies showed a two-year local control of 82-93% [7]. The results from the 3D IGABT studies compares especially favourable in larger (≥T2) tumours. In the international multicentre RetroEMBRAVE study actuarial five-year local control was 75% versus 0-70% in the 2D brachytherapy era [7, 24]. The concept of image-guided adaptive brachytherapy has been gradually adopted for primary vaginal cancer. In the last decade, an increasing number of publications on image-guided brachytherapy were published indicating improved local and pelvic control and improved survival in comparison to 2D-radiograph based brachytherapy. Two year local control rates are in the range of 82-93% and two year overall survival is 62-91% (Table 3)[7].The benefit of IGABT, with the use of an intracavitary/interstitial approach if necessary, seems especially pronounced in the advanced tumours (T3/4), with an increased pelvic control of approximately 15% compared to earlier published results [7, 24]. The most advanced data on image-guided brachytherapy was reported in the RetroEMBRAVE study comprising 148 patients treated between 2001-2016 with relatively homogeneous treatment schedules. At a median follow-up of 29 months, two- and five-year local control was 86% and 83%; disease-free survival (DFS) was 73% and 66%, and overall survival (OS) was 79% and 68%, respectively. Differences in local tumour stage (5 year local control: T1/2 vs T3/4: 85% vs 75%) and in nodal status (5 year disease free survival: N0 vs N1: 74% vs 46%) had impact on clinical outcome [24]. Known prognostic factors for oncological outcome in primary vaginal cancer are age, lymph node metastases, stage, tumour size, and histological type [7]. In addition, the use of concurrent chemotherapy and the use of brachytherapy seems to result in better outcome [1, 14]. Results regarding oncological outcomes in the treatment of vaginal recurrences before and after the introduction of image-guided

11. MONITORING

Movements and displacement of cylinder-type applicators with or without additional use of interstitial needles are generally larger and more frequent than with tandem-ring applicators in cervical cancer [35]. Displacements typically imply caudal shifts or rotations and can cause major changes in the dose distribution. Therefore, optimal fixation of the applicator to avoid any shifts are of utmost importance. Recommendations for fixation are difficult as they depend on the local infrastructure and individual work flows. However, in general, perineal sutures or sutures through the labia majora and taping or bandages can substantially reduce movements and should be applied according to the applicator type