Organ and Function Preservation in Gastrointestinal Malignancies.

Radiation plays an important role in organ preservation for gastrointestinal malignancies, with a watch and wait strategy enabling surgery to be avoided in patients who are not suitable or who are refusing surgery. Brachytherapy boost allows the radiation dose to be escalated, which plays a pivotal role in the successful outcome of achieving organ preservation. Here we describe the role of brachytherapy in two common gastrointestinal malignancies (oesophagus and rectum). Their indications and how the brachytherapy procedures are carried out, together with the dose and fractionation commonly used are discussed. The use of brachytherapy needs to be included in the training curriculum at all academic centres so that its use is developed by the newer generation of radiation oncologists. Its current non-use due to bias, lack of training and availability is no longer justified, given the overwhelming published evidence for the role of brachytherapy to improve organ preservation for both radical treatment and palliation in gastrointestinal malignancies.

Relationship of Urethral Dose and Genitourinary Toxicity Among Patients Receiving Vaginal High Dose Rate Interstitial Brachytherapy.

AIMS: Interstitial brachytherapy (ISBT) plays an important role in the management of locally advanced gynaecological malignancies. However, the relationship between urinary toxicity and dose to the urethra is not well understood. We sought to evaluate the correlation between urethral dose and the incidence of genitourinary complications among patients undergoing vaginal high dose rate ISBT. MATERIALS AND METHODS: Eighty-three patients treated with ISBT between August 2014 and April 2018 were retrospectively reviewed. CTCAE version 5.0 was used to grade toxicity. Individual treatment plans were evaluated to collect dose parameters. Urethral contours were added to the structure sets using a uniform 1 cm diameter brush and minimum doses to the hottest 0.1, 0.2 and 0.5 cm3 (D0.1cm3, D0.2cm3 and D0.5cm3) of the urethra were obtained. Total (ISBT ± external beam radiotherapy) equivalent doses in 2 Gy fractions (EQD2) received by the targets and organs at risk were calculated. Numerical counts (%) and medians (interquartile range) were used to characterise the data. Fisher's exact and the Mann-Whitney-Wilcox tests were used as appropriate. Receiver operator curve analysis was used to define the urethral threshold dose that correlated to genitourinary toxicity. RESULTS: The median age and follow-up times were 67 years (59-75) and 25 months (16-37), respectively. Patients had predominantly primary endometrial (49%) and vaginal (37%) cancer, with four (5%) patients with metastatic rectal cancer to the vagina. Twenty-four of 79 (30%) patients experienced acute genitourinary toxicity and 34 of 71 (48%) experienced late genitourinary toxicity. In both analyses, the median urethral dose was significantly higher among those with toxicity. Receiver operator curve analysis indicated that D0.1cm3, D0.2cm3 and D0.5cm3 of the urethra were associated with the development of toxicity at doses >78, >71 and >62 Gy, respectively. CONCLUSION: Urethral dose seems to predict genitourinary toxicity in ISBT of vaginal tumours. Further study with an expanded cohort and longer follow-up is warranted.

Salvage Re-irradiation With Single-modality Interstitial Brachytherapy for the Treatment of Recurrent Gynaecological Tumours in the Pelvis: A Multi-institutional Study.

AIMS: Recurrent gynaecological tumours can cause significant morbidity with limited salvage options. This study investigates the strategy of salvage single-modality interstitial brachytherapy (SM-ISBT) for recurrent gynaecological pelvic cancer at two specialised ISBT centres. MATERIALS AND METHODS: Patients who had received salvage SM-ISBT for pelvic recurrence of gynaecological cancers from September 2008 to January 2017 were included. None had distant metastasis at the time of recurrence. Local control, progression-free and overall survival and long-term toxicities were evaluated. RESULTS: Twenty-six patients with a median follow-up of 24 months (range 2.5-106.3 months) after SM-ISBT were included. Primary cancer sites were endometrium (20), cervix (4), vulva (1) and vagina (1). All patients had prior whole-pelvic external beam irradiation and 16 had prior brachytherapy. The median disease-free survival prior to SM-ISBT was 20.3 months (interquartile range 9.9-30.5). SM-ISBT was delivered with high dose rate technique over three to six fractions. The median high-risk clinical target volume was 34.6 cm3, with a median D90 of 29.1 Gy (range 16.1-64.6). The median bladder, rectum and sigmoid D2cm3 were 15.5, 18.7 and 3.7 Gy, respectively. After SM-ISBT, complete and partial responses were achieved in 17 (64%) and 5 (19%) patients, respectively. Two (7.4%) patients had grade 3 toxicities (both vaginal stenosis), with no grade 4 complications. Eighteen patients (69%) recurred, including local, regional and metastatic in 14 (54%), 8 (30%) and 5 (19%) patients, respectively. Two-year local control, progression-free survival and overall survival were 50, 38 and 78%, respectively. In follow-up, 12 patients (46%) remained in local control. CONCLUSIONS: Salvage SM-ISBT re-irradiation for pelvic recurrence of gynaecological malignancies was feasible and safe. With limited salvage options, the local control obtained in more than a quarter of patients seems reasonable. Further efforts are needed to establish a consensus about the optimal patient selection, dose fractionation, implant technique and combination with systemic therapies.