In vivo dosimetry in pelvic brachytherapy.

ADVANCES IN KNOWLEDGE: This paper describes the potential role for in vivo dosimetry in the reduction of uncertainties in pelvic brachytherapy, the pertinent factors for consideration in clinical practice, and the future potential for in vivo dosimetry in the personalisation of brachytherapy.

Anal squamous cell carcinoma: a retrospective case series.

BACKGROUND: Anal cancer is a relatively rare cancer with 660 cases diagnosed in 2000-2015 in Ireland (1). The current standard treatment is radical chemoradiotherapy (CRT). The aim of our study was to review the treatment and outcomes of patients with localised anal squamous cell carcinoma (SCC), who received radical treatment in our radiation oncology network between 2008 and 2014 inclusive. METHODS: Data were collected retrospectively from ARIA® oncology information system and patient charts. Statistical analyses were performed using IBM® SPSS® statistical software version 25.0. RESULTS: Seventy-nine cases of anal SCC were identified. Mean age of patients at commencement of radiotherapy (RT) was 60.2 years (standard deviation: 13.1 years). The most common total RT dose was 50.4 Gy in 28 fractions (N = 58; 73.4%). Median follow-up was 5.6 years. Two (2.6%) patients had persistent disease, seventeen (21.8%) patients developed loco-regional recurrence and nine (11.5%) patients developed solid organ metastases, four of whom had complete treatment response at the primary site. Eight patients underwent salvage anal surgery following completion of RT. Median overall survival was 10.5 years (95% confidence interval (CI) 5.1-15.8 years), median loco-regional relapse-free survival was 10.4 years (95% CI 4.4-16.3 years) and median disease-free survival was 9.3 years (95% CI 6.3-12.2 years). CONCLUSION: Our study demonstrates that treatment for anal SCC and outcomes following definitive CRT in Ireland during the study period were comparable to international standards.

Deep inspiration breath hold versus free breathing technique in mediastinal radiotherapy for lymphoma.

OBJECTIVE: Radiotherapy plays an important role in the management of lymphoma and many patients with lymphoma are cured with treatment. Risk of secondary malignancy and long-term cardiac and pulmonary toxicity from mediastinal radiotherapy exists. Delivery of radiotherapy using a deep inspiration breath-hold (DIBH) technique increases lung volume and has the potential to reduce dose to heart and lungs. We undertook a prospective study to assess the dosimetric differences in DIBH and free breathing (FB) plans in patients requiring mediastinal radiotherapy in clinical practice. METHODS: We performed both FB and DIBH planning scans on 35 consecutive patients with mediastinal lymphoma needing radiotherapy. Contours and plans were generated for both data sets and dosimetric data were compared. All patients were planned using volumetric modulated arc therapy (VMAT). Data were compared for FB and DIBH plans with each patient acting as their own control using the related-samples Wilcoxon signed rank test. RESULTS: DIBH significantly reduced lung doses (mean 10.6 vs 11.4Gy, p < 0.0005; V20 16.8 vs 18.3%, p = 0.001) and spinal cord maximum dose (20.6 vs 22.8Gy, p = 0.001). DIBH increased breast V4 (38.5% vs 31.8%, p = 0.006) and mean right breast dose (4.2 vs 3.6Gy, p = 0.010). There was no significant difference in heart doses when the entire study cohort was considered, however, mean heart dose tended to be lower with DIBH for upper mediastinal (UM) tumours (4.3 vs 4.9Gy, p = 0.05). CONCLUSION: Our study describes the potential benefit of DIBH in a population reflective of clinical practice. DIBH can decrease radiation dose to lungs, heart and spinal cord, however, may increase dose to breasts. DIBH is not always superior to FB, and the clinical significance of differences in dose to organs at risk in addition to the time required to treat patients with DIBH must be considered when deciding the most appropriate radiotherapy technique for each patient. ADVANCES IN KNOWLEDGE: To our knowledge, this is the largest study comparing DIBH and FB planning for patients with lymphoma receiving mediastinal radiotherapy in clinical practice. It demonstrates the impact of an increasingly common radiotherapy technique on dose to organs at risk and the subsequent potential for long-term radiotherapy side-effects.