The role of radiotherapy in newly diagnosed primary CNS lymphoma: A descriptive review and a pragmatic approach to clinical practice.

Earlier, prior to the development of effective systemic therapy, monotherapy with whole-brain radiotherapy (WBRT) was widely used to treat primary central nervous system lymphoma (PCNSL). Recently, chemotherapy, especially with high dose methotrexate (HDMTX), has largely replaced WBRT as upfront treatment, and the most accepted standard of care is induction with a combination drug therapy followed by consolidation therapy with either autologous stem-cell transplantation (ASCT) or radiation. Whilst WBRT is an effective component of treatment, it is occasionally associated with risk of permanent, irreversible neurotoxicity when doses of more than 30 Gy are used. Hence, there has been a strong focus on the optimization of radiotherapy (RT) which includes dose reduction in the consolidation phase. In this comprehensive review, we have summarized the progress on clinical results and evidence considering the role and use of radiation including combined treatment modalities, low-dose radiotherapy, and neurotoxicity. Finally, we present a practical approach to low-dose WBRT and boosting higher doses to the gross tumor that can be integrated into clinical practice.

Real-world clinical outcomes with daily image-guided IMRT in extremity soft tissue sarcomas.

PURPOSE: We report the clinical outcomes of patients with soft tissue sarcomas (STS) arising in extremities treated with image-guided intensity modulated radiotherapy (IG-IMRT) at our institute. Local control of the tumors treated with RT was the primary end point of this study. Analyzing overall survival and long-term toxicities were the secondary objectives. METHODS AND MATERIALS: The database of the patients with STS who received wide local excision and IG-IMRT at our institution from January 2012 to December 2020 was reviewed. Radiation was offered either preoperatively or postoperatively as part of multi-modality treatment. RESULTS: Thirty-three consecutive patients were identified and included for analysis. Twenty-eight patients (84.8%) received postoperative adjuvant radiotherapy. Dedicated MRI simulation studies were performed in 31 patients (93.9%) in the treatment position. RapidArc IMRT technique was used in 31 patients (93.9%). A total of 2954 images were acquired during 991 treatment sessions. Errors exceeding 1 mm in the x, y and z directions were corrected online before the treatment. With a median follow-up of 36 months, two patients (6.1%) developed local recurrence. The 3-year local control was 90.9% (95% CI, 0.76 - 0.98), and the 5-year overall survival was 71.7% (95% CI, 0.44 - 0.88). One patient (3.03%) sustained a pathological fracture during the follow-up period. CONCLUSION: Our results showed that IMRT with daily imaging offered excellent local control with acceptable long-term toxicity, as well as being feasible and practical to implement in our routine clinical practice.

Delineating and sparing functional nephrons for radiotherapy in the case of lymphoma with polycystic kidney disease.

PURPOSE: It is imperative to spare functioning kidneys from high radiation doses when they are near enough to radiotherapy (RT) target volumes in patients with polycystic kidney disease (PKD). To achieve this intent, we designed the unique approach that we report here. METHODS AND MATERIALS: The patient who has PKD, presented with B-cell lymphoma involving paraaortic lymph nodes. After completing chemotherapy, RT was planned to the residual nodal disease. The diagnostic positron emission tomography computed tomography (PETCT) scan was fused with the RT planning CT scan. 18F-2-deoxy-2(F)-fluro-d-glucose (FDG) avid active kidneys were contoured separately, and the treatment plan was optimized to avoid these volumes. RESULTS: The functional volume was 17.52% of the right kidney whereas it was 7.44% of the left. The mean doses were 4.61 Gy and 4.2 Gy, respectively. The baseline estimated glomerular filtration rate (eGFR) was >60 mL/min; at 18 months follow-up, it was 62 mL/min. CONCLUSIONS: Delineation of functional nephrons was feasible while utilizing the staging FDG-PETCT scan for radiotherapy contouring in our patient, which aided to achieve the optimal dose-volume constraints. Further studies are warranted to analyze and quantify the benefit of this easily accessible method in the future.

Voluntary Deep Inspiration Breath-hold Reduces the Heart Dose Without Compromising the Target Volume Coverage During Radiotherapy for Left-sided Breast Cancer.

BACKGROUND: During radiotherapy of left-sided breast cancer, parts of the heart are irradiated, which may lead to late toxicity. We report on the experience of single institution with cardiac-sparing radiotherapy using voluntary deep inspiration breath hold (V-DIBH) and compare its dosimetric outcome with free breathing (FB) technique. PATIENTS AND METHODS: Left-sided breast cancer patients, treated at our department with postoperative radiotherapy of breast/chest wall +/- regional lymph nodes between May 2015 and January 2017, were considered for inclusion. FB-computed tomography (CT) was obtained and dose-planning performed. Cases with cardiac V25Gy ≥ 5% or risk factors for heart disease were coached for V-DIBH. Compliant patients were included. They underwent additional CT in V-DIBH for planning, followed by V-DIBH radiotherapy. Dose volume histogram parameters for heart, lung and optimized planning target volume (OPTV) were compared between FB and BH. Treatment setup shifts and systematic and random errors for V-DIBH technique were compared with FB historic control. RESULTS: Sixty-three patients were considered for V-DIBH. Nine (14.3%) were non-compliant at coaching, leaving 54 cases for analysis. When compared with FB, V-DIBH resulted in a significant reduction of mean cardiac dose from 6.1 +/- 2.5 to 3.2 +/- 1.4 Gy (p < 0.001), maximum cardiac dose from 51.1 +/- 1.4 to 48.5 +/- 6.8 Gy (p = 0.005) and cardiac V25Gy from 8.5 +/- 4.2 to 3.2 +/- 2.5% (p < 0.001). Heart volumes receiving low (10-20 Gy) and high (30-50 Gy) doses were also significantly reduced. Mean dose to the left anterior coronary artery was 23.0 (+/- 6.7) Gy and 14.8 (+/- 7.6) Gy on FB and V-DIBH, respectively (p < 0.001). Differences between FB- and V-DIBH-derived mean lung dose (11.3 +/- 3.2 vs. 10.6 +/- 2.6 Gy), lung V20Gy (20.5 +/- 7 vs. 19.5 +/- 5.1 Gy) and V95% for the OPTV (95.6 +/- 4.1 vs. 95.2 +/- 6.3%) were non-significant. V-DIBH-derived mean shifts for initial patient setup were ≤ 2.7 mm. Random and systematic errors were ≤ 2.1 mm. These results did not differ significantly from historic FB controls. CONCLUSIONS: When compared with FB, V-DIBH demonstrated high setup accuracy and enabled significant reduction of cardiac doses without compromising the target volume coverage. Differences in lung doses were non-significant.

MRI Reduces Variation of Contouring for Boost Clinical Target Volume in Breast Cancer Patients Without Surgical Clips in the Tumour Bed.

BACKGROUND: Omitting the placement of clips inside tumour bed during breast cancer surgery poses a challenge for delineation of lumpectomy cavity clinical target volume (CTVLC). We aimed to quantify inter-observer variation and accuracy for CT- and MRI-based segmentation of CTVLC in patients without clips. PATIENTS AND METHODS: CT- and MRI-simulator images of 12 breast cancer patients, treated by breast conserving surgery and radiotherapy, were included in this study. Five radiation oncologists recorded the cavity visualization score (CVS) and delineated CTVLC on both modalities. Expert-consensus (EC) contours were delineated by a senior radiation oncologist, respecting opinions of all observers. Inter-observer volumetric variation and generalized conformity index (CIgen) were calculated. Deviations from EC contour were quantified by the accuracy index (AI) and inter-delineation distances (IDD). RESULTS: Mean CVS was 3.88 +/- 0.99 and 3.05 +/- 1.07 for MRI and CT, respectively (p = 0.001). Mean volumes of CTVLC were similar: 154 +/- 26 cm3 on CT and 152 +/- 19 cm3 on MRI. Mean CIgen and AI were superior for MRI when compared with CT (CIgen: 0.74 +/- 0.07 vs. 0.67 +/- 0.12, p = 0.007; AI: 0.81 +/- 0.04 vs. 0.76 +/- 0.07; p = 0.004). CIgen and AI increased with increasing CVS. Mean IDD was 3 mm +/- 1.5 mm and 3.6 mm +/- 2.3 mm for MRI and CT, respectively (p = 0.017). CONCLUSIONS: When compared with CT, MRI improved visualization of post-lumpectomy changes, reduced interobserver variation and improved the accuracy of CTVLC contouring in patients without clips in the tumour bed. Further studies with bigger sample sizes are needed to confirm our findings.