Can adjuvant pelvic radiation therapy after local excision or polypectomy for T1 and T2 rectal cancer offer an alternative option to radical surgery?

PURPOSE: To determine outcomes after adjuvant pelvic local radiation therapy (RT) +/- concurrent chemotherapy for T1 and T2 rectal carcinomas treated with local excision or polypectomy. METHODS: We retrospectively identified adult patients with histologically proven T1 and T2 rectal adenocarcinoma, diagnosed incidentally at time of local excision or polypectomy between 01 January 2007 and 31 December 2019, and appropriately staged to confirm N0 M0 status. Patients were excluded if they had recurrent cancer or had received total mesorectal excision (TME): anterior resection (AR) or abdominoperineal resection (APR). Patient, tumour and treatment factors, together with disease and toxicity outcomes were collected from institutional medical records, correspondence and investigation reports. Descriptive statistical analyses were employed. The primary endpoint was loco-regional control and secondary endpoints were treatment-related toxicity, disease free survival, overall survival and rate of surgical salvage for pelvic recurrence. RESULTS: The median age of the 15 eligible patients was 73 (range 49-82 years). There were 9 men (60%) and 6 women (40%). The majority had T1 disease (80%) and most had received endomucosal resection (80%). All patients received 43-52Gy (EQD2) to the primary and 43-48Gy (EQD2) to the pelvis with 46.6% receiving concurrent chemotherapy (infusional 5-FU or oral capecitabine). At median follow up of 51 months, there were no local or regional recurrences. One patient experienced an isolated distant relapse at 48 months without any locoregional recurrence. CONCLUSION: Our findings demonstrate good locoregional disease control with the use of adjuvant pelvic RT for T1 and T2 rectal adenocarcinoma initially treated with polypectomy or local (non-oncological) excision. These findings indicate that adjuvant pelvic RT may provide an alternative to TME surgery in patients with incidentally detected early rectal cancers.

Patient-Specific Heart Constraint: A Tool for Optimization and Evaluation of Mean Heart Dose in Breast Cancer Patients.

PURPOSE: Our institution introduced a patient-specific heart constraint (PSHC) and a mean heart dose (MHD) constraint of 4 Gy for all patients receiving breast radiation therapy (RT) with a simultaneous boost (SIB). This was introduced as a method to calculate the predicted MHD before optimizing IMRT fields. We sought to determine whether the introduction of a PSHC reduced MHD, while maintaining optimally dosed treatment plans. MATERIAL/METHODS: Patients were retrospectively divided into 2 groups, pre- and postintroduction of the PSHC. The breast and SIB Planning Target Volumes (PTVs) were prescribed to 50 Gy and 57 Gy, respectively, in 25 fractions. Plans were generated using a hybrid IMRT technique, 30 Gy using an open tangential field arrangement, and 27 Gy using IMRT fields. The PSHC was calculated using MHD of open tangential field × 2. A paired t test compared PTV coverage and heart doses between cohorts (P < .05 significant). RESULTS: A total of 264 patients were included (138 pre-PSHC and 126 post-PSHC) with 137 right-sided and 127 left-sided treatments. MHD was significantly reduced across both right-sided (-0.4 Gy, P < .0001) and left-sided (-1.2 Gy, P < .0001) treatments overall. Left-sided treatments were further examined between free breathing and deep inspiration breath-hold (DIBH). DIBH showed reduction in MHD, although it was not significant (-0.46 Gy, P = .34). Heart V5 Gy showed reduction in right-sided (-1%, P = .002) and left-sided (-9.2%, P < .0001) treatments overall. Left-sided free breathing showed significant reduction (-8.8%, P < .0001), and DIBH also showed significant reduction (-5.1%, P = .0034). Tumor bed doses remained above the 54.15 Gy (95% of 57 Gy) threshold for all plans. CONCLUSION: Introduction of a PSHC can reduce MHD and V5 Gy for patients receiving whole breast RT with SIB while maintaining optimally dosed plans, with the greatest benefit shown for left-sided, free-breathing treatments.

Left-sided breast cancer loco-regional radiotherapy with deep inspiration breath-hold: Does volumetric-modulated arc radiotherapy reduce heart dose further compared with tangential intensity-modulated radiotherapy?

INTRODUCTION: Left-sided breast cancer radiotherapy has been associated with an increase in cardiac mortality. This study investigated the potential heart-sparing effect of volumetric-modulated arc radiotherapy (VMAT). We compared VMAT to tangential intensity-modulated radiotherapy (t-IMRT) in the loco-regional treatment of left-sided breast cancer, including internal mammary nodal irradiation, based on deep inspiration breath-hold (DIBH) and free-breathing (FB). METHODS: Radiotherapy for 15 patients was re-planned. Four plans were compared: t-IMRT-DIBH; VMAT-DIBH; t-IMRT-FB; VMAT-FB. Prescribed dose was 50 Gy in 25 fractions. T-IMRT plans were generated using tangentially orientated fields. VMAT plans were generated using two partial arcs (average arc 190°). RESULTS: Mean heart dose (MHD) was 5 ± 2.4 Gy, 5.7 ± 1.4 Gy, 9.7 ± 3.3 Gy and 8.1 ± 2.0 Gy for t-IMRT-DIBH, VMAT-DIBH, IMRT-FB and VMAT-FB respectively. The difference in MHD between IMRT-DIBH and VMAT-DIBH was not significant (P = 0.14). VMAT-DIBH significantly spared the volume of heart irradiated to doses of 20 Gy and above (p < 0.05), however, resulted in a significantly higher V5 Gy (P < 0.001), compared to t-IMRT-DIBH. VMAT-DIBH resulted in higher combined lung mean (11 ± 0.8 Gy vs. 8.8 ± 1.1 Gy, P < 0.001) and higher contralateral breast mean dose (5 ± 1 Gy vs. 1.6 ± 1.2 Gy, P < 0.001) compared with t-IMRT-DIBH. CONCLUSIONS: On average, there was no significant difference in MHD between VMAT-DIBH and t-IMRT-DIBH. However, VMAT-DIBH was found to benefit a select group of patients. For patients in whom the MHD was >6.3 Gy with t-IMRT-DIBH, the use of VMAT-DIBH resulted in a benefit in reducing the MHD.

A phantom assessment of achievable contouring concordance across multiple treatment planning systems.

In this paper, the highest level of inter- and intra-observer conformity achievable with different treatment planning systems (TPSs), contouring tools, shapes, and sites have been established for metrics including the Dice similarity coefficient (DICE) and Hausdorff Distance. High conformity values, e.g. DICE(Breast_Shape)=0.99±0.01, were achieved. Decreasing image resolution decreased contouring conformity.

Review of deep inspiration breath-hold techniques for the treatment of breast cancer.

Radiation treatment to the left breast is associated with increased cardiac morbidity and mortality. The deep inspiration breath-hold technique (DIBH) can decrease radiation dose delivered to the heart and this may facilitate the treatment of the internal mammary chain nodes. The aim of this review is to critically analyse the literature available in relation to breath-hold methods, implementation, utilisation, patient compliance, planning methods and treatment verification of the DIBH technique. Despite variation in the literature regarding the DIBH delivery method, patient coaching, visual feedback mechanisms and treatment verification, all methods of DIBH delivery reduce radiation dose to the heart. Further research is required to determine optimum protocols for patient training and treatment verification to ensure the technique is delivered successfully.