Hypofractionated postmastectomy radiotherapy with helical tomotherapy in patients with immediate breast reconstruction: dosimetric results and acute/intermediate toxicity evaluation

The aim of this study was to evaluate the dosimetry and toxicity of hypofractionation in postmastectomy radiotherapy (PMRT) with intensity-modulated radiotherapy (IMRT) in breast cancer (BC) patients. Stage II-III BC patients with implant-based immediate breast reconstruction received PMRT to the chest wall (CW) and to the infra/supraclavicular nodal region (NR) using a 15-fraction schedule (2.67 Gy/fraction) and helical IMRT (Tomotherapy^® System, Accuray Incorporated, Sunnyvale, CA). A score was assigned to each treatment plan in terms of planning target volume (PTV) coverage of CW and NR and the sparing of the organs at risk (OARs). The total score for each plan was calculated. Toxicity was prospectively assessed according to validated scales. Data from 120 consecutive patients treated in the period 2012-2015 were analysed with a median follow-up from the end of radiotherapy of 13.2 months (range 0.0-35 months). 70.8% (85/120) of the plans had high total scores as a result of an optimal coverage of both CW and RN and optimal sparing of all OARs. The maximum acute toxicity was of grade 2 in 36.7% of the cases. Early late toxicity was mild in the majority of cases. In the study population, helical tomotherapy-based IMRT produced optimal treatment plans in most cases. Acute and late toxicity was mild/moderate. Hypofractionated helical IMRT appears to be safe and feasible in the moderate term for PMRT.

Second Malignancies following Breast Cancer Treatment: A Case-Control Study Based on the Peridose Methodology. ALLEGRO Project (Task 5.4)

Aims and background

To calculate peripheral radiation dose to the second primary site in patients who have developed a second malignancy after breast cancer radiotherapy (index cases) and to compare it with dose in the analogous anatomical site in radiotherapy-treated breast cancer patients who did not experience a second malignancy (controls). To evaluate the feasibility of Peridose-software peripheral dose calculation in retrospective case-control studies.

Material and study design

A case-control study on 12,630 patients who underwent adjuvant breast radiotherapy was performed. Minimum 5-year follow-up was required. Each index case was matched with 5 controls by 1) year of birth, 2) year of radiotherapy and 3) follow-up duration. Peridose-software was used to calculate peripheral dose.

Results

195 second cancers were registered (0.019% of all patients treated with adjuvant irradiation). Several methodological limitations of the Peridose calculation were encountered including impossibility to calculate the peripheral dose in the patients treated with intraoperative or external electron beam radiotherapy, in case of second tumors located at <15 cm from the radiotherapy field etc. Moreover, Peridose requires full radiotherapy data and the distance between radiotherapy field and second primary site. Due to these intrinsic limitations, only 6 index cases were eligible for dose calculation. Calculated doses at the second cancer site in index cases and in an analogous site in controls ranged between 7.5 and 145 cGy. The mean index-control dose difference was −3.15 cGy (range, −15.8 cGy and +2.7 cGy).

Conclusions

The calculated peripheral doses were low and the index-control differences were small. However, the small number of eligible patients precludes a reliable analysis of a potential dose-response relationship. Large patient series followed for a long period and further improvement in the methodology of the peripheral dose calculation are necessary in order to overcome the methodological challenges of the study.

Salvage High Dose Rate Brachytherapy after Primary External Beam Irradiation in Localized Prostate Cancer: A Case Report

No standard treatment exists for locally relapsed prostate cancer after primary external beam radiotherapy with no evidence of distant metastases. Radical prostatectomy, brachytherapy, cryotherapy and high-intensity focused ultrasound are currently used as local salvage treatments. Data on the safety and effectiveness of high dose rate (HDR) brachytherapy in this scenario are limited. We report on a patient who has no evidence of disease and no late urinary or gastrointestinal toxicity 33 months after receiving HDR treatment for recurrent prostate cancer.

High-Dose-Rate Interstitial Brachytherapy in Early Stage Buccal Mucosa and Lip Cancer: Report on the Consecutive 12 Patients and Review of the Literature

Aims and background

To evaluate clinical outcome and toxicity using high-dose-rate brachytherapy as monotherapy in head and neck carcinomas.

Methods

Between September 2004 and April 2010, a series of 12 patients with lip (7 patients) or buccal mucosa (5 patients) cancers were treated by exclusive interstitial high-dose-rate brachytherapy. The median age of the patients was 71.5 years (range, 47–87). Stages were T1N0M0 and T2N0M0 in 6 and 6 patients, respectively. A dose of 27 to 54 Gy in 9 to 16 fractions, 3 to 4.5 Gy per fraction, 2 fractions per day with a minimal gap of 6 h in between was delivered.

Results

After a median follow-up of 46 months (range, 10–85), the disease-free and overall survival was 83% (10 of 12 patients) and 50% (6 of 12 patients), respectively. The crude local control in the lip cancer patients was 100% and in the buccal mucosa cancer patients was 60%. No severe toxicity was registered.

Conclusions

High-dose-rate brachytherapy is feasible and safe and offers the possibility to treat patients in an outpatient regimen.

Electron Beam Intraoperative Radiotherapy (ELIOT) in Pregnant Women with Breast Cancer: From in Vivo Dosimetry to Clinical Practice

BACKGROUND

The aim of this study was to confirm our preliminary results with in vivo dosimetry in non-pregnant breast cancer patients receiving electron beam intraoperative radiotherapy (ELIOT) and to report on the first treatment in a pregnant woman.

PATIENTS AND METHODS

Following our previous experience, 5 non-pregnant patients receiving ELIOT to the tumor bed after breast-conserving surgery (BCS) were studied with thermoluminescent dosimeters positioned in the subdiaphragmatic region, within the uterus, and in the ovarian region. In December 2011, the first pregnant breast cancer patient underwent BCS and ELIOT (21 Gy at 90% isodose) during the 15th week of gestation.

RESULTS

The mean dose to the subdiaphragmatic external region in the 5 non-pregnant patients was 5.57 mGy, while pelvic measurements were below 1 mGy. The actual dosimetry of the pregnant patient showed a mean subdiaphragmatic dose of 4.34 mGy, a mean suprapubic dose of 1.64 mGy, and mean ovarian doses of 1.48 mGy (right-sided) and 1.44 mGy (left-sided). The expected dose to the fetus was estimated as 0.84 mGy (0.004% of the prescribed dose).

CONCLUSION

ELIOT as an anticipated boost to the breast could be considered in pregnant women in the early second trimester, postponing whole-breast irradiation after delivery.

Recent advances in radiation oncology

Radiotherapy (RT) is very much a technology-driven treatment modality in the management of cancer. RT techniques have changed significantly over the past few decades, thanks to improvements in engineering and computing. We aim to highlight the recent developments in radiation oncology, focusing on the technological and biological advances. We will present state-of-the-art treatment techniques, employing photon beams, such as intensity-modulated RT, volumetric-modulated arc therapy, stereotactic body RT and adaptive RT, which make possible a highly tailored dose distribution with maximum normal tissue sparing. We will analyse all the steps involved in the treatment: imaging, delineation of the tumour and organs at risk, treatment planning and finally image-guidance for accurate tumour localisation before and during treatment delivery. Particular attention will be given to the crucial role that imaging plays throughout the entire process. In the case of adaptive RT, the precise identification of target volumes as well as the monitoring of tumour response/modification during the course of treatment is mainly based on multimodality imaging that integrates morphological, functional and metabolic information. Moreover, real-time imaging of the tumour is essential in breathing adaptive techniques to compensate for tumour motion due to respiration. Brief reference will be made to the recent spread of particle beam therapy, in particular to the use of protons, but also to the yet limited experience of using heavy particles such as carbon ions. Finally, we will analyse the latest biological advances in tumour targeting. Indeed, the effectiveness of RT has been improved not only by technological developments but also through the integration of radiobiological knowledge to produce more efficient and personalised treatment strategies.

Multimodal image registration for the identification of dominant intraprostatic lesion in high-precision radiotherapy treatments

PURPOSE

The integration of CT and multiparametric MRI (mpMRI) is a challenging task in high-precision radiotherapy for prostate cancer. A simple methodology for multimodal deformable image registration (DIR) of prostate cancer patients is presented.

METHODS

CT and mpMRI of 10 patients were considered. Organs at risk and prostate were contoured on both scans. The dominant intraprostatic lesion was additionally delineated on MRI. After a preliminary rigid image registration, the voxel intensity of all the segmented structures in both scans except the prostate was increased by a specific amount (a constant additional value, A), in order to enhance the contrast of the main organs influencing its position and shape. 70 couples of scans were obtained by varying A from 0 to 800 and they were subsequently non-rigidly registered. Quantities derived from image analysis and contour statistics were considered for the tuning of the best performing A.

RESULTS

A = 200 resulted the minimum enhancement value required to obtain statistically significant superior registration results. Mean centre of mass distance between corresponding structures decreases from 7.4 mm in rigid registration to 5.3 mm in DIR without enhancement (DIR-0) and to 2.7 mm in DIR with A = 200 (DIR-200). Mean contour distance was 2.5, 1.9 and 0.67 mm in rigid registration, DIR-0 and DIR-200, respectively. In DIR-200 mean contours overlap increases of +13 and +24% with respect to DIR-0 and rigid registration, respectively.

CONCLUSION

Contour propagation according to the vector field resulting from DIR-200 allows the delineation of dominant intraprostatic lesion on CT scan and its use for high-precision radiotherapy treatment planning. Advances in knowledge: We investigated the application of a B-spline, mutual information-based multimodal DIR coupled with a simple, patient-unspecific but efficient contrast enhancement procedure in the pelvic body area, thus obtaining a robust and accurate methodology to transfer the functional information deriving from mpMRI onto a planning CT reference volume.

Dosimetric characterization of 3D printed bolus at different infill percentage for external photon beam radiotherapy

BACKGROUND AND PURPOSE

3D printing is rapidly evolving and further assessment of materials and technique is required for clinical applications. We evaluated 3D printed boluses with acrylonitrile butadiene styrene (ABS) and polylactide (PLA) at different infill percentage.

MATERIAL AND METHODS

A low-cost 3D printer was used. The influence of the air inclusion within the 3D printed boluses was assessed thoroughly both with treatment planning system (TPS) and with physical measurements. For each bolus, two treatment plans were calculated with Monte Carlo algorithm, considering the computed tomography (CT) scan of the 3D printed bolus or modelling the 3D printed bolus as a virtual bolus structure with a homogeneous density. Depth dose measurements were performed with Gafchromic films.

RESULTS

High infill percentage corresponds to high density and high homogeneity within bolus material. The approximation of the bolus in the TPS as a homogeneous material is satisfying for infill percentages greater than 20%. Measurements performed with PLA boluses are more comparable to the TPS calculated profiles. For boluses printed at 40% and 60% infill, the discrepancies between calculated and measured dose distribution are within 5%.

CONCLUSIONS

3D printing technology allows modulating the shift of the build-up region by tuning the infill percentage of the 3D printed bolus in order to improve superficial target coverage.