Large Prostate Volume Does Not Negatively Impact Health-Related Quality of Life in Patients with Prostate Cancer Treated with Ultrahypofractionated Stereotactic Body Radiotherapy.

BACKGROUND: Survival outcomes after primary radiotherapy for localized prostate cancer (PCa) are excellent, regardless of the specific treatment modality. For this reason, health-related quality of life (HRQOL) has come to play an ever more important role in treatment selection. Stereotactic body radiation therapy (SBRT) is increasingly used to treat patients with PCa. However, the impact of prostate volume on HRQOL is not clear. In this study, we aimed to determine whether a large prostate volume negatively influences HRQOL outcomes in patients undergoing ultrahypofractionated SBRT. MATERIAL AND METHODS: We conducted a prospective study of 530 men with low- and intermediate-risk localized PCa. All patients were treated from 2013 to 2017 with SBRT (Cyberknife system). HRQOL data were collected at baseline (pre-treatment), immediately after treatment, and at 12 and 24 months. QOL variables were assessed with the European Organization for Research and Treatment of Cancer QLQ-C30 and PR-25 module. Differences in the QLQ-C30 scales were considered clinically relevant when the change was >10 points. For the analysis, patients were classified into two groups according to prostate volume (≤60 vs. >60 cm3). RESULTS: The prostate volume was ≤60 cm3 in 415 patients (78.3%) and >60 cm3 in 115 (21.7%). No between-group differences were observed at baseline for any of the following variables: clinical stage; hormonal therapy; marital status; educational level; or employment status. No clinically-significant deterioration (functional and symptom scales) was observed in either group between the baseline and 24-month assessment. There were no clinically-relevant differences between the groups on any of the HRQOL variables, regardless of the prostate volume. CONCLUSIONS: This study shows that a large prostate volume (>60 cm3) does not appear to negatively impact HRQOL outcomes at two years in patients with localized prostate cancer treated with ultrahypofractionated SBRT administered with the CyberKnife system.

Dosimetric Comparison of Ultra-Hypofractionated and Conventionally Fractionated Radiation Therapy Boosts for Patients with High-Risk Prostate Cancer.

Recent comparison of an ultra-hypofractionated radiotherapy (UF-RT) boost to a conventionally fractionated (CF-RT) option showed similar toxicity and disease control outcomes. An analysis of the treatment plans for these patients is needed for evaluating calculated doses for different organs, treatment beam-on time, and requirements for human and financial resources. Eighty-six plans for UF-RT and 93 plans for CF-RT schemes were evaluated. The biologically equivalent dose, EQD2, summed for the first phase and the boost, was calculated for dose-volume parameters for organs at risk (OARs), as well as for the PTV1. ArcCHECK measurements for the boost plans were used for a comparison of planned and delivered doses. Monitor units and beam-on times were recorded by the Eclipse treatment planning system. Statistical analysis was performed with a significance level of 0.05. Dosimetric parameter values for OARs were well within tolerance for both groups. EQD2 for the PTV1 was on average 84 Gy for UF-RT patients and 76 Gy for CF-RT patients. Gamma passing rate for planned/delivered doses comparison was above 98% for both groups with 3 mm/3% distance to agreement/dose difference criteria. Total monitor units per fraction were 647 ± 94 and 2034 ± 570 for CF-RT and UF-RT, respectively. The total delivery time for boost radiation for the patients in the UF-RT arm was, on average, four times less than the total time for a conventional regimen with statistically equal clinical outcomes for the two arms in this study.

Impact of different optimization strategies on the compatibility between planned and delivered doses during radiation therapy of cervical cancer.

PURPOSE: To analyse the impact of different optimization strategies on the compatibility between planned and delivered doses during radiotherapy of cervical cancer. MATERIAL/METHODS: Four treatment plans differing in optimisation strategies were prepared for ten cervical cancer cases. These were: volumetric modulated arc therapy with (_OPT) and without optimization of the doses in the bone marrow and for two sets of margins applied to the clinical target volume that arose from image guidance based on the bones (IG(B)) and soft tissues (IG(ST)). The plans were subjected to dosimetric verification by using the ArcCHECK system and 3DVH software. The planned dose distributions were compared with the corresponding measured dose distributions in the light of complexity of the plans and its deliverability. RESULTS: The clinically significant impact of the plans complexity on their deliverability is visible only for the gamma passing rates analysis performed in a local mode and directly in the organs. While more general analyses show statistically significant differences, the clinical relevance of them has not been confirmed. The analysis showed that IG(ST)_OPT and IG(B)_OPT significantly differ from IG(ST) and IG(B). The clinical acceptance of IG(ST)_OPT obtained for hard combinations of gamma acceptance criteria (2%/2 mm) confirm its satisfactory deliverability. In turn, for IG(B)_OPT in the case of the rectum, the combination of 2%/2 mm did not meet the criteria of acceptance. CONCLUSION: Despite the complexity of the IG(ST)_OPT, the results of analysis confirm the acceptance of its deliverability when 2%/2 mm gamma acceptance criteria are used during the analysis.

Relations between dose cumulated in organs at risk and treatment based on different image-guidance strategies of cervical cancer.

PURPOSE: In this study, relations between dose cumulated in organs at risk and treatment based on different image guidance strategies (IG) of cervical cancer were analyzed. MATERIAL/METHODS: Thirty patients with cervical cancer were subjected to analysis. The first phase of the study involved analysis of shifts resulting from the registration process and calculations of margins based on shifts data. The margin was calculated for two imaging scenarios - based on the analysis of bones and soft tissues. The margins thus obtained were used in the second phase of the study where the VMAT and IMRT treatment plans were prepared and, in consequence, analyzed in the light of the dose distribution. RESULTS: Using different IG implicates different margins for specified parts of the CTV. IG based on bones allows to establish margins for lymph nodes (CTV2) that are smaller than margins for the vagina/paravaginal tissues (CTV1). The opposite applies to the IG based on soft tissues, for which margins for CTV1 are smaller than for CTV2. While decreasing the margins for CTV1 reduces the doses in the bladder and rectum, doses cumulated in the bone marrow are independent of the size of the margin resulting from the type of IG used. Nevertheless, the average doses and the values of normal tissue complication probability in the bone marrow were smaller for VMAT than for IMRT. CONCLUSION: The VMAT plan and image guidance based on soft tissue registration for the vagina/paravaginal tissues are recommended for radiotherapy of cervical cancer patients.

Relations between doses cumulated in bone marrow and dose delivery techniques during radiation therapy of cervical and endometrial cancer.

PURPOSE: To compare normal tissue complication probability (NTCP) and average doses in the bone marrow (BM), obtained for five different radiotherapy delivery and planning strategies of cervical and endometrial cancer. MATERIAL/METHODS: 50 patients were taken to analysis. For each case, 3 different dose delivery techniques were used: 4-field, X15MV, 3DCRT; 7-field, X6MV, IMRT; and 2-arc, X6MV, VMAT. Two optimization scenarios were used for the IMRT and VMAT plans generation: with (+) and without (-) the inclusion of the BM as an optimized structure. Average doses and dose-volume histogram parameters for the PTV, BM, bladder, rectum, bowels and femoral heads were compared. In addition, the BM doses were analyzed with respect to the PTV and/or volume of the BM, and NTCP for the BM were computed. RESULTS: The dose in PTV for evaluated plans was similar. The worst doses in organs at risk were obtained for 3DCRT. Using the BM during the optimization of IMRT and VMAT reduces an average dose in BM without increasing the doses in the bladder, rectum and bowels. Differences between doses in BM for IMRT(+) and VMAT(+) plans were similar while NTCP was lower for VMAT(+). A correlation between average dose in BM and the volume ratio of BM and PTV was found for each technique. CONCLUSION: Using the BM during the optimization of the IMRT and VMAT plans effectively reduces the dose in BM without increasing the dose in the bladder, rectum and bowels. The VMAT(+) plans were characterized by the lowest NTCP.

Conversion of the helical tomotherapy plans to the step-and-shoot IMRT plans for patients with hip prosthesis during radiotherapy for prostate cancer.

PURPOSE: To evaluate the SharePlan software in conversion of helical tomotherapy (HT) to a step and shoot IMRT (sIMRT) for patients with high-risk prostate cancer and hip prosthesis. METHODS: Analysis was performed for 16 consecutive patients treated on HT. The HT plans were converted to sIMRT plans. 3DCRT, sliding window IMRT (dIMRT) and VMAT plans for a c-arm linear accelerator (CLA) were created manually. The doses in planning target volume (PTV), bladder, rectum, bowels, femoral heads and hip prosthesis were compared using: (i) a qualitative analysis of doses in averaged dose-volume histograms, (ii) a quantitative, ranking procedure performed for each patient separately, and (iii) statistical testing based on the Friedman ANOVA and Nemenyi method. RESULTS: For the bladder, rectum, and femoral head, the best dose distributions were observed for HT and sIMRT and then for dIMRT, VMAT, and finally for 3DCRT (p-values were, respectively, 0.002, 0.004 and p = 0.024). For the bowels, 3DCRT was significantly different from the rest of the techniques (p = 0.009). For the hip prosthesis, the differences were only between 3DCRT and HT/sIMRT (p = 0.038). CONCLUSION: The SharePlan is an efficient tool for the conversion of HT plans for patients with prostate cancer and hip prosthesis. Dose distributions in sIMRT and in HT plans are similar and are generally better than in CLA plans.

Estimation of the planning organ at risk volume for the lenses during radiation therapy for nasal cavity and paranasal sinus cancer.

INTRODUCTION: To establish the optimal planning risk volume (PRV) of the lenses for patients who are receiving radiotherapy to the nasal cavity and paranasal sinus (NCPSC). METHODS: Geometrical uncertainties of the lenses were evaluated for a prospective group of patients (G1). Differences between planned and delivered maximum doses to the lenses were evaluated for every fraction. The relationship between dose differences and geometrical uncertainties were analysed to establish an optimal PRV for the lenses. Obtained results were verified in the second group (G2) of patients for whom calculated PRV was applied. RESULTS: Data of 426 observations for 15 patients from G1 were investigated. The systematic and random errors equalled, respectively, 0.6 mm and 2.3 mm in the medio-lateral direction; 0.8 mm and 1.6 mm in the cranio-caudal direction; and 0.4 mm and 1.5 mm in the anterio-posterior direction. The clinical PRV for the lenses was established at 2 mm. Applied margin was evaluated for 10 patients from G2. The dose distribution in the planning target volume (PTV) for G1 and for G2 was comparable (P = 0.122), whereas the differences between planned and delivered doses in the lenses were significantly smaller for G2 (P = 0.013). CONCLUSION: The study showed that for radiotherapy of NCPSC, the PRV for the lenses could be defined as 2 mm. This margin does not affect the dose distribution in the PTV and effectively reduces the differences between planned and delivered doses in the lenses.

Impact of the spinal cord position uncertainty on the dose received during head and neck helical tomotherapy.

INTRODUCTION: The study aims to establish the optimal planning risk volume (PRV) to the spinal cord (SC) for oropharyngeal cancer patients during adaptive radiation therapy with concurrent chemotherapy. METHODS: Geometrical uncertainties of the SC were evaluated. Differences between planned and delivered maximum doses to each part of the SC were established for every fraction dose and for cumulative dose. Maximum doses were evaluated as a dose received in 0.5 and 1 cm(3) of the analysed part of the SC defined as C1-C2, C3-C4, C5-C6 and C7-Th1 where Cn was a n-th cervical vertebra (n = 1, … , 7) and Th1 was the first thoracic vertebra. Finally, relations between dose differences and geometrical uncertainties were analysed using a relative risk (RR) and the importance of the PRV dose gradient to establish an optimal PRV for the SC. RESULTS: Prospective study based on the 875 observations from 25 oropharyngeal cancer patients was performed. The C1-C2 part of the SC is most exposed to risk of overdosage during chemoradiation for patients with oropharyngeal cancer due to its proximity to the clinical target volume (CTV). Doses received by other parts of the SC are smaller, with the lowest dose delivered to C7-Th1. For the C1-C2, delivered dose was higher than planned dose by 11%, while for the C7-Th1, this difference was smaller than 7%. The lowest movement of individual parts of the SC were detected for the C1-C2 and the highest for the C7-Th1. The standard deviations of the mean shift ranged respectively from 0.9 to 1.4 mm and from 1.3 to 2.9 mm. For each part of the SC delivered dose was smaller than planned dose to the PRV (RR < 1). CONCLUSION: Our study showed that for chemoradiation of oropharyngeal cancer, using daily image guidance and proper plan adaptation scheme, the current PRV margin for the SC could be reduced to 4 mm.

Tomotherapy - a different way of dose delivery in radiotherapy.

AIM OF THE STUDY: Helical tomotherapy is one of the methods of radiotherapy. This method enables treatment implementation for a wide spectrum of clinical cases. The vast array of therapeutic uses of helical tomotherapy results directly from the method of dose delivery, which is significantly different from the classic method developed for conventional linear accelerators. The paper discusses the method of dose delivery by a tomotherapy machine. Moreover, an analysis and presentation of treatment plans was performed in order to show the therapeutic possibilities of the applied technology. Dose distributions were obtained for anaplastic medulloblastoma, multifocal metastases to brain, vulva cancer, tongue cancer, metastases to bones, and advanced skin cancer. Tomotherapy treatment plans were compared with conventional linear accelerator plans. RESULTS: Following the comparative analysis of tomotherapy and conventional linear accelerator plans, in each case we obtained the increase in dose distribution conformity manifested in greater homogeneity of doses in the radiation target area for anaplastic medulloblastoma, multifocal metastases to brain, vulva cancer, metastases to bones, and advanced skin cancer, and the reduction of doses in organs at risk (OAR) for anaplastic medulloblastoma, vulva cancer, tongue cancer, and advanced skin cancer. The time of treatment delivery in the case of a tomotherapy machine is comparable to the implementation of the plan prepared in intensity-modulated radiotherapy (IMRT) technique for a conventional linear accelerator. In the case of tomotherapy the application of a fractional dose was carried out in each case during one working period of the machine. For a conventional linear accelerator the total value of the fractional dose in the case of anaplastic medulloblastoma and metastases to bones was delivered using several treatment plans, for which a change of set-up was necessary during a fraction. CONCLUSION: The obtained results confirm that tomotherapy offers the possibility to obtain precise treatment plans together with the simplification of the therapeutic system.