Hypofractionated radiotherapy for early breast cancer: Review of phase III studies

Breast-conserving surgery including whole breast irradiation has long been a recommended procedure for early breast cancer. However, conventionally fractionated radiotherapy requires a lengthy hospitalisation or prolonged commuting to a hospital for radiotherapy. In recent years, hypofractionated radiotherapy has increasingly been used. This method involves higher fraction doses (above 2 Gy) as compared to conventional radiotherapy, so the total dose can be delivered in fewer fractions and in a shorter overall treatment time. This review aims at presenting most important outcomes of four randomised studies comparing conventional and hypofractionated radiotherapy schemes including a total of 7000 patients. These studies have not shown apparent differences in treatment efficacy, incidence of late post-radiotherapy complications or cosmetic effects during a 5–10 year follow-up, but longer observation is warranted to fully evaluate the safety of this method. Currently, major societies consider modestly hypofractionated radiotherapy schemes as a routine management in selected groups of patients undergoing breast-conserving surgery. However, this method should be used cautiously in patients with lymph node metastases, big breasts, receiving chemotherapy or trastuzumab, or those under 50 years of age.     

Novel knowledge-based treatment planning model for hypofractionated radiotherapy of prostate cancer patients

PurposeTo demonstrate the strength of an innovative knowledge-based model-building method for radiotherapy planning using hypofractionated, multi-target prostate patients.Material and methodsAn initial RapidPlan model was trained using 48 patients who received 60 Gy to prostate (PTV60) and 44 Gy to pelvic nodes (PTV44) in 20 fractions. To improve the model's goodness-of-fit, an intermediate model was generated using the dose-volume histograms of best-spared organs-at-risk (OARs) of the initial model. Using the intermediate model and manual tweaking, all 48 cases were re-planned. The final model, trained using these re-plans, was validated on 50 additional patients. The validated final model was used to determine any planning advantage of using three arcs instead of two on 16 VMAT cases and tested on 25 additional cases to determine efficacy for single-PTV (PTV60-only) treatment planning.ResultsFor model validation, PTV V_95% of 99.9% was obtained by both clinical and knowledge-based planning. D_1% was lower for model plans: by 1.23 Gy (PTV60, CI = [1.00, 1.45]), and by 2.44 Gy (PTV44, CI = [1.72, 3.16]). OAR sparing was superior for knowledge-based planning: ΔD_mean = 3.70 Gy (bladder, CI = [2.83, 4.57]), and 3.22 Gy (rectum, CI = [2.48, 3.95]); ΔD_2% = 1.17 Gy (bowel bag, CI = [0.64, 1.69]), and 4.78 Gy (femoral heads, CI = [3.90, 5.66]). Using three arcs instead of two, improvements in OAR sparing and PTV coverage were statistically significant, but of magnitudes < 1 Gy. The model failed at reliable DVH predictions for single PTV plans.ConclusionsOur knowledge-based model delivers efficient, consistent plans with excellent PTV coverage and improved OAR sparing compared to clinical plans.     

Stereotactic ablative radiotherapy for oligometastatic prostate cancer

BackgroundThe present study assessed clinical outcomes of stereotactic body radiotherapy (SBRT) in oligometastatic prostate cancer patients.Materials and methodsBetween 2017 and 2020, 37 lesions (12 osseous and 25 nodal targets) detected with conventional and/or functional imaging, were treated in 29 patients (pts), in different clinical settings: de novo oligometastatic (2 pts), oligorecurrent castration-sensitive (19 pts), castration-resistant (6 pts) prostate cancers and oligoprogressive disease during systemic therapy (2 pts). SBRT was delivered with volumetric modulated arc therapy up to a total dose of 21 Gy given in 3 fractions for bone and 30 Gy in 5 fractions for nodal metastases. A total of 34% of pts received hormonal therapy. We evaluated biochemical control [prostate serum antigen (PSA) increase < 10%)], progression free-survival (PFS) (time from SBRT to biochemical progression), local control (LC) (time from SBRT to in-field radiologic progression), hormone/systemic therapy-free survival, acute and late toxicities.ResultsAt 3 months, biochemical response was observed in 20/29 pts (69%). At a median follow-up of 17 months (range 6–33), 8/20 (40%) of the 3-month responders remained free from progression. Two-year PFS and LC were 37% and 70%, respectively. In-field progression occurred in 3/37 (8%) lesions. Hormone/systemic therapy was delayed by an average of 11.6 months (range 3–28). No significant difference in PFS based on the type of lesion or concomitant endocrine therapy was observed and no toxicity > grade 2 was reported.ConclusionsSBRT for oligometastatic prostate cancer offers a good biochemical/local control and tangible delay of hormone/systemic therapy without major toxicities.     

Phase I dose escalation trial of stereotactic radiotherapy prior to robotic prostatectomy in high risk prostate cancer

BackgroundThe aim of the study was to investigate the safety of combining preoperative stereotactic body radiotherapy (SBRT) with robotic radical prostatectomy (RP) for high risk prostate cancer (HRCaP). Many patients with HRCaP will require adjuvant or salvage radiotherapy after RP. The addition of preoperative SBRT before RP may spare patients from subsequent prolonged courses of RT.Materials and methodsEligible patients had NCC N HRCaP and received a total of 25 Gy or 30 Gy in five daily fractions of SBRT to the prostate and seminal vesicles followed by robotic RP with pelvic lymphadenectomy 31–45 days later. The primary endpoint was prevalence of acute genitourinary (GU) and gastrointestinal (GI) toxicity. Secondary endpoints were patient-reported quality of life (QOL) and biochemical recurrence (BcR).ResultsThree patients received preoperative SBRT to 25 Gy and four received 30 Gy. Median follow-up was 18 months. Highest toxicity was grade 2 and 3 in six (85.7%) and one (14.3%) patients, respectively. All patients developed grade 2 erectile dysfunction and 4 of 7 (57%) developed grade 2 urinary incontinence (UI) within a month after surgery. One patient developed acute grade 3 UI, but there was no grade ≥ 4 toxicity. One patient experienced acute grade 2 hemorrhoidal bleeding. On QOL, acute GU complaints were common and peaked within 3 months. Bowel symptoms were mild. Two patients with pN+ experienced BcR.ConclusionsPreoperative SBRT before robotic RP in HRCaP is feasible and safe. The severity of acute GU toxicity with preoperative SBRT may be worse than RP alone, while bowel toxicity was mild.     

Volumetric image-guided conformal radiotherapy for localized prostate cancer: Analysis of dosimetric and clinical factors affecting acute and late toxicity

Aim

To identify factors influencing toxicity in patients affected by localized prostate cancer treated with conformal image-guided radiotherapy.

Breast cancer hypofractionated radiotherapy in 2-weeks with 2D technique: 5-year clinical outcomes of a phase 2 trial

BackgroundTo report clinical outcomes and late toxicities of a 2-week hypofractionated post-operative loco-regional radiotherapy in patients with breast cancer.Materials and methodsThis trial was approved by the Institutional Ethics Committee and registered with gov, no. {"type":"clinical-trial","attrs":{"text":"NCT02460744","term_id":"NCT02460744"}}NCT02460744. Between June 2013 and October 2014, 50 patients with breast cancer, post mastectomy or breast conserving surgery (BCS) were included in this study, of whom 10 had BCS. Patients were planned on a 2-dimentional (2D) simulator with 2 tangential fields and an incident supraclavicular field. Radiotherapy dose was 34 Gy/10#/2 weeks and a sequential boost of 10 Gy/5#/1 wk in BCS patients. The primary endpoint was the rate of acute skin toxicities previously reported. Here, we report the secondary end points of late toxicities, cosmesis, local recurrence, disease-free survival (DFS) and overall survival (OS). Late skin toxicities were recorded according to the Radiotherapy and Oncology Group (RTOG) scoring criteria. Cosmetic outcomes were assessed using the Harvard/National Surgical Adjuvant Breast and Bowel Project (NSABP)/RTOG breast cosmesis and the Late Effects Normal Tissue/Subjective Objective Management Analytic (LENT/SOMA) scales for the breast and chest wall, respectively. Kaplan-Meier estimates of DFS and OS were calculated, and 5-year DFS and OS rates (with approximate 95% CIs) were estimated.ResultsLate grade ≥ 2 chest wall induration, hypopigmentation and subcutaneous fibrosis were seen in 3 (6%), 3 (6%) and 1 (2%) patients, respectively. Chest wall cosmesis was excellent/good in 34 (72%) and fair/bad in 13 (28%) patients. In BCS patients, grade 2 skin induration, subcutaneous fibrosis and edema was observed in 1 patient (11%) each. Cosmesis was excellent/good in 7 (78%) and fair/bad in 2 (22%) patients. Late grade ≥ 2 arm edema, pain and shoulder stiffness were reported by 1 (2%), 2 (4%) and 2 (4%) patients, respectively. No local recurrences were observed. Five patients developed distant metastases (10%). Seven patients died (14%). The 5-year DFS and OS rate was 90% (95% CI: 77–96%) and 88% (95% CI: 75–94%), respectively.ConclusionHypofractionated radiotherapy in 2 weeks in patients with breast cancer was associated with minimal late toxicity, good cosmetic outcome and excellent local control. This trial may be of relevance for developing countries where resources are limited.     

Postoperative radiotherapy in prostate cancer: Analysis of prognostic factors in a series of 282 patients

Aim

To assess the outcomes of patients treated with postoperative RT in relation to the possible prognostic factors.

Background

Postoperative radiotherapy (RT) has been proved to reduce the risk of biochemical recurrence in high-risk prostate cancer patients. Baseline prostate specific antigen (PSA), pathological Gleason score (GS), positive surgical margins, nodal status and seminal vesicle invasion are independent predictors of biochemical relapse.

Materials and methods

The clinical records of 282 patients who underwent postoperative RT were retrospectively reviewed. The prognostic value of postoperative PSA, preoperative risk class, nodal status, pathological GS, margins status, and administration of hormonal therapy (HT) was analyzed.

Results

Postoperative RT was delivered with a median dose to the prostatic fossa of 66 Gy (range 50–72) in 1.8–2 Gy/fraction. Median follow-up was 23.1 months (range 6–119). Five-year actuarial biochemical disease-free survival (bDFS) and overall survival rates were 76% and 95%, respectively. Higher bDFS was found for patients with postoperative PSA <0.02 ng/ml (p = 0.03), low preoperative risk class (p = 0.01), pN0 (p = 0.003), GS 4–6 (p = 0.0006), no androgen deprivation therapy (p = 0.02), and irrespective of surgical margin status (p = 0.10). Multivariate analysis showed that postoperative PSA and Gleason score had a significant impact on bDFS (p = 0.039 and p = 0.05, respectively).

Conclusions

Postoperative RT with a dose of 66 Gy offers an acceptable toxicity and an optimal disease control after radical prostatectomy in patients with different risk features. A postoperative PSA >0.02 ng/ml could be considered as a prognostic factor and a tool to select patients at risk for progression.     

Differences in toxicity and outcome associated with circadian variations between patients undergoing daytime and evening radiotherapy for prostate adenocarcinoma

This retrospective study tested the hypothesis that disease control and treatment-related toxicity in patients undergoing high-dose radiotherapy (HDRT) for prostate cancer varies in a circadian manner. Patients with localized prostate adenocarcinoma receiving HDRT (median 78 Gy) to the prostate and involved seminal vesicle(s) without elective pelvic irradiation were divided into a daytime treatment (before 5 PM) group (n = 267) and evening treatment (after 5 PM) group (n = 142). Biochemical failure (Phoenix definition), acute and late gastrointestinal (GI) and genitourinary toxicities (Common Terminology Criteria for Adverse Events version 4), biochemical failure-free survival (BFFS) and freedom from late toxicity were assessed. Analyses were performed by binary logistic regression and Cox proportional hazard regression. The median follow-up was 68 months, and 75% of patients were ≥70 years old. Evening HDRT was significantly associated with worse freedom from ≥grade 2 late GI complications (hazard ratio = 2.96; p < 0.001). The detrimental effect of evening HDRT was significant in patients older than 70 years old (p < 0.001) but not in younger patients (p = 0.63). In a subgroup of propensity score-matched cohort with T2b–T3 disease (n = 154), the 5-year BFFS was worse in the evening group than the daytime group (72% vs. 85%, hazard ratio = 1.95, p = 0.05). Our study indicates that evening HDRT may lead to more GI complications, especially in older patients, and worse BFFS in patients with T2b–T3 disease.     

Long-term follow-up results of endorectal balloon-assisted helical tomotherapy for localized prostate cancer patients in the high-risk group of gastrointestinal adverse events

BackgroundEndorectal balloon (ERB) has been shown to reduce rectal radiation dose and late gastrointestinal toxicities in patients with prostate cancer. However, the usefulness of ERBs for patients with prostate cancer whose rectal shape or size is suboptimal has not been investigated. The purpose of this study was to present the long-term follow-up results of ERB-assisted helical tomotherapy for localized prostate cancer patients whose initial radiation treatment planning (RTP) was unacceptable due to suboptimal rectal shape or size.Materials and methodsOf 541 consecutive patients with localized prostate cancer, 10 were included in this study whose RTPs without ERBs did not meet dose constraints due to: 1) Intestinal intrusion, 2) Small rectum; or 3) Unstable rectal shape. We re-planned using ERBs and delivered 76 Gy in 38 fractions, and evaluated the long-term usefulness and safety of ERB-assisted helical tomotherapy.ResultsAt a median follow-up of 109 months, there were no local recurrences of prostate cancer. The overall, cause-specific, and progression-free survivals at 10 years were 90.0%, 100%, and 83%, respectively. Adverse events of grade 3 or higher were not observed during or after ERB-assisted helical tomotherapy.ConclusionsWhen intestinal intrusion, a small rectum, or an unstable rectal shape is an obstacle for administering helical tomotherapy, ERBs might be the solution.     

Current status of androgen suppression and radiotherapy for patients with prostate cancer

Analogous to the impact of anti-estrogen therapy in breast cancer, anti-androgen therapy may have a greater impact on the castrate male with non-metastatic disease. The use of castration or a LHRH drug alone, does not appear to adequately suppress intra-prostatic DHT (Dihydrotestosterone) levels. Normal prostate elements appear to be more efficient than metastatic elements at converting DHT precursors to active DHT. Thus, blocking this step may be more critical for clinically localized disease. Laverdiere et al. reported a 2 year positive (+) biopsy rate of 65% with XRT alone compared to 28% when 3 months of NHT preceded radiotherapy, but 5% if NHT was continued for a total of 10.5 months of combined androgen blockade (CAB). Bolla et al. incorporated one month of NHT prior to XRT followed by 3 years of an LHRH drug. An improvement in local control, disease free survival and overall survival of nearly 20% was noted at 5 years. Thus far, these important studies demonstrate that a survival benefit may require long term adjuvant hormonal therapy. There is a need for further studies to define the optimal timing and duration of CAB and the role of XRT. Long term data recently provided by the Radiation Therapy Oncology Group (RTOG) may provide insights into criteria for defining which patients are likely to benefit the most from long term CAB.     

Impact of COVID-19 on the curative treatment of prostate cancer: a national cross-sectional study

BackgroundCOVID-19 pandemic affected access to cancer treatment worldwide. However, there is a lack of data about the impact in developing countries. The objective was to evaluate COVID-19 impact on curative prostate cancer (Pca) treatment in Brazil.Materials and methodsWith data extracted from the Brazilian Ministry of Health database, the Non-COVID and COVID periods were analyzed to compare the absolute number of radical prostatectomy (RP) and radiotherapy (RT) executed in the country and regions.ResultsWith data from 50,169 Pca patients (Non-COVID = 28,106 cases and COVID = 22,063) treated with RP or RT in Brazil, a significant decline in patients receiving RT or RP (−6.043 cases; p = 0.0001) was detected. Both treatment procedures (RT or PR) were reduced in all five Brazilian regions comparing the Non-COVID and COVID periods. Overall, there was a reduction on RP and RT procedures in 92% (24/25) and 76% (19/25) of the evaluated states, respectively. Comparing the variation of RT and RP per state between COVID and Non-COVID period, there is a significant difference (−18.6% vs. −29%, p = 0.03) with a higher negative impact on the RP group. The RT and RP variation had no significant relationship with the incidence of COVID cases in the states. Limitations include the non-evaluation of treatment combinations, the impact of hypofractionated radiotherapy, and other factors influencing the treatment choice.ConclusionsDuring the COVID-19 pandemic, the curative treatment with RP and RT of Pca was abruptly limited and affected. However, the number of RP was more impacted than RT during the COVID period.     

Shrinkage of the non-malignant prostate gland volume after receiving incidental radiotherapy for rectal cancer

BackgroundThe purpose of this study was to assess the impact of coincidental radiotherapy on the volume of the non-malignant prostate gland in rectal cancer patients treated with neo-adjuvant radiotherapy.Materials and methodsIn this retrospective analysis, thirty male patients with rectal cancer who had neoadjuvant radiotherapy met the inclusion criteria. These patients had pre-treatment magnetic resonance imaging (MRI) and at least one post-treatment MRI of the pelvis and the whole of their prostate volume received the full prescribed radiotherapy dose; 45 Gy in 25 fractions (n = 22), 45 Gy in 20 fractions (n = 4) and 25 Gy in 5 fractions (n = 4).ResultsThe median age of this patient cohort was 66 years (range: 30–87). With a median interval between pre-treatment MRI and first MRI post-treatment of 2 months (range: 1–11), the mean prostate volume reduced from 36.1 cm³ [standard deviation (SD) 14.2] pre-radiotherapy to 31.3 cm³ (SD 13.0) post radiotherapy and this difference was significant (p = 0.0004).ConclusionRadiotherapy may cause shrinkage in volume of normal (non-malignant) prostate. Further research is required in this field, since these results may be of some comfort to men contemplating the consequences of radiotherapy on their quality of life. The authors suggest recording flow-rate and international prostate symptom score (IPSS) during rectal radiotherapy as a next step.     

Short term clinical outcomes of accelerated hypofractionated radiotherapy in inoperable non-small cell lung cancer patients

BackgroundThis study aimed to evaluate short term clinical outcomes of accelerated hypofractionated radiotherapy (AHR T) regarding locoregional response (LRR), symptoms relief and acute toxicities in non-small cell lung cancer (NSCLC) patients. The radical treatment for inoperable NSCLC is intolerable for some patients. An alternative RT regime should be considered for them.Materials and methodsInoperable NSCLC patients who could not tolerate radical treatment were treated with AHRT (45 Gy in 15 fractions over three weeks) by using the 3-dimensional conformal (RT) technique. The LRR was assessed by chest computed tomography (CT) performed before and 6 weeks after RT. Relief of symptoms such as cough, dyspnoea and chest pain was evaluated during RT and 6 and 12 weeks after RT, compared with the status before RT. Treatment-related acute toxicities such as dysphagia and radiation dermatitis were observed during and 6 and 12 weeks after RT.ResultsTotal 65 patients (seven patients of stage II and fifty-eight patients of stage III) were included. Partial response was seen in 70.8% of patients, and stable disease was seen in 29.2% while there was neither complete response nor progressive disease after RT. Statistically significant associations were found between tumour response vs. pre-treatment tumour size and tumour response vs. performance status of the patients. Satisfactory symptom relief was found after RT, but severe acute dysphagia and radiation dermatitis (more than grade 3) were not observed.ConclusionSatisfactory LRR, symptom relief and acute toxicities were achieved by this regime. Long term studies are recommended to evaluate late toxicities and survival outcome further.Trial registration noTCTR20200110001     

Improving outcomes in high-risk prostate cancer with radiotherapy

There have been significant improvements in the radiotherapeutic management of patients with high risk prostate cancer. Randomized trials have clearly demonstrated improved outcomes with the combination of radiotherapy in conjunction with androgen deprivation. While these trials have utilized low doses of radiotherapy in the range of 70 Gy, recent studies have suggested that significant benefits of combined androgen deprivation therapy with dose escalated radiotherapy are also observed. The use of high radiation dose levels in the setting of high risk prostate cancer is important, and strategies which combine external beam radiotherapy with a brachytherapy boost may provide an opportunity for even greater intensification of the radiation dose to the prostate target. Systemic therapies, second generation anti-androgen therapy and novel targeted agents integrated with radiotherapy will open up new vistas and challenges for further improved outcomes in patients with high-risk disease.     

Multiparametric magnetic resonance imaging-guided salvage radiotherapy in prostate cancer

AimTo analyse the efficacy and toxicity of postprostatectomy SRT in patients with a BCR evaluated with mpMRI.BackgroundMultiparametric magnetic resonance imaging (mpMRI) has the ability to detect the site of pelvic recurrence in patients with biochemical recurrence (BCR) after radical prostatectomy (RP). However, we do not know the oncological outcomes of mpMRI-guided savage radiotherapy (SRT).ResultsLocal, lymph node, and pelvic bone recurrence was observed in 13, 4 and 2 patients, respectively. PSA levels were significantly lower in patients with negative mpMRI (0.4 ng/mL [0.4]) vs. positive mpMRI (2.2 ng/mL [4.1], p = 0.003). Median planning target volume doses in patients with visible vs. non-visible recurrences were 76 Gy vs. 70 Gy. Overall, mean follow-up was 41 months (6–81). Biochemical relapse-free survival (bRFS) at 3 years was 82.3% and 82.5%, respectively, for the negative and positive mpMRI groups (p = 0.800). Three-year rates of late grade ≥2 urinary and rectal toxicity were 14.8% and 1.9%, respectively; all but one patient recovered without sequelae.ConclusionSRT to the macroscopic recurrence identified by mpMRI is a feasible and well-tolerated option. In this study, there were no differences in bRFS between MRI-positive and MRI-negative patients, indicating effective targeting of MRI-positive lesions.     

Comparison of pre-treatment and in-vivo dosimetry for advanced radiotherapy of prostate cancer

BackgroundThe usage of advanced radiotherapy techniques requires validation of a previously calculated dose with the precise delivery with a linear accelerator. This study aimed to review and evaluate new verification methods of dose distribution. Moreover, our purpose was to define an internal protocol of acceptance for in-vivo measurements of dose distribution.Materials and methodsThis study included 43 treatment plans of prostate cancer calculated using the Monte Carlo algorithm. All plans were delivered using the Volumetric Modulated Arc Therapy (VMAT) technique of advanced radiotherapy by the linear accelerator Elekta VersaHD. The dose distribution was verified using: MatriXX, iViewDose, and in-vivo measurements. The verification also included recalculation of fluence maps of quality assurance plans in another independent algorithm.ResultsThe acceptance criterion of 95% points of dose in agreement was found for pre-treatment verification using MatriXX; the average γ value was 99.09 ± 0.93 (SD) and 99.64 ± 0.35 (SD) for recalculation in the Collapse Cone algorithm. Moreover, using the second algorithm in the verification process showed a positive correlation ρ = 0.58, p < 0.001. However, verification using iViewDose in a phantom and in-vivo did not meet this γ-pass rate.ConclusionsEvaluation of gamma values for in-vivo measurements utilizing iViewDose software was helpful to establish an internal dosimetry protocol for prostate cancer treatments. We assumed value at a minimum of 50% points of the dose in agreement with the 3%/3 mm criterion as an acceptable compliance level. The recalculated dose distribution of QA plans in regard to the Collapse Cone algorithm in the other treatment planning system can be used as a pre-treatment verification method used by a medical physicist in their daily work. The effectiveness of use in iViewDose software, as a pre-treatment tool, is still debatable, unlike the MatriXX device.     

A comparison of a moderately hypofractionated IMRT planning technique used in a randomised UK external beam radiotherapy trial with an in-house technique for localised prostate cancer

AimTo compare the radiotherapy technique used in a randomised trial with VMAT and an in-house technique for prostate cancer.BackgroundTechniques are evolving with volumetric modulated arc therapy (VMAT) commonly used. The CHHiP trial used a 3 PTV forward planned IMRT technique (FP_CH). Our centre has adopted a simpler two PTV technique with locally calculated margins.Materials and methods25 patients treated with FP_CH to 60 Gy in 20 fractions were re-planned with VMAT (VMAT_CH) and a two PTV protocol (VMAT_60/52 and VMAT_60/48). Target coverage, conformity index (CI), homogeneity index (HI), monitor units (MU) and dose to the rectum, bladder, hips and penile bulb were compared.ResultsPTV coverage was high for all techniques. VMAT_CH plans had better CI than FP_CH (p ≤  0.05). VMAT_60/52/48 plans had better CI than VMAT_CH. FP_CH had better HI and fewer MU than VMAT (p ≤  0.05). More favourable rectum doses were found for VMAT _CH than FP_CH (V_48.6, V_52.8, V₅₇, p ≤  0.05) with less difference for bladder (p ≥  0.05). Comparing VMAT_CH to VMAT_60/52/48 showed little differences for the bladder and rectum but VMAT_CH had larger penile bulb doses (V_40.8, V_48.6, mean, D_2, p ≤  0.05). Femoral head doses (V_40.8) were similarly low for all techniques (p = ≥ 0.05).ConclusionVMAT produced more conformal plans with smaller rectum doses compared to FP_CH albeit worse HI and more MU. VMAT_60/52 and VMAT_60/48 plans had similar rectal and bladder doses to VMAT_CH but better CI and penile bulb doses which may reduce toxicity.     

Impact of rotational errors of whole pelvis on the dose of prostate-based image-guided radiotherapy to pelvic lymph nodes and small bowel in high-risk prostate cancer

BackgroundThe target volume increases when the prostate and pelvic lymph nodes (PLNs) are combined, and the fiducial markers (FMs) are placed at the edge of the irradiation field. Thus, the position of FMs may be changed by the rotational errors (REs) of “whole pelvis”. The aim of this study was to examine the impact of REs of “whole pelvis” on the dose of FMs-based image-guided radiotherapy to the PLNs and the small bowel in prostate cancer including the PLNs.Materials and methodsWe retrospectively evaluated 10 patients who underwent prostate cancer radiotherapy involving the PLNs. The position of FMs was calculated from the radiographs obtained before and after the 6D correction of pelvic REs. We simulated the delivery dose considering the daily pelvic REs and calculated the difference from the planned dose in the D_98% of the PLN clinical target volume and the D_2cc, and V_45Gy of the small bowel.ResultThe position of FMs strongly correlated with the pelvic REs in the pitch direction (r = 0.7788). However, the mean delivered doses to PLNs for 10 patients were not significantly different from the planned doses (p = 0.625). Although the D_2cc and V_45Gy of the small bowel strongly correlated with the pitch rotation of the pelvis, there was no significant difference between the delivered and planned doses (p = 0.922 and p = 0.232, respectively).ConclusionThe dosimetric effect of pelvic REs on the dose to PLNs and the small bowel was negligible during the treatment course.