Benefits Of Intensity-modulated Radiotherapy Research Articles

Racial and Ethnic Health Disparities in Delay to Initiation of Intensity-Modulated Radiotherapy

The benefits of intensity-modulated radiotherapy (IMRT) over standard radiotherapy (RT), including decreased toxicity and improved quality of life, have been demonstrated in many cancer sites. Timely initiation of RT is critical, yet many factors can affect the interval to initiation of treatment (IIT). Delays may contribute to worse cancer outcomes such as increased locoregional recurrence and decreased survival. We aimed to examine racial health inequities associated with delayed initiation of IMRT.The National Cancer Database was queried to identify the ten sites with the highest total number of cancer patients treated with definitive intent IMRT. Exclusions included stage IV, age < 18, unknown insurance status, unknown race, and adjuvant or palliative intent RT. Race and ethnicity were classified as non-Hispanic White (NHW), non-Hispanic Black (NHB), Hispanic, Asian, Native American/Eskimo, and Hawaiian/Pacific islander. IIT was broken into quartiles for each disease site, with the first two quartiles classified as "no delay" and the 4th quartile classified as "delayed." Multivariable logistic regression for delayed IIT was performed for each disease site using clinical and demographic covariates. Duration of IIT was compared between subgroups using two-sample t-tests.Among 350,425 patients treated with IMRT from 2004-2017, NHB and Hispanic patients were significantly more likely to have delayed IIT with IMRT for nearly all disease sites compared to NHW patients (see Table 1). IIT was significantly longer for NHB (Median 87 d [days], P < 0.001) and Hispanic patients (Median 76 d, P < 0.001) compared to NHW patients (Median 67 d). A separate analysis revealed NHB and Hispanic patients were also more likely to have delays in standard 3D conformal RT, however the median difference in IIT compared to NHW was smaller than in those receiving IMRT (NHB median 58d, Hispanic median 55d, NHW median 45d, P < 0.001).Significant racial and ethnic disparities in the likelihood and duration of treatment delay were observed. These findings raise concerns that delays in initiation of IMRT in Black and Hispanic patients may contribute to the previously documented differences in cancer outcomes. Investigating sources of these delays, including insurance authorization/denials, is urgently needed to improve timely initiation of IMRT. Table 1: Association between race/ethnicity and IIT.

Impact of VMAT-IMRT compared to 3D conformal radiotherapy on anal sphincter dose distribution in neoadjuvant chemoradiation of rectal cancer

BackgroundNeoadjuvant radio- or chemoradiation (nIRT) therapy is the standard treatment for loco-regional advanced rectal cancer patients of the lower or middle third. Currently, intensity modulated radiation therapy (IMRT) is not the recommended radiation technique even though IMRT has advantages compared to 3D-radiation regarding dose sparing to organs at risk like small bowel and urinary bladder. So far, the benefit of IMRT concerning the anal sphincter complex is not examined. With this study we intended to evaluate the dose distribution on the anal sphincters of rectal cancer patients treated with IMRT in comparison with 3D-techniques.MethodsWe selected 16 patients for the IMRT-group and 16 patients for the 3D-group with rectal cancer of the middle third who were treated in our institute. All patients received 45 Gy in a chemoradiation protocol. Patients in both groups were matched regarding stage, primary tumor distance to the anal verge and size of the tumor. We delineated the internal and external anal sphincters, the addition of both sphincters and the levator ani muscle in all patients. Subsequently, we evaluated and compared dose parameters of the different sphincters in both groups and analysed the configuration of the isodoses in the area of the caudal radiation field, respectively.ResultsMost of the relevant dose parameters of the caudal sphincters (Dmean, Dmedian, V10–V40) were significantly reduced in the IMRT-group compared to the 3D-group. Accordingly, the isodoses at the caudal edge of the target volume in the IMRT group demonstrated a steep dose fall. The levator ani muscle always was included into the planned target volumes and received the full dose in both groups.ConclusionsThe modern VMAT-IMRT can significantly reduce the dose to the anal sphincters for rectal cancer patients of the middle third who were treated with conventional chemoradiation therapy.

Risk-adapted survival benefit of IMRT in early-stage NKTCL: a multicenter study from the China Lymphoma Collaborative Group

AbstractThis study evaluated the survival benefit of intensity-modulated radiation therapy (IMRT) compared with 3-dimension conformal radiation therapy (3D-CRT) in a large national cohort of patients with early-stage extranodal nasal-type natural killer/T-cell lymphoma (NKTCL). This retrospective study reviewed patients with early-stage NKTCL treated with high-dose radiation therapy (RT; ≥45 Gy) at 16 Chinese institutions. Patients were stratified into 1 of 4 risk groups based on the number of risk factors: low risk (no factors), intermediate-low risk (1 factor), intermediate-high risk (2 factors), and high-risk (3-5 factors). Of the 1691 patients, 981 (58%) received IMRT, and 710 (42%) received 3D-CRT. Unadjusted 5-year overall survival (OS) and progression-free survival (PFS) were 75.9% and 67.6%, respectively, for IMRT compared with 68.9% (P = .004) and 58.2% (P < .001), respectively, for 3D-CRT. After propensity score match and multivariable analyses to account for confounding factors, IMRT remained significantly associated with improved OS and PFS. The OS and PFS benefits of IMRT persisted in patients treated with modern chemotherapy regimens. Compared with 3D-CRT, IMRT significantly improved OS and PFS for high-risk and intermediate-high–risk patients but provided limited benefits for low-risk or intermediate-low–risk patients. A risk-adapted survival benefit profile of IMRT can be used to select patients and make treatment decisions.

Multi-criteria optimization achieves superior normal tissue sparing in intensity-modulated radiation therapy for oropharyngeal cancer patients

ObjectivesTo evaluate the benefit of intensity-modulated radiation therapy (IMRT) with multi-criteria optimization (MCO) in patients with oropharyngeal cancer (OPC) and compare the dose difference between the MCO plans navigated by physicians and dosimetrists. Materials and methodsThe conventional IMRT plans (nonMCO) and MCO IMRT plans navigated by physicians and dosimetrists (MCOp and MCOd) were created for 30patients with OPC. All the plans were reviewed, and the planning time and dose-volume parameters were compared. ResultsThe difference of D95 among three kinds of plans was not significant (p > 0.05). The maximum dose and D2 of spinal cord, brain stem, the mean dose of bilateral parotids, cochlea, oral cavity and glottic larynx were lower in MCO plans than those in nonMCO plans (p < 0.017). Furthermore, MCOp showed better bilateral parotids, oral cavity and glottic larynx sparing compared to MCOd (p < 0.017), in which the magnitude was related to the overlapping volume of the corresponding organ at risk (OAR) and targets. The active planning time was reduced by a median of 94.3 min (MCOd vs. nonMCO) or 91.6 min (MCOp vs. nonMCO). ConclusionMCO IMRT plans significantly reduced the dose of OARs and the active planning time, without compromising the target coverage in OPC patients; navigations by physicians could be beneficial to the dose sparing of the OARs with high complication rate and those overlapping with targets; the constraints could be the predominant factor affecting the results of optimization in the MCO IMRT planning.

Intensity Modulated Radiation Therapy Improves Survival in Early-Stage Supraglottic Larynx Cancer

Early stage supraglottic larynx cancers treated with definitive radiotherapy (RT) require treatment of the bilateral neck because of high rates of regional spread. Compared to older techniques, modern intensity modulated radiation therapy (IMRT) has been shown to precisely target tumor and draining nodal regions with the potential to spare organs at risk including those essential for prevention of aspiration. However, previous hospital-based studies have demonstrated decreased survival associated with the use of IMRT compared to 3D and 2D radiotherapy techniques in glottic larynx. We used the National Cancer Data Base (NCDB) to study the impact of the IMRT technique on overall survival of supraglottic tumors. We searched the NCDB for cT1-T2 N0 supraglottic larynx cancer managed with definitive RT alone between 2004 to 2012. Mortalities within 3 months were excluded to minimize survivorship bias. All relevant demographic, tumor specific, and treatment data were recorded. Propensity score matching (PSM) was utilized to match 1:1 patients treated with IMRT with patients treated with 3D/2D techniques for all treatment and demographic variables. The overall survival (OS) benefit of IMRT over non-IMRT techniques was estimated using univariate (UVA) log-rank tests and multivariate (MVA) Cox models. Factors demonstrating significance of P<0.05 on UVA analysis were included in MVA analysis. A forward stepwise selection was used to confirm robustness of model parameters. From 2004 to 2012, a total of 2,429 patients with cT1-2N0 supraglottic larynx cancers who received definitive RT were identified, 907 of which were treated with IMRT. A total of 1,814 patients were identified within the PSM cohort, with a median follow-up of 39 months (range 3-129 months). After matching, patients who received IMRT (N=907) were more likely to be treated after 2008 than patients with no IMRT (44% vs. 71%). Otherwise there was no significant difference (p > 0.05) in any demographic or treatment factor between groups. In total there were 756 deaths, with a median survival of 81 months (95% CI 73–89 mos.) in the IMRT patients and 68 months (95% CI 63-73 mos.) for the non-IMRT patients. IMRT was significantly associated with improved OS in UVA (HR: 0.81 (0.70-0.94 p<0.001) analysis, along with age younger than 50, female gender, well differentiated disease, T1 stage, good performance status, income > $38K, and private insurance, treatment at academic center. In the MVA Cox proportional hazards models, IMRT remained significantly associated with improved overall survival (HR: 0.85 (0.73-0.98) p<0.001). All other factors entered remained significant in MVA except grade. This largest hospital-based-analysis indicates IMRT techniques are associated with improved OS in early-stage cancer of the supraglottic larynx when compared to 3D and 2D techniques.

Advances in radiotherapy techniques and delivery for non-small cell lung cancer: benefits of intensity-modulated radiation therapy, proton therapy, and stereotactic body radiation therapy.

The 21st century has seen several paradigm shifts in the treatment of non-small cell lung cancer (NSCLC) in early-stage inoperable disease, definitive locally advanced disease, and the postoperative setting. A key driver in improvement of local disease control has been the significant evolution of radiation therapy techniques in the last three decades, allowing for delivery of definitive radiation doses while limiting exposure of normal tissues. For patients with locally-advanced NSCLC, the advent of volumetric imaging techniques has allowed a shift from 2-dimensional approaches to 3-dimensional conformal radiation therapy (3DCRT). The next generation of 3DCRT, intensity-modulated radiation therapy and volumetric-modulated arc therapy (VMAT), have enabled even more conformal radiation delivery. Clinical evidence has shown that this can improve the quality of life for patients undergoing definitive management of lung cancer. In the early-stage setting, conventional fractionation led to poor outcomes. Evaluation of altered dose fractionation with the previously noted technology advances led to advent of stereotactic body radiation therapy (SBRT). This technique has dramatically improved local control and expanded treatment options for inoperable, early-stage patients. The recent development of proton therapy has opened new avenues for improving conformity and the therapeutic ratio. Evolution of newer proton therapy techniques, such as pencil-beam scanning (PBS), could improve tolerability and possibly allow reexamination of dose escalation. These new progresses, along with significant advances in systemic therapies, have improved survival for lung cancer patients across the spectrum of non-metastatic disease. They have also brought to light new challenges and avenues for further research and improvement.

Multi-criteria optimization achieves superior normal tissue sparing in a planning study of intensity-modulated radiation therapy for RTOG 1308-eligible non-small cell lung cancer patients

PurposeIn this planning study, we studied the benefit of intensity-modulated radiation therapy (IMRT) with multi-criteria optimization (MCO) in locally advanced non-small cell lung carcinoma (NSCLC). MethodsWe selected 10 consecutive patients with gross tumor within 1cm of the esophagus eligible for RTOG 1308, randomized phase II trial of 70Gy protons vs photons. Planning was performed per protocol. In addition, a novel approach for esophagus sparing was applied by making the contralateral esophagus (CE) an avoidance structure. MCO and non-MCO plans underwent double-blinded review. Plan differences in dose–volume histogram parameters were analyzed. ResultsMedian plan differences were mean lung dose=0.8Gy (p=0.01), lung V20=1.1% (p=0.06), heart V30=1.0% (p=0.03), heart V45=0.6% (p=0.03), esophagus V60=1.2% (p=0.04), and CE V45=3.2% (p=0.01), all favoring MCO over non-MCO. PTV coverage with 95% dose was ⩾98.0% for both plans. There were 5 minor protocol deviations with non-MCO plans and 2 with MCO. Median improvement of active planning time with MCO was 88min (p<0.01). Physicians preferred 8 MCO and 2 non-MCO plans (p=0.04). ConclusionsMCO plans yielded significant improvements in organ-at-risk sparing without compromising target coverage, consumed less dosimetrist time, and were preferred by physicians. We suggest incorporating MCO into prospective clinical trials.

P0176 Dosimetric comparison of volumetric intensity-modulated arc (RapidArc) therapy, intensity-modulated radiotherapy, and 3D conformal radiotherapy for primary liver tumours

Background To compare the dosimetric outcomes of volumetric arc radiotherapy (RapidArc), intensity-modulated radiotherapy (IMRT), and 3D conformal radiotherapy (3DCRT) plans for primary liver tumours. Methods 7 patients with localised unresectable hepatocellular carcinoma were included in this study. CT simulation was done with voluntary deep inspiratory breath-holding after administering 80–90 mL of intravenous iodinated contrast. The mean tumour size was 5.6 cm (range 2.1–9.8) and two patients had multiple lesions (range 1–3). All patients were planned for partial liver irradiation for a total dose of 50–66 Gy in 2 Gy per fraction with conformal techniques. 3DCRT, IMRT, and RapidArc plans were generated using Eclipse planning system v.13 and dosimetric analysis was done to evaluate the plan quality and efficiency, including CI, HI, MU delivered, PTV D mean and D max . IMRT plans had 3–5 fields and RapidArc plans had 3–5 arcs. V 10 ,V 20 ,V 30 and V 40 of normal liver and D mean of organs at risk (OAR) and D max of spinal cord were also evaluated. Analysis was done using ANOVA and paired t -test with two tailed p Findings All the three techniques had comparable PTV coverage, dose homogeneity, and OAR sparing. IMRT and Rapid Arc had a significantly better conformity index than 3DCRT ( p = 0.03). The high dose areas within the normal liver; V 40 and V 30 were significantly lower in RapidArc and IMRT plans ( p = 0.03 and p = 0.04, respectively), although no significant differences were noted between IMRT and RapidArc. One patient could not attain the normal liver constraint V 33 Interpretation RapidArc and IMRT provide better normal liver sparing and conformity than 3DCRT. However, RapidArc was not better than IMRT for liver protection. Further large trials are required to clearly establish the benefits of IMRT and Rapid Arc techniques to treat primary liver tumours.

Comparative Effectiveness of Intensity-Modulated Versus 3D Conformal Radiation Therapy Among Medicare Patients with Stage III Lung Cancer

The clinical benefit of intensity-modulated radiation therapy (IMRT) compared to 3D conformal radiation (3D-RT) has not been well established for locally advanced non-small-cell lung cancer (NSCLC). Using SEER-Medicare, we identified Medicare beneficiaries diagnosed with stage III NSCLC who received potentially curative (≥ 25 fractions) thoracic IMRT or 3D-RT from 2002-2009. Overall survival and number of hospital days within 90 days of radiation were analyzed using Cox proportional hazard and negative binomial regression models, respectively. Propensity score adjustment was used to control for clinical and demographic variables associated with outcomes. IMRT comprised an increasing proportion of conformal thoracic radiation for NSCLC, rising from 3.0% in 2002 to 26.8% in 2009. Use of IMRT varied significantly by year of diagnosis, facility type, and geographic region and was more likely to be used among patients receiving chemotherapy or with higher comorbidity scores. Among patients receiving potentially curative treatment, there was no difference in overall survival (propensity adj HR .99, p = 0.83) or number of hospital days in the 90 days following radiation start (propensity adj HR 1.15, p = 0.23). When radiation is used to treat locally advanced NSCLC, IMRT is increasingly preferred to 3D-RT. However, among patients receiving potentially curative radiation there was no significant difference in overall survival or time spent hospitalized following treatment.

Efficacy and toxicity of chemoradiation in patients with anal cancer--a retrospective analysis.

BackgroundConcurrent chemotherapy and radiation therapy is the preferred standard of care for patients with anal cancer. Several studies have suggested a benefit of intensity-modulated radiation therapy (IMRT) compared with 3D-conformal radiation (3D-CRT) regarding acute toxicity. This study evaluates outcome and toxicity of patients undergoing IMRT/Tomotherapy or 3D-CRT at our institution.MethodsA cohort of 105 anal cancer patients was treated with chemoradiation or radiation alone (16.2%) between January 2000 and December 2011. 37 patients received 3D-CRT while 68 patients were treated with IMRT. Follow-up exams were performed every 3 to 6 months for a minimum of 3 years and then annually.ResultsMedian follow-up was 41.4 months (2.8 – 158.4). Overall survival (OS), Progression-free survival (PFS) and local control (LC) at 3 years was 70.3%, 66.5%, 78.3% in the 3D-CRT group and 82.9%, 66.5%, 75.3% in the IMRT group without statistically significant difference. 3-year Colostomy-free survival (CFS) was 85.7% in the IMRT/Tomotherapy group and 91.8% in the 3D-CRT group (p = 0.48). No grade 4 toxicity was found in both groups. Severe (G2/3) acute skin toxicity (94.6% vs. 63.2%; p < 0.001) and acute gastrointestinal toxicity rate (67.6% vs. 47.1%; p = 0.03) was significantly higher with 3D-CRT compared to IMRT/Tomotherapy.ConclusionThe use of IMRT can reduce acute severe side effects of the skin and gastrointestinal tract but did not demonstrate improved results regarding OS, PFS, LC and CFS.

A volumetric approach to path-length measurements is essential when treating radiotherapy with modulated beams

The established dosimetric benefits of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy have lead to their increased use in prostate radiotherapy. Complimenting these techniques, volumetric image guidance has supported increased positional accuracy. In addition, 3-dimensional image guidance has also allowed for assessment of potential dosimetric variation that can be attributed to a deformation of either internal or external structures, such as rectal distension or body contour. Compounding these issues is the variation of tissue density through which the new field position passes and also the variation of dose across a modulated beam. Despite the growing level of interest in this area, there are only a limited number of articles that examine the effect of a variation in beam path length, particularly across a modulated field. IMRT and volumetric-modulated radiation therapy (VMAT) fields are dynamic in nature, and the dose gradient within these fields is variable. Assessment of variation of path length away from the beam׳s central axis and across the entire field is vital where there is considerable variation of dose within the field, such as IMRT and VMAT. In these cases, reliance on the traditional central axis to focus skin distances is no longer appropriate. This article discusses these more subtle challenges that may have a significant clinical effect if left unrecognized and undervalued.

Randomized Controlled Trial of Intensity-Modulated Radiotherapy for Early Breast Cancer: 5-Year Results Confirm Superior Overall Cosmesis

There are few randomized controlled trial data to confirm that improved homogeneity with simple intensity-modulated radiotherapy (IMRT) decreases late breast tissue toxicity. The Cambridge Breast IMRT trial investigated this hypothesis, and the 5-year results are reported. Standard tangential plans of 1,145 trial patients were analyzed; 815 patients had inhomogeneous plans (≥ 2 cm(3) receiving 107% of prescribed dose: 40 Gy in 15 fractions over 3 weeks) and were randomly assigned to standard radiotherapy (RT) or replanned with simple IMRT; 330 patients with satisfactory dose homogeneity were treated with standard RT and underwent the same follow-up as the randomly assigned patients. Breast tissue toxicities were assessed at 5 years using validated methods: photographic assessment (overall cosmesis and breast shrinkage compared with baseline pre-RT photographs) and clinical assessment (telangiectasia, induration, edema, and pigmentation). Comparisons between different groups were analyzed using polychotomous logistic regression. On univariate analysis, compared with standard RT, fewer patients in the simple IMRT group developed suboptimal overall cosmesis (odds ratio [OR], 0.68; 95% CI, 0.48 to 0.96; P = .027) and skin telangiectasia (OR, 0.58; 95% CI, 0.36 to 0.92; P = .021). No evidence of difference was seen for breast shrinkage, breast edema, tumor bed induration, or pigmentation. The benefit of IMRT was maintained on multivariate analysis for both overall cosmesis (P = .038) and skin telangiectasia (P = .031). Improved dose homogeneity with simple IMRT translates into superior overall cosmesis and reduces the risk of skin telangiectasia. These results are practice changing and should encourage centers still using two-dimensional RT to implement simple breast IMRT.

Intensity‐modulated versus conventional radiation therapy for oropharyngeal carcinoma: Long‐term dysphagia and tumor control outcomes

The purpose of this study was to determine the relative clinical benefits of intensity-modulated radiation therapy (IMRT) versus conventional radiotherapy (CRT) in the treatment of patients with oropharyngeal carcinoma. We compared tumor control and toxicity outcomes in 132 patients with stage III to IVA/B oropharyngeal carcinoma treated with definitive chemoradiation in the human papillomavirus (HPV) era. Patients treated with IMRT had lower rates of xerostomia (p = .01) and shorter duration of gastrostomy-tube dependence (p < .0001), but increased risk of cervical esophageal stricture (p = .03). The overall rates of late dysphagia were not different between the 2 groups (p = .40). In multivariate analysis, IMRT was a significant predictor of decreased disease-specific mortality (hazard ratio [HR] = 0.24; p = .03) after adjustment for T-category and active smoking. After adjustment for T classification, IMRT use was associated with a trend toward a significant decrease in locoregional failure (HR = 0.17; p = .08). The incidence of late dysphagia is similar in IMRT and CRT, but the mechanism of dysphagia is different.

Global and health-related quality of life after intensity-modulated radiation therapy for head and neck cancer

This study aims to evaluate the current literature regarding the effects of conventional radiation therapy (CRT) versus intensity-modulated radiation therapy (IMRT) on global quality of life (QoL) among patients treated for head and neck cancer. A PubMed literature review was performed. Only articles comparing global QoL scores in head and neck cancer patients treated with CRT versus IMRT were included. Studies were scrutinized for methodology, level of evidence and limitations. Outcomes were evaluated for external validity, level of evidence and applicability. Between 2005 and 2012, 14 eligible studies (six prospective, two randomized controlled trials) were identified. Although all presented data comment on the advantages of IMRT, differences in study design made comparisons difficult. The vast majority of these were also limited by relatively small sample sizes and heterogeneity with respect to patient and treatment-related characteristics. Although more robust evidence is needed in the future, the published data reasonably support the benefits of IMRT as compared with CRT (either 2D or 3D) in improving QoL, beginning at approximately 3–6 months post-treatment, and possibly potentiating with time up to 2 and 3 years.

VortigERN: Variation of radiotherapy target volume definition, dose to organs at risk (OAR), and clinical target volumes using anatomic (CT) versus combined anatomic and molecular imaging (PET-CT): Intensity-modulated radiotherapy delivered using a tomotherapy hi art machine.

TPS267 Background: Intensity-modulated radiotherapy (IMRT) has become the standard of care for radical radiotherapy treatment of head and neck squamous cell carcinomas (SCC). Whle benefits of IMRT include improving long-term xerostomia, accurate target localization is necessary to prevent geographical miss while sparing organs at risk (OAR). Although standard radiotherapy treatment planning (RTP) is performed using contrast enhanced CT scans (CE-CT), molecular imaging using 18FDG PET-CT scans are increasingly being explored to improve tumor localization. Recurrence following IMRT usually occurs within the high-dose area with early data raising the possibility of increased cure rates with dose escalation. Vortigern addresses the issue of optimal imaging for RTP volume definition and explores dose escalation in oropharyngeal SCC. Methods: Patients with oropharyngeal SCC suitable for radical radiotherapy are consented to take part in the study, 14 out of the planned 30 have been recruited. A PET-CT scan is a...

A dosimetric comparison of intensity-modulated radiotherapy versus conventional tangential irradiation for breast cancer after breast-conserving surgery

Objective To evaluate the dosimetric benefits of intensity-modulated radiotherapy (IMRT) for early stage breast cancer after breast-conserving surgery. Methods Ten patients with stage Tis～2N0M0 breast cancer receiving breast-conserving surgery were selected for the study. Six cases were on the left, four were on the right. A dosimetric comparison of IMRT with conventional wedged tangential technique was performed on each patient using three dimensional treatment planning. The total prescribed dose for both plans was 50 Gy/25 fractions. Dose volume histograms (DVH) were used to compare the planning target volume (PTV) and organs at risks(OARS). Results The PTV coverage in IMRT plan was similar to that of the conventional plan (97.83 % vs 97.61%). A better dose uniformity throughout the whole breast was achieved by IMRT plan. The percentage of PTV receiving less than 95 % prescribed dose and more than 103 % prescribed dose (inhomogeneity index IHI), decreased from 25.42 % to 2.71%: the percentage of PTV receiving more than 105 % prescribed dose (V105 %) decreased from 25.79 % to 1.08 %. A better amelioration of IHI and reduction of V105 % in IMRT plans were observed in the relatively large PTV subgroup. The Dmean and percentage of volume receiving more than 30 Gy (V30) of heart from 6.72 Gy to 4.95 Gy, and from 7.23 % to 1.04 %. the Dmean and percentage of volume receiving more than 20 Gy (V20) of ipsilateral from 9.19 Gy to 7.65 Gy, and from 22.34 % to 20.18 %; the Dmean of contralateral breast decreased from 5.12 Gy to 3.52 Gy;the Dmean of contralateral lung decreased from 2.76 Gy to 1.79 Gy; the Dmean of liver decreased from 7.23 Gy to 1.04 Gy for right side patients. Conclusion Forward planning IMRT based on a standard tangential beam arrangement significantly improves the dose homogeneity throughout the target volume of intact breast and reduces the dose to OARS, especially in patients with large breast volumes who might be proposed as candidates of IMRT for intact breast. Key words: Breast neoplasms; Radiotherapy; Intensity modulation radiation therapy; Threedimensional treatment planning; DVH; Breast-conserving surgery

Clinical application of intensity-modulated radiotherapy for head and neck cancer

Intensity-modulated radiotherapy (IMRT) is a modern treatment technique that allows one to shape the dose to the target volume and to reduce the dose delivered to healthy tissue. Over the last decade, IMRT has been implemented for head and neck cancer treatment, with the aim of reducing the dose delivered to the parotid glands and improving the dose coverage of complex target volumes located close to critical structures. The potential benefits of IMRT in terms of salivary function preservation and better local control have contributed to the rapid diffusion of this new technology. However, it should not be overlooked that IMRT is a novel treatment technique and that its clinical application represents a paradigm shift in the practice of radiation oncology. The purpose of this article is to review the clinical experience with IMRT for head and neck cancer treatment and to discuss some important issues related to its implementation.

Superiority of intensity-modulated radiotherapy over three-dimensional conformal radiotherapy combined with brachytherapy in nasopharyngeal carcinoma: a planning study

A planning study was performed in order to investigate the potential benefits of intensity-modulated radiotherapy using a simultaneous integrated multi-target treatment technique (SIMT-IMRT) over highly optimized three-dimensional conformal radiotherapy combined with intracavitary brachytherapy (3D-CRT + IBT) for the treatment of nasopharyngeal carcinoma (NPC). The subjects were eight patients with Stages I-IV NPC. For each case, two sets of plans were prepared after delineation of gross tumour volumes, three planning target volumes (PTVs) and 17 organs at risk (OARs). Dose prescriptions for PTVs were 72.6 Gy, 66 Gy and 52.8 Gy in 33 fractions for SIMT-IMRT vs 72 Gy (66 Gy in 33 fractions for 3D-CRT and 3 Gy twice for IBT), 66 Gy (in 33 fractions) and 46 Gy (in 23 fractions) for 3D-CRT + IBT plans. Compared with the combined plans, SIMT-IMRT provided superior results for the primary tumour (PT) in terms of mean equivalent uniform dose (67 Gy vs 63.7 Gy, p = 0.016). IMRT plans increased the mean tumour control probability (TCP) values (both uncorrected and corrected for accelerated tumour repopulation after 28 days) for PT when compared with 3D-CRT + IBT (98% and 94.3% vs 95.8% and 89.9%, respectively, p = 0.016). Mean doses to middle/external ears, parotid glands and temporomandibular joints were significantly lower in IMRT plans. Our conclusion is that, for all stages of NPC, SIMT-IMRT was superior to highly optimized 3D-CRT + IBT in terms of tumour coverage, increased local TCP, and dose reduction to some OARs. We recommend that SIMT-IMRT should be considered as a first-line radiotherapy technique for NPC.

Inter- and Intrafractional Tumor and Organ Movement in Patients With Cervical Cancer Undergoing Radiotherapy: A Cinematic-MRI Point-of-Interest Study

Internal tumor and organ movement is important when considering intensity-modulated radiotherapy for patients with cancer of the cervix because of the tight margins and steep dose gradients. In this study, the internal movement of the tumor, cervix, and uterus were examined using serial cinematic magnetic resonance imaging scans and point-of-interest analysis. Twenty patients with Stage IB-IVA cervical cancer underwent pelvic magnetic resonance imaging before treatment and then weekly during external beam radiotherapy. In each 30-min session, sequential T(2)-sagittal magnetic resonance imaging scans were obtained. The points of interest (cervical os, uterine canal, and uterine fundus) were traced on each image frame, allowing the craniocaudal and anteroposterior displacements to be measured. The mean displacements and trends were analyzed using mixed linear models. Prediction intervals were calculated to determine the internal target margins. Large interscan motion was found for all three points of interest that was only partially explained by the variations in bladder and rectal filling. The intrascan motion was much smaller. Both inter- and intrascan motion was greatest at the fundus of the uterus, less along the canal, and least at the cervical os. The isotropic internal target margins required to encompass 90% of the interscan motion were 4 cm at the fundus and 1.5 cm at the os. In contrast, smaller margins of 1 cm and 0.45 cm, respectively, were adequate to encompass the intrascan motion alone. Daily soft-tissue imaging with correction for interfractional motion or adaptive replanning will be important if the benefits of intensity-modulated radiotherapy are to be maximized in women with cervical cancer.

Cost effectiveness of whole breast IMRT for reduction of moist desquamation

17004 Background: Cost minimization studies have compared conventional whole breast radiation therapy (C-WBRT) to whole breast intensity modulated radiation therapy (IMRT). Consistently, IMRT has proved to be far more expensive. The weakness of cost minimization studies is that they assume the outcomes and toxicities of the treatment modalities in question are identical. Data from a case- control trial and a recent randomized controlled trial show that IMRT reduces the incidence of moist desquamation. We performed an analysis to estimate the cost effectiveness of breast IMRT to prevent moist desquamation. Methods: The direct medical costs of C-WBRT and IMRT were estimated using the 2006 Medicare Fee Schedule. We assumed rates of moist desquamation of 48 to 31% in accordance with Pignol, et al., ASTRO 2006. The cost effectiveness ratio (additional dollars spent per case of desquamation avoided) was calculated under two circumstances: 1) every patient received IMRT, or 2) only those patients destined to desquamate were treated with IMRT. Results: The direct medical costs of C-WBRT are $7,948 vs. $29,790 for IMRT. Thus, the marginal cost of IMRT is $22,142. In circumstance 1, the marginal cost to avoid one case of desquamation is $130,247. In circumstance 2, this cost is $62,518. Conclusions: The two circumstances described above are extremes that bound the range of cost estimates. Patient risk factors for desquamation, such as large breast size, can be used to identify high risk patients, obviating the need to treat all patients with IMRT. However, perfect prospective identification of all patients destined to desquamate is unlikely. Instead, the true marginal cost to avoid one case of moist desquamation will lie between $62,518 and $130,247. This cost may be too high to justify the benefit of reduced acute skin toxicity, but it is likely that the benefits of IMRT have been underestimated. IMRT may shorten the duration of moist desquamation. Late effects such as breast fibrosis and color variegation of the skin caused by desquamation as well as dose to the heart and lungs may be decreased by IMRT. If new data support these benefits, then IMRT may become a more cost effective option. No significant financial relationships to disclose.