Compensatory enlargement of the liver after treatment of hepatocellular carcinoma with carbon ion radiotherapy - Relation to prognosis and liver function

Background and purpose

To examine whether liver volume changes affect prognosis and hepatic function in patients treated with carbon ion radiotherapy (CIRT) for hepatocellular carcinoma (HCC).

Material and methods

Between April 1995 and March 2003, among the cases treated with CIRT, 43 patients with HCC limited to the right hepatic lobe were considered eligible for the study. The left lateral segment was defined as the non-irradiated region. Liver volume was measured using contrast CT at 0, 3, 6, and 12 months after CIRT. We examined serum albumin, prothrombin activity, and total bilirubin level as hepatic functional reserve.

Results

After CIRT, the non-irradiated region showed significant enlargement, and enlarged volume of this region 3 months after CIRT ?50 cm³ was a prognostic factor. The 5-year overall survival rates were 48.9% in the larger enlargement group (enlarged volume of non-irradiated region 3 months after CIRT ?50 cm³) and 29.4% in the smaller enlargement group (as above, <50 cm³). The larger enlargement group showed better hepatic functional reserve than the smaller enlargement group 12 months after CIRT.

Conclusions

This study suggests that compensatory enlargement in the non-irradiated liver after CIRT contributes to the improvement of prognosis.     

Prognostic parameters for acute esophagus toxicity in Intensity Modulated Radiotherapy and concurrent chemotherapy for locally advanced non-small cell lung cancer

Background and purpose

The aim of this study was to correlate clinical and dosimetric variables with acute esophageal toxicity (AET) following Intensity Modulated Radiotherapy (IMRT) with concurrent chemotherapy for locally advanced non-small cell lung cancer (NSCLC). In addition, timeline of AET was reported.

Material and methods

153 patients with locally advanced NSCLC treated with 66 Gy/2.75 Gy/24 fractions of radiotherapy and concurrent daily low dose cisplatin were selected. Medical records and treatments of these patients were retrospectively reviewed. Maximum AET grade ?2 and maximum grade 3 were the endpoints of this study. Dates for onset, maximum and recovery (to baseline) of AET were reported. Univariate and multivariate analysis were applied to correlate clinical, tumor, dosimetric and chemotherapy dose variables to AET grade ?2 and grade 3.

Results

AET grade 2 occurred in 37% and grade 3 in 20% of the patients. The median onset of AET was around day 15 for all grades. The median onset of the maximum grade was day 30 for both grades 2 and 3. The median duration was 43 days for grade 1, 50 days for grade 2 and >80 days for grade 3. Of the grade 3 AET patients, 48% recovered within 3 months. Esophagus V50, ethnic background, and the number of cisplatin administrations were significantly correlated with grade 3 AET.

Conclusions

For NSCLC patients treated with concurrent chemotherapy and IMRT A higher number of cisplatin administrations, non-Caucasian background and higher V50oes were associated with grade 3 AET. The median onset of AET grade 3 is 15 days after the start of treatment, maximized at day 30, with a median duration of >80 days.     

A retrospective comparison of proton therapy and carbon ion therapy for stage I non-small cell lung cancer

Background and purpose

This retrospective study aimed to compare the clinical outcomes and late toxicities of proton therapy (PT) with those of carbon ion therapy (CIT) for stage I non-small cell lung cancer (NSCLC).

Material and methods

A total of 111 patients who underwent particle therapy for stage I NSCLC between April 2003 and December 2009 were enrolled in this study. PT (n = 70) and CIT (n = 41) were delivered to total doses of 52.8–80 GyE in 4–26 fractions and 52.8–70.2 GyE in 4–26 fractions, respectively. The median follow-up time was 41 months.

Results

Differences in outcome between the PT and CIT groups regarding 3-year overall survival (72% and 76%, respectively), progression-free survival (44% and 53%, respectively), and local control (81% and 78%, respectively) were not statistically significant. In multivariate analysis, the type of treatment beam did not correlate with overall survival. The severity of late toxicities was comparable between the two groups.

Conclusions

Clinical results in the PT group were comparable to those in the CIT group. However, this study was a retrospective analysis of a highly heterogeneous population. Consequently, more homogeneous prospective data, large multicentric databases and, ideally, randomized trials are warranted.     

Post-chemoradiation intraoperative electron-beam radiation therapy boost in resected locally advanced rectal cancer: Long-term results focused on topographic pattern of locoregional relapse

Background

Patients with locally advanced rectal cancer (LARC) have a dismal prognosis. We investigated outcomes and risk factors for locoregional recurrence (LRR) in patients treated with preoperative chemoradiotherapy (CRT), surgery and IOERT.

Methods

A total of 335 patients with LARC [?cT3 93% and/or cN+ 69%) were studied. In multivariate analyses, risk factors for LRR, IFLR and OFLR were assessed.

Results

Median follow-up was 72.6 months (range, 4–205). In multivariate analysis distal margin distance ?10 mm [HR 2.46, p = 0.03], R1 resection [HR 5.06, p = 0.02], tumor regression grade 1–2 [HR 2.63, p = 0.05] and tumor grade 3 [HR 7.79, p < 0.001] were associated with an increased risk of LRR. A risk model was generated to determine a prognostic index for individual patients with LARC.

Conclusions

Overall results after multimodality treatment of LARC are promising. Classification of risk factors for LRR has contributed to propose a prognostic index that could allow us to guide risk-adapted tailored treatment.     

Stereotactic ablative radiotherapy (SABR) using 70 Gy in 10 fractions for non-small cell lung cancer: Exploration of clinical indications

Background and purpose

We report our outcomes for patients with NSCLC treated with SABR to 70 Gy in 10 fractions and propose indications for this regimen as well as new dose–volume constraints.

Materials and methods

Volumetric image-guided SABR was used to treat 82 patients with clinical challenging NSCLC, not suitable for 50 Gy in 4 fractions, to a final dose of 70 Gy in 10 fractions. Endpoints included overall survival (OS), toxicity, and disease control.

Results

At a median follow-up time of 21.1 months, 2-year OS and local control rates were 66.9% and 96.2%, respectively. The most common side effects were radiation pneumonitis (14.6% grade 2, 2.4% grade 3), followed by chest wall pain (4.9% grade 2, 1.2% grade 3). Multivariate analysis revealed chest wall V50 > 60 cm³ to be associated with chest wall pain. No patient developed brachial plexopathy. One patient with bronchial tree tumor invasion died of hemoptysis.

Conclusions

SABR with 70 Gy in 10 fractions appears to achieve excellent local control and acceptable toxicity for clinically challenging cases with improved tolerance of the chest wall and brachial plexus as compared with 50 Gy in 4 fractions. This regimen may not be suitable in patients with tumor invading critical central structures. More studies are needed to validate our conclusions.     

Dose-volume histogram and dose-surface histogram analysis for skin reactions to carbon ion radiotherapy for bone and soft tissue sarcoma

Background and purpose

To evaluate the usefulness of the dose-volume histogram (DVH) and dose-surface histogram (DSH) as clinically relevant and available parameters that helped to identify bone and soft tissue sarcoma patients at risk of developing late skin reactions, including ulceration, when treated with carbon ion radiotherapy.

Materials and methods

Thirty-five patients with bone and soft tissue sarcoma treated with carbon ion beams were studied. The clinical skin reactions were evaluated. Some pretreatment variables were compared with the grade of late skin reactions.

Results

Average DVH and DSH were established in accordance with the grading of the skin reactions. Prescribed dose, the difference in depths between the skin surface and the proximal extent of the tumor, and some DVH/DSH parameters were correlated with late skin reaction (≧grade 3) according to univariate analysis. Furthermore, the area irradiated with over 60 GyE (S₆₀ > 20 cm²) on DSH was the most important factor by multivariate analysis.

Conclusions

The area irradiated with over 60 GyE (S₆₀ > 20 cm²) on DSH was found to be a parameter for use as a predictor of late skin reactions.     

Critical assessment of preoperative and operative risk factors for complications after iterative peritonectomy procedures

Aims

This study is the first to evaluate the clinical and treatment-related risk factors for perioperative toxicity and mortality in patients with peritoneal recurrence that underwent iterative cytoreductive surgery (CRS) with or without perioperative intraperitoneal chemotherapy (PIC). The aim is to improve patient selection.

Methods

Fifty-seven consecutive iterative CRS procedures were performed in 40 patients between June 2000 and September 2008. Forty-seven patients were administered PIC. Adverse events were rated from grades I to V with increasing severity. Grade I toxicity was self limiting; grade II required medical intervention; grade III required an invasive intervention; grade IV required returning to intensive care unit or operating theatre; and grade V resulted in patient death during hospital stay. Risk factors for grades III and IV/V toxicity were determined.

Results

The mortality rate was 2%. The grades III and IV/V toxicity rate was 18% and 19%, respectively. A peritoneal cancer index ≥16 (p = 0.020), operation length ≥9 h (p = 0.045), number of peritonectomy procedures ≥2 (p = 0.045) and a suboptimal cytoreduction (p = 0.031) were the risk factors for grade IV/V toxicity.

Conclusions

Iterative CRS and PIC procedures have an acceptable rate of perioperative toxicity in carefully selected patients. Patients with high tumour burden requiring extensive surgical dissection are at highest risk of a severe adverse event. Thorough preoperative evaluation of patients is necessary to improve both perioperative and postoperative outcomes.     

IORT with electrons as boost strategy during breast conserving therapy in limited stage breast cancer: Long term results of an ISIORT pooled analysis

Purpose

Linac-based intraoperative radiotherapy with electrons (IOERT) was implemented to prevent local recurrences after breast conserving therapy (BCT) and was delivered as an intraoperative boost to the tumor bed prior to whole breast radiotherapy (WBI). A collaborative analysis has been performed by European ISIORT member institutions for long term evaluation of this strategy.

Material and methods

Until 10/2005, 1109 unselected patients of any risk group have been identified among seven centers using identical methods, sequencing and dosage for intra- and postoperative radiotherapy. A median IOERT dose of 10 Gy was applied (90% reference isodose), preceding WBI with 50–54 Gy (single doses 1.7–2 Gy).

Results

At a median follow up of 72.4 months (0.8–239), only 16 in-breast recurrences were observed, yielding a local tumor control rate of 99.2%. Relapses occurred 12.5–151 months after primary treatment. In multivariate analysis only grade 3 reached significance (p = 0.031) to be predictive for local recurrence development. Taking into account patient age, annual in-breast recurrence rates amounted 0.64%, 0.34%, 0.21% and 0.16% in patients <40 years; 40–49 years; 50–59 years and ?60 years, respectively.

Conclusion

In all risk subgroups, a 10 Gy IOERT boost prior to WBI provided outstanding local control rates, comparing favourably to all trials with similar length of follow up.     

Intensity-modulated radiation therapy for head and neck cancer: Systematic review and meta-analysis

Background and purpose

Intensity-modulated radiation therapy (IMRT) provides the possibility of dose-escalation with better normal tissue sparing. This study was performed to assess whether IMRT can improve clinical outcomes when compared with two-dimensional (2D-RT) or three-dimensional conformal radiation therapy (3D-CRT) in patients with head and neck cancer.

Methods and materials

Only prospective phase III randomized trials comparing IMRT with 2D-RT or 3D-CRT were eligible. Combined surgery and/or chemotherapy were allowed. Two authors independently selected and assessed the studies regarding eligibility criteria and risk of bias.

Results

Five studies were selected. A total of 871 patients were randomly assigned for 2D-RT or 3D-CRT (437), versus IMRT (434). Most patients presented with nasopharyngeal cancers (82%), and stages III/IV (62.1%). Three studies were classified as having unclear risk and two as high risk of bias. A significant overall benefit in favor of IMRT was found (hazard ratio – HR = 0.76; 95% CI: 0.66, 0.87; p < 0.0001) regarding xerostomia scores grade 2–4, with similar loco-regional control and overall survival.

Conclusions

IMRT reduces the incidence of grade 2–4 xerostomia in patients with head and neck cancers without compromising loco-regional control and overall survival.     

Hypofractionated intensity-modulated arc therapy for lymph node metastasized prostate cancer: Early late toxicity and 3-year clinical outcome

Background and purpose

For patients with N1 prostate cancer (PCa) aggressive local therapies can be advocated. We evaluated clinical outcome, gastro-intestinal (GI) and genito-urinary (GU) toxicity after intensity modulated arc radiotherapy (IMAT) + androgen deprivation (AD) for N1 PCa.

Material and methods

Eighty patients with T1-4N1M0 PCa were treated with IMAT and 2–3 years of AD. A median dose of 69.3 Gy (normalized isoeffective dose at 2 Gy per fraction: 80 Gy [α/β = 3]) was prescribed in 25 fractions to the prostate. The pelvic lymph nodes received a minimal dose of 45 Gy. A simultaneous integrated boost to 72 Gy and 65 Gy was delivered to the intraprostatic lesion and/or pathologically enlarged lymph nodes, respectively.GI and GU toxicity was scored using the RTOG/RILIT and RTOG-SOMA/LENT-CTC toxicity scoring system respectively. Three-year actuarial risk of grade 2 and 3/4 GI–GU toxicity and biochemical and clinical relapse free survival (bRFS and cRFS) were calculated with Kaplan–Meier statistics.

Results

Median follow-up was 36 months. Three-year actuarial risk for late grade 3 and 2 GI toxicity is 8% and 20%, respectively. Three-year actuarial risk for late grade 3–4 and 2 GU toxicity was 6% and 34%, respectively. Actuarial 3-year bRFS and cRFS was 81% and 89%, respectively. Actuarial 3-year bRFS and cRFS was, respectively 26% and 32% lower for patients with cN1 disease when compared to patients with cN0 disease.

Conclusion

IMAT for N1 PCa offers good clinical outcome with moderate toxicity. Patients with cN1 disease have poorer outcome.     

Predictive parameters of symptomatic radiation pneumonitis following stereotactic or hypofractionated radiotherapy delivered using volumetric modulated arcs

Purpose

To identify dosimetric factors that predict development of radiation pneumonitis (RP) following stereotactic or hypofractionated radiotherapy for lung tumors.

Methods

Seventy-nine consecutive patients with either a planning target volume (PTV) > 100 cm³ (n = 69) or prior pneumonectomy or bi-lobectomy (n = 13) were identified. Radiation doses (range: 5–50 Gy, with 5 Gy increments) were converted to equivalent doses (EQD_2 Gy) (α/β = 3). Total lung (TL), ipsilateral (IL) and contralateral lung (CL) volumes minus PTV, receiving 5 Gy (V5) up to 50 Gy (V50) and mean lung dose (MLD) were analyzed. Predictors of grade ?3 RP (CTCAEv4.03) were identified with concordance-statistics (C-statistic) and p-values used to quantify the performance of the model. Factors found to be significant were entered into a recursive partitioning analysis (RPA).

Results

Median PTV was 150 cm³. Grade ?3 RP was observed in 8 patients (10%). In univariable analysis, CL-MLD, CL-V5-15, TL-MLD, TL-V5-V10 and ITV size were predictive of RP (p < 0.05). In multivariable analysis, contralateral MLD (p = .007) and ITV (p = .063) were the strongest predictors of grade ?3 RP, with excellent discrimination (C-statistic: 0.868).

Conclusion

Contralateral MLD and ITV size are both strong predictors of grade ?3 RP post treatment. Planning constraints should aim to keep contralateral MLD below 3.6 Gy.     

Acute phase response before treatment predicts radiation esophagitis in non-small cell lung cancer

Background and purpose

Radiation esophagitis (RE) represents an inflammatory reaction to radiation therapy (RT). We hypothesized that aspects of the physiologic acute phase response (APR) predicts RE.

Material and methods

We retrospectively analyzed 285 patients with non-small cell lung cancer (NSCLC) treated with definitive radiation. The primary analysis was the association of pretreatment lab values reflective of the APR with symptomatic (grade ?2) RE. Univariate and multivariate odds ratios (ORs) were calculated to test associations of clinical and pretreatment lab values with RE. Optimal cutpoints and multivariable risk stratification groupings were determined via recursive partitioning analysis.

Results

Pretreatment platelet counts were higher and hemoglobin levels lower in patients who developed RE (P < 0.05). Based on these two pre-treatment risk factors, an APR score was defined as 0 (no risk factors), 1 (either risk factor), or 2 (both risk factors). APR score was significantly associated with RE in both univariate (OR = 2.3 for each point, 95% confidence interval [CI] 1.5–3.4, P = 0.001) and multivariate (OR = 2.1, 95% CI 1.3–3.4, P = 0.002) analyses.

Conclusions

The APR score may represent a novel metric to predict RE. However, pending validation in an independent dataset, caution is advised when interpreting these results given their retrospective and thus exploratory nature.     

Phase II study of oral S-1 and cisplatin with concurrent radiotherapy for locally advanced non-small-cell lung cancer

Purpose

To determine the efficacy and safety of oral S-1 in combination with cisplatin and thoracic radiotherapy in patients with unresectable stage III non-small-cell lung cancer (NSCLC).

Methods and materials

S-1 (50 mg/m²) was administered orally twice daily for 14 days, with cisplatin (40 mg/m²) on days 1 and 8 of each cycle every 3 weeks, for 2–4 cycles. Thoracic radiation therapy was administered in 2 Gy fractions five times weekly for a total dose of 60 Gy. The primary endpoint was the response rate, and secondary endpoints included progression-free survival, overall survival and safety.

Results

Forty-one patients were enrolled in this study. The objective response rate was 87.8% (98% CI: 77.8–97.8%). The median progression-free survival was 467 days (15.4 months), and the median survival time was 904 days (29.7 months). The overall survival rates at 1- and 2-years were 85.7% and 52.9%, respectively. Hematological toxicities included grade 3/4 neutropenia (17%) and grade 3/4 leukopenia (27%). No grade 3 febrile neutropenia was detected, and grade 3/4 non-hematological toxicities were also mild. A grade 3 gastrointestinal hemorrhage was observed in one patient.

Conclusions

The combination of oral S-1 plus cisplatin with concurrent radiotherapy is a promising treatment with a high efficacy and lower toxicity in patients with locally advanced NSCLC.     

Cardiac comorbidity is an independent risk factor for radiation-induced lung toxicity in lung cancer patients

Purpose

To test the hypothesis that cardiac comorbidity before the start of radiotherapy (RT) is associated with an increased risk of radiation-induced lung toxicity (RILT) in lung cancer patients.

Material and methods

A retrospective analysis was performed of a prospective cohort of 259 patients with locoregional lung cancer treated with definitive radio(chemo)therapy between 2007 and 2011 (ClinicalTrials.gov Identifiers: NCT00572325 and NCT00573040). We defined RILT as dyspnea CTCv.3.0 grade ?2 within 6 months after RT, and cardiac comorbidity as a recorded treatment of a cardiac pathology at a cardiology department. Univariate and multivariate analyses, as well as external validation, were performed. The model-performance measure was the area under the receiver operating characteristic curve (AUC).

Results

Prior to RT, 75/259 (28.9%) patients had cardiac comorbidity, 44% of whom (33/75) developed RILT. The odds ratio of developing RILT for patients with cardiac comorbidity was 2.58 (p < 0.01). The cross-validated AUC of a model with cardiac comorbidity, tumor location, forced expiratory volume in 1 s, sequential chemotherapy and pretreatment dyspnea score was 0.72 (p < 0.001) on the training set, and 0.67 (p < 0.001) on the validation set.

Conclusion

Cardiac comorbidity is an important risk factor for developing RILT after definite radio(chemo)therapy of lung cancer patients.     

Dosimetric predictors of esophageal toxicity after stereotactic body radiotherapy for central lung tumors

Background and purpose

Stereotactic body radiotherapy (SBRT) to central lung tumors can cause esophageal toxicity, but little is known about the incidence or risk factors. We reviewed central lung SBRT patients to identify dosimetric factors predictive of esophageal toxicity.

Materials and methods

We assessed esophageal toxicity in 125 SBRT patients. Using biological equivalent doses with α/β = 10 Gy (BED₁₀), dose–volume histogram variables for the esophagus (D_v and V_d) were assessed for correlation with grade ?2 acute toxicity.

Results

Incidence of grade ?2 acute toxicity was 12% (n = 15). Highly significant logistic models were generated for D_5cc and D_max (p < 0.001). To keep the complication rate <20%, the model requires that D_5cc ? 26.3 BED₁₀. At 2 years, the probability of complication with BED₁₀D_5cc > 14.4 Gy was 24%, compared to 1.6% if ?14.4 Gy.

Conclusions

This novel analysis provides guidelines to predict acute esophageal toxicity in lung SBRT. Dose to the hottest 5cc and D_max of the esophagus were the best predictors of toxicity. Converting the BED₁₀ limits to physical doses, D_5cc to the esophagus should be kept less than 16.8, 18.1 and 19.0 Gy for 3, 4, and 5 fractions, respectively, to keep the acute toxicity rate <20%.     

Feasibility of proton beam therapy for reirradiation of locoregionally recurrent non-small cell lung cancer

Background and purpose

Options are limited for patients with intrathoracic recurrence of non-small cell lung cancer (NSCLC) who previously received radiation. We report our 5-year experience with the toxicity and efficacy of proton beam therapy (PBT) for reirradiation.

Materials and methods

Thirty-three patients underwent PBT reirradiation for intrathoracic recurrent NSCLC at a single institution. All patients had had RT for NSCLC (median initial dose 63 Gy in 33 fractions), with median interval to reirradiation of 36 months. Median reirradiation dose was 66 Gy (RBE) in 32 fractions. Toxicity was scored with CTCAE v4.0, and survival outcomes were estimated using Kaplan–Meier.

Results

Thirty-one patients (94%) completed reirradiation. At a median 11 months’ follow-up, 1-year rates of overall survival, progression-free survival, locoregional control, and distant metastasis-free survival were 47%, 28%, 54%, and 39%. Rates of severe (grade ?3) toxicity were 9% esophageal, 21% pulmonary; 1 patient had grade 4 esophagitis, and 2 had grade 4 pulmonary toxicity. Nine patients experienced a second in-field failure.

Conclusions

PBT is an option for treating recurrent NSCLC. However, the rates of locoregional recurrence and distant metastasis are high and the potential for toxicity significant. The risks and benefits of PBT must be carefully weighed in each case.     

Preoperative intensity-modulated and image-guided radiotherapy with a simultaneous integrated boost in locally advanced rectal cancer: Report on late toxicity and outcome

Background and purpose

The addition of chemotherapy to preoperative radiotherapy has been established as the standard of care for patients with cT3-4 rectal cancer. As an alternative strategy, we explored intensity-modulated and image-guided radiotherapy (IMRT–IGRT) with a simultaneous integrated boost (SIB) in a prospective phase II study. Here, we report outcome and late toxicity after a median follow-up of 54 months.

Methods and materials

A total of 108 patients were treated preoperatively with IMRT–IGRT, delivering a dose of 46 Gy in fractions of 2 Gy. Patients (n = 57) displaying an anticipated circumferential resection margin (CRM) of less than 2 mm based on magnetic resonance imaging received a SIB to the tumor up to a total dose of 55.2 Gy.

Results

The absolute incidence of grade ?3 late gastrointestinal and urinary toxicity was 9% and 4%, respectively, with a 13% rate of any grade ?3 late toxicity. The actuarial 5-year local control (LC), progression-free survival (PFS) and overall survival (OS) were 97%, 57%, and 68%. On multivariate analysis, R1 resection and pN2 disease were associated with significantly impaired OS.

Conclusions

The use of preoperative IMRT–IGRT with a SIB resulted in a high 5-year LC rate and non-negligible late toxicity.     

Fatigue during chemoradiotherapy for nasopharyngeal cancer and its relationship to radiation dose distribution in the brain

Background and purpose

Fatigue during head and neck radiotherapy may be related to radiation dose to the central nervous system (CNS). The impact of patient, tumour, and dosimetric variables on acute fatigue was assessed in nasopharyngeal cancer patients undergoing chemoradiotherapy.

Material and methods

Radiation dose to the following retrospectively-delineated CNS structures; brainstem, cerebellum, pituitary gland, pineal gland, hypothalamus, hippocampus and basal ganglia (BG) and clinical variables were related to incidence of ? grade 2 fatigue in 40 patients.

Results

Sixty per cent of patients reported fatigue during and following radiotherapy. Dmean and D2 to the BG and Dmean to the pituitary gland were significantly associated with fatigue during radiation (P < 0.01). Dmean to the cerebellum was associated with fatigue following radiotherapy and at any time (P < 0.01). After adjusting for clinical factors, an association remained between fatigue during radiotherapy and mean dose and D2 to the pituitary gland and BG (P = 0.012, 0.036, 0.009 and 0.018) and mean dose to the cerebellum following radiation and at any time (P = 0.042 and 0.029).

Conclusion

Disruption of connections between BG, cerebellum, and higher cortical centres or disruption of pituitary-regulated hormonal balance may be implicated in the pathophysiology of radiation-related fatigue.     

Second cancer risk after 3D-CRT,IMRT and VMAT for breast cancer

Purpose

Second cancer risk after breast conserving therapy is becoming more important due to improved long term survival rates. In this study, we estimate the risks for developing a solid second cancer after radiotherapy of breast cancer using the concept of organ equivalent dose (OED).

Materials and methods

Computer-tomography scans of 10 representative breast cancer patients were selected for this study. Three-dimensional conformal radiotherapy (3D-CRT), tangential intensity modulated radiotherapy (t-IMRT), multibeam intensity modulated radiotherapy (m-IMRT), and volumetric modulated arc therapy (VMAT) were planned to deliver a total dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were created and the OEDs calculated. Second cancer risks of ipsilateral, contralateral lung and contralateral breast cancer were estimated using linear, linear-exponential and plateau models for second cancer risk.

Results

Compared to 3D-CRT, cumulative excess absolute risks (EAR) for t-IMRT, m-IMRT and VMAT were increased by 2 ± 15%, 131 ± 85%, 123 ± 66% for the linear-exponential risk model, 9 ± 22%, 82 ± 96%, 71 ± 82% for the linear and 3 ± 14%, 123 ± 78%, 113 ± 61% for the plateau model, respectively.

Conclusion

Second cancer risk after 3D-CRT or t-IMRT is lower than for m-IMRT or VMAT by about 34% for the linear model and 50% for the linear-exponential and plateau models, respectively.