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Featured researches published by Noah C. Choi.


Journal of Clinical Oncology | 1997

Potential impact on survival of improved tumor downstaging and resection rate by preoperative twice-daily radiation and concurrent chemotherapy in stage IIIA non-small-cell lung cancer.

Noah C. Choi; Robert W. Carey; W Daly; Douglas J. Mathisen; John Wain; Cameron D. Wright; Thomas R. Lynch; Michael L. Grossbard; Hermes C. Grillo

PURPOSE The main objectives of this study were (a) to ascertain the feasibility and toxicity of preoperative twice-daily radiation therapy and concurrent chemotherapy, surgery, and postoperative therapy in stage IIIA (N2) non-small-cell lung cancer (NSCLC), and (b) to evaluate tumor response, resection rate, pathologic tumor downstaging, and survival. METHODS Eligibility included biopsy-proven N2 lesion (stage IIIA) by mediastinoscopy, Karnofsky performance score > or = 70, and weight loss less than 5% in the 3 months before diagnosis. The treatment program consisted of two courses of preoperative cisplatin, vinblastine, and fluorouracil (5-FU); 42 Gy concurrent radiation at 1.5 Gy per fraction in two fractions per day; surgery on day 57; and one more course of postoperative chemotherapy and 12 to 18 Gy of concurrent twice-daily radiation. RESULTS Forty-two patients with stage IIIA (N2) NSCLC (27 men and 15 women, age 38 to 77 years) were enrolled onto this prospective study. Forty of 42 patients tolerated the intended dose (42 Gy) of preoperative radiation and 37 of 39 resected patients received prescribed postoperative radiation. The intended dose of chemotherapy was given in 100%, 70%, and 60% of patients for the first, second, and third courses of chemotherapy. Marked dysphagia that required intravenous hydration was noted in 14% of patients (six of 42). Myelotoxicities included grade > or = 3 granulocytopenia in 23% and thrombocytopenia in 6% of 113 chemotherapy courses. Febrile neutropenia that required hospital admission was noted in 9% of 113 chemotherapy courses. Surgical resection was performed in 93% of patients. Treatment-related mortality was noted in 7% of patients. The overall survival rates by the Kaplan-Meier method were 66%, 37%, and 37% at 2,3, and 5 years, respectively, with a median follow-up time of 48 months. Pathologic examination of the surgical specimen showed a downward shift in tumor extent from stage IIIA (N2) to stage II (N1) in 33%, to stage I (NO) in 24% (10 of 42), and to stage 0 (TONO) in 9.5%, for a total of 67%. The degree of tumor downstaging was also translated into a survival benefit: 5-year survival rates from the time of surgery were 79%, 42%, and 18% for postoperative tumor stages 0 and I, II, and III, respectively (P = .04). CONCLUSION Concurrent chemoradiotherapy using twice-daily radiation is an effective induction regimen that resulted in 67% tumor downstaging, and an encouraging 37% 5-year survival rate. The degree of tumor downstaging may be a useful intermediate end point for survival benefit in stage IIIA (N2) NSCLC.


Annals of Oncology | 2011

Implementing multiplexed genotyping of non-small-cell lung cancers into routine clinical practice

Lecia V. Sequist; Rebecca S. Heist; Alice T. Shaw; Panos Fidias; Rachel Rosovsky; Jennifer S. Temel; Inga T. Lennes; Subba R. Digumarthy; Belinda A. Waltman; E. Bast; Swathi Tammireddy; L. Morrissey; Alona Muzikansky; S. B. Goldberg; Justin F. Gainor; Colleen L. Channick; John C. Wain; Henning A. Gaissert; Dean M. Donahue; Ashok Muniappan; Cameron D. Wright; Henning Willers; Douglas J. Mathisen; Noah C. Choi; José Baselga; Thomas J. Lynch; Leif W. Ellisen; Mari Mino-Kenudson; Darrell R. Borger; Anthony John Iafrate

BACKGROUND Personalizing non-small-cell lung cancer (NSCLC) therapy toward oncogene addicted pathway inhibition is effective. Hence, the ability to determine a more comprehensive genotype for each case is becoming essential to optimal cancer care. METHODS We developed a multiplexed PCR-based assay (SNaPshot) to simultaneously identify >50 mutations in several key NSCLC genes. SNaPshot and FISH for ALK translocations were integrated into routine practice as Clinical Laboratory Improvement Amendments-certified tests. Here, we present analyses of the first 589 patients referred for genotyping. RESULTS Pathologic prescreening identified 552 (95%) tumors with sufficient tissue for SNaPshot; 51% had ≥1 mutation identified, most commonly in KRAS (24%), EGFR (13%), PIK3CA (4%) and translocations involving ALK (5%). Unanticipated mutations were observed at lower frequencies in IDH and β-catenin. We observed several associations between genotypes and clinical characteristics, including increased PIK3CA mutations in squamous cell cancers. Genotyping distinguished multiple primary cancers from metastatic disease and steered 78 (22%) of the 353 patients with advanced disease toward a genotype-directed targeted therapy. CONCLUSIONS Broad genotyping can be efficiently incorporated into an NSCLC clinic and has great utility in influencing treatment decisions and directing patients toward relevant clinical trials. As more targeted therapies are developed, such multiplexed molecular testing will become a standard part of practice.


Journal of Clinical Oncology | 1992

Neoadjuvant chemotherapy and radiotherapy followed by surgery in stage IIIA non-small-cell carcinoma of the lung: report of a Cancer and Leukemia Group B phase II study.

Gary M. Strauss; James E. Herndon; David D. Sherman; Douglas J. Mathisen; Robert W. Carey; Noah C. Choi; Vishram B. Rege; Caron Modeas; Mark R. Green

PURPOSE This phase II trial was designed to evaluate the feasibility, toxicity, response rates, and survival for neoadjuvant chemotherapy and radiotherapy (RT) followed by surgical resection in newly diagnosed patients with surgically staged IIIA non-small-cell lung carcinoma (NSCLC). PATIENTS AND METHODS Previously untreated patients with NSCLC underwent bronchoscopy, chest and abdominal computed tomography (CT), bone scan, and surgical staging of the mediastinum. Neoadjuvant treatment consisted of concurrent chemotherapy and RT. Patients then underwent surgical resection, which was followed in turn by additional chemotherapy and RT. Chemotherapy included cisplatin 100 mg/m2 on days 1 and 29, vinblastine 3 mg/m2 on days 1 and 3 and 29 and 31, and fluorouracil (5-FU) 30 mg/kg/d by infusion on days 1 to 3 and 29 to 31 (FVP). RT began on day 1 and included 3,000 cGy in 15 fractions. Surgery took place on day 55, and one more cycle of chemotherapy and an additional 3,000 cGy of RT began on day 85. RESULTS Forty-one eligible patients (median follow-up, 53 months) were studied. N2 disease was present in 80%, whereas 20% had T3N0 or T3N1 lesions. Response to neoadjuvant chemotherapy and RT included no complete responses (CR), 21 (51%) partial responses (PR) or regressions, 19 (46%) stable disease (SD), and one (2%) progressive disease (PD). Thirty-one patients underwent surgery, and 25 were resected. In four of the 25 resection specimens, no viable tumor was present, whereas in three of the six unresectable patients, extensive biopsy results demonstrated only necrotic tumor. The maximum response achieved using all protocol treatment was 27 (66%) CRs, seven (17%) PRs or regression, six (15%) SDs, and one (2%) PD. Toxicity was substantial and primarily hematologic. There were six (15%) treatment-related deaths, which included three perioperative deaths and three chemotherapy-related toxicity deaths. The Kaplan-Meier curve indicated a 1-year survival of 58% and a median survival of 15.5 months. Nine patients (22%) remain disease-free. CONCLUSIONS There was a reasonably high rate of PR associated with concurrent neoadjuvant chemotherapy and RT, and a high percentage of patients who ultimately were rendered completely disease-free. However, treatment-related morbidity and mortality was common. Median survival seemed to be only modestly improved beyond that achieved with less intensive means of treatment. However, a group has emerged of patients who enjoy prolonged disease-free survival and possible cure.


Lung Cancer | 2002

FDG–PET in staging and restaging non-small cell lung cancer after neoadjuvant chemoradiotherapy: correlation with histopathology

Jin-Sook Ryu; Noah C. Choi; Alan J. Fischman; Thomas J. Lynch; Douglas J. Mathisen

This study was performed to investigate the utility of FDG-PET for: (1) initial staging, and (2) restaging of the primary and mediastinal nodal lesions 2 weeks after the completion of preoperative chemoradiotherapy in patients with stage III non-small cell lung cancer (NSCLC). Twenty-six patients with histologically confirmed stage III NSCLC were accrued to this study from April 1993 to July 1998. They included 21 with stage IIIA (N2) NSCLC who were enrolled into an institutional phase II study, and 5 patients with a highly selected subset of stage IIIB disease characterized by the presence of microscopic metastatic disease in contralateral mediastinal lymph nodes who were also treated with preoperative chemoradiotherapy; N3 lesions (n=3) and minimal T4 lesions. Demographic characteristics included median age 62 years (a range from 47 to 73) and gender ratio of male 15 to female 11. Histologic types of tumor consisted of squamous cell carcinoma 6, adenocarcinoma 11, large cell carcinoma 5, and non-small cell carcinoma 4. All patients had FDG-PET imaging of the chest before the initiation and 2 weeks after completion of preoperative therapy. The FDG-PET images were evaluated qualitatively for uptake at the primary tumor sites and mediastinal lymph nodes. Standard uptake values (SUVs) were also calculated for the primary tumors and all PET findings were correlated with surgical histopathologic data. Preoperative chemoradiotherapy resulted in complete pathologic response in 8 of 26 primary lesions. By qualitative analysis, 96% of these tumors showed level 3 or 4 uptake before preoperative chemoradiotherapy. After chemoradiotherapy, 57% (15/26) of patients showed at least a one level decrease in uptake, and the sensitivity and specificity of FDG-PET for differentiating residual tumor from pathologic complete response were 67% (12/18) and 63% (5/8). Mean SUV was 14.87+/-7.11 at baseline and decreased to 5.72+/-3.35 after chemoradiotherapy (n=21, P<0.00001). When a value of 3.0 was used as the SUV cut-off, sensitivity and specificity were 88 and 67%, respectively. The mean values of visual intensity were 3.87+/-0.35 and 3.8+/-0.51 for patients who achieved pathologic complete response (n=8) and for those who showed residual cancer after the preoperative therapy (n=18), respectively. The mean SUVs were 16.97+/-8.52 and 14.03+/-6.61 for patients who achieved pathologic complete response (n=6) and for those who showed residual cancer (n=15) after the preoperative therapy, respectively. Therefore, the degree of FDG uptake before preoperative chemoradiotherapy did not provide predictive value for subsequent tumor response. For mediastinal initial staging, the sensitivity and specificity of FDG-PET were 75 and 90.5%. The sensitivity and specificity of FDG-PET for mediastinal restaging were 58.0 and 93.0%. These results indicate that FDG-PET is useful for monitoring the therapeutic effect of neoadjuvant chemoradiotherapy in patients with stage III NSCLC. For the primary lesions, SUV based analysis has high sensitivity but limited specificity for detecting residual tumor. In contrast, for restaging of mediastinal lymph nodes, FDG-PET is highly specific, but has limited sensitivity.


Journal of Clinical Oncology | 1998

Phase I study to determine the maximum-tolerated dose of radiation in standard daily and hyperfractionated-accelerated twice-daily radiation schedules with concurrent chemotherapy for limited-stage small-cell lung cancer

Noah C. Choi; James E. Herndon; Julian G. Rosenman; Robert W. Carey; Chung T. Chung; Stephen Bernard; Louis A. Leone; Stephen Seagren; Mark R. Green

PURPOSE An improvement in radiation dose schedule is necessary to increase local tumor control and survival in limited-stage small-cell lung cancer. The goal of this study was to determine the maximum-tolerated dose (MTD) of radiation (RT) in both standard daily and hyperfractionated-accelerated (HA) twice-daily RT schedules in concurrent chemoradiation. METHODS The study design consisted of a sequential dose escalation in both daily and HA twice-daily RT regimens. RT dose to the initial volume was kept at 40 to 40.5 Gy, while it was gradually increased to the boost volume by adding a 7% to 11 % increment of total dose to subsequent cohorts. The MTD was defined as the radiation dose level at one cohort below that which resulted in more than 33% of patients experiencing grade > or = 4 acute esophagitis and/or grade > or = 3 pulmonary toxicity. The study plan included nine cohorts, five on HA twice-daily and four on daily regimens for the dose escalation. Chemotherapy consisted of three cycles of cisplatin 33 mg/m2/d on days 1 to 3 over 30 minutes, cyclophosphamide 500 mg/m2 on day 1 intravenously (IV) over 1 hour, and etoposide 80 mg/m2/d on days 1 to 3 over 1 hour every 3 weeks (PCE) and two cycles of PE. RT was started at the initiation of the fourth cycle of chemotherapy. RESULTS Fifty patients were enrolled onto the study. The median age was 60 years (range, 38-79), sex ratio 2.3:1 for male to female, weight loss less than 5% in 73%, and performance score 0 to 1 in 94% and 2 in 6% of patients. In HA twice-daily RT, grade > or = 4 acute esophagitis was noted in two of five (40%), two of seven (29%), four of six (67%), and five of six patients (86%) at 50 (1.25 Gy twice daily), 45, 50, and 55.5 Gy in 1.5 Gy twice daily, 5 d/wk, respectively. Grade > or = 3 pulmonary toxicity was not seen in any of these 24 patients. Therefore, the MTD for HA twice-daily RT was judged to be 45 Gy in 30 fractions over 3 weeks. In daily RT, grade > or = 4 acute esophagitis was noted in zero of four, zero of four, one of five (20%), and two of six patients (33%) at 56, 60, 66, and 70 Gy on a schedule of 2 Gy per fraction per day, five fractions per week. Grade > or = 3 pneumonitis was not observed in any of the 19 patients. Thus, the MTD for daily RT was judged to be at least 70 Gy in 35 fractions over 7 weeks. Grade 4 granulocytopenia and thrombocytopenia were observed in 53% and 6% of patients, respectively, during the first three cycles of PCE. During chemotherapy cycles 4 to 5, grade 4 granulocytopenia and thrombocytopenia were noted in 43% and 29% of patients at 45 Gy in 30 fractions over 3 weeks (MTD) by HA twice-daily RT and 50% and 17% at 70 Gy in 35 fractions over 7 weeks (MTD) by daily RT, respectively. The overall tumor response consisted of complete remission (CR) in 51% (24 of 47), partial remission (PR) in 38% (1 8 of 47), and stable disease in 2% (one of 47). The median survival time of all patients was 24.4 months and 2- and 3-year survival rates were 53% and 28%, respectively. With regard to the different radiation schedules, 2- and 3-year survival rates were 52% and 25% for the HA twice-daily and 54% and 35% for the daily RT cohorts. CONCLUSION The MTD of HA twice-daily RT was determined to be 45 Gy in 30 fractions over 3 weeks, while it was judged to be at least 70 Gy in 35 fractions over 7 weeks for daily RT. A phase III randomized trial to compare standard daily RT with HA twice-daily RT at their MTD for local tumor control and survival would be a sensible research in searching for a more effective RT dose-schedule than those that are being used currently.


International Journal of Radiation Oncology Biology Physics | 1980

Basis for new strategies in postoperative radiotherapy of bronchogenic carcinoma

Noah C. Choi; Hermes C. Grillo; Mary Gardiello; J. Gordon Scannell; Earle W. Wilkins

In order to improve our understanding of the role of postoperative radiotherapy and to search for new strategies in the management of N1 N2 T3 stage carcinoma of the lung, we analyzed results of treatment in 148 of 166 patients who were registered at the Massachusetts General Hospital Tumor Registry from 1971–1977 with a pathological diagnosis of N1 N2, T3 carcinoma of the lung after pulmonary resection. Ninety-three patients received postoperative radiotherapy and another 55 were followed without further treatment. Patients with adenocarcinome showed significant improvement of survival by postoperative radiotherapy; actuarial NED (no evidence of disease) survival rates were 85 % and 51 % at 1 year, and 43 % and 8 % at 5 years for S + RT (patients treated with surgery plus postoperative radiotherapy) and S (patients treated with surgery only) groups, respectively, (P < 0.01). The brain was the most common site of failure in adenocarcinoma, 53 % and 58 % of all failures occurred in the brain in S and S + RT groups suggesting elective whole brain irradiation in a future trial. For the sguamous cell carcinoma group, there was no improved survival in the irradiated patients, actuarial NED survival rates were 63 % for both S + RT and S groups at 2 years, and 42 % and 33 % for S + RT and S groups at 4 years. These figures should be considered in the light of the following: In 52 % (24/46) of S + RT vs. 27% (8/29) of S group, disease was in N2, T3 stages. Regional recurrence was the most common failure in squamous cell carcinoma; 76% (13/17) and 45% (10/22) of all failures were in the regional area in S and S + RT groups. Regional failure in S + RT group was noted with radiation dose up to 5000 rad (TDF 82) which suggests radiation dose higher than 5000 rad in future trial.


Cancer | 1981

Improved survival of patients with unresectable non-small-cell bronchogenic carcinoma by an innovated high-dose En-Bloc radiotherapeutic approach

Noah C. Choi; Joanne Doucette

From 1972 to 1977, 162 patients were treated with definitive radiotherapy for the underlying unresectable non‐small‐cell bronchogenic carcinoma by a radiotherapeutic technique that had sequentially evolved from a low‐dose (40–45 gray) small‐volume approach (AP‐PA POP) to a high‐dose (60–64 gray) large‐volume en‐bloc approach (AP‐PA POP plus AP‐RPO‐LPO) which included the primary tumor and the entire regional lymphatics including both supraclavicular areas. Median survival and short‐term survival up to 1.5 years were independent of radiation doses (40–64 gray) and target volumes studies. However, long‐term survival ⩾ 2 years was radiation‐dose and target‐volume dependent: actuarial survival 36% and 28% vs. 10% and 3% for the high‐dose (60–64 gray) en‐bloc approach vs. Low‐dose (40–45 gray) small‐volume radiotherapy at 2 and 3 years, respectively, with a minimum follow‐up of 2 years, P < 0.05. Actuarial five‐year survival rate 7.5% was obtained with radiation dose ⩾ 50 gray. However, there was no five‐year survivor among patients who were treated with radiation dose < 50 gray. Local tumor control is radiation‐dose dependent: local tumor control rates at ⩾ 18 months were 76% vs. 29% by 56–64 gray vs. 40–49 gray, respectively, P < 0.05. The patterns of failure appeared to be tumor‐histology dependent; for squamous cell carcinoma, the primary and regional lymphatic areas are the most common sites of failure, and for adenocarcinoma, it is the brain or bone. The high‐dose en‐bloc radiotherapy has been very well tolerated; 5% (4/80) incidence of symptomatic pneumonitis has been observed.


International Journal of Radiation Oncology Biology Physics | 2002

Dose-response relationship between probability of pathologic tumor control and glucose metabolic rate measured with FDG PET after preoperative chemoradiotherapy in locally advanced non-small-cell lung cancer

Noah C. Choi; Alan J. Fischman; Andrzej Niemierko; Jin-Sook Ryu; Thomas J. Lynch; John C. Wain; Cameron D. Wright; Panos Fidias; Douglas J. Mathisen

PURPOSE To determine the dose-response relationship between the probability of tumor control on the basis of pathologic tumor response (pTCP) and the residual metabolic rate of glucose (MRglc) in response to preoperative chemoradiotherapy in locally advanced non-small-cell lung cancer and to define the level of residual MRglc that corresponds to pTCP 50% and pTCP > or = 95%. METHODS AND MATERIALS Quantitative dynamic 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography was performed to measure regional MRglc at the primary lesion before and 2 weeks after preoperative chemoradiotherapy in an initial group of 13 patients with locally advanced NSCLC. A simplified kinetic method was developed subsequently from the initial dynamic study and used in the subsequent 16 patients. The preoperative radiotherapy programs consisted of (1) a split course of 42 Gy in 28 fractions within a period of 28 days using a twice-daily treatment schedule for Stage IIIA(N2) NSCLC (n = 18) and (2) standard once-daily radiation schedule of 45-63 Gy in 25-35 fractions during a 5-7-week period (n = 11). The preoperative chemotherapy regimens included two cycles of cisplatin, vinblastine, and 5-fluorouracil (n = 24), cisplatin and etoposide (n = 2), and cisplatin, Taxol, and 5-fluorouracil (n = 3). Patients free of tumor progression after preoperative chemoradiotherapy underwent surgery. The degree of residual MRglc measured 2 weeks after preoperative chemoradiotherapy and 2 weeks before surgery was correlated with the pathologic tumor response. The relationship between MRglc and pTCP was modeled using logistic regression. RESULTS Of 32 patients entered into the study, 29 (16 men and 13 women; 30 lesions) were evaluated for the correlation between residual MRglc and pathologic tumor response. Three patients did not participate in the second study because of a steady decline in general condition. The median age was 60 years (range 42-78). One of the 29 patients had two separate lesions, and MRglc was measured in each separately. The tumor histologic types included squamous cell carcinoma (n = 9), adenocarcinoma (n = 13), large cell carcinoma (n = 6), and poorly differentiated carcinoma (n = 2). The extent of the primary and nodal disease was as follows: Stage IIB (T3N0M0), Pancoast tumor (n = 2); Stage IIIA, T2-T3N2M0 (n = 18); Stage IIIB: T1-T3N3M0 (n = 5) and T4N0M0 (n = 2); a second lesion, T1 (n = 1); and localized stump recurrence (n = 2). A pathologically complete response was obtained in 14 (47%) of the 30 lesions. The remaining 16 lesions had residual cancer. The mean baseline value of the maximal MRglc was 0.333 +/- 0.087 micromol/min/g (n = 16), and it was reduced to 0.0957 +/- 0.059 micromol/min/g 2 weeks after chemoradiotherapy (p = 0.011). The correlation between residual MRglc and pTCP was made using an increment value of 0.02 micromol/min/g between the maximal and minimal values of MRglc. A pathologically complete response was obtained in 6 of 6 patients with residual MRglc of < or = 0.050 micromol/min/g, 3 of 4 with < or = 0.070, 4 of 7 with < or = 0.090, 0 of 4 with < or = 0.110, 1 of 3 with < or = 0.130, and 0 of 6 with > or = 0.130 micromol/min/g. The fitted logistic model showed that residual MRglc corresponding to pTCP 50% and pTCP > or = 95% was 0.076 and < or = 0.040 micromol/min/g, respectively. CONCLUSION The correlation between the gradient of residual MRglc after chemoradiotherapy and pTCP is an inverse dose-response relationship. Residual MRglc of 0.076 and < or = 0.040 micromol/min/g, representing pTCP 50% and pTCP > or = 95%, respectively, may be useful surrogate markers for the tumor response to radiotherapy or chemoradiotherapy in lung cancer.


The Annals of Thoracic Surgery | 1988

Preoperative chemotherapy, surgical resection, and selective postoperative therapy for squamous cell carcinoma of the esophagus☆

Alan D. Hilgenberg; Robert W. Carey; Earle W. Wilkins; Noah C. Choi; Douglas J. Mathisen; Hermes C. Grillo

In an attempt to improve on the long-term survival rate of patients with esophageal squamous cell carcinoma, we designed a study in which treatment included preoperative chemotherapy with fluorouracil and cisplatin, surgical resection, and selective postoperative chemotherapy or radiation therapy. Between 1981 and 1986, 35 patients with potentially resectable lesions were entered into the study. After chemotherapy, 13 of 35 patients (37%) had a complete clinical response, 7 (20%) had a partial response, and 15 (43%) had no response. One patient sustained a serious toxic reaction (renal failure). Twenty-seven patients underwent surgical resection, with 1 hospital death (3.7%). Selective postoperative radiotherapy or chemotherapy was administered to 69%. The actuarial survival of all resected patients at 42 months was 54% (standard error, 10%). Multivariate analysis showed significant factors associated with 3-year survival were: (1) complete clinical response to chemotherapy; (2) absence of wall penetration in the specimen; and (3) microscopic or no disease in the specimen. We conclude that this multimodality treatment method improves the intermediate-term survival of patients with squamous cell carcinoma of the esophagus.


Physics in Medicine and Biology | 2006

Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations.

Stella Flampouri; S Jiang; Greg Sharp; J Wolfgang; Abhijit Patel; Noah C. Choi

The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the delivered dose, and compare our delivered dose with doses estimated using prior techniques.

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