Three-field Technique Research Articles

An IMRT planning technique for treating whole breast or chest wall with regional lymph nodes on Halcyon and Ethos.

Field size limitations on Halcyon and Ethos treatment machines largely preclude use of the conventional monoisocentric three-field technique for breast/chest wall and regional lymph nodes. We present an alternative, IMRT-based planning approach that facilitates treatment on Halcyon and Ethos while preserving plan quality. Eight breast and regional node cases (four left-sided, four right-sided) were planned for an Ethos machine using a 15-17 field IMRT technique. Institutional plan quality metrics for CTV and PTV coverage and OAR sparing were assessed. Five plans (four right-sided, one left-sided) were also planned using a hybrid 3D multisocenter technique. CTV coverage and OAR sparing were compared to the IMRT plans. Eclipse scripting tools were developed to aid in beam placement and plan evaluation through a set of dosimetric scorecards, and both are shared publicly. On average, the IMRT plans achieved breast CTV and PTV coverage at 50Gy of 97.9% and 95.7%, respectively. Supraclavicular CTV and PTV coverages at 45Gy were 100% and 95.5%. Axillary lymph node CTV and PTV coverages at 45Gy were 100% and 97.1%, and IMN CTV coverage at 45Gy was 99.2%. Mean ipsilateral lung V20 Gy was 19.3%, and average mean heart dose was 1.6Gy for right-sided cases and 3.0Gy for left-sided. In comparison to the hybrid 3D plans, IMRT plans achieved higher breast and supraclavicular CTV coverage (99.9%vs. 98.6% and 99.9%vs. 93.4%), higher IMN coverage (99.6%vs. 78.2%), and lower ipsilateral lung V20 Gy (19.6%vs. 28.2%). Institutional plan quality benchmarks were achieved for all eight cases using the IMRT-based planning approach. The IMRT-based planning approach offered superior conformity and OAR sparing than a competing hybrid 3D approach.

A Dosimetric Analysis of Incidental Radiation to the Internal Mammary Nodes with a Three-field Chest Wall Technique

Objectives: The authors’ aim was to conduct a dosimetric analysis of the incidental radiation dose to the internal mammary node (IMN) region using a three-field chest wall technique (TFCWT). Methods: This retrospective study utilized 3D-conformal radiotherapy plans of 50 post-mastectomy patients (25 left-sided and 25 right-sided). All plans used the TFCWT, composed of narrowed tangents matched medially to an AP electron field, and prescribed a total dose of 50 Gy in 28 fractions. The IMNs were not intentionally treated in all included plans. Results: The mean dose to the IMN-planning target volume (IMN-PTV) was 45.1 Gy (26.4 - 55.6, SD 6.5). Minimum doses received by 95% and 90% of the IMN-PTV were 29.3 Gy (8 - 49, SD 10.0) and 34.0 Gy (10.0 - 52.0, SD 8.6), respectively. The percent volume of IMN-PTV receiving 100%, 95%, 90%, and 80% were 47.4% (3 - 94, SD 21.6), 55.6% (6 - 97, SD 22.4), 61.92% (7 - 98, SD 22.2), and 72.61% (18-100, SD 20.2), respectively. The average ipsilateral lung V20 Gy (with supraclavicular fields) was 25.0% (16 - 29, SD 3.4), and the average heart mean dose was 2.5 Gy (0.5 - 7.9, SD 1.58). Conclusion: Although the results suggest increased IMN radiation doses with the TFCWT when compared historically to standard tangents, the incidental doses are comparatively less than that traditionally prescribed to the IMNs in high-risk patients. It is unknown whether this incidental IMN dose confers any clinical benefit.

Dosimetric comparison of three-field and four-field 3D conformal radiation therapy ballistics for rectal cancer treatment

The tremendous improvement made over the last ten years in radiotherapy has been achieved mainly by developing particle acceleration techniques. Three-dimensional conformal radiation therapy [3D-CRT] is crucially applied for decreasing the shape of advanced rectal tumors yet has several side consequences. Our investigation examined the dose distribution in planning target volumes (PTV), the protection of healthy organs at risk (OAR), and the quality of therapy for the two strategies based on the three fields and four fields ballistic used in treating rectal cancers. Using the Varian Linear Accelerator system (Varian Medical Systems, Inc., Palo Alto, CA, USA) integrated with an Eclipse MLC 2100 planning system including Pencil Beam Convolution PBC dose calculation algorithm. Two different treatments of rectal cancer based on the two approaches are performed. A dosimetric comparison of the parameters is made to evaluate the feasibility of each ballistic. These parameters, including the target volume coverage indicators, included average dose, conformity index (CI), and homogeneity index (HI) of planning tumor volume; OAR included the bladder and bilateral proximal femurs. The results achieved in this dosimetric comparative study advocate for the clinical application of three fields ballistic in all specialties already compared, except for the planning target volume PTV dose distribution. The study has shown that the three-field technique (an anterior and two opposing lateral fields with the portals orientation 0°, 90°, 270°) and applied energy photons of 18 MV and 6 MV provides the best bladder protection. According to the dose distribution in the target (PTV), all evaluated plans have not indicated any significant differences. The risk of morbidity in the femoral heads for all the applied methods, in a dose up to 56.396 Gy, was not a therapeutic problem. However, the three-field approach with beams orientation 0°, 120°, 240°gave the best sparing effect for femoral heads.

Dosimetric analysis of breast cancer tumor bed boost: An interstitial brachytherapy vs. external beam radiation therapy comparison for deeply seated tumors

PurposeTo dosimetrically compare interstitial brachytherapy (MIBT) vs. EBRT (3DCRT and high-energy electron beams) for deep-seated tumor bed boosts (depth ≥4 cm) in early-stage breast cancer. Methods and MaterialsPlanning CTs of fifteen left-side breast cancer patients previously treated with MIBT boost chosen for this study. MIBT, 3DCRT (three-field technique), and enface high-energy electron (15–18 MeV) plans retrospectively generated on these images. To minimize intrapatient target contour inconsistency, due to a technical limitation for transferring identical contours from brachytherapy to EBRT planning system, spherical volumes delineated as hypothetical CTVs (CTV-H) (depth ≥4 cm with considering the geometry of the brachytherapy implant) instead of original lumpectomy cavities (which had irregular contours). In EBRT, PTV-H=CTV-H+5 mm. To account for beam penumbra, additional PTV-H to beam-edge margins added (3DCRT = 5 mm; electron = 10 mm). Included organs at risk (OARs) were ipsilateral breast, skin, ribs, lung, and heart. Prescribed dose-fractionations were 12 Gy/3fractions (MIBT) and 16 Gy/8fractions (EBRT) (BED = 24 Gy, breast cancer Alpha/Beta = 4 Gy). Biologically equivalent DVH parameters for all techniques compared. ResultsMean CTV-H depth was 6 cm. Normal breast V25%–V100%; skin V10%–V90%; rib V25%–V75%; lung V5%–V25%; heart V10%; mean lung dose; ribs/lung Dmax were lower in MIBT vs. 3CDRT. MIBT reduced breast V25%–V125%; skin V25%–V125%; rib V25%–V75% and V100%; lung V25%–V90%; heart V10%–V50%; skin/ribs/lung Dmax compared to electrons. In contrast, breast V125%–V250% and V175%–V250% were increased in MIBT vs. 3DCRT and electron plans, respectively. Electron plans had the minimum mean heart dose. ConclusionsFrom a dosimetric point of view, in deeply-seated lumpectomy beds, MIBT boost better protects OARs from exposure to medium and high doses of radiation compared to 3DCRT and high energy electron beams (except more ipsilateral breast hot spots).

Preoperative radiotherapy and concurrent chemotherapy with bolus 5-fluorouracil for rectal cancer: a prospective analysis of 98 patients

Surgical resection of rectal cancer is associated with a high pelvic recurrence rate. Preoperative large-fraction radiotherapy (RT) with a short interval after local excision has been associated with a significant improvement in locoregional recurrence rates and overall survival, but with high rates of toxicity. We here present the results of our combined-modality treatment protocol for patients with locally advanced rectal cancer. Between September 1999 and June 2005, 98 patients were prospectively entered into the protocol. Eligibility criteria included any of the following: cT3-4 disease, clinically positive lymph nodes, or tumor located less than 6 cm from the anal verge. RT was delivered with a three-field technique to a dose of 45 Gy, plus an optional 5.4-9 Gy boost. Chemotherapy, administered concomitantly with RT, consisted of bolus 5-fluorouracil (5-FU) 500 mg days 1-5 followed by 5-FU 600 mg/m2 and leucovorin 50 mg on days 16, 23, 30 and 37. Surgery was performed 6-8 weeks after RT completion and was followed by 8 courses of 5-FU 900 mg/m2 and leucovorin 100 mg/m2 every 14 days. Low anterior resection was performed in 64.5% of the patients and in 38.8% of those with tumors located less than 6 cm from the anal verge. All patients except one had clear pathological margins, 68.8% had negative nodes, and pathological complete response was seen in 13.5%. With a median follow-up of 31.5 months, 3 patients (3.0%) had locoregional recurrence, 19 (19.3%) developed distant metastasis, and 10 patients (10.1%) died. The estimated median disease-free survival was 70.6 months. Grade 3 or 4 gastrointestinal toxicity was seen in 24.5% of the patients and 3.0% had neutropenic fever. One fatal toxicity occurred during treatment. Our results suggest that our combined-modality treatment protocol is well tolerated and achieves high locoregional control in this unselected population. The overall survival results are also encouraging. Further studies are required to confirm the toxicity profile and survival results of this regimen.

Evolution in the Treatment of Esophageal Disease at a Single Academic Institution: 2004-2013.

Management of benign and malignant esophageal disease has changed rapidly over the past decade. The aim of this study was to analyze evolution in surgical management of esophageal disease at a single academic medical center during this period. We reviewed a retrospective cohort of patients who underwent esophagectomy between 2004 and 2013. Patient, institutional, treatment, and outcomes variables were reviewed. 317 patients were analyzed. Median age was 63.5 years; 80% were male. Average inhospital mortality rate was 3.8%. Operative indications changed significantly from 2004 to 2013, with more operations performed for invasive malignancy (77% vs. 95%) and fewer for high-grade dysplasia (12% vs. 3%, P = .008). In 2004, Ivor Lewis esophagectomy was the most common surgical technique, but the three-field technique was the operation of choice in 2013. A minimally invasive approach was used in 19% of cases in 2004 and 100% of cases in 2013 (P < .001). Anastomotic leak ranged from 0% to 21% with no significant difference over the study period (P = .18). Median lymph node harvest increased from seven to 18 nodes from 2004 to 2013 (P = .001). Hospital length of stay decreased from 15 to 8 days (P = .001). In 2013, 79% of patients were discharged to home, compared to 73% in 2004 (P = .04). Over the last decade, our treatment of esophageal disease has evolved from a predominantly open Ivor Lewis to a minimally invasive three-field approach. Operations for malignancy have also increased dramatically. Postoperative complications and mortality were not significantly changed, but were consistently low during the latter years of the study.

Minimally Invasive Ivor Lewis Esophagectomy

The two main types of esophageal cancer are squamous cell carcinoma, which comprises the majority of cases world-wide, and adenocarcinoma, which is diagnosed with increasing frequency and now accounts for more than 50% of cases in the western hemisphere. Smoking and alcohol consumption are strongly linked to squamous cell carcinoma, and the most important etiologic risk factor for adenocarcinoma is Barrett's esophagus, which occurs in 10 to 15% of patients with gastro-oesophageal reflux disease. Patients generally present with dysphagia and weight loss, and diagnosis is made via endoscopy and biopsy. The surgical treatment of esophageal cancer is dependent upon the location of the cancer, the depth of invasion, and the presence of lymph node metastasis. Smaller tumors that only involve the mucosal layer of the esophagus may be removed by endoscopic mucosal resection, but larger, more invasive tumors require esophageal resection. Esophagectomy can be approached via the trans-hiatal (Orringer), trans-thoracic (Ivor-Lewis), or three-field (McKeown) techniques, and anastomosis between the stomach and the shortened esophagus is achieved through either a gastric pull up or colonic/jejunal interposition. The addition of neoadjuvant chemotherapy for locally-advanced adenocarcinoma has been shown to increase survival compared with surgery alone, and is the standard treatment in these cases. Here, we present the case of a female patient with dysphagia who was found to have a locally-advanced distal esophageal adenocarcinoma. In this case, a minimally-invasive Ivor Lewis esophagectomy was performed with neoadjuvant chemotherapy.

The potential role of modern radiotherapy techniques in the treatment of malignant spinal cord compression: a dose planning study

AbstractAimTo investigate the doses given to the kidneys and the small intestines for three radiation therapy techniques [anterior–posterior (APPA) fields, three fields and volumetric-modulated arc therapy (VMAT)] for spinal cord compression (SCC) patients with metastatic disease in the lower thoracic or lumbar spine and to monitor the time spent by clinicians and dose planners.IntroductionRadiation therapy is one of the main treatment modalities for SCC. Typical palliative radiation therapy techniques have used APPA fields or a three-field technique.However, as delivery techniques have evolved dramatically over the past decades, VMAT has gained wide acceptance. VMAT allows for a dose reduction in the organs at risk. Such a dose reduction may result in less toxicity.The use of the VMAT technique may require more time for contouring and planning compared with the APPA and three-field techniques. Any potential dosimetric benefit of VMAT must not be outweighed by large amounts of extra time spent by clinicians and dose planners.Materials and methodsFor 20 patients treated with radiation therapy for SCC at our hospital, we created a VMAT plan, and the more traditionally used APPA and three-field plans. The mean kidney doses and the volume of bowel, which received 20 Gy, were extracted for each plan. The correlations between parameters for three techniques were determined.Furthermore, the time required for contouring targets for five patients; and the time required to plan five patients, was recorded.ResultsVMAT lead to the most conformal distributions: the high-dose areas were restricted to the target volume, whereas the healthy tissue, especially the bowel, received a lower dose. In contrast, the APPA plan lead to a larger volume of bowel being irradiated, whereas the three-field technique spared the bowel at the expense of a higher dose to the kidneys.The average contouring time was 16 minutes, the average planning time was 38 minutes.ConclusionPatients treated for SCC in the lower thoracic or lumbar region may benefit from VMAT treatment, as it reduces the dose to the bowel and kidneys compared with APPA or three-field treatments.

Evaluation of a Belly Board immobilisation device for rectal cancer patients receiving pre-operative chemoradiation

AbstractPurposeTo evaluate the efficacy of a Belly Board immobilisation device for rectal cancer patients.Materials and methodsA randomised trial in patients receiving neo-adjuvant chemoradiation for rectal carcinoma was established. Patients were treated, prone with control arm, according to standard departmental protocol and experimental arm with the use of a Belly Board. All treatments were planned using a three-field technique. The primary endpoints were reproducibility and irradiated small bowel volume. Questionnaires were used to assess secondary endpoints of patient comfort, ease of set-up and acute toxicities.ResultsPre-planned interim analysis was performed after recruiting 30 patients. In all, 348 portal images were analysed retrospectively. Around 8 out of 12 parameters measuring set-up reproducibility were in favour of the Belly Board arm. Random error in the anterior–posterior direction was improved and statistically significant in the experimental arm (95% CI; p≤0·05). Small bowel V15 was significantly lower in the Belly Board position (mean V15=14·5%) compared with the standard position (mean V15=21·4%), paired t-test 95% CI; p=0·035. Also, patients’ comfort satisfaction was greater in the Belly Board arm.ConclusionsSet-up reproducibility, small bowel V15, patient comfort and satisfaction were all significantly improved by the use of the Belly Board.

Acute effects of pelvic irradiation on the adult uterus revealed by dynamic contrast-enhanced MRI

Pelvic radiation therapy (RT) can influence fertility in female rectal cancer survivors. Data regarding its effects on the adult uterus are scant. This study aims to evaluate the uterus before and after RT, using dynamic contrast-enhanced MRI. Eligible patients (n=10) received RT for rectal cancer, had an intact uterus and underwent dynamic contrast-enhanced MRI before and after RT. Seven patients were pre-menopausal. Patients received pelvic RT (median, 50.2 Gy) with concurrent 5-fluorouracil. Five patients were treated with intensity modulated RT (IMRT) and five with a three-field technique. The median D95 of the uterus was 30 Gy; D05 was 48 Gy; and V95 was 97%. The median cervical D95 was 45 Gy; D05, 50 Gy; and V95, 100%. Cervical dose was higher with IMRT than with three-field plans (p≤0.038). On T2 MRI, the junctional zone was visible in nine patients before and in one after RT (p=0.001). Median cervical length (2.3 vs 3.0 cm) and endometrial thickness (2.6 vs 5.9 mm) were reduced after RT (p≤0.008). In pre-menopausal patients, the volume transfer constant, K(trans), (0.069 vs 0.195, p=0.006) and the extracellular extravascular volume fraction, V(e), (0.217 vs 0.520, p=0.053) decreased. Pelvic RT significantly affected uterine anatomy and perfusion. Cervical dose was higher with IMRT than three-field plans, but no attempt was made to constrain the dose. Pelvic RT significantly affects the adult uterus. These findings are crucial to understand the potential consequences of RT on fertility, and they lay the groundwork for further prospective studies.

Evaluation the Effect of Photon Beam Energies on Organ at Risk Doses in Three-Dimensional Conformal Radiation Therapy

As regards, the selection of appropriate energy in radiotherapy tumors that are placed in non-homogen areas is important, so the aim of the present study is evaluating the effect of 6 and 15MV photon beam energies on dose distribution in 3D-CRT for lower esophageal and rectal cancers. 12 patients with lower esophageal cancer and 12 patients with rectal cancer respectively, with the prescription dose of 7000 cGy and 5040 cGy were studied. For treatment of esophagus the three-field technique and for treatment of rectum the four-field technique was used. In the thoracic area, the spinal cord and in the pelvis, the bladder and head of femurs were considered as OARs. For comparing the results, all parameters used for treatment planning except the photon beam energy were kept constant. After performing the treatment planning with two different energies in each region, the received dose rate of spinal cord, bladder and head of femurs as OARs and dose distribution in PTVs were studied. The results of this study showed that the difference between doses received by OARs in 6MV and 15MV therapeutic plans, resulted 5.2, 5.06 and -9.14%, respectively. Also the PTVs received dose difference of esophagus and rectum in the performed therapeutic plans with energy of 6 MV than energy of 15MV is 1.52 and -0.63%, respectively. We found that using of low energy photons in lower esophageal treatment and high energy photons in the rectal treatment provides the better dose coverage. Finally, with such as therapeutic plans the cumulative dose of organs at risk will be reduced.

Induction chemotherapy followed by chemoradiotherapy and total mesenteric excision for locally advanced rectal cancer with resectable metastases.

526 Background: Optimal management of patients with locally advanced rectal cancer (LARC) and synchronous, resectable metastases remains controversial and treatment decisions benefit from a multidisciplinary approach. To better characterize the role of induction chemotherapy followed by chemoradiation and surgery, we evaluated patterns of distal progression and overall survival in this subset of patients. Methods: We reviewed records of 25 LARC patients with synchronous resectable metastases treated with induction chemotherapy (ICT) followed by 5-fluorouracil-based concurrent chemoradiation (CRT) at our institution between December 2006 and December 2010. Radiation was delivered using a standardized three-field technique or IMRT. The incidence and sites of failure were analyzed. Overall survival (OS) and progression-free survival (PFS) were calculated from the completion of CRT using the Kaplan-Meier method. Results: Of the 25 patients who received ICT followed by CRT, 21 (84%) underwent total mesorectal excision and metastectomy. Eleven patients (44%) had liver metastases. The median ICT duration was 2.4 months. Twenty patients (80%) received a FOLFOX-based ICT regimen and 5 patients (20%) received irinotecan-based chemotherapy. Two patients had unresectable disease, one was medically inoperable, and surgery was aborted due to intra-operative complications in one patient. Eighteen of the 21 were NED after surgery and metastatectomy (86%) with 24% pathologic complete response rate in the primary tumor; 10 (56%) received adjuvant chemotherapy. None of the patients recurred locally. Six of the 18 (33%) progressed distally, four of whom had received adjuvant chemotherapy. Four distal recurrences were in the lungs. With a median follow-up of 29.6 months, the 3-year OS was 50.4%. Median OS and PFS were 25.1 months and 13.5 months, respectively. Conclusions: ICT prior to CRT is associated with acceptable toxicity, substantial primary tumor regression, and promising clinical outcomes in patients with high-risk LARC with synchronous, resectable metastatic disease.

Poster - Thur Eve - 60: Physical and dynamic wedges in radiotherapy for rectal cancer: A dosimetric comparison.

The aim of this study is to compare the dosimetry of the physical wedge (PW) and enhanced dynamic wedge (EDW) in radiotherapy of rectal cancer. Two wedge angles of 45° and 60° were used in the comparison due to the size of the pelvis contour. 6 and 15 MV photon beams produced from a Varian 21 CD linear accelerator were used. Thirty rectum patients were investigated using the three-field technique. Treatment plans using the PWs and EDWs were created using the Eclipse treatment planning system. Monitor units, plan normalization value, maximum and minimum doses in the planning target volume (PTV), dose conformity index, dose homogeneity index and uniformity index were determined for each treatment plan. The average dose coverage for the PTV with EDW and PW plans were compared. The PTV received prescription doses of 100.9±0.74%, 101.01±1.63% for the EDW (45°, 60°) compared to 101.2±1.65%, 101.3±1.33% for the PW (45°, 60°). Homogeneity indices were (0.11±0.02%, 0.11±0.05%) for the EDW (45°, 60°), and (0.15±0.1%, 0.16±0.11%) for the PW (45°, 60°), respectively. The EDW at 45° had better target coverage with higher conformity index value of 0.98 ± 0.01 compared to the other wedges. A statistically significant (p < 0.01) change in plan normalization values and fewer monitor units were found using the EDW at 45°. We conclude that the EDW at 45° results in an improvement to the plan evaluation parameters presented and thus increases dose efficacy for radiotherapy of rectal cancer.

Cognitive performance after postoperative pituitary radiotherapy: a dosimetric study of the hippocampus and the prefrontal cortex

The hippocampus and prefrontal cortex (PFC) are important for memory and executive functioning and are known to be sensitive to radiotherapy (RT). Radiation dosimetry relates radiation exposure to specific brain areas. The effects of various pituitary RT techniques were studied by relating detailed dosimetry of the hippocampus and PFC to cognitive performance. In this cross-sectional design, 75 non-functioning pituitary macroadenoma (NFA) patients (61±10 years) participated and were divided into irradiated (RT+, n=30) and non-irradiated (RT-, n=45) groups. The RT+ group (who all received 25 fractions of 1.8 Gy; total dose: 45 Gy) consisted of three RT technique groups: three-field technique, n=10; four-field technique, n=15; and five-field technique, n=5. Memory and executive functioning were assessed by standardized neuropsychological tests. A reconstruction of the dose distributions for the three RT techniques was made. The RT doses on 30, 50, and 70% of the volume of the left and right hippocampus and PFC were calculated. Cognitive test performance was not different between the four groups, despite differences in radiation doses applied to the hippocampi and PFC. Age at RT, time since RT, and the use of thyroid hormone varied significantly between the groups; however, they were not related to cognitive performance. This study showed that there were no significant differences on cognitive performance between the three-, four-, and five-field RT groups and the non-irradiated patient group. A dose-response relationship could not be established, even with a radiation dose that was higher on most of the volume of the hippocampus and PFC in case of a four-field RT technique compared with the three- and five-field RT techniques.

Preoperative Radiotherapy and Concurrent Chemotherapy with Bolus 5-Fluorouracil for Rectal Cancer: A Prospective Analysis of 98 Patients

Surgical resection of rectal cancer is associated with a high pelvic recurrence rate. Preoperative large-fraction radiotherapy (RT) with a short interval after local excision has been associated with a significant improvement in locoregional recurrence rates and overall survival, but with high rates of toxicity. We here present the results of our combined-modality treatment protocol for patients with locally advanced rectal cancer. Between September 1999 and June 2005, 98 patients were prospectively entered into the protocol. Eligibility criteria included any of the following: cT3-4 disease, clinically positive lymph nodes, or tumor located less than 6 cm from the anal verge. RT was delivered with a three-field technique to a dose of 45 Gy, plus an optional 5.4-9 Gy boost. Chemotherapy, administered concomitantly with RT, consisted of bolus 5-fluorouracil (5-FU) 500 mg days 1-5 followed by 5-FU 600 mg/m2 and leucovorin 50 mg on days 16, 23, 30 and 37. Surgery was performed 6-8 weeks after RT completion and was followed by 8 courses of 5-FU 900 mg/m2 and leucovorin 100 mg/m2 every 14 days. Low anterior resection was performed in 64.5% of the patients and in 38.8% of those with tumors located less than 6 cm from the anal verge. All patients except one had clear pathological margins, 68.8% had negative nodes, and pathological complete response was seen in 13.5%. With a median follow-up of 31.5 months, 3 patients (3.0%) had locoregional recurrence, 19 (19.3%) developed distant metastasis, and 10 patients (10.1%) died. The estimated median disease-free survival was 70.6 months. Grade 3 or 4 gastrointestinal toxicity was seen in 24.5% of the patients and 3.0% had neutropenic fever. One fatal toxicity occurred during treatment. Our results suggest that our combined-modality treatment protocol is well tolerated and achieves high locoregional control in this unselected population. The overall survival results are also encouraging. Further studies are required to confirm the toxicity profile and survival results of this regimen.

Role of neo-adjuvant chemoradiation in locally advanced rectal cancers.

To determine the radiologic downstaging and histological response after neo-adjuvant concurrent chemoradiation in locally advanced rectal cancers. Case series. Radiation Oncology department of Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, from December 2004 to November 2005. Thirty patients with histopathologically confirmed locally advanced carcinoma rectum who had not received any treatment (chemotherapy, radiotherapy or surgery) prior to presentation were enrolled. Radiation therapy was delivered with a three-field technique to a dose of 50.4 Gy over 5 weeks at the rate of 1.8 Gy/day. Two cycles of chemotherapy were given synchronously, which comprised of 5-fluorouracil 350 mg/m2 and folinic acid 20 mg/m2 continuous intravenous infusion over first five days and last five days of radiotherapy. Surgery was planned 4-6 weeks later to chemoradiation after radiologic post therapy staging. Viable specimens were identified and toxicity was observed. All patients completed treatment without modification. Radiologic downstaging was found in 56.7%, stable disease was seen in 30.0% and progressive disease was present in 13.3% of the patients. Radiologically complete resolution of tumour was not observed. Pathological complete resolution of tumour was achieved in 3.3% and near complete resolution was observed in 13.3% of the patients. In 86.6% cases, a total gross tumour resection with no macroscopic residual disease was possible. All the patients tolerated the treatment well. Neo-adjuvant chemoradiation for locally advanced rectal cancers is associated with high resectability rate and is relatively safe with acceptable morbidity which favours its use in future.

Probabilities of Pulmonary and Cardiac Complications and Radiographic Parameters in Breast Cancer Radiotherapy

Purpose: To evaluate the relationship between the normal tissue complication probability (NTCP) of 3- dimensional (3-D) radiotherapy and the radiographic parameters of 2-dimensional (2-D) radiotherapy such as central lung distance (CLD) and maximal heart distance (MHD). Materials and Methods: We analyzed 110 patients who were treated with postoperative radiotherapy for breast cancer. A two-field tangential technique, a three-field technique, and the reverse hockey stick method were used. The radiation dose administered to whole breast or the chest wall was 50.4 Gy, whereas a 45 Gy was administered to the supraclavicular field. The NTCPs of the hea rt and lung were calculated by the modified Lyman model and the relative seriality model. Results : For all patients, the NTCPs of radiation-induced pneumonitis and cardiac mortality were 0.5% and 0.7%, respectively. The NTCP of radiation-induced pneumonitis was higher in patients treated with the reverse hockey stick method than in those treated by other two techniques (0.0%, 0.0%, 3.1%, p <0.001). The NTCP of radiation-induced pneumonitis increased with CLD. The NTCP of cardiac mortality increased with MHD (R 2 =0.808). Conclusion : We found a close correlation between the NTCP of 3-D radiothe rapy and 2-D radiographic parameters. Our results are useful to reanalyze the previous 2- D based clinical reports about breast radiation therapy complications as a viewpoint of NTCP.

Stereotactic Body Radiation Therapy Boost in Locally Advanced Pancreatic Cancer

To investigate the clinical application of a stereotactic body radiation therapy (SBRT) boost in locally advanced pancreatic cancer patients with a focus on local efficacy and toxicity. We retrospectively reviewed 30 patients with locally advanced and nonmetastatic pancreatic cancer who had been treated between 2004 and 2006. Follow-up duration ranged from 4 to 41 months (median, 14.5 months). A total dose of 40 Gy was delivered in 20 fractions using a conventional three-field technique, and then a single fraction of 14, 15, 16, or 17 Gy SBRT was administered as a boost without a break. Twenty-one patients received chemotherapy. Overall and local progression-free survival were calculated and prognostic factors were evaluated. One-year overall survival and local progression-free survival rates were 60.0% and 70.2%, respectively. One patient (3%) developed Grade 4 toxicity. Carbohydrate antigen 19-9 response was found to be an independent prognostic factor for survival. Our findings indicate that a SBRT boost provides a safe means of increasing radiation dose. Based on the results of this study, we recommend that a well controlled Phase II study be conducted on locally advanced pancreatic cancer.

Predicting Grade 3 Acute Diarrhea During Radiation Therapy for Rectal Cancer Using a Cutoff-Dose Logistic Regression Normal Tissue Complication Probability Model

Understanding the dose-volume relationship of small bowel irradiation and severe acute diarrhea may help reduce the incidence of this side effect during adjuvant treatment for rectal cancer. Consecutive patients treated curatively for rectal cancer were reviewed, and the maximum grade of acute diarrhea was determined. The small bowel was outlined on the treatment planning CT scan, and a dose-volume histogram was calculated for the initial pelvic treatment (45 Gy). Logistic regression models were fitted for varying cutoff-dose levels from 5 to 45 Gy in 5-Gy increments. The model with the highest LogLikelihood was used to develop a cutoff-dose normal tissue complication probability (NTCP) model. There were a total of 152 patients (48% preoperative, 47% postoperative, 5% other), predominantly treated prone (95%) with a three-field technique (94%) and a protracted venous infusion of 5-fluorouracil (78%). Acute Grade 3 diarrhea occurred in 21%. The largest LogLikelihood was found for the cutoff-dose logistic regression model with 15 Gy as the cutoff-dose, although the models for 20 Gy and 25 Gy had similar significance. According to this model, highly significant correlations (p <0.001) between small bowel volumes receiving at least 15 Gy and toxicity exist in the considered patient population. Similar findings applied to both the preoperatively (p = 0.001) and postoperatively irradiated groups (p = 0.001). The incidence of Grade 3 diarrhea was significantly correlated with the volume of small bowel receiving at least 15 Gy using a cutoff-dose NTCP model.

A virtual matching technique for three-field breast irradiation using 3-D planning

Patients with breast cancer are often treated with radiation to the breast (or chest wall) and draining regional lymph nodes. This is typically performed with a three-field technique in which an anterior supraclavicular field is matched to opposed tangent fields. A single isocenter technique is not always possible. Several techniques have been described to create a perfect match using a conventional simulator. We describe and test a simple, fast and accurate technique to estimate the couch and collimator angles required for a perfect geometric match using 3-D treatment planning software. This method requires no mathematical formulae and is verifiable relative to patient anatomy. An external skin contour is created on the axial slice at the match line and displayed with a 3-D representation. Using a beam's eye view (BEV) of a tangent field, small couch and collimator rotation adjustments are made sequentially until the contour edges are superimposed. The virtual external contour technique was easy to use, gave verification of the match in the BEV and yielded estimates of couch and collimator rotations very close to those calculated using published formulae.