To investigate the association between dose to various anatomical structures and dysphagia among patients with head and neck cancer treated by definitive intensity-modulated radiotherapy (IMRT) and ...concurrent chemotherapy.
Thirty-nine patients with squamous cancer of the head and neck were treated by definitive concurrent chemotherapy and IMRT to a median dose of 70 Gy (range, 68 to 72). In each patient, a gastrostomy tube (GT) was prophylacticly placed prior to starting treatment. Prolonged GT dependence was defined as exceeding the median GT duration of 192 days. Dysphagia was scored using standardized quality-of-life instruments. Dose-volume histogram (DVH) data incorporating the superior/middle pharyngeal constrictors (SMPC), inferior pharyngeal constrictor (IPC), cricoid pharyngeal inlet (CPI), and cervical esophagus (CE) were analyzed in relation to prolonged GT dependence, dysphagia, and weight loss.
At 3 months and 6 months after treatment, 87% and 44% of patients, respectively, were GT dependent. Spearman's rho analysis identified statistical correlations (p < 0.05) between prolonged GT dependence or high grade dysphagia with IPC V65, IPC V60, IPC Dmean, and CPI Dmax. Logistic regression model showed that IPC V65 > 30%, IPC V60 > 60%, IPC Dmean > 60 Gy, and CPI Dmax > 62 Gy predicted for greater than 50% probability of prolonged GT dependence.
Our analysis suggests that adhering to the following parameters may decrease the risk of prolonged GT dependence and dysphagia: IPC V65 < 15%, IPC V60 < 40%, IPC Dmean < 55 Gy, and CPI Dmax < 60 Gy.
Purpose: To identify a clinically relevant and available parameter upon which to identify non-small cell lung cancer (NSCLC) patients at risk for pneumonitis when treated with three-dimensional (3D) ...radiation therapy.
Methods and Materials: Between January 1991 and October 1995, 99 patients were treated definitively for inoperable NSCLC. Patients were selected for good performance status (96%) and absence of weight loss (82%). All patients had full 3D treatment planning (including total lung dose–volume histograms DVHs) prior to treatment delivery. The total lung DVH parameters were compared with the incidence and grade of pneumonitis after treatment.
Results: Univariate analysis revealed the percent of the total lung volume exceeding 20 Gy (V20), the effective volume (Veff) and the total lung volume mean dose, and location of the tumor primary (upper versus lower lobes) to be statistically significant relative to the development of ≥ Grade 2 pneumonitis. Multivariate analysis revealed the V20 to be the single independent predictor of pneumonitis.
Conclusions: The V20 from the total lung DVH is a useful parameter easily obtained from most 3D treatment planning systems. The V20 may be useful in comparing competing treatment plans to evaluate the risk of pneumonitis for our individual patient treatment and may also be a useful parameter upon which to stratify patients or prospective dose escalation trials.
Radiation Therapy Oncology Group (RTOG) 0515 is a Phase II prospective trial designed to quantify the impact of positron emission tomography (PET)/computed tomography (CT) compared with CT alone on ...radiation treatment plans (RTPs) and to determine the rate of elective nodal failure for PET/CT-derived volumes.
Each enrolled patient underwent definitive radiation therapy for non-small-cell lung cancer (≥ 60 Gy) and had two RTP datasets generated: gross tumor volume (GTV) derived with CT alone and with PET/CT. Patients received treatment using the PET/CT-derived plan. The primary end point, the impact of PET/CT fusion on treatment plans was measured by differences of the following variables for each patient: GTV, number of involved nodes, nodal station, mean lung dose (MLD), volume of lung exceeding 20 Gy (V20), and mean esophageal dose (MED). Regional failure rate was a secondary end point. The nonparametric Wilcoxon matched-pairs signed-ranks test was used with Bonferroni adjustment for an overall significance level of 0.05.
RTOG 0515 accrued 52 patients, 47 of whom are evaluable. The follow-up time for all patients is 12.9 months (2.7-22.2). Tumor staging was as follows: II = 6%; IIIA = 40%; and IIIB = 54%. The GTV was statistically significantly smaller for PET/CT-derived volumes (98.7 vs. 86.2 mL; p < 0.0001). MLDs for PET/CT plans were slightly lower (19 vs. 17.8 Gy; p = 0.06). There was no significant difference in the number of involved nodes (2.1 vs. 2.4), V20 (32% vs. 30.8%), or MED (28.7 vs. 27.1 Gy). Nodal contours were altered by PET/CT for 51% of patients. One patient (2%) has developed an elective nodal failure.
PET/CT-derived tumor volumes were smaller than those derived by CT alone. PET/CT changed nodal GTV contours in 51% of patients. The elective nodal failure rate for GTVs derived by PET/CT is quite low, supporting the RTOG standard of limiting the target volume to the primary tumor and involved nodes.
We conducted a clinical study to correlate oral cavity dose with clinical mucositis, perform in vivo dosimetry, and determine the feasibility of obtaining buccal mucosal cell samples in patients ...undergoing head-and-neck radiation therapy. The main objective is to establish a quantitative dose response for clinical oral mucositis.
Twelve patients undergoing radiation therapy for head-and-neck cancer were prospectively studied. Four points were chosen in separate quadrants of the oral cavity. Calculated dose distributions were generated by using AcQPlan and Eclipse treatment planning systems. MOSFET dosimeters were used to measure dose at each sampled point. Each patient underwent buccal sampling for future RNA analysis before and after the first radiation treatment at the four selected points. Clinical and functional mucositis were assessed weekly according to National Cancer Institute Common Toxicity Criteria, Version 3.
Maximum and average doses for sampled sites ranged from 7.4-62.3 and 3.0-54.3 Gy, respectively. A cumulative point dose of 39.1 Gy resulted in mucositis for 3 weeks or longer. Mild severity (Grade </= 1) and short duration (</=1 week) of mucositis were found at cumulative point doses less than 32 Gy. Polymerase chain reaction consistently was able to detect basal levels of two known radiation responsive genes.
In our sample, cumulative doses to the oral cavity of less than 32 Gy were associated with minimal acute mucositis. A dose greater than 39 Gy was associated with longer duration of mucositis. Our technique for sampling buccal mucosa yielded sufficient cells for RNA analysis using polymerase chain reaction.
In the context of national calls for reorganizing cancer clinical trials, the National Cancer Institute sponsored a 2-day workshop to examine challenges and opportunities for optimizing radiotherapy ...quality assurance (QA) in clinical trial design.
Participants reviewed the current processes of clinical trial QA and noted the QA challenges presented by advanced technologies. The lessons learned from the radiotherapy QA programs of recent trials were discussed in detail. Four potential opportunities for optimizing radiotherapy QA were explored, including the use of normal tissue toxicity and tumor control metrics, biomarkers of radiation toxicity, new radiotherapy modalities such as proton beam therapy, and the international harmonization of clinical trial QA.
Four recommendations were made: (1) to develop a tiered (and more efficient) system for radiotherapy QA and tailor the intensity of QA to the clinical trial objectives (tiers include general credentialing, trial-specific credentialing, and individual case review); (2) to establish a case QA repository; (3) to develop an evidence base for clinical trial QA and introduce innovative prospective trial designs to evaluate radiotherapy QA in clinical trials; and (4) to explore the feasibility of consolidating clinical trial QA in the United States.
Radiotherapy QA can affect clinical trial accrual, cost, outcomes, and generalizability. To achieve maximum benefit, QA programs must become more efficient and evidence-based.
To generate a reproducible step-wise guideline for the delineation of the lumbosacral plexus (LSP) on axial computed tomography (CT) planning images and to provide a preliminary dosimetric analysis ...on 15 representative patients with rectal or anal cancers treated with an intensity-modulated radiotherapy (IMRT) technique.
A standardized method for contouring the LSP on axial CT images was devised. The LSP was referenced to identifiable anatomic structures from the L4-5 interspace to the level of the sciatic nerve. It was then contoured retrospectively on 15 patients treated with IMRT for rectal or anal cancer. No dose limitations were placed on this organ at risk during initial treatment planning. Dosimetric parameters were evaluated. The incidence of radiation-induced lumbosacral plexopathy (RILSP) was calculated.
Total prescribed dose to 95% of the planned target volume ranged from 50.4 to 59.4 Gy (median 54 Gy). The mean (± standard deviation SD) LSP volume for the 15 patients was 100 ± 22 cm(3) (range, 71-138 cm(3)). The mean maximal dose to the LSP was 52.6 ± 3.9 Gy (range, 44.5-58.6 Gy). The mean irradiated volumes of the LSP were V40Gy = 58% ± 19%, V50Gy = 22% ± 23%, and V55Gy = 0.5% ± 0.9%. One patient (7%) was found to have developed RILSP at 13 months after treatment.
The true incidence of RILSP in the literature is likely underreported and is not a toxicity commonly assessed by radiation oncologists. In our analysis the LSP commonly received doses approaching the prescribed target dose, and 1 patient developed RILSP. Identification of the LSP during IMRT planning may reduce RILSP. We have provided a reproducible method for delineation of the LSP on CT images and a preliminary dosimetric analysis for potential future dose constraints.
Purpose: Locoregional tumor control for locally advanced cancers with radiation therapy has been unsatisfactory. This is in part associated with the phenomenon of tumor hypoxia. Assessing hypoxia in ...human tumors has been difficult due to the lack of clinically noninvasive and reproducible methods. A recently developed positron emission tomography (PET) imaging-based hypoxia measurement technique which employs a Cu(II)-diacetyl-bis(
N
4-methylthiosemicarbazone) (Cu-ATSM) tracer is of great interest. Oxygen electrode measurements in animal experiments have demonstrated a strong correlation between low tumor pO
2 and excess
60Cu-ATSM accumulation. Intensity-modulated radiation therapy (IMRT) allows selective targeting of tumor and sparing of normal tissues. In this study, we examined the feasibility of combining these novel technologies to develop hypoxia imaging (Cu-ATSM)-guided IMRT, which may potentially deliver higher dose of radiation to the hypoxic tumor subvolume to overcome inherent hypoxia-induced radioresistance without compromising normal tissue sparing.
Methods and Materials: A custom-designed anthropomorphic head phantom containing computed tomography (CT) and positron emitting tomography (PET) visible targets consisting of plastic balls and rods distributed throughout the “cranium” was fabricated to assess the spatial accuracy of target volume mapping after multimodality image coregistration. For head-and-neck cancer patients, a CT and PET imaging fiducial marker coregistration system was integrated into the thermoplastic immobilization head mask with four CT and PET compatible markers to assist image fusion on a Voxel-Q treatment-planning computer. This system was implemented on head-and-neck cancer patients, and the gross tumor volume (GTV) was delineated based on physical and radiologic findings. Within GTV, regions with a
60Cu-ATSM uptake twice that of contralateral normal neck muscle were operationally designated as ATSM-avid or hypoxic tumor volume (
hGTV) for this feasibility study. These target volumes along with other normal organs contours were defined and transferred to an inverse planning computer (Corvus, NOMOS) to create a hypoxia imaging-guided IMRT treatment plan.
Results: A study of the accuracy of target volume mapping showed that the spatial fidelity and imaging distortion after CT and PET image coregistration and fusion were within 2 mm in phantom study. Using fiducial markers to assist CT/PET imaging fusion in patients with carcinoma of the head-and-neck area, a heterogeneous distribution of
60Cu-ATSM within the GTV illustrated the success of
60Cu-ATSM PET to select an ATSM-avid or hypoxic tumor subvolume (
hGTV). We further demonstrated the feasibility of Cu-ATSM-guided IMRT by showing an example in which radiation dose to the
hGTV could be escalated without compromising normal tissue (parotid glands and spinal cord) sparing. The plan delivers 80 Gy in 35 fractions to the ATSM-avid tumor subvolume and the GTV simultaneously receives 70 Gy in 35 fractions while more than one-half of the parotid glands are spared to less than 30 Gy.
Conclusion: We demonstrated the feasibility of a novel Cu-ATSM-guided IMRT approach through coregistering hypoxia
60Cu-ATSM PET to the corresponding CT images for IMRT planning. Future investigation is needed to establish a clinical-pathologic correlation between
60Cu-ATSM retention and radiation curability, to understand tumor re-oxygenation kinetics, and tumor target uncertainty during a course of radiation therapy before implementing this therapeutic approach to patients with locally advanced tumor.
To evaluate in a Phase I trial the feasibility and toxicity of dose-escalated three-dimensional conformal radiotherapy (3D-CRT) concurrent with chemotherapy in patients with primary supratentorial ...glioblastoma (GBM).
A total of 209 patients were enrolled. All received 46 Gy in 2-Gy fractions to the first planning target volume (PTV(1)), defined as the gross tumor volume (GTV) plus 1.8 cm. A subsequent boost was given to PTV(2), defined as GTV plus 0.3 cm. Patients were stratified into two groups (Group 1: PTV(2) <75 cm(3); Group 2: PTV(2) >or=75 cm(3)). Four RT dose levels were evaluated: 66, 72, 78, and 84 Gy. Carmustine 80 mg/m(2) was given during RT, then every 8 weeks for 6 cycles. Pretreatment characteristics were well balanced.
Acute and late Grade 3/4 RT-related toxicities were no more frequent at higher RT dose or with larger tumors. There were no dose-limiting toxicities (acute Grade >or=3 irreversible central nervous system toxicities) observed on any dose level in either group. On the basis of the absence of dose-limiting toxicities, dose was escalated to 84 Gy in both groups. Late RT necrosis was noted at 66 Gy (1 patient), 72 Gy (2 patients), 78 Gy (2 patients), and 84 Gy (3 patients) in Group 1. In Group 2, late RT necrosis was noted at 78 Gy (1 patient) and 84 Gy (2 patients). Median time to RT necrosis was 8.8 months (range, 5.1-12.5 months). Median survival in Group 1 was 11.6-19.3 months. Median survival in Group 2 was 8.2-13.9 months.
Our study shows the feasibility of delivering higher than standard (60 Gy) RT dose with concurrent chemotherapy for primary GBM, with an acceptable risk of late central nervous system toxicity.
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