Regiane S. Andrade

Conventional 3D conformal versus intensity-modulated radiotherapy for the adjuvant treatment of gynecologic malignancies: a comparative dosimetric study of dose–volume histograms☆

OBJECTIVE The goals of this study were to evaluate the feasibility of pelvic intensity-modulated radiotherapy (IMRT) in the adjuvant treatment of gynecologic malignancies and to compare the dose-volume histograms (DVHs) and determine the potential impact on acute and long-term toxicity based on the dose to target and nontarget tissues for both planning techniques. METHODS Ten consecutive patients referred for adjuvant radiotherapy for gynecologic malignancies at the University of Pittsburgh School of Medicine and Magee-Womens Hospital were selected for CT-based treatment planning using the ADAC 3D version 4.2g and the NOMOS Corvus IMRT version 4.0. Normal tissues and critical structures were contoured on axial CT slices by both systems in conjunction with a gynecologic radiologist. These regions included internal, external, and common iliac nodal groups, rectum, upper 4 cm of vagina, bladder, and small bowel. Conventional treatment planning included 3D four-field box using 18-MV photons designed to treat a volume from the L(5)/S(1) border superiorly to the bottom of the ischial tuberosity on the AP/PA field and shaped blocks on the lateral fields to minimize the dose to the rectum and small bowel. A seven-field technique using 6-MV photons was used for IMRT. Restraints on small bowel for IMRT were set at 23.0 Gy +/- 5% and 35.0 Gy+/- 5% for the rectum and 37.5 Gy +/- 5% for the bladder while simultaneously delivering full dose (45.0 Gy) to the intrapelvic nodal groups in 1.8-Gy daily fractions. The dose-volume histograms where then compared for both treatment delivery systems. RESULTS The volume of each organ of interest (small bowel, bladder, and rectum) receiving doses in excess of 30 Gy was compared in the 3D and IMRT treatment plans. The mean volume of small bowel receiving doses in excess of 30 Gy was reduced by 52% with IMRT compared with 3D. A similar advantage was noted for the rectum (66% reduction) and the bladder (36% reduction). The nodal regions at risk and the upper vagina all received the prescribed dose of 45.0 Gy. CONCLUSIONS Intensity-modulated radiotherapy appears to offer several advantages over conventional 3D radiotherapy (3D CRT) planning for adjuvant radiotherapy for gynecologic malignancies. These include a significant reduction in treatment volume for bladder, rectum, and small bowel. It is anticipated that this reduction in volume of normal tissue irradiated would translate into overall reduction in acute and potentially late treatment-related toxicity. Prospective trials are necessary to better evaluate the advantages in a larger group of patients.

Stereotactic Body Radiotherapy for Recurrent Squamous Cell Carcinoma of the Head and Neck: Results of a Phase I Dose-Escalation Trial

PURPOSE To evaluate the safety and efficacy of stereotactic body radiotherapy (SBRT) in previously irradiated patients with squamous cell carcinoma of the head and neck (SCCHN). PATIENTS AND METHODS In this Phase I dose-escalation clinical trial, 25 patients were treated in five dose tiers up to 44 Gy, administered in 5 fractions over a 2-week course. Response was assessed according to the Response Evaluation Criteria in Solid Tumors and [(18)F]-fluorodeoxyglucose standardized uptake value change on positron emission tomography-computed tomography (PET-CT). RESULTS No Grade 3/4 or dose-limiting toxicities occurred. Four patients had Grade 1/2 acute toxicities. Four objective responses were observed, for a response rate of 17% (95% confidence interval 2%-33%). The maximum duration of response was 4 months. Twelve patients had stable disease. Median time to disease progression was 4 months, and median overall survival was 6 months. Self-reported quality of life was not significantly affected by treatment. Fluorodeoxyglucose PET was a more sensitive early-measure response to treatment than CT volume changes. CONCLUSION Reirradiation up to 44 Gy using SBRT is well tolerated in the acute setting and warrants further evaluation in combination with conventional and targeted therapies.

Deferring Planned Neck Dissection Following Chemoradiation for Stage IV Head and Neck Cancer: The Utility of PET-CT†

Objective: To determine whether combined positron emission tomography and computed tomography (PET‐CT) may be of value in deferring planned neck dissections for patients with advanced head and neck squamous cell carcinoma (HNSCC).

PET-CT in radiation oncology: the impact on diagnosis, treatment planning, and assessment of treatment response.

Objective:To review the role of hybrid positron emission tomography (PET)-computed tomography (CT) systems in the design and management of cancer patients in the modern radiation oncology practice. PET is co-registered with CT and incorporated into a systematic approach to the staging, management, and assessment of response and surveillance of a variety of oncologic diagnoses. Methods:A review of the literature of functional imaging such as PET-CT in staging, treatment plan design, assessment of response and detection of recurrence for tumors involving the head and neck, lung, esophagus, rectum amongst others. Results:PET and PET-CT offer significant advantages which include more accurate staging which often results in management changes in roughly one-third of patients across a number of disease site. More accurate target definition may augment highly conformal radiation treatment plans using intensity-modulated radiation therapy and stereotactic radiosurgery and radiotherapy. Conclusion:The emerging data appears to suggest the functional imaging may be a more useful tool to evaluate the therapeutic effect of treatment, detect early failures and prognosticate long-term outcome.

The Impact of Tumor Volume and Radiotherapy Dose on Outcome in Previously Irradiated Recurrent Squamous Cell Carcinoma of the Head and Neck Treated With Stereotactic Body Radiation Therapy

Purpose:To assess the effect of stereotactic body radiotherapy (SBRT) dose and tumor volume on outcomes in patients with recurrent, previously irradiated squamous cell carcinoma of the head and neck. Materials and Methods:A total of 96 patients with recurrent, previously irradiated squamous cell carcinoma of the head and neck were treated with SBRT using Cyberknife and Trilogy-intensity-modulated radiosurgery. Kaplan-Meier survival analyses were used to estimate locoregional control (LRC) and overall survival rates. Response was evaluated using positron emission tomography/computed tomography or computed tomography and detailed physical examination. Results:The median follow-up for all patients was 14 months (2–39 months). The median dose of prior radiation was 68.4 Gy (32–170 Gy). Patients were divided into 4 SBRT dose groups: I (15–28 Gy/n = 29), II (30–36 Gy/n = 22), III (40 Gy/n = 18), and IV (44–50 Gy/n = 27). The median gross tumor volume (GTV) was 24.3 cm3 (2.5–162 cm3). For GTV ≤25 cm3 (n = 50), complete response rates were 27.8%/30%/45.5%/45.5%, and for GTV >25 cm3 (n = 46), complete response rates were 20%/25%/42.8%/50% for SBRT groups I–IV, respectively. The 1-/2-/3-year LRC rates for doses 40 to 50 Gy were 69.4%/57.8%/41.1%, respectively, whereas for 15 to 36 Gy, they were 51.9%/31.7%/15.9%, respectively (P = 0.02). The overall 1- and 2-year overall survival rates were 58.9% and 28.4%, respectively. Treatment was well tolerated with no grade 4/5 toxicities. Conclusions:Dose escalation up to 50 Gy in 5 fractions is feasible with SBRT for recurrent head and neck squamous cell carcinoma. Higher SBRT doses were associated with significantly higher LRC rates. Large tumor volume required higher SBRT doses to achieve optimal response rates compared with smaller tumor volume.

FOUR-DIMENSIONAL COMPUTED TOMOGRAPHY-BASED INTERFRACTIONAL REPRODUCIBILITY STUDY OF LUNG TUMOR INTRAFRACTIONAL MOTION

PURPOSE To evaluate the interfractional reproducibility of respiration-induced lung tumors motion, defined by their centroids and the intrafractional target motion range. METHODS AND MATERIALS Twentythree pairs of four-dimensional/computed tomography scans were acquired for 22 patients. Gross tumor volumes were contoured, Clinical target volumes (CTVs) were generated. Geometric data for CTVs and lung volumes were extracted. The motion tracks of CTV centroids, and CTV edges along the cranio-caudal, anterior-posterior, and lateral directions were evaluated. The Pearson correlation coefficient for motion tracks along the cranio-caudal direction was determined for the entire respiratory cycle and for five phases about the end of expiration. RESULTS The largest motion extent was along the cranio-caudal direction. The intrafractional motion extent for five CTVs was <0.5 cm, the largest motion range was 3.59 cm. Three CTVs with respiration-induced displacement >0.5 cm did not exhibit the similarity of motion, and for 16 CTVs with motion >0.5 cm the correlation coefficient was >0.8. The lung volumes in corresponding phases for cases that demonstrated CTVs motion similarity were reproducible. No correlation between tumor size and mobility was found. CONCLUSION Target motion reproducibility seems to be present in 87% of cases in our dataset. Three cases with dissimilar motion indicate that it is advisable to verify target motion during treatment. The adaptive adjustment to compensate the possible interfractional shifts in a target position should be incorporated as a routine policy for lung cancer radiotherapy.

Four-dimensional computed tomography-based respiratory-gated whole-abdominal intensity-modulated radiation therapy for ovarian cancer: a feasibility study.

This study assesses the feasibility and implementation of respiratory-gated whole-abdominal intensity-modulated radiation therapy (RG-WAIMRT). Three patients were treated with RG-WAIMRT. The planning target volume (PTV1) included the entire peritoneal cavity and a pelvic boost field was created (PTV2). The dose prescribed was 30 Gy to PTV1 and 14.4 Gy to PTV2. For comparison, a conventional three-dimensional (3D) plan was generated for each patient. In the WAIMRT plan, an average of 90% of PTV1 received 30 Gy compared to 70% for the conventional 3D plan. The percent volume receiving 30 Gy (V30) for liver averaged 54% (WAIMRT) vs 43% (3D). The percent volume receiving 20 Gy (V20) for kidneys averaged 19% vs 0%, and the mean V20 for bone marrow was 74% vs 83%, respectively. Major acute toxicities were anemia (grade 2: 1/3), leukopenia (grade 3: 2/3 patients), and thrombocytopenia (grade 2: 1/3 patients, grade 3: 1/3 patients). One patient could not complete the whole-abdomen field after 19.5 Gy because of persistent nausea. No major subacute toxicity has been reported. WAIMRT demonstrated superior target coverage and reduced dose to bone marrow, with a slightly increased dose to liver and kidneys. WAIMRT is a novel and feasible technique for ovarian cancer treatment.

A SIMPLE AND EFFECTIVE DAILY PAIN MANAGEMENT METHOD FOR PATIENTS RECEIVING RADIATION THERAPY FOR PAINFUL BONE METASTASES

PURPOSE The incidence of painful bone metastases increases with longer survival times. Although external beam radiation therapy (EBRT) is an effective palliative treatment, it often requires several days from the start of treatment to produce a measurable reduction in pain scores and a qualitative amelioration of patient pain levels. Meanwhile, the use of analgesics remains the best approach early on in the treatment course. We investigated the role of radiation therapists as key personnel for collecting daily pain scores to supplement assessments by physician and oncology nursing staff and manage pain more effectively during radiation treatment. METHODS AND MATERIALS Daily pain scores were obtained by the radiation therapists for 89 patients undertaking a total of 124 courses of EBRT for bone metastases and compared with pretreatment pain scores. The majority of patients (71%) were treated to 30 Gy (range, 20-37.5) in 10 fractions (range, 8-15 fractions). RESULTS One hundred nineteen treatment courses (96%) were completed. Pain scores declined rapidly to 37.5%, 50%, and 75% of the pretreatment levels by Days 2, 4, and 10, respectively. Pain was improved in 91% of patients with only 4% of worse pain at the end of treatment. Improved pain scores were maintained in 83% of patients at 1-month follow-up, but in 35% of them, the pain was worse than at the end of treatment. CONCLUSIONS Collection of daily pain scores by radiation therapists was associated with an effective reduction in pain scores early on during EBRT of painful osseous metastases.

Radiation Treatment Planning for Head and Neck Malignancies

Innovative approaches have been incorporated to radiation therapy over the last decades. The technologic advances, such as intensity modulated radiation therapy and image guided radiation have resulted in a modern era for this oncologic modality. The mix of imaging approach using computed tomography (CT), magnetic resonance, and positron emission tomography (PET) have been of great value to ascertain the accuracy of tumor target delineation. The use of functional imaging, especially PET/CT, has been incorporated to the modern radiation oncology practice to better define the tumor extent and augment the treatment plan design, as well as response assessment. This article focuses on radiation treatment planning and the integration of PET/CT for head and neck cancer radiation therapy.

SU‐FF‐J‐85: 4DCT‐Based Study of Tumor and Lung Kinematics During Respiratory Cycle

Purpose: To evaluate the intra‐fractional correlation of lungtumors and lungs motion induced by respiration.Method and Materials: Ten 4DCT scans acquired for treatment planning were used. Three patients had also a second scan in the middle of the treatment (after 4–5 weeks). All targets were in lower lobe of the lungs. GTVs for all phases were manually contoured and CTVs generated. AL1 geometrical data were computed from DICOM‐RT files. The lung volumes, their aeration, the motion tracks of lungs and CTV centroids along the cranio‐caudal, anterior‐posterior and lateral directions were determined for ten breathing phases obtained with 4DCT scan. The lung mechanics as demonstrated by the their ventilation map were evaluated from CT scans. The Pearson correlation coefficients between the lungs and CTV centroids for motion tracks along the axes of each patient were determined. Results: The volume of the CTVs ranged from 30 to 140cc (median=72cc). The motion of targets centroids along the C‐C direction ranged from 1 to 3.5cm (median=1.6cm; for AP and RL median=0.3cm). The lungs and CTV motion along C‐C direction exhibited high correlation (two cases in [0.7, 0.8]; rest>0.8). There are no correlation present for other directions. The examined CTVs did not exhibit any significant deformation during respiration. They were not attached to any immobile anatomical structure. The lung aeration pattern and target motion along the lungs cranio‐caudal direction appear reproducible for three cases with two 4DCT scans. The changes in target volume did not affect the motion correlation. Conclusion:Lungkinematics appear to control tumor motion along the cranio‐caudal direction for targets fully embedded in inferior part of the lungs. Assuming correspondence between lung function and regional aeration one can potentially use this information in treatment planning to spare these regions.