K.L. Leonard

The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation

PURPOSE To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). METHODS AND MATERIALS Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. RESULTS At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. CONCLUSIONS The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were not associated with late toxicity.

A 17-year retrospective study of institutional results for eye plaque brachytherapy of uveal melanoma using 125I, 103Pd, and 131Cs and historical perspective

PURPOSE To compare overall survival, local and distant failure rates, ocular toxicity, and vision preservation in patients treated with eye plaque brachytherapy at Tufts Medical Center with those in the published literature. METHODS AND MATERIALS Records were reviewed for 53 patients with the diagnosis of uveal melanoma treated with plaque brachytherapy at Tufts Medical Center over the past 17 years. American Joint Committee on Cancer staging (T1, T2, or T3) were 4, 39, and 10 patients, respectively. All the patients were treated using (125)I (n=37), (103)Pd (n=5), or (131)Cs (n=11) to a dose of 85Gy (documented as 100Gy before 1996 for the same physical dose). RESULTS With a mean followup of 75 months, 38 of 53 patients were still alive. Five patients (all (125)I) developed liver metastases (9%) with no evidence of local failure. There were 10 definitive local failures and four additional transpupillary thermo-therapy procedures performed to ensure local control for lesions slow to respond. Twelve patients (23%) required enucleation. At most recent followup, 32 patients (71%) maintained 20/200 vision or better in the treated eye. In this first report of (131)Cs plaque therapy with a mean followup of 20 months, there were two transpupillary thermo-therapy procedures and one definitive failure requiring enucleation after 10 months. CONCLUSIONS Our disease control and ocular results were comparable to those in the literature given the extended followup. We are developing a multi-institutional, prospective clinical protocol for considering radionuclide selection and other prescriptive criteria.

Survival among patients with 10 or more brain metastases treated with stereotactic radiosurgery

OBJECT The goal of this study was to evaluate outcomes in patients with ≥ 10 CNS metastases treated with Gamma Knife stereotactic radiosurgery (GK-SRS). METHODS Patients with ≥ 10 brain metastases treated using GK-SRS during the period between 2004 and 2010 were identified. Overall survival and local and regional control as well as necrosis rates were determined. The influence of age, sex, histological type, extracranial metastases, whole-brain radiation therapy, and number of brain metastases was analyzed using the Kaplan-Meier method. Univariate (log-rank) analyses were performed, with a p value of < 0.05 considered significant. RESULTS Fifty-three patients with ≥ 10 brain metastases were treated between 2004 and 2010. All had a Karnofsky Performance Status score of ≥ 70. Seventy-two percent had either non-small cell lung cancer (38%) or breast cancer (34%); melanoma, small cell lung cancer, renal cell carcinoma, and testicular, colon, and ovarian cancer contributed the remaining 28%. On average, 10.9 lesions were treated in a single session. Sixty-four percent of patients received prior whole-brain radiation therapy. The median survival was 6.5 months. One-year overall survival was 42% versus 14% when comparing breast cancer and other histological types, respectively (p = 0.074). Age, extracranial metastases, number of brain metastases, and previous CNS radiation therapy were not significant prognostic factors. Although the median time to local failure was not reached, the median time to regional failure was 3 months. Female sex was associated with longer time to regional failure (p = 0.004), as was breast cancer histological type (p = 0.089). No patient experienced symptomatic necrosis. CONCLUSIONS Patients with ≥ 10 brain metastases who received prior CNS radiation can safely undergo repeat treatment with GK-SRS. With median survival exceeding 6 months, aggressive local treatment remains an option; however, rapid CNS failure is to be expected. Although numbers are limited, patients with breast cancer represent one group of individuals who would benefit most, with prolonged survival and extended time to CNS recurrence.

Radiobiology for eye plaque brachytherapy and evaluation of implant duration and radionuclide choice using an objective function

PURPOSE Clinical optimization of Collaborative Ocular Melanoma Study (COMS) eye plaque brachytherapy is currently limited to tumor coverage, consensus prescription dosage, and dose calculations to ocular structures. The biologically effective dose (BED) of temporary brachytherapy treatments is a function of both chosen radionuclide R and implant duration T. This study endeavored to evaluate BED delivered to the tumor volume and surrounding ocular structures as a function of plaque position P, prescription dose, R, and T. METHODS Plaque-heterogeneity-corrected dose distributions were generated with MCNP5 for the range of currently available COMS plaques loaded with sources using three available low-energy radionuclides. These physical dose distributions were imported into the PINNACLE(3) treatment planning system using the TG-43 hybrid technique and used to generate dose volume histograms for a T = 7 day implant within a reference eye geometry including the ciliary body, cornea, eyelid, foveola, lacrimal gland, lens, optic disc, optic nerve, retina, and tumor at eight standard treatment positions. The equation of Dale and Jones was employed to create biologically effective dose volume histograms (BEDVHs), allowing for BED volumetric analysis of all ROIs. Isobiologically effective prescription doses were calculated for T = 5 days down to 0.01 days, with BEDVHs subsequently generated for all ROIs using correspondingly reduced prescription doses. Objective functions were created to evaluate the BEDVHs as a function of R and T. These objective functions are mathematically accessible and sufficiently general to be applied to temporary or permanent brachytherapy implants for a variety of disease sites. RESULTS Reducing T from 7 to 0.01 days for a 10 mm plaque produced an average BED benefit of 26%, 20%, and 17% for (103)Pd, (125)I, and (131)Cs, respectively, for all P; 16 and 22 mm plaque results were more position-dependent. (103)Pd produced a 16%-35% BED benefit over (125)I, whereas (131)Cs produced a 3%-7% BED detriment, independent of P, T, and plaque size. Additionally, corresponding organ at risk physical doses were lowest using (103)Pd in all circumstances. CONCLUSIONS The results suggest that shorter implant durations may correlate with more favorable outcomes compared to 7 day implants when treating small or medium intraocular lesions. The data also indicate that implant duration may be safely reduced if the prescription physical dose is likewise diminished and that (103)Pd offers a substantial radiobiological benefit over (125)I and (131)Cs irrespective of plaque position, implant duration, and tumor size.

BEDVH--A method for evaluating biologically effective dose volume histograms: Application to eye plaque brachytherapy implants

PURPOSE A method is introduced to examine the influence of implant duration T, radionuclide, and radiobiological parameters on the biologically effective dose (BED) throughout the entire volume of regions of interest for episcleral brachytherapy using available radionuclides. This method is employed to evaluate a particular eye plaque brachytherapy implant in a radiobiological context. METHODS A reference eye geometry and 16 mm COMS eye plaque loaded with (103)Pd, (125)I, or (131)Cs sources were examined with dose distributions accounting for plaque heterogeneities. For a standardized 7 day implant, doses to 90% of the tumor volume ( (TUMOR)D(90)) and 10% of the organ at risk volumes ( (OAR)D(10)) were calculated. The BED equation from Dale and Jones and published α/β and μ parameters were incorporated with dose volume histograms (DVHs) for various T values such as T = 7 days (i.e.,  (TUMOR) (7)BED(10) and  (OAR) (7)BED(10)). By calculating BED throughout the volumes, biologically effective dose volume histograms (BEDVHs) were developed for tumor and OARs. Influence of T, radionuclide choice, and radiobiological parameters on  (TUMOR)BEDVH and  (OAR)BEDVH were examined. The nominal dose was scaled for shorter implants to achieve biological equivalence. RESULTS  (TUMOR)D(90) values were 102, 112, and 110 Gy for (103)Pd, (125)I, and (131)Cs, respectively. Corresponding  (TUMOR) (7)BED(10) values were 124, 140, and 138 Gy, respectively. As T decreased from 7 to 0.01 days, the isobiologically effective prescription dose decreased by a factor of three. As expected,  (TUMOR) (7)BEDVH did not significantly change as a function of radionuclide half-life but varied by 10% due to radionuclide dose distribution. Variations in reported radiobiological parameters caused  (TUMOR) (7)BED(10) to deviate by up to 46%. Over the range of (OAR)α/β values,  (OAR) (7)BED(10) varied by up to 41%, 3.1%, and 1.4% for the lens, optic nerve, and lacrimal gland, respectively. CONCLUSIONS BEDVH permits evaluation of the relative biological effectiveness for brachytherapy implants. For eye plaques,  (TUMOR)BEDVH and  (OAR)BEDVH were sensitive to implant duration, which may be manipulated to affect outcomes.

A Phase I Study of Dasatinib with Concurrent Chemoradiation for Stage III Non-Small Cell Lung Cancer

Objectives: Src family kinases (SFKs) are expressed in non-small cell lung cancer (NSCLC) and may be involved in tumor growth and metastases. Inhibition of SFK may also enhance radiation. The purpose of this study was to evaluate if a maximum dose of 100 mg of dasatinib could be safely administered with concurrent chemoradiation and then continued as maintenance for patients with newly diagnosed stage III NSCLC. Methods: Patients with stage III locally advanced NSCLC received paclitaxel, 50 mg/m2/week, with carboplatin area under the curve (AUC) = 2, weekly for 7 weeks, and concurrent radiotherapy, 64.8 Gy. Three dose levels of dasatinib 50, 70, and 100 mg/day were planned. Results: 11 patients with locally advanced NSCLC were entered. At the 70 mg dose level 1 patient had grade 5 pneumonitis not responsive to therapy, and one patient had reversible grade 3 pneumonitis and grade 3 pericardial effusion. Due to these toxicities the Brown University Oncology Group Data Safety Monitoring Board terminated the study. Conclusion: Dasatinib could not be safely combined with concurrent chemoradiation for stage 3 lung cancer due to pneumonitis.

A novel ytterbium-169 brachytherapy source and delivery system for use in conjunction with minimally invasive wedge resection of early-stage lung cancer

PURPOSE To describe a novel source-delivery system for intraoperative brachytherapy in patients with early-stage lung cancer that is readily adaptable to a video-assisted thoracoscopic surgery approach and can be precisely delivered to achieve optimal dose distribution. METHODS AND MATERIALS Radioactive ytterbium-169 ((169)Yb) was sealed within a titanium tube 0.28 mm in diameter and then capped and resealed by titanium wires laser welded to the tube to serve as the legs of a tissue-fastening system. Dose simulations were performed using Monte Carlo computer code (Los Alamos National Laboratory, Los Alamos, NM) to mimic the geometric and elemental compositions of the source, fastening apparatus, and surroundings. RESULTS Five test source capsules were subjected to a tensile load to failure. Failure in each capsule occurred in the wire of the fastener leg; there were no weld failures. Monte Carlo simulations and subsequent dose measurement showed the perturbation by the source legs in the deployed (bent over) position to be small (4-5%) for (169)Yb and much less than that for iodine-125 (32%). CONCLUSION We have developed a (169)Yb brachytherapy source-delivery system that can be used in conjunction with commercially available surgical stapling instruments, facilitates the precise placement of brachytherapy sources relative to the surgical margin, assures the seeds remain fixed in their precise position for the duration of the treatment, overcomes the technical difficulties of manipulating the seeds through the narrow surgical incision associated with video-assisted thoracoscopic surgery, and reduces the radiation dose to the clinicians.

Axillary lymph node dose with tangential whole breast radiation in the prone versus supine position: a dosimetric study

BackgroundProne breast positioning reduces skin reaction and heart and lung dose, but may also reduce radiation dose to axillary lymph nodes (ALNs).MethodsWomen with early stage breast cancer treated with whole breast irradiation (WBI) in the prone position were identified. Patients treated in the supine position were matched for treating physician, laterality, and fractionation. Ipsilateral breast, tumor bed, and Level I, II, and III ALNs were contoured according to the RTOG breast atlas. Clips marking surgically removed sentinel lymph nodes (SLN)s were contoured. Treatment plans developed for each patient were retrospectively analyzed. V90% and V95% was calculated for each axillary level. When present, dose to axillary surgical clips was calculated.ResultsTreatment plans for 46 women (23 prone and 23 supine) were reviewed. The mean V90% and V95% of ALN Level I was significantly lower for patients treated in the prone position (21% and 14%, respectively) than in the supine position (50% and 37%, respectively) (p < 0.0001 and p < 0.0001, respectively). Generally, Level II & III ALNs received little dose in either position. Sentinel node biopsy clips were all contained within axillary Level I. The mean V95% of SLN clips was 47% for patients treated in the supine position and 0% for patients treated in the prone position (p < 0.0001). Mean V90% to SLN clips was 96% for women treated in the supine position but only 13% for women treated in the prone position.ConclusionsStandard tangential breast irradiation in the prone position results in substantially reduced dose to the Level I axilla as compared with treatment in the supine position. For women in whom axillary coverage is indicated such as those with positive sentinel lymph node biopsy who do not undergo completion axillary dissection, treatment in the prone position may be inappropriate.

Comparison of endorectal ultrasound versus pelvic magnetic resonance imaging for radiation treatment planning in locally advanced rectal cancer

PURPOSE Current National Comprehensive Cancer Network guidelines for rectal cancer recommend tumor and nodal staging using endorectal ultrasound (EUS) or pelvic magnetic resonance imaging (MRI). EUS and MRI have similar accuracy for staging rectal cancers. The relative benefits of each modality for radiation therapy (RT) treatment planning are unknown. METHODS AND MATERIALS EUS, MRI, and treatment planning computed tomography scans were reviewed for 6 patients with locally advanced rectal cancer treated with neoadjuvant chemotherapy followed by neoadjuvant chemoradiation therapy. Thirty rectal gross tumor volumes (GTVs) were contoured: 2 GTVEUS (contoured independently by 2 radiation oncologists), 2 GTVMRI, and one GTV treatment (contoured by the treating physician for the original treatment plan) per patient from the original treatment plan. GTVEUS was based on colonoscopy and EUS. GTVMRI was based on T2 postgadolinium MRI sequences fused with treatment planning computed tomography. GTVEUS and GTVMRI volume, craniocaudal length, and number of suspicious lymph nodes (LN) were compared between EUS vs MRI and compared to GTV treatment. Agreement between contours was calculated as the percentage of overlapping slices over total slices for MRI and EUS-based contours. Paired t test was used to assess relationships between imaging modality and treatment volume, craniocaudal length, and LN number. RESULTS For volume and craniocaudal length, mean GTVEUS was significantly smaller than mean GTVMRI (P = .02 and P = .04, respectively). The mean number of suspicious LN identified by MRI was significantly greater than by EUS (4.8 vs 3.0; P = .03). Agreement between radiation oncologist GTV contours was greater for GTVMRI than for GTVEUS (71% vs 44%), although not statistically significantly so (P = .11). CONCLUSIONS Pelvic MRI for RT treatment planning in locally advanced rectal cancer generates more comprehensive and reproducible GTV contours than does the use of EUS. Pelvic MRI can be recommended to aid in RT treatment planning for all eligible patients undergoing RT for locally advanced rectal cancer.

Prescription dose evaluation for APBI with noninvasive image-guided breast brachytherapy using equivalent uniform dose.

PURPOSE Noninvasive image-guided breast brachytherapy (NIBB) is an attractive novel approach to deliver accelerated partial breast irradiation (APBI). Calculations of equivalent uniform dose (EUD) were performed to identify the appropriate APBI dose for this technique. METHODS AND MATERIALS APBI plans were developed for 15 patients: five with three-dimensional conformal APBI (3D-CRT), five with multi-lumen intracavitary balloons (m-IBB), and five simulating NIBB treatment. Prescription doses of 34.0 and 38.5 Gy were delivered in 10 fractions for m-IBB and 3D-CRT, respectively. Prescription doses ranging from 34.0 to 38.5 Gy were considered for NIBB. Dose-volume histogram data from all 3D-CRT, m-IBB, and NIBB plans were used to calculate the biologically effective EUD and corresponding EUD to the PTV_eval using the following equation: EUD = EUBED/(n [1 + EUD/α/β]). An α/β value of 4.6 Gy was assumed for breast tumor. EUD for varying NIBB prescription doses were compared with EUD values for the other APBI techniques. RESULTS Mean PTV_eval volume was largest for 3D-CRT (372.9 cm(3)) and was similar for NIBB and m-IBB (88.7 and 87.2 cm(3), respectively). The EUD value obtained by prescribing 38.5 Gy with 3D-CRT APBI was 38.6 Gy. The EUD value of 34.0 Gy prescribed with m-IBB was 34.4 Gy. EUD values for NIBB ranged from 33.9 to 38.2 Gy for prescription doses ranging from 34.0 to 38.5 Gy. CONCLUSIONS Using EUD calculations to compare APBI techniques and treatment doses, a prescription dose of 36.0 Gy in 10 fractions using NIBB has a comparable biologic equivalent dose to other established brachytherapy techniques.