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Mary E Platek,
Mary E Reid,
Gregory E Wilding, Wainwright Jaggernauth,
Nestor R Rigual,
Wesley L Hicks,
Saurin R Popat,
Graham W Warren,
Maureen Sullivan,
Wade L Thorstad,
Mohamed K Khan,
Thom R Loree,
Anurag K Singh
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ABSTRACT: This study was carried out to determine if markers of nutritional status predict for locoregional failure following intensity-modulated radiation therapy (IMRT) with concurrent chemoradiotherapy (CCRT) for squamous cell carcinoma of the head and neck (SCCHN).
We performed a retrospective chart review of 78 patients with SCCHN who received definitive CCRT. We compared patient factors, tumor characteristics, and nutritional status indicators between patients with and without locoregional failure.
Fifteen of 78 patients (19%) experienced locoregional failure. Median follow-up for live patients was 38 months. On univariate analysis, pretreatment percentage of ideal body weight (%IBW) (p < .01), pretreatment hemoglobin (p = .04), and treatment duration (p < .01) were significant predictors of failure. On multivariate analysis, pretreatment %IBW (p = .04) and treatment time (p < .01) remained statistically significant.
Although treatment time is an accepted risk factor for failure, differences in outcome for patients with head and neck cancer undergoing definitive CCRT based on pretreatment %IBW should be examined further.
Head & Neck 11/2011; 33(11):1561-8. · 2.40 Impact Factor
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ABSTRACT: To analyze the effect of tungsten shields present in a Fletcher-Suit-Delclos ovoid by comparing the dose distribution computed by a treatment planning system (TPS) to the delivered dose distribution measured by radiochromic film dosimetry.
Gafchromic/EBT films were carefully wrapped around the caps (diameter 20-25 mm) of shielded as well as unshielded ovoids, including their anterior and posterior ends. The ovoids were irradiated to a dose of 300 cGy using a high-dose rate remote afterloading unit. The films were scanned using Vidar VXR-16 Scanner. The dose distribution in the planes above, below, and on the sides of the ovoid were compared with the dose distribution computed by TPS, which does not account for the presence of shields.
The dose distributions obtained about the unshielded ovoid from film dosimetry was in order of what is computed by TPS (90% measurements ± 5%, maximum 8%). The dose reduction in the anterior part of the shielded ovoid affects maximally the dose to the bladder where a reduction up to 20% was noted. The reduction of dose in the posterior part of the ovoid, which is designed to shield rectum was as high as 23%. Where the shields are not present, insignificant difference in the measured and computed dose values was noticed.
The TPS may substantially overestimate the dose to the bladder and rectum, including regions that lie in the shadow of the solid angle subtended by the shields if it does not account for the presence of tungsten shields.
Brachytherapy 10/2010; 10(3):232-41. · 1.47 Impact Factor
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ABSTRACT: Controversy exists regarding optimal management of high risk localized endometrial cancer. Given that vaginal brachytherapy (VB) alone is used routinely at our institution, we retrospectively reviewed our outcomes among high risk patients defined according to the PORTEC, GOG 99, and/or Aalders randomized trials of pelvic radiation versus observation to determine if acceptable rates of locoregional control could be achieved with vaginal brachytherapy alone in this highest risk patient population.
The Roswell Park Cancer Institute hospital tumor registry was used to identify all patients with Stage I or IIA endometrial cancer treated between January 1992 and June 2006. A total of 464 patients were identified. Of 261 patients who received post-operative RT, 225 received VB alone. Of those 225, 87 met the high risk criteria as designated by PORTEC (at least 2 of the following high risk features: age>60, Grade 3, and/or myometrial invasion >or=Occurrences of the mathematical operator' (='were changed to 'OE'. Please check.-->50%), GOG 99 (any age with 3 high risk features: Grade 2-3, >66% myometrial invasion, and/or LVSI; age >or=50 with 2 high risk features; or age >or=70 with 1 high risk feature), and/or Aalders (Stage IC, Grade 3). Descriptive recurrence statistics are provided.
Among 87 high risk patients treated with VB alone, 36, 77, and 14 were high risk per PORTEC, GOG 99, and Aalders respectively. Forty (46%) underwent pelvic lymph node dissection. With a median follow-up of 52 months, 3 (3.4%) pelvic recurrences were observed including 1 vaginal recurrence, 1 pelvic recurrence, and 1 local recurrence involving both the vagina and pelvis. All 3 local recurrences were successfully salvaged with pelvic RT+/-surgery.
This represents one of the largest known series of high risk localized endometrial cancer treated with VB alone. The observed 3.4% locoregional recurrence compares favorably with the 5% locoregional recurrence noted among the highest risk patients receiving pelvic RT in the PORTEC, GOG 99, and Aalders randomized trials. In this single institution experience, the 3 local recurrences were salvaged. Based on these findings, we will continue to use VB alone in the adjuvant setting for patients with high risk localized endometrial cancer.
Gynecologic Oncology 11/2009; 116(3):404-7. · 3.89 Impact Factor
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ABSTRACT: In film-based intracavitary brachytherapy for cervical cancer, position of the rectal markers may not accurately represent the anterior rectal wall. This study was aimed at analyzing the variability of rectal dose estimation as a result of interfractional variation of marker placement. A cohort of five patients treated with multiple-fraction tandem and ovoid high-dose-rate (HDR) brachytherapy was studied. The cervical os point and the orientation of the applicators were matched among all fractional plans for each patient. Rectal points obtained from all fractions were then input into each clinical treated plan. New fractional rectal doses were obtained and a new cumulative rectal dose for each patient was calculated. The maximum interfractional variation of distances between rectal dose points and the closest source positions was 1.1 cm. The corresponding maximum variability of fractional rectal dose was 65.5%. The percentage difference in cumulative rectal dose estimation for each patient was 5.4%, 19.6%, 34.6%, 23.4%, and 13.9%, respectively. In conclusion, care should be taken when using rectal markers as reference points for estimating rectal dose in HDR cervical brachytherapy. The best estimate of true rectal dose for each fraction should be determined by the most anterior point among all fractions.
Medical dosimetry: official journal of the American Association of Medical Dosimetrists 10/2009; 35(4):269-73. · 1.26 Impact Factor
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ABSTRACT: Optimal management of early-stage uterine papillary serous carcinoma (UPSC) remains controversial. We reviewed our outcomes in this patient population.
The Roswell Park Cancer Institute (RPCI) tumor registry identified all patients with Stages I and IIA UPSC treated between January 1992 and June 2006. The Fisher's exact test was used to compare recurrence rates by adjuvant therapy received. Overall survival (OS) estimates were made using the Kaplan-Meier method.
Fifty-eight patients with Stage I or IIA UPSC underwent surgery. Thirty-four patients (59%) were surgically staged. Among 21 patients with Stage IA disease, 15 received adjuvant therapy. With a median follow-up of 44.7 months, only one recurrence was observed in a patient who received adjuvant brachytherapy. The 5-year OS was 66%. Among 37 patients with Stages IB-IIA, 30 patients received adjuvant therapy. With a median follow-up of 29 months, there were 7 recurrences. The 5-year OS was 60%. Although there were no significant differences in recurrence by adjuvant therapy received, a significant OS benefit was found in those who received radiation. There was no significant difference in OS distributions of those patients who received Carboplatin/Paclitaxel chemotherapy.
Despite the limitations of our retrospective study, we have shown that even comprehensively staged early-stage UPSC patients are still at risk for recurrence despite adjuvant therapy received. Hence, all patients with this histologic diagnosis should be considered at high risk for recurrence and counseled appropriately regarding the risks and benefits of adjuvant therapy.
Gynecologic Oncology 09/2009; 115(2):249-56. · 3.89 Impact Factor
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ABSTRACT: To determine whether baseline hemoglobin level and radiation treatment interruptions predict for loco-regional failure after intensity-modulated radiation therapy (IMRT) with concurrent chemotherapy for definitive treatment of squamous cell carcinoma of the head and neck (SCCHN).
This retrospective review identified 78 consecutive patients treated with definitive concurrent chemoradiation for SCCHN. Patients were treated with IMRT to 70 Gy in 35 daily fractions to the high-dose target volume and 56 Gy to the elective target volume.
Median age of the cohort was 62 (37-81). Median follow-up was 12 months. Tumor sites included: oropharynx (54%), larynx (36%), oral cavity (5%), and hypopharynx (5%). Fifteen of 78 patients (19%) experienced loco-regional failure. These included: 6 primary site failures, 5 regional failures, and 4 failures in both the primary site and regional lymph nodes. All but one failure occurred in the high-dose target volume. Only duration of radiation treatment and baseline hemoglobin levels were significant predictors of local control. Loco-regional failure occurred in 6 of 13 patients (46%) with radiation treatment interruptions (>1 week) versus 9 of 65 patients (14%) completing radiation therapy without interruption (P = 0.0148). Loco-regional failure occurred in 7 of 19 patients (37%) whose pretreatment hemoglobin level was <12 g/dL compared with 8 of 59 patients (14%) with hemoglobin levels > or = 12 (P = 0.042).
Overall radiation treatment time and pretreatment hemoglobin level were significant predictors for loco-regional failure after definitive concurrent chemotherapy and IMRT for SCCHN.
American journal of clinical oncology 08/2009; 32(6):587-91. · 2.21 Impact Factor
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ABSTRACT: In intraoperative high-dose-rate (IOHDR) brachytherapy, a 2-dimensional (2D) geometry is typically used for treatment planning. The assumption of planar geometry may cause serious errors in dose delivery for target surfaces that are, in reality, curved. A study to evaluate the magnitude of these errors in clinical practice was undertaken. Cylindrical phantoms with 6 radii (range: 1.35-12.5 cm) were used to simulate curved treatment geometries. Treatment plans were developed for various planar geometries and were delivered to the cylindrical phantoms using catheters inserted into Freiburg applicators of varying dimension. Dose distributions were measured using radiographic film. In comparison to the treatment plan (for a planar geometry), the doses delivered to prescription points were higher on the concave side of the geometry, up to 15% for the phantom with the smallest radius. On the convex side of the applicator, delivered doses were up to 10% lower for small treated areas (<or= 5 catheters) but, interestingly, the dose error was negligible for large treated areas (>5 catheters). Our measurements have shown inaccuracy in dose delivery when the original planar treatment plan is delivered with a curved applicator. Dose delivery errors arising from the use of planar treatment plans with curved applicators may be significant.
Medical dosimetry: official journal of the American Association of Medical Dosimetrists 01/2009; 34(1):63-74. · 1.26 Impact Factor
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ABSTRACT: The incidence rate of malignant melanoma has shown a rapid worldwide rise in recent years. The staging and management of head and neck melanoma presents some unique challenges. Surgery remains the cornerstone of treatment, while sentinel node biopsy is the most accurate staging modality for regional disease. The complex regional anatomy and lymphovascular drainage of this region may account for the increased biologic aggressiveness and treatment challenges of this disease. Improved understanding of the radiobiology of melanoma has resulted in new adjuvant radiotherapy approaches, yielding improved control rates. The treatment outcomes of metastatic head and neck melanoma remain disappointing but important progress has been made in the understanding of melanoma biology.
Expert Review of Anti-infective Therapy 04/2008; 8(3):403-12. · 2.65 Impact Factor
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Dermatologic Surgery 07/2007; 33(6):749-55. · 1.80 Impact Factor
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ABSTRACT: Three dimensional conformal radiation therapy (3DCRT) for prostate cancer is most commonly delivered with high-energy photons, typically in the range of 10-21 MV. With the advent of Intensity Modulated Radiation Therapy (IMRT), an increase in the number of monitor units (MU) relative to 3DCRT has lead to a concern about secondary malignancies. This risk becomes more relevant at higher photon energies where there is a greater neutron contribution. Subsequently, the majority of IMRT prostate treatments being delivered today are with 6-10 MV photons where neutron production is negligible. However, the absolute risk is small [Hall, E. J. Intensity Modulated Radiation Therapy, Protons, and the Risk of Second Cancers. Int J Radiat Oncol Bio Phys 65, 1-7 (2006); Kry, F. S., Salehpour, M., Followill, D. S., Stovall, M., Kuban, D. A., White, R. A., and Rosen, I. I. The Calculated Risk of Fatal Secondary Malignancies From Intensity Modulated Radiation Therapy. Int J Radiat Oncol Bio Phys 62, 1195-1203 (2005).] and therefore it has been suggested that the use of an 18MV IMRT may achieve better target coverage and normal tissue sparing such that this benefit outweighs the risks. This paper investigates whether 18MV IMRT offer better target coverage and normal tissue sparing. Computed Tomography (CT) image sets of ten prostate cancer patients were acquired and two separate IMRT plans were created for each patient. One plan used 6 MV beams, and the other used 18 MV, both in a coplanar, non-opposed beam geometry. Beam arrangements and optimization constraints were the same for all plans. This work includes a comparison and discussion of the total integral dose, neutron dose conformity index, and total number of MU for plans generated with both energies.
Technology in cancer research & treatment 05/2007; 6(2):139-46. · 2.02 Impact Factor
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ABSTRACT: Brachytherapy plays an important role in the definitive treatment of cervical cancers by radiotherapy. In the present study, we investigated whether sliding-window intensity-modulated radiation therapy (IMRT) can achieve a pear-shaped distribution with a similar sharp dose falloff identical to that of brachytherapy. The computed tomography scans of a tandem and ovoid patient were pushed to both a high dose rate (HDR) and an IMRT treatment planning system (TPS) after the rectum, bladder, and left and right femoral heads had been outlined, ensuring identical structures in both planning systems. A conventional plan (7 Gy in 5 fractions, defined as the average dose to the left and right point A) was generated for HDR treatment. The 150%, 125%, 100%, 75%, 50%, and 25% isodose curves were drawn on each slice and then transferred to the IMRT TPS. The 100% isodose envelope from the HDR plan was the target for IMRT planning. A 7-field IMRT plan using 6-MV X-ray beams was generated and compared with the HDR plan using isodose conformity to the target and 125% volume, dose-volume histograms, and integral dose. The resulting isodose distribution demonstrated good agreement between the HDR and IMRT plans in the 100% and 125% isodose range. The dose falloff in the HDR plan was much steeper than that in the IMRT plan, but it also had a substantially higher maximum dose. Integral dose for the target, rectum, and bladder were found to be 6.69 J, 1.07 J, and 1.02 J in the HDR plan; the respective values for IMRT were 3.47 J, 1.79 J, and 1.34 J. Our preliminary results indicate that the HDR dose distribution can be replicated using a standard sliding-window IMRT dose delivery technique for points lying closer to the three-dimensional isodose envelope surrounding point A. Differences in radiobiology and patient positioning between the two techniques merit further consideration.
Journal of Applied Clinical Medical Physics 02/2007; 8(3):2450. · 1.29 Impact Factor
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ABSTRACT: Most brachytherapy planning systems are based on a dose calculation algorithm that assumes an infinite scatter environment surrounding the target volume and applicator. Dosimetric errors from this assumption are negligible. However, in intraoperative high-dose-rate brachytherapy (IOHDR) where treatment catheters are typically laid either directly on a tumor bed or within applicators that may have little or no scatter material above them, the lack of scatter from one side of the applicator can result in underdosage during treatment. This study was carried out to investigate the magnitude of this underdosage.
IOHDR treatment geometries were simulated using a solid water phantom beneath an applicator with varying amounts of bolus material on the top and sides of the applicator to account for missing tissue. Treatment plans were developed for 3 different treatment surface areas (4 x 4, 7 x 7, 12 x 12 cm(2)), each with prescription points located at 3 distances (0.5 cm, 1.0 cm, and 1.5 cm) from the source dwell positions. Ionization measurements were made with a liquid-filled ionization chamber linear array with a dedicated electrometer and data acquisition system.
Measurements showed that the magnitude of the underdosage varies from about 8% to 13% of the prescription dose as the prescription depth is increased from 0.5 cm to 1.5 cm. This treatment error was found to be independent of the irradiated area and strongly dependent on the prescription distance. Furthermore, for a given prescription depth, measurements in planes parallel to an applicator at distances up to 4.0 cm from the applicator plane showed that the dose delivery error is equal in magnitude throughout the target volume.
This study demonstrates the magnitude of underdosage in IOHDR treatments delivered in a geometry that may not result in a full scatter environment around the applicator. This implies that the target volume and, specifically, the prescription depth (tumor bed) may get a dose significantly less than prescribed. It might be clinically relevant to correct for this inaccuracy.
International Journal of Radiation OncologyBiologyPhysics 05/2005; 61(5):1582-6. · 4.11 Impact Factor
