A unified multi-activation (UMA) model of cell survival curves over the entire dose range for calculating equivalent doses in stereotactic body radiation therapy (SBRT), high dose rate brachytherapy (HDRB), and stereotactic radiosurgery (SRS).

PURPOSE: Application of linear-quadratic (LQ) model to large fractional dose treatments is inconsistent with observed cell survival curves having a straight portion at high doses. We have proposed a unified multi-activation (UMA) model to fit cell survival curves over the entire dose range that allows us to calculate EQD2 for hypofractionated SBRT, SRT, SRS, and HDRB. METHODS: A unified formula of cell survival S = n / e D D o + n - 1 using only the extrapolation number of n and the dose slope of Do was derived. Coefficient of determination, R2 , relative residuals, r, and relative experimental errors, e, normalized to survival fraction at each dose point, were calculated to quantify the goodness in modeling of a survival curve. Analytical solutions for α and ß, the coefficients respectively describe the linear and quadratic parts of the survival curve, as well as the α/ß ratio for the LQ model and EQD2 at any fractional doses were derived for tumor cells undertaking any fractionated radiation therapy. RESULTS: Our proposed model fits survival curves of in-vivo and in-vitro tumor cells with R2  > 0.97 and r < e. The predicted α, ß, and α/ß ratio are significantly different from their values in the LQ model. Average EQD2 of 20-Gy SRS of glioblastomas and melanomas metastatic to the brain, 10-Gy × 5 SBRT of the lung cancer, and 7-Gy × 5 HDRB of endometrial and cervical carcinomas are 36.7 (24.3-48.5), 114.1 (86.6-173.1),, and 45.5 (35-52.6) Gy, different from the LQ model estimates of 50.0, 90.0, and 49.6 Gy, respectively. CONCLUSION: Our UMA model validated through many tumor cell lines can fit cell survival curves over the entire dose range within their experimental errors. The unified formula theoretically indicates a common mechanism of cell inactivation and can estimate EQD2 at all dose levels.

Image-guided high-dose-rate intracavitary brachytherapy in the treatment of medically inoperable early-stage endometrioid type endometrial adenocarcinoma.

PURPOSE: The purpose of this case series is to describe the treatment and outcomes of a cohort of patients with inoperable early-stage endometrioid endometrial cancer with 3D image-guided high-dose-rate (HDR) intracavitary brachytherapy. MATERIALS AND METHODS: A review was performed of patients with early-stage endometrial cancer who underwent primary radiation treatment between 2010 and 2016. Staging and treatment planning were performed CT, pelvic ultrasound, and pelvic MRI. Gross tumor volume (GTV) was defined as the MRI or ultrasound demonstrated endometrial stripe width, with the entire uterine corpus, cervix, and proximal vagina representing the clinical target volume (CTV). Dosimetry calculations were performed in each fraction of HDR brachytherapy. RESULTS: Eight patients received external beam radiation therapy followed by intracavitary HDR brachytherapy. Seven patients underwent intracavitary HDR brachytherapy alone. In all patients, mean cumulative dose to 90% (D90) of GTV was 95.99 Gy in equivalent dose in 2 Gy fractions (EQD2, α/ß = 10). Mean cumulative D90 EQD2 to CTV was 51.64 Gy. Average follow-up was 29 months. Four patients died from concurrent disease(s) at an average of 2.83 years after completion of treatment. Except for 1 (6.6%) patient who recurred at 9 months following completion of treatment, all patients remained disease-free for the remainder of follow-up. CONCLUSIONS: In patients who are poor surgical candidates and have early-stage endometrioid type endometrial carcinoma, image-guided HDR intracavitary brachytherapy carries minimal side effects and a high response rate.

Radiation therapy with concurrent chemotherapy for locally advanced cervical carcinoma: outcome analysis with emphasis on the impact of treatment duration on outcome.

Objective. To assess the effectiveness and toxicity of carboplatin concurrent with pelvic external beam radiation and low-dose rate brachytherapy and to assess the impact that adherence to the treatment plan has on outcomes. Methods. Retrospective chart review of 56 patients treated from January 2001 to December 2010. Results. Median follow-up was 68 months. Optimal dose of radiation (ORT) was defined as a minimal cervical dose exceeding 70 Gy, point A dose of 80-90 Gy, and duration not exceeding 56 days. Only 50% received ORT. In multivariable analyses we only found ORT to be statistically significant predictor for progression-free survival (PFS) and overall survival (OS) (HR [95% CI] for non-ORT vs. ORT: 2.4 [1.2, 5.1], P = 0.014 for PFS and 2.2 [1.1, 4.6], P = 0.035 for OS). The 5-year PFS in patients who received ORT was better than that in patients who received non-ORT, 56% vs. 22% (95% CI: [36%, 72%] vs. [9%, 39%]). Patients who received ORT had a better 5-year OS as well (59% vs. 33%; 95% CI: [38%, 75%] vs. [16%, 51%]). Conclusion. Patients with locally advanced cervical cancer treated with weakly carboplatin or cisplatin, teletherapy, and low dose-dose rate brachytherapy have poorer outcomes when treatment duration is prolonged.

Early-stage central lung cancer and volumetric modulated arc therapy: a dosimetric case study with literature review.

BACKGROUND/AIM: In the present article we review on the use of Volumetric Modulated Arc Therapy (VMAT) for a small lung nodule that was centrally located in close proximity to the mediastinal structures. CASE REPORT: An inoperable patient with central, clinical stage IA adenocarcinoma of the right lung was treated with external-beam radiation therapy of 52.5 Gy in 15 factions. A single 360° coplanar arc VMAT plan (360-VMAT) was used for treatment and compared to step-and-shoot Intensity Modulation Radiotherapy (IMRT) and a single 180° ipsilateral partial arc VMAT plan (180-VMAT). RESULTS: Planning Target Volume (PTV) coverage was not different, and 360-VMAT had the highest dose homogeneity. Both 360-VMAT and 180-VMAT reduced esophageal dose compared to IMRT. While IMRT had the lowest lung dose, all 3 plans achieved acceptable sparing of the lung. 180-VMAT had the highest dose conformity. Both 360-VMAT and 180-VMAT improved esophageal sparing compared to IMRT. CONCLUSION: Use of VMAT in early-stage, centrally located NSCLC is a promising treatment approach and merits additional investigation.

Improvement in peripheral blood disease burden in patients with Sézary syndrome and leukemic mycosis fungoides after total skin electron beam therapy.

BACKGROUND: There is a paucity of effective therapies for patients with Sézary syndrome and advanced mycosis fungoides with peripheral blood involvement. Total skin electron beam (TSEB) radiation therapy is an extremely effective skin-directed therapy for these patients, but, until recently, it was thought not to signifcantly affect the peripheral blood malignant T-cell population. OBJECTIVE: We conducted this study to determine if TSEB has therapeutic effect on the peripheral blood in patients with advanced mycosis fungoides and Sézary syndrome. METHODS: All patients on stable medication regimens seen in our photopheresis facility who received TSEB therapy between January 2008 and October 2011 at Temple University Hospital, Philadelphia, PA, were analyzed retrospectively for improvement in the peripheral blood, as documented by flow cytometry. RESULTS: Six of 11 patients achieved 50% or greater decrease in their peripheral blood malignant T-cell population after TSEB therapy, for an overall response rate of 55%. Within the group of patients who had a response in the skin, 67% also had a response in the peripheral blood. LIMITATIONS: This analysis is limited in 3 ways. First, the sample described is small. Second, the results may be confounded by the fact that each patient was on other systemic therapies in addition to TSEB, albeit stable pre-existing regimens. The time interval between completion of TSEB therapy and repetition of flow cytometry was not standardized among patients, which may result in an underestimation of the overall response to TSEB therapy. CONCLUSION: In patients with advanced mycosis fungoides and Sézary syndrome, the peripheral blood tumor burden may improve after treatment with TSEB.

Use of image-guided stereotactic body radiation therapy in lieu of intracavitary brachytherapy for the treatment of inoperable endometrial neoplasia.

PURPOSE: Retrospective analysis of patients with invasive endometrial neoplasia who were treated with external beam radiation therapy followed by stereotactic body radiation therapy (SBRT) boost because of the inability to undergo surgery or brachytherapy. METHODS AND MATERIALS: We identified 11 women with stage I-III endometrial cancer with a median age of 78 years that were not candidates for hysterectomy or intracavitary brachytherapy secondary to comorbidities (91%) or refusal (9%). Eight patients were American Joint Committee on Cancer (AJCC) stage I (3 stage IA, 5 stage IB), and 3 patients were AJCC stage III. Patients were treated to a median of 4500 cGy at 180 cGy per fraction followed by SBRT boost (600 cGy per fraction×5). RESULTS: The most common side effect was acute grade 1 gastrointestinal toxicity in 73% of patients, with no late toxicities observed. With a median follow-up of 10 months since SBRT, 5 patients (45%) experienced locoregional disease progression, with 3 patients (27%) succumbing to their malignancy. At 12 and 18 months from SBRT, the overall freedom from progression was 68% and 41%, respectively. Overall freedom from progression (FFP) was 100% for all patients with AJCC stage IA endometrial carcinoma, whereas it was 33% for stage IB at 18 months. The overall FFP was 100% for International Federation of Obstetrics and Gynecology grade 1 disease. The estimated overall survival was 57% at 18 months from diagnosis. CONCLUSION: In this study, SBRT boost to the intact uterus was feasible, with encouragingly low rates of acute and late toxicity, and favorable disease control in patients with early-stage disease. Additional studies are needed to provide better insight into the best management of these clinically challenging cases.

Repeat stereotactic body radiation therapy for patients with pulmonary malignancies who had previously received SBRT to the same or an adjacent tumor site.

OBJECTIVES: Retrospective analysis of patients with recurrences at or closely adjacent to the site of prior lung stereotactic body radiation therapy (SBRT) who received repeat SBRT. MATERIALS AND METHODS: Nine patients with non-small cell lung cancer (n = 8) or oligometastatic colonic adenocarcinoma (n = 1) were treated with image-guided lung SBRT to a median of 60 Gy (range, 30-60) in a median of 3 fractions (3-5). Patients developed in-field relapse (n = 3) or recurrence adjacent (≤ 3.5 cm away) to the previous tumor location (n = 6) and received 2 nd lung SBRT to a median of 60 Gy. RESULTS: Median follow-up after 2 nd SBRT was 22 months (4-40). All completed prescribed course of repeat SBRT and acute toxicity was limited. There was no grade >3 late toxicity. 3 (33.3%) patients developed Grade 3 late reactions: 2 pulmonary and 1 chest wall pain. Late pulmonary toxicity included 2 (22.2%) patients with Grade 3 and 3 (33.3%) with Grade 2. One patient (11.1%) had late Grade 3 and 1 (11.1%) Grade 2 chest wall pain. 1 (11.1%) developed Grade 2 late brachial plexopathy. No myelopathy was observed. Two patients developed progression of tumors treated by 2 nd SBRT. Local recurrence free survival and overall survival was 75% and 68.6%, respectively at 2 years. Relative volume of ipsilateral lung receiving 5 Gy (V5) and V10 were lower for 2 nd SBRT. CONCLUSION: Repeat image-guided SBRT for patients with small peripheral recurrences was feasible and severe toxicity was not observed. Additional studies are needed to evaluate the safety and efficacy of lung reirradiation using 2 nd SBRT.

Optimization and quality assurance of an image-guided radiation therapy system for intensity-modulated radiation therapy radiotherapy.

To develop a quality assurance (QA) of XVI cone beam system (XVIcbs) for its optimal imaging-guided radiotherapy (IGRT) implementation, and to construe prostate tumor margin required for intensity-modulated radiation therapy (IMRT) if IGRT is unavailable. XVIcbs spatial accuracy was explored with a humanoid phantom; isodose conformity to lesion target with a rice phantom housing a soap as target; image resolution with a diagnostic phantom; and exposure validation with a Radcal ion chamber. To optimize XVIcbs, rotation flexmap on coincidency between gantry rotational axis and that of XVI cone beam scan was investigated. Theoretic correlation to image quality of XVIcbs rotational axis stability was elaborately studied. Comprehensive QA of IGRT using XVIcbs has initially been explored and then implemented on our general IMRT treatments, and on special IMRT radiotherapies such as head and neck (H and N), stereotactic radiation therapy (SRT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). Fifteen examples of prostate setup accounted for 350 IGRT cone beam system were analyzed. IGRT accuracy results were in agreement ± 1 mm. Flexmap 0.25 mm met the manufacturer's specification. Films confirmed isodose coincidence with target (soap) via XVIcbs, otherwise not. Superficial doses were measured from 7.2-2.5 cGy for anatomic diameters 15-33 cm, respectively. Image quality was susceptible to rotational stability or patient movement. IGRT using XVIcbs on general IMRT treatments such as prostate, SRT, SRS, and SBRT for setup accuracy were verified; and subsequently coordinate shifts corrections were recorded. The 350 prostate IGRT coordinate shifts modeled to Gaussian distributions show central peaks deviated off the isocenter by 0.6 ± 3.0 mm, 0.5 ± 4.5 mm in the X(RL)- and Z(SI)-coordinates, respectively; and 2.0 ± 3.0 mm in the Y(AP)-coordinate as a result of belly and bladder capacity variations. Sixty-eight percent of confidence was within ± 4.5 mm coordinates shifting. IGRT using XVIcbs is critical to IMRT for prostate and H and N, especially SRT, SRS, and SBRT. To optimize this modality of IGRT, a vigilant QA program is indispensable. Prostate IGRT reveals treatment accuracy as subject to coordinates' adjustments; otherwise a 4.5-mm margin is required to allow for full dose coverage of the clinical target volume, notwithstanding toxicity to normal tissues.

Total skin electron beam therapy may be associated with improvement of peripheral blood disease in Sézary syndrome.

Total skin electron beam radiation is an effective therapy for palliation of the cutaneous symptoms of the most common types of cutaneous T-cell lymphomas, mycosis fungoides and Sézary syndrome. We report 4 cases of patients with Sézary syndrome who had significant improvement in their blood burden of malignant cells in addition to complete cutaneous responses to total skin electron beam therapy. The data from these 4 patients illustrate the potential for total skin electron beam to be used as both a skin and blood tumor debulking agent, and not merely as a palliation for skin symptoms.

Three-dimensional conformal radiotherapy for treatment of extensive juvenile angiofibroma: report on two cases.

These case reports describe the application of three-dimensional conformal radiotherapy for the treatment of extensive juvenile angiofibroma. The affected areas included the pterygomaxillary fossa, infratemporal fossa, orbit, middle cranial fossa and maxillary sinus. Three-dimensional conformal radiotherapy was used to deliver the tumor dose of 3800-4140 cGy. The radiation dose to the surrounding normal structures including the optic nerve, optic chiasm, spinal cord, parotid and brain was limited. The tumor showed an excellent clinical and radiological response in both patients. There was no appreciable late toxicity. In conclusion, three-dimensional conformal radiotherapy provides several advantages over conventional radiotherapy in the treatment of extensive juvenile angiofibroma.