Multi-institutional analysis of stereotactic body radiotherapy for sarcoma pulmonary metastases: High rates of local control with favorable toxicity.

BACKGROUND/OBJECTIVES: Oligometastatic sarcoma pulmonary metastases (PM's) are traditionally treated with resection and/or chemotherapy. We hypothesize that stereotactic body radiotherapy (SBRT) is an effective, safe alternative to surgery that can achieve excellent local control (LC) with a favorable toxicity profile. METHODS: Patients treated with SBRT for sarcoma PM's from 2011 to 2016 at Massachusetts General Hospital and the University of Pennsylvania were included. Median dose was 50 Gy. Patients underwent computed tomography (CT) or positron emission tomography/CT Q3 months post-SBRT. RESULTS: 44 patients with 56 separate PM's were treated with SBRT. Median age was 59 (range 19-82). 82% received prior chemotherapy, 66% had prior pulmonary resections (range, 1-5 resections), and 32% received prior thoracic radiotherapy. Median lesion size was 2.0 cm (range, 0.5-8.1 cm). Median follow-up was 16 months and 25 months for patients alive at last follow-up. Overall survival at 12 and 24 months was 74% (95% confidence interval [CI], 67%-81%) and 46% (95% CI, 38%-55%). LC at 12 and 24 months was 96% (95% CI, 93%-98%) and 90% (95% CI, 84%-96%). LC and overall survival did not differ based on age, gender, histology, fractionation, lesion location, or size (P > .05). Three developed Common Terminology Criteria for Adverse Events version 4 grade-2 chest-wall toxicities; one had grade-2 pneumonitis. CONCLUSIONS: In the first multi-institutional series on SBRT for sarcoma PM's, SBRT has excellent LC and is well-tolerated. SBRT should be considered as an alternative/complement to resection.

Efficacy and safety of stereotactic body radiation therapy for the treatment of pulmonary metastases from sarcoma: A potential alternative to resection.

BACKGROUND/OBJECTIVES: Oligometastatic sarcoma pulmonary metastases (PM) are typically treated with resection and/or chemotherapy. We hypothesize that stereotactic body radiotherapy (SBRT) can be an alternative to surgery that can achieve high rates of local control (LC) with limited toxicity. METHODS: Thirty consecutive sarcoma patients received SBRT to 39 PM's from 2011 to 2015 at two university hospitals to a median dose of 50 Gy in 4-5 fractions with CyberKnife or linear accelerator. Patients underwent CT or PET/CT scans q3 months after SBRT. RESULTS: 77% received prior chemotherapy, 70% had 1-3 prior pulmonary resections, and 26% received prior thoracic radiotherapy. Median lesion size was 2.4 cm (range 0.5-8.1 cm). Median follow-up was 16 and 23 months for patients alive at last follow-up. At 12 and 24 months, LC was 94% and 86%, and OS was 76% and 43%. LC and OS did not differ by SBRT technique, fractionation regimen, lesion location, histology, or size (all P > 0.05). Three developed grade 2 chest-wall toxicity with no other grade ≥2 toxicities. CONCLUSIONS: This is the largest series on SBRT for sarcoma PM's and demonstrates that SBRT is well-tolerated with excellent LC across tumor locations and sizes. SBRT should be considered in these patients, and prospective studies are warranted. J. Surg. Oncol. 2016;114:65-69. © 2016 Wiley Periodicals, Inc.

Twenty-five year results of the national cancer institute randomized breast conservation trial.

Breast conservation therapy (BCT) consisting of lumpectomy and postoperative radiation has become an accepted alternative to mastectomy (MRM) for the treatment of early stage breast cancer. We currently report the 25 year outcomes of a single institution, prospective, randomized clinical trial at the National Cancer Institute. 237 women with pathologically confirmed invasive breast tumors 5 cm or less were accrued between 1979 and 1987 and randomized to receive either BCT or MRM. Overall survival was the primary endpoint. Patients with node positive disease were included and treated with doxorubicin and cyclophosphamide. Both arms received axillary dissection. BCT patients had radiation to the whole breast followed by a boost. At a median follow-up of 25.7 years, overall survival was 43.8% for the MRM group and 37.9% for BCT (P = 0.38). Although the cumulative incidence of a disease-free survival event was higher in BCT patients (29.0% MRM vs. 56.4% BCT, P = 0.0017), the additional treatment failures were primarily isolated ipsilateral breast tumor recurrences (IBTR's) requiring salvage mastectomy. 22.3% of BCT patients experienced an IBTR. Distant disease and second cancers were similar in both arms. After 25 years, long term survival between BCT and MRM continues to be similar in patients treated for early stage breast cancer. Patients receiving BCT may be at risk for additional treatment-related morbidity, which may occur as a late event. Further studies are required to delineate patients at higher risk for these events, and prolonged follow up should be encouraged after treatment for all women.

Biological Principles of Stereotactic Body Radiation Therapy (SBRT) and Stereotactic Radiation Surgery (SRS): Indirect Cell Death.

PURPOSE: To review the radiobiological mechanisms of stereotactic body radiation therapy stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS). METHODS AND MATERIALS: We reviewed previous reports and recent observations on the effects of high-dose irradiation on tumor cell survival, tumor vasculature, and antitumor immunity. We then assessed the potential implications of these biological changes associated with SBRT and SRS. RESULTS: Irradiation with doses higher than approximately 10 Gy/fraction causes significant vascular injury in tumors, leading to secondary tumor cell death. Irradiation of tumors with high doses has also been reported to increase the antitumor immunity, and various approaches are being investigated to further elevate antitumor immunity. The mechanism of normal tissue damage by high-dose irradiation needs to be further investigated. CONCLUSIONS: In addition to directly killing tumor cells, high-dose irradiation used in SBRT and SRS induces indirect tumor cell death via vascular damage and antitumor immunity. Further studies are warranted to better understand the biological mechanisms underlying the high efficacy of clinical SBRT and SRS and to further improve the efficacy of SBRT and SRS.

The road not taken and choices in radiation oncology.

Accomplishments and contributions in a career in radiation oncology, and in medicine in general, involve individual choices that impact the direction of a specialty, decisions in patient care, consequences of treatment outcome, and personal satisfaction. Issues in radiation oncology include: the development and implementation of new radiation treatment technology; the use of multimodality and biologically based therapies; the role of nonradiation "energy" technologies, often by other medical specialties, including the need for quality assurance in treatment and data reporting; and the type of evidence, including appropriate study design, analysis, and rigorous long-term follow-up, that is sought before widespread implementation of a new treatment. Personal choices must weigh: the pressure from institutions-practices, departments, universities, and hospitals; the need to serve society and the underserved; the balance between individual reward and a greater mission; and the critical role of personal values and integrity, often requiring difficult and "life-defining" decisions. The impact that each of us makes in a career is perhaps more a result of character than of the specific details enumerated on one's curriculum vitae. The individual tapestry weaved by choosing the more or less traveled paths during a career results in many pathways that would be called success; however, the one path for which there is no good alternative is that of living and acting with integrity.

Infrared navigation system for light dosimetry during pleural photodynamic therapy.

Pleural photodynamic therapy (PDT) is performed intraoperatively for the treatment of microscopic disease in patients with malignant pleural mesothelioma. Accurate delivery of light dose is critical to PDT efficiency. As a standard of care, light fluence is delivered to the prescribed fluence using eight isotropic detectors in pre-determined discrete locations inside the pleural cavity that is filled with a dilute Intralipid solution. An optical infrared (IR) navigation system was used to monitor reflective passive markers on a modified and improved treatment delivery wand to track the position of the light source within the treatment cavity during light delivery. This information was used to calculate the light dose, incorporating a constant scattered light dose and using a dual correction method. Calculation methods were extensively compared for eight detector locations and seven patient case studies. The light fluence uniformity was also quantified by representing the unraveled three-dimensional geometry on a two-dimensional plane. Calculated light fluence at the end of treatment delivery was compared to measured values from isotropic detectors. Using a constant scattered dose for all detector locations along with a dual correction method, the difference between calculated and measured values for each detector was within 15%. Primary light dose alone does not fully account for the light delivered inside the cavity. This is useful in determining the light dose delivered to areas of the pleural cavity between detector locations, and can serve to improve treatment delivery with implementation in real-time in the surgical setting. We concluded that the standard deviation of light fluence uniformity for this method of pleural PDT is 10%.

Evaluation of Light Fluence Distribution Using an IR Navigation System for HPPH-mediated Pleural Photodynamic Therapy (pPDT).

Uniform light fluence distribution for patients undergoing photodynamic therapy (PDT) is critical to ensure predictable PDT outcomes. However, current practice when delivering intrapleural PDT uses a point source to deliver light that is monitored by seven isotropic detectors placed within the pleural cavity to assess its uniformity. We have developed a real-time infrared (IR) tracking camera to follow the movement of the light point source and the surface contour of the treatment area. The calculated light fluence rates were matched with isotropic detectors using a two-correction factor method and an empirical model that includes both direct and scattered light components. Our clinical trial demonstrated that we can successfully implement the IR navigation system in 75% (15/20) of the patients. Data were successfully analyzed in 80% (12/15) patients because detector locations were not available for three patients. We conclude that it is feasible to use an IR camera-based system to track the motion of the light source during PDT and demonstrate its use to quantify the uniformity of light distribution, which deviated by a standard deviation of 18% from the prescribed light dose. The navigation system will fail when insufficient percentage of light source positions is obtained (<30%) during PDT.

Understanding High-Dose, Ultra-High Dose Rate, and Spatially Fractionated Radiation Therapy.

The National Cancer Institute's Radiation Research Program, in collaboration with the Radiosurgery Society, hosted a workshop called Understanding High-Dose, Ultra-High Dose Rate and Spatially Fractionated Radiotherapy on August 20 and 21, 2018 to bring together experts in experimental and clinical experience in these and related fields. Critically, the overall aims were to understand the biological underpinning of these emerging techniques and the technical/physical parameters that must be further defined to drive clinical practice through innovative biologically based clinical trials.

Quantitative comparison of tissue oxygen and motexafin lutetium uptake by ex vivo and noninvasive in vivo techniques in patients with intraperitoneal carcinomatosis.

Near-infrared diffuse reflectance spectroscopy (DRS) has been used to noninvasively monitor optical properties during photodynamic therapy (PDT). This technique has been extensively validated in tissue phantoms; however, validation in patients has been limited. This pilot study compares blood oxygenation and photosensitizer tissue uptake measured by multiwavelength DRS with ex vivo assays of the hypoxia marker, 2-(2-nitroimida-zol-1[H]-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide (EF5), and the photosensitizer (motexafin lutetium, MLu) from tissues at the same tumor site of three tumors in two patients with intra-abdominal cancers. Similar in vivo and ex vivo measurements of MLu concentration are carried out in murine radiation-induced fibrosarcoma (RIF) tumors (n=9). The selection of optimal DRS wavelength range and source-detector separations is discussed and implemented, and the association between in vivo and ex vivo measurements is examined. The results demonstrate a negative correlation between blood oxygen saturation (StO(2)) and EF5 binding, consistent with published relationships between EF5 binding and electrode measured pO(2), and between electrode measured pO(2) and StO(2). A tight correspondence is observed between in vivo DRS and ex vivo measured MLu concentration in the RIF tumors; similar data are positively correlated in the human intraperitoneal tumors. These results further demonstrate the potential of in vivo DRS measurements in clinical PDT.

Effect of photosensitizer dose on fluence rate responses to photodynamic therapy.

Photodynamic therapy (PDT) regimens that conserve tumor oxygenation are typically more efficacious, but require longer treatment times. This makes them clinically unfavorable. In this report, the inverse pairing of fluence rate and photosensitizer dose is investigated as a means of controlling oxygen depletion and benefiting therapeutic response to PDT under conditions of constant treatment time. Studies were performed for Photofrin-PDT of radiation-induced fibrosarcoma tumors over fluence rate and drug dose ranges of 25-225 mW cm(-2) and 2.5-10 mg kg(-1), respectively, for 30 min of treatment. Tumor response was similar among all inverse regimens tested, and, in general, tumor hemoglobin oxygen saturation (SO2) was well conserved during PDT, although the highest fluence rate regimen (225 mWx2.5 mg) did lead to a modest but significant reduction in SO2. Regardless, significant direct tumor cell kill (>1 log) was detected during 225 mWx2.5 mg PDT, and minimal normal tissue toxicity was found. PDT effect on tumor oxygenation was highly associated with tumor response at 225 mWx2.5 mg, as well as in all other regimens tested. These data suggest that high fluence rate PDT can be carried out under oxygen-conserving, efficacious conditions at low photosensitizer dose. Clinical confirmation and application of these results will be possible through use of minimally invasive oxygen and photosensitizer monitoring technologies, which are currently under development.

Photofrin uptake in the tumor and normal tissues of patients receiving intraperitoneal photodynamic therapy.

PURPOSE: A phase II trial of Photofrin-mediated i.p. photodynamic therapy shown in a previous report limited efficacy and significant acute, but not chronic, toxicity. A secondary aim of this trial and the subject of this report is to determine Photofrin uptake in tumor and normal tissues. EXPERIMENTAL DESIGN: Patients received Photofrin, 2.5 mg/kg, i.v., 48 hours before debulking surgery. Photofrin uptake was measured by spectroflurometric analysis of drug extracted from tumor and normal tissues removed at surgery. Differences in drug uptake among these tissues were statistically considered using mixed-effects models. RESULTS: Photofrin concentration was measured in 301 samples collected from 58 of 100 patients enrolled on the trial. In normal tissues, drug uptake significantly (P<0.0001) differed as a function of seven different tissue types. In the toxicity-limiting tissue of intestine, the model-based mean (SE) Photofrin level was 2.70 ng/mg (0.32 ng/mg) and 3.42 ng/mg (0.24 ng/mg) in full-thickness large and small intestine, respectively. In tumors, drug uptake significantly (P=0.0015) differed as a function of patient cohort: model-based mean Photofrin level was 3.32 to 5.31 ng/mg among patients with ovarian, gastric, or small bowel cancer; 2.09 to 2.45 ng/mg among patients with sarcoma and appendiceal or colon cancer; and 0.93 ng/mg in patients with pseudomyxoma. Ovarian, gastric, and small bowel cancers showed significantly higher Photofrin uptake than full-thickness large and/or small intestine. However, the ratio of mean drug level in tumor versus intestine was modest (

A phase II trial of intraperitoneal photodynamic therapy for patients with peritoneal carcinomatosis and sarcomatosis.

PURPOSE: A previous phase I trial of i.p. photodynamic therapy established the maximally tolerated dose of Photofrin (Axcan Pharma, Birmingham, AL)-mediated photodynamic therapy and showed encouraging efficacy. The primary objectives of this phase II study were to determine the efficacy and toxicities of i.p. photodynamic therapy in patients with peritoneal carcinomatosis and sarcomatosis. EXPERIMENTAL DESIGN: Patients received Photofrin 2.5 mg/kg i.v. 48 hours before debulking surgery. Intraoperative laser light was delivered to the peritoneal surfaces of the abdomen and pelvis. The outcomes of interest were (a) complete response, (b) failure-free survival time, and (c) overall survival time. Photosensitizer levels in tumor and normal tissues were measured. RESULTS: One hundred patients were enrolled into one of three strata (33 ovarian, 37 gastrointestinal, and 30 sarcoma). Twenty-nine patients did not receive light treatment. All 100 patients had progressed by the time of statistical analysis. The median failure-free survival and overall survival by strata were ovarian, 2.1 and 20.1 months; gastrointestinal cancers, 1.8 and 11.1 months; sarcoma, 3.7 and 21.9 months. Substantial fluid shifts were observed postoperatively, and the major toxicities were related to volume overload. Two patients died in the immediate postoperative period from bleeding, sepsis, adult respiratory distress syndrome, and cardiac ischemia. CONCLUSIONS: Intraperitoneal Photofrin-mediated photodynamic therapy is feasible but does not lead to significant objective complete responses or long-term tumor control. Heterogeneity in photosensitizer uptake and tumor oxygenation, lack of tumor specificity for photosensitizer uptake, and the heterogeneity in tissue optical properties may account for the lack of efficacy observed.

PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT).

Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important dosimetry quantity for PDT. However, the detected photosensitizer fluorescence may be distorted by variations in the absorption and scattering of both excitation and fluorescence light in tissue. Therefore, correction of the measured fluorescence for distortion due to variable optical properties is required for absolute quantification of photosensitizer concentration. In this study, we have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and photosensitizer fluorescence data. We measured PDT dose at four sites in the pleural cavity during pleural PDT. We have determined an empirical optical property correction function using Monte Carlo simulations of fluorescence for a range of physiologically relevant tissue optical properties. Parameters of the optical property correction function for Photofrin fluorescence were determined experimentally using tissue-simulating phantoms. In vivo measurements of photosensitizer fluorescence showed negligible photobleaching of Photofrin during the PDT treatment, but large intra- and inter-patient heterogeneities of in vivo Photofrin concentration are observed. PDT doses delivered to 22 sites in the pleural cavity of 8 patients were different by 2.9 times intra-patient and 8.3 times inter-patient.

A Comparison of Dose Metrics to Predict Local Tumor Control for Photofrin-mediated Photodynamic Therapy.

This preclinical study examines light fluence, photodynamic therapy (PDT) dose and "apparent reacted singlet oxygen," [1 O2 ]rx , to predict local control rate (LCR) for Photofrin-mediated PDT of radiation-induced fibrosarcoma (RIF) tumors. Mice bearing RIF tumors were treated with in-air fluences (50-250 J cm-2 ) and in-air fluence rates (50-150 mW cm-2 ) at Photofrin dosages of 5 and 15 mg kg-1 and a drug-light interval of 24 h using a 630-nm, 1-cm-diameter collimated laser. A macroscopic model was used to calculate [1 O2 ]rx and PDT dose based on in vivo explicit dosimetry of the drug concentration, light fluence and tissue optical properties. PDT dose and [1 O2 ]rx were defined as a temporal integral of drug concentration and fluence rate, and singlet oxygen concentration consumed divided by the singlet oxygen lifetime, respectively. LCR was stratified for different dose metrics for 74 mice (66 + 8 control). Complete tumor control at 14 days was observed for [1 O2 ]rx ≥ 1.1 mm or PDT dose ≥1200 µm J cm-2 but cannot be predicted with fluence alone. LCR increases with increasing [1 O2 ]rx and PDT dose but is not well correlated with fluence. Comparing dosimetric quantities, [1 O2 ]rx outperformed both PDT dose and fluence in predicting tumor response and correlating with LCR.

State of dose prescription and compliance to international standard (ICRU-83) in intensity modulated radiation therapy among academic institutions.

PURPOSE: The purpose of this study was to evaluate dose prescription and recording compliance to international standard (International Commission on Radiation Units & Measurements [ICRU]-83) in patients treated with intensity modulated radiation therapy (IMRT) among academic institutions. METHODS AND MATERIALS: Ten institutions participated in this study to collect IMRT data to evaluate compliance to ICRU-83. Under institutional review board clearance, data from 5094 patients-including treatment site, technique, planner, physician, prescribed dose, target volume, monitor units, planning system, and dose calculation algorithm-were collected anonymously. The dose-volume histogram of each patient, as well as dose points, doses delivered to 100% (D100), 98% (D98), 95% (D95), 50% (D50), and 2% (D2), of sites was collected and sent to a central location for analysis. Homogeneity index (HI) as a measure of the steepness of target and is a measure of the shape of the dose-volume histogram was calculated for every patient and analyzed. RESULTS: In general, ICRU recommendations for naming the target, reporting dose prescription, and achieving desired levels of dose to target were relatively poor. The nomenclature for the target in the dose prescription had large variations, having every permutation of name and number contrary to ICRU recommendations. There was statistically significant variability in D95, D50, and HI among institutions, tumor site, and technique with P values < .01. Nearly 95% of patients had D50 higher than 100% (103.5 ± 6.9) of prescribed dose and varied among institutions. On the other hand, D95 was close to 100% (97.1 ± 9.4) of prescribed dose. Liver and lung sites had a higher D50 compared with other sites. Pelvic sites had a lower variability indicated by HI (0.13 ± 1.21). Variability in D50 is 101.2 ± 8.5, 103.4 ± 6.8, 103.4 ± 8.2, and 109.5 ± 11.5 for IMRT, tomotherapy, volume modulated arc therapy, and stereotactic body radiation therapy with IMRT, respectively. CONCLUSIONS: Nearly 95% of patient treatments deviated from the ICRU-83 recommended D50 prescription dose delivery. This variability is significant (P < .01) in terms of treatment site, technique, and institution. To reduce dosimetric and associated radiation outcome variability, dose prescription in every clinical trial should be unified with international guidelines.