Non-Animal Stabilized Hyaluronic Acid (NASHA) Gel Marker vs. Surgical Clips for Tumor Bed Delineation in Breast Cancer Using MR-Simulation

PURPOSE/OBJECTIVE(S)

Consistent delineation of the tumor bed (TB) after breast conserving surgery (BCS) is critical and remains a challenge with increasing prevalence of oncoplastic surgeries. Clips are generally used to help TB identification on CT-simulation but they are not well identified on MR-simulation. The aim of this study is to assess whether the use of NASHA gel with MR-simulation yields similar interobserver variability (inter-OV) compared to clips with CT-simulation.

MATERIALS/METHODS

This prospective single arm feasibility study included patients eligible for BCS. After lumpectomy, the surgeon placed both clips (>5) and NASHA gel drops as markers to define the TB. Patients underwent CT and MRI simulation scans. Five radiation oncologists and one radiologist delineated the TB aided by clips on CT, and gel on MRI. The observers also assessed the visibility and utility of the gel (scale from 1 to 10), as well as the cavity visualization score (CVS, scale from 1 to 5). The primary endpoint was the inter-OV of the delineated TB using the overlap difference of contours using clips and CT versus gel and MRI, with the conformity index measured according to the pair definition of the Dice Similarity Coefficient (DSC).

RESULTS

Of the 35 patients recruited, 30 were eligible for inter-OV analysis of TB delineation and 5 patients required further breast surgery for positive margins. One third of the eligible patients underwent an oncoplastic procedure. There were no significant differences between inter-OV of delineated TB using clips and CT versus gel and T2-weighted MRI with the mean DSC (0.60 vs 0.62, p = 0.364). The observers reported higher usefulness of gel in patients with an oncoplastic procedure than not (median US 8.2 vs 6.6, p = 0.024), and higher visibility of gel in patients who had their scans within 6 weeks than beyond post-op (median VS 8.1 vs 6.1, p = 0.013). When the CVS was higher (3-5), the median US of gel was lower (5.9 vs 7.8, p = 0.004), and the conformity index of clip and CT delineated TB was higher (median DSC 0.72 vs 0.53, p <0.001). Interestingly, a higher CVS did not lead to significantly higher conformity index of gel and T2-weighted MR delineated TB (mean DSC 0.67 vs 0.58, p = 0.073). NASHA gel injection added a median of 3 minutes to the operating theatre (OT) time and was rated as 'easy' in 89% of cases by surgeons. There were no immediate adverse events (AE) in OT, while 2 of 35 patients later experienced a grade 3 AE - hematoma which required evacuation in OT day 1 post-BCS, and infected seroma which required drainage and washout in OT 2 months post-BCS and axillary dissection. These reflect common risks with standard BCS and are not clearly attributed to gel injection alone.

CONCLUSION

Use of NASHA gel leads to similar inter-OV of BC TB delineation compared to >5 clips. NASHA gel is hence a reliable alternative to clips when MR-simulation is used.

TUmor-volume to breast-volume RAtio for improving COSmetic results in breast cancer patients (TURACOS); a randomized controlled trial

BACKGROUND

Cosmetic result following breast conserving surgery (BCS) for cancer influences quality of life and psychosocial functioning in breast cancer patients. A preoperative prediction of expected cosmetic result following BCS is not (yet) standard clinical practice and therefore the choice for either mastectomy or BCS is still subjective. Recently, we showed that tumour volume to breast volume ratio as well as tumour location in the breast are independent predictors of superior cosmetic result following BCS. Implementation of a prediction model including both factors, has not been studied in a prospective manner. This study aims to improve cosmetic outcome by implementation of a prediction model in the treatment decision making for breast cancer patients opting for BCS.

METHODS/DESIGN

Multicentre, single-blinded, randomized controlled trial comparing standard preoperative work-up to a preoperative work-up with addition of the prediction model. Tumour volume to breast volume ratio and tumour location in the breast will be used to predict cosmetic outcome in invasive breast cancer patients opting for BCS. Three dimensional (3D)-ultrasonography will be used to measure the tumour volume to breast volume ratio needed for the prediction model. Sample size was estimated based on a 14% improvement in incidence of superior cosmetic result one year after BCS (71% in the control group versus 85% in the intervention group). Primarily cosmetic outcome will be evaluated by a 6-member independent panel. Secondary endpoints include; (1) patient reported outcome measured by BREAST-Q, EORTC-QLQ-C30/BR23 and EQ-5D-5 L (2) cosmetic outcome as assessed through the BCCT.core software, (3) radiation-induced reaction (4) surgical treatment performed, (5) pathological result and (6) cost-effectiveness. Follow-up data will be collected for 3 years after surgery or finishing radiotherapy.

DISCUSSION

This randomized controlled trial examines the value of a preoperative prediction model for the treatment-decision making. It aims for a superior cosmetic result in breast cancer patients opting for BCS. We expect improvement of patients' quality of life and psychosocial functioning in a cost-effective way.

TRIAL REGISTRATION

Prospectively registered, February 17th 2015, at 'Nederlands Trialregister - NTR4997 '.

Abstract P3-12-22: Reproducibility of automated coronary artery calcification scoring on radiotherapy treatment planning computed tomography scans of breast cancer patients

Introduction: Presence of coronary artery calcifications (CAC) is a major independent risk factor for cardiovascular (CV) disease. CAC can be visualized on CT scans. Most breast cancer patients planned for radiotherapy (RT) receive planning CT scans. These scans may provide a reliable estimate of a patients' CV risk. This study evaluated the feasibility and reproducibility of an automated algorithm for CAC scoring on RT planning CT scans of breast cancer patients.

Methods: This study was conducted within the Utrecht cohort for Multiple BReast cancer intErvention studies and Long-term evaLuAtion (UMBRELLA), and includes 562 breast cancer patients undergoing RT at University Medical Center Utrecht. Planning CT scans were performed using a 16-slice scanner (16 x 0.75 mm collimation, 3 mm thickness, 120 kVp, with or without breath hold (BH), without ECG synchronization). CAC were automatically scored using an algorithm developed with chest CT scans that considers lesions &gt;130 Hounsfield units as CAC. CAC were identified using a supervised pattern recognition based on texture, size, and spatial features. To test validity of automated CAC scoring, manually scoring by an expert was performed in all scans with CAC (n = 80) and a random sample of scans without CAC (n = 83). Interscan reproducibility of automated CAC scoring was assessed in patients having two scans (n = 295). All scans with CAC score ≥ 1000 were manually checked and corrected if appropriate. Agatston calcification scores were analyzed continuously and categorically (0, 1-10, 11-100, 101-400, &gt;400). Agreement and reliability for categories were determined with proportional agreement (%) and linearly weighted kappa. Reliability of Agatston scores were assessed with Intraclass correlation coefficients (ICC).

Results: Of 562 patients, 129 (23%) patients had CAC scores &gt; 0 with a mean of 93 (standard deviation: 166). Four patients had CAC scores ≥ 1000, which were erroneous and corrected. Of the 163 CT scans scored manually and automatically, 58 (36%) were performed with BH. Proportion of agreement was 79% (95% Confidence Interval (CI): 0.72-0.85) for all 163 scans: 88% (0.76-0.95) for 58 scans with BH and 74% (0.65-0.82) for 105 scans without. Proportion of agreement beyond chance was 0.80 (95% CI: 0.74-0.87) for all scans: 0.86 (0.77-0.96) with BH and 0.77 (0.684-0.853) without. Agatston score ICC was 0.86 (95% CI: 0.82-0.90) for all scans: 0.95 (0.91-0.97) with BH and 0.67 (0.55-0.76) without. For the interscan reproducibility (n = 295), the majority of patients (81%) had one scan with BH and one scan without. Proportion of agreement was 84% (95% CI: 0.79-0.88) and reliability was 0.61 (95% CI: 0.50-0.72). Agatston score ICC was 0.75 (95% CI: 0.69-0.80).

Conclusion: Automated CAC scoring on RT planning CT scans of breast cancer patients is feasible. Agreement with manually scored scans is high and higher in CT scans performed with BH. Interscan reproducibility is fair. Automated CAC scores ≥ 1000 should to be manually checked and corrected if necessary. Automated CAC scoring on RT planning CT scans of breast cancer patients is available for all patients undergoing RT, and can provide information on CV risk at no additional cost.

Citation Format: Gernaat SAM, de Vos BD, Isgum I, Rijnberg N, Bijlsma RM, Takx RAP, Pignol JP, Leiner T, Grobbee DE, van der Graaf Y, van den Bongard DHJG, Verkooijen HM. Reproducibility of automated coronary artery calcification scoring on radiotherapy treatment planning computed tomography scans of breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-22.

Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images

Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 [Formula: see text] formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.

Age at diagnosis predicts local recurrence in women treated with breast-conserving surgery and postoperative radiation therapy for ductal carcinoma in situ: a population-based outcomes analysis

PURPOSE

The main goal of treating ductal carcinoma in situ (dcis) is to prevent the development of invasive breast cancer. Most women are treated with breast-conserving surgery (bcs) and radiotherapy. Age at diagnosis may be a risk factor for recurrence, leading to concerns that additional treatment may be necessary for younger women. We report a population-based study of women with dcis treated with bcs and radiotherapy and an evaluation of the effect of age on local recurrence (lr).

METHODS

All women diagnosed with dcis in Ontario from 1994 to 2003 were identified. Treatments and outcomes were collected through administrative databases and validated by chart review. Women treated with bcs and radiotherapy were included. Survival analyses were performed to evaluate the effect of age on outcomes.

RESULTS

We identified 5752 cases of dcis; 1607 women received bcs and radiotherapy. The median follow-up was 10.0 years. The 10-year cumulative lr rate was 27% for women younger than 45 years, 14% for women 45-50 years, and 11% for women more than 50 years of age (p < 0.0001). The 10-year cumulative invasive lr rate was 22% for women younger than 45 years, 10% for women 45-50 years, and 7% for women more than 50 years of age (p < 0.0001). On multivariate analyses, young age (<45 years) was significantly associated with lr and invasive lr [hazard ratio (hr) for lr: 2.6; 95% confidence interval (ci): 1.9 to 3.7; p < 0.0001; hr for invasive lr: 3.0; 95% ci: 2.0 to 4.4; p < 0.0001]. An age of 45-50 years was also significantly associated with invasive lr (hr: 1.6; 95% ci: 1.0 to 2.4; p = 0.04).

CONCLUSIONS

Age at diagnosis is a strong predictor of lr in women with dcis after treatment with bcs and radiotherapy.

Variability in Radiation Oncologists' Opinion on the Indication of a Bolus in Post-mastectomy Radiotherapy: an International Survey

AIMS

Post-mastectomy radiotherapy (PMRT) decreases locoregional recurrence and increases survival for women with large tumours and/or node-positive disease. The American Society of Clinical Oncology has published treatment guidelines, but has also indicated that the optimal technique for PMRT remains unknown. The objective of this study was to evaluate the variability in which a bolus is currently used in PMRT and to identify the clinical situations in which a bolus is used.

MATERIALS AND METHODS

In 2004, an e-mail survey was sent to all active physician members of the American Society for Therapeutic Radiology and Oncology, the Canadian Association of Radiation Oncologists and the European Society for Therapeutic Radiology and Oncology. The survey focused on the technical details regarding the use of a bolus in PMRT.

RESULTS

In total, 1035 responses were obtained: 642 from the Americas (568 from the USA), 327 from Europe and 66 from Australasia. Respondents from the Americas were significantly more likely to always use a bolus (82%) than the Europeans (31%), as were the Australasians (65%) (P < 0.0001). Europeans were significantly more likely to use a bolus for specific indications (P < 0.0001). The results also showed wide variation in the schedule of application (every day [33%] and alternate days [46%]) and thickness used (< 1 cm [35%] and > or = 1 cm [48%]).

CONCLUSIONS

There is a wide variation in the use of a bolus in PMRT with significant regional differences. This probably translates into a variation in the dose delivered to the skin and may have an effect on local recurrence and/or toxicity. A randomised clinical trial is needed to evaluate the benefit and toxicity associated with the use of a bolus in PMRT.

Radiotherapy for a solitary brain metastasis during pregnancy: a method for reducing fetal dose

A patient presented during the second half of pregnancy with a solitary brain metastasis from lung cancer. This case shows that, using a new patient position, it is possible to shield the fetus efficiently. This new method consisted of whole brain irradiation with parallel pair treatment by lateral fields with the patient in a supine position with maximal neck extension. The dose to the fetus has been considerably reduced (0.3 cGy total dose) compared with previous techniques. The prescribed tumour dose was 30 Gy.

Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,alpha) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.

[Alternating chemotherapy and hyperfractionated accelerated radiotherapy in non-metastatic inflammatory breast cancer]

PURPOSE

Based on encouraging results reported in alternating radiotherapy and chemotherapy in inflammatory breast carcinoma, we have tried in this study to optimize locoregional treatment with a hyperfractionated accelerated radiotherapy schedule alternating with chemotherapy.

PATIENTS AND METHODS

From May 1991 to May 1995, 54 patients, previously untreated, with non-metastatic inflammatory breast cancer were entered in an alternating protocol consisting of eight courses of combined chemotherapy and two series of loco-regional hyperfractionated accelerated radiotherapy with a total dose of 66 Gy. Hyperfractionated accelerated radiotherapy was started after three courses of neoadjuvant chemotherapy (Adriamycin, Vincristine, Cyclophosphamide, Methotrexate, 5-fluoro-uracile) administered every 21 days +/- G.CSF. The first series delivered 45 Gy/three weeks to the breast, the axillary, subclavicular and internal mammary nodes, with two daily sessions of 1.5 Gy separated by an interval of eight hours; the second series consisted of a boost (21 Gy/14 fractions/10 d) alternating with another regimen of anthracycline-based-chemotherapy (a total of five cycles every three weeks). Hormonal treatment was given to all patients.

RESULTS

Of the 53 patients evaluated at the end of the treatment, 44 (83%) had a complete clinical response, seven (13%) had a partial response (> 50%) and two (4%) had tumoral progression. Of the 51 patients who were locally controlled, 18 (35%) presented a locoregional recurrence (LRR); eight (15%) had to undergo a mastectomy. All the patients but two with LRR developed metastases or died of local progressive disease and 26 (50%) developed metastases. With a median follow-up of 39 months (range: 4-74 months), survival rates at three and five years were respectively, 66 and 45% for overall survival and 45 and 36% for disease-free survival.

CONCLUSION

Alternating a combination of chemotherapy and hyperfractionated accelerated radiotherapy is a well-tolerated regimen which provides acceptable local control. The systemic dissemination remains the major problem of inflammatory breast carcinoma and further clinical trials using alternative drug regimens are warranted.

[Radiotherapy of high grade glioma: use of fast neutrons, therapy and enhancement by neutron capture]

Among high linear energy transfer (LET) irradiations techniques, those using fast neutrons are able to eradicate glioblastoma cells. At least a 13 grays (Gy) irradiation dose has to be used, but high morbidity is observed in case of over 11 Gy irradiation. So, no therapeutic windows have been found despite the fact that more than 900 patients were included in clinical trials. Boron neutron capture therapy (BNCT) uses alpha emitting nuclear reactions, produced within tumoral cells by boron neutron captures. (10)B is specifically loaded inside tumoral cells via a boronated molecule, and the tissues are then irradiated with thermal or epithermal neutrons. Although this type of irradiation is yet considered as a regular method in Japan, USA and Europe have started clinical trials, currently in progress, in order to define the BNCT place in the post-operative care of high grade glioma. Non-removable tumors may benefit from boron neutron capture enhancement of fast neutron irradiation, i.e. the combination of these two methods. Preliminary studies show that a "biological" dose enhancement of 20 % could be obtained within the tumor when a concentration of 100 microg/g of (10)B is targeted into it. These concentrations are achievable by intra-arterial administration of (10)boronophenylalanine (BPA) or borosulfhydryl (BSH). Recently, some publications have also demonstrated that the thermal neutron flux yielded within the irradiated tissues could be increased. Clinical trials, using this technique, are planned in USA and Europe.

[Concurrent split-course chemotherapy and radiotherapy for unresectable stage III non-small cell lung cancer: preliminary results of a Phase II study]

PURPOSE

We initiated at Hospital de Mulhouse a prospective phase II study to assess a split-course concurrent radiochemotherapy in locally advanced non-small cell lung cancer.

MATERIALS AND METHODS

From March 1996 to December 1997, 28 patients were included in our study. All patients had a stage III cancer. The chemotherapy scheduled included vinorelbine (20 mg/m2/d, d1 and d5), cisplatin (20 mg/m2/d, from d1 to d5), and 5-Fluorouracil (350 mg/m2/d, from d1 to d5 by continuous infusion). The planned irradiation dose was 12.5 Gy per week with one daily fraction of 2.5 Gy from d1 to d5. Cycles were repeated every four weeks, for four cycles (50 Gy). Patients with a partial or complete response were proposed a fifth cycle.

RESULTS

Of the 28 patients of the study, only 27 were analysed; one patient had a metastatic disease at diagnosis. Major hematologic toxicity occurred in 26% of the patients. One to five cycles of chemoradiotherapy were administrated per patient (median: four). Four patients had received fewer than three cycles and their responses were not assessable. Of the 23 patients assessed, 12 responses (52%) were observed, three CR (13%) and nine PR (39%). Median follow-up was 14 months, and median survival 13.5 months. One- and two-year survival rates were respectively 63% and 14%. Local control rates was 11%, and 44% of the patients had a metastatic evolution.

CONCLUSION

Very preliminary results of this phase II study are disappointing, and quite inferior to the published results using chemoradiotherapy with conventional or hyperfractionated radiotherapy. Hematologic toxicity is restrictive. This type of chemoradiotherapy cannot be recommended.

Beam collimation and bolusing material optimizations for 10boron neutron capture enhancement of fast neutron (BNCEFN): definition of the optimum irradiation technique

PURPOSE

In boron-10 neutron capture enhancement of fast neutron irradiation (BNCEFN), the dose enhancement is correlated to the 10B concentration and thermal neutron flux. A new irradiation technique is presented to optimize the thermal neutron flux.

METHODS AND MATERIALS

The coupled FLUKA and MCNP-4A Monte Carlo codes were used to simulate the neutron production and transport for the Nice and Orleans facilities.

RESULTS

The new irradiation technique consists of a 20-cm lead blocks additional collimator, placed close to the patient's head, which is embedded in a pure graphite cube. A 24-fold thermal neutron flux increase is calculated between a 5 x 5 cm2 primary collimated field, with the patient's head in the air, and the same field size irradiated with the optimum irradiation technique. This increase is more important for the p(60)+Be Nice beam than for the p(34)+Be Orleans one. The thermal neutron flux is 2.1 x 10(10) n(th)/Gy for each facility. Assuming a 100 microg/g 10B concentration, a physical dose enhancement of 22% is calculated. Moreover, the thermal neutron flux becomes independent of the field size and the phantom head size.

CONCLUSION

This technique allows conformal irradiation of the tumor bed, while the thermal neutron flux is enhanced, and spreads far around the tumor.

Boron neutron capture enhancement (BNCE) of fast neutron irradiation for glioblastoma: increase of thermal neutron flux with heavy material collimation, a theoretical evaluation

Despite the fact that fast neutron irradiation of glioblastoma has shown on autopsies an ability to sterilize tumors, no therapeutic windows have been found for these particles due to their toxicity toward normal brain. Therefore, the Boron Neutron Capture Enhancement (BNCE) of fast neutron beam has been suggested. This paper addresses the problem of fast neutron beam collimation, which induces a dramatic decrease of the thermal neutron flux in the depth of the tissues when smaller irradiation fields are used. Thermoluminescent dosimeter TLD-600 and TLD-700 were used to determine the thermal neutron flux within a Plexiglas phantom irradiated under the Nice Biomedical Cyclotron p(60)+Be(32) fast neutron beam. A BNCE of 4.6% in physical dose was determined for a 10 x 10 cm2 field, and of 10.4% for a 20 x 20 cm2 one. A Dose Modification Factor of 1.19 was calculated for CAL 58 glioblastoma cells irradiated thanks to the larger field. In order to increase the thermal flux in depth while shaping the beam, heavy material collimation was studied with Monte Carlo simulations using coupled FLUKA and MCNP-4A codes. The use of 20 cm width lead blocks allowed a 2 fold thermal neutron flux increase in the depth of the phantom, while shielding the fast neutron beam with a fast neutron dose transmission of 23%. Using the DMF of 1.19, a BNCE of 40% was calculated in the beam axis. This enhancement might be sufficient to open, at least theoretically, a therapeutic window.

Epidermal growth factor receptor and labeling index are independent prognostic factors in glial tumor outcome

The aim of this study was to perform a multivariate analysis including clinical and biological prognostic factors on glial tumor outcome. Seventy-nine patients were analyzed (48 men and 31 women; mean age = 56 years, range = 16-77 years): 7 had a benign glial tumor (grades 1 and 2), 21 had an anaplastic glial tumor (grade 3), and 51 had a glioblastoma (grade 4). Median follow-up was 17.9 months for patients who survived (50 patients died). Biopsies were obtained at time of diagnosis (complete tumor resection in 62 patients and stereotaxic biopsies in 17 patients). Epidermal growth factor receptor (EGFR) was measured by a binding assay, and labeling index (LI) was measured by tritiated thymidine incorporation. EGFR varied from 4 to 73,110 fmol/mg protein (mean = 3912 fmol/mg protein; median = 374 fmol/mg protein; n = 79). LI varied between 0.1 and 16.5% (mean = 6.2%; median = 5.2%; n = 40). Log10 EGFR was significantly and positively correlated with patient age. LI was significantly different according to tumor histology. Univariate Cox analysis (end point was cancer death) showed that age (P = 0.027), log10 EGFR (P = 0.025), and LI (P = 0.0019) were significant continuous variables, the survival being shortened when the covariable increased; tumor resection (P = 0.015, relative risk = 0.45) and histology (P = 0.0009) were significant categorical factors. A multivariate Cox analysis (forward selection) including age, histology, tumor resection, log10 EGFR, and LI revealed that log10 EGFR, LI, and tumor resection were the only independent significant predictors of survival. This multivariate approach reveals that the clinical prognostic factors of glial tumors, namely age and tumor histology, disappear, to the benefit of intrinsic characteristics of the tumor, i.e., EGFR expression and LI, suggesting that coupled EGFR and LI determination could be a useful tool for better evaluation of glial tumor outcome.

Combined use of FLUKA and MCNP-4A for the Monte Carlo simulation of the dosimetry of 10B neutron capture enhancement of fast neutron irradiations

Boron neutron capture enhancement (BNCE) of the fast neutron irradiations use thermal neutrons produced in depth of the tissues to generate neutron capture reactions on 10B within tumor cells. The dose enhancement is correlated to the 10B concentration and to thermal neutron flux measured in the depth of the tissues, and in this paper we demonstrate the feasibility of Monte Carlo simulation to study the dosimetry of BNCE. The charged particle FLUKA code has been used to calculate the primary neutron yield from the beryllium target, while MCNP-4A has been used for the transport of these neutrons in the geometry of the Biomedical Cyclotron of Nice. The fast neutron spectrum and dose deposition, the thermal flux and thermal neutron spectrum in depth of a Plexiglas phantom has been calculated. The thermal neutron flux has been compared with experimental results determined with calibrated thermoluminescent dosimeters (TLD-600 and TLD-700, respectively, doped with 6Li or 7Li). The theoretical results were in good agreement with the experimental results: the thermal neutron flux was calculated at 10.3 X 10(6) n/cm2 s1 and measured at 9.42 X 10(6) n/cm2 s1 at 4 cm depth of the phantom and with a 10 cm X 10 cm irradiation field. For fast neutron dose deposition the calculated and experimental curves have the same slope but different shape: only the experimental curve shows a maximum at 2.27 cm depth corresponding to the build-up. The difference is due to the Monte Carlo simulation which does not follow the secondary particles. Finally, a dose enhancement of, respectively, 4.6% and 10.4% are found for 10 cm X 10 cm or 20 cm X 20 cm fields, provided that 100 micrograms/g of 10B is loaded in the tissues. It is anticipated that this calculation method may be used to improve BNCE of fast neutron irradiations through collimation modifications.

Selective delivery of 10B to soft tissue sarcoma using 10B-L-borophenylalanine for boron neutron capture therapy

Boron neutron capture therapy (BNCT) may improve the locoregional control of radio/chemoresistant tumours like soft tissues sarcomas (STS). This technique uses the 10B(n,alpha)7Li nuclear reaction to destroy tumour cells, provided that a sufficient amount of 10B may be carried selectively into them. In order to evaluate the targeting potential of 10B-L-borophenylalanine (BPA) a 10B biodistribution study was carried out in 24 Wistar rats bearing Yoshida sarcoma. Six animals received increasing intraperitoneal doses of BPA (300, 600 and 1200 mg kg-1), while the remainder received a BPA dose of 600 mg kg-1 but with a sacrifice at six different time points: 1, 2, 4, 6, 9 and 12 h. The 10B concentrations in the tumours, normal tissues and blood were analysed with neutron capture radiography (NCR). The analysis shows that 36 micrograms g-1 (+/- 4 SD) of 10B may be incorporated into the tumour, with a ratio of 13 (+/- 4 SD) versus the muscle and a ratio of 15 (+/- 3 SD) versus the blood, 6 h after an intraperitoneal injection of 600 mg kg-1 of BPA. The BPA appears to be abundantly incorporated in the tumour, and the kidney proximal tubule area. These data suggest that BNCT using BPA may provide an improved therapeutic ratio for the treatment of STS.

Proton therapy in ophthalmology: status report and problems encountered

The proton therapy facility of the Centre Antoine-Lacassagne in Nice began treatment of ocular tumors in June 1991. Up to October 1995, a total number of 600 patients were treated. An overview of the cases treated during the first 4 years of activity is given and the main problems encountered in the field, possibly interacting with the accuracy and reliability of the dose distribution, are listed.

Boron neutron capture irradiation: setting up a clinical programme in Nice

Neutron capture irradiation aims to selectively destroy tumor cells using 10B(n,alpha)7Li nuclear reactions produced within themselves. Following the capture reaction, an alpha particle and a, 7Li ion are emitted. Carrying an energy of 2.79 MeV, they destroy all molecular structures along their path close to 10 microns. These captures, used exclusively with a 'slow' neutron irradiation, provide a neutron capture therapy (BNCT). If they are used in addition to a fast neutron beam irradiation, they provide a neutron capture potentiation (NCP). The Centre Antoine-Lacassagne in Nice is actively involved in the European Demonstration Project for BNCT of grade IV glioblastomas (GBM) after surgical excision and BSH administration. Taking into account the preliminary results obtained in Japan, work on an 'epithermal' neutron target compatible with various cyclotron beams is in progress to facilitate further developments of this technique. For NCP, thermalized neutron yield has been measured in phantoms irradiated in the fast neutron beam of the biomedical cyclotron in Nice. A thermal peak appears after 5 cm depth in the tissues, delayed after the fast neutron peak at 1.8 cm depth. Thus, a physical overdosage of 10% may be obtained if 100 ppm of 10B are assumed in the tissues. Our results using CAL 58 GBM cell line demonstrate a dose modification factor (DMF) of 1.19 when 100 ppm of boric acid are added to the growth medium. Thus for the particles, issued from neutron capture, a biological efficiency at least twice that of fast neutrons can be derived. These results, compared with historical data on fast neutron irradiation of glioblastoma, suggest that a therapeutic window may be obtained for GBM.

Changes in biological effectiveness with depth of the Medicyc neutron therapy beam

V79 cells were exposed to fast neutrons generated by 60 MeV p-->Be produced by the cyclotron Medicyc at four different depths: 1.3, 25.8, 72.2 and 116.8 mm. Survival was assessed by the in vitro colony method. Mean inactivation doses (MID) were significantly different among the four points. The ratio of MID was used to determine the relative efficiency of the neutron beam at these points. Compared to 25.8 mm depth, a 40% increase in biological effect was observed at the superficial point versus a 14 to 16% decrease in effect for the deeper points. This is ascribed to absorption of low energy neutrons near the surface and to beam hardening with depth. Taking in consideration the relative physical dose delivered, these findings suggest that skin-sparing may be markedly reduced and that the lower effectiveness with depth should be kept in mind when dealing with deep tumours.

[Neutron capturing irradiation: principle, current results and perspectives]

Neutron capture irradiation aims to selectively destroy the tumoral cells with nuclear reactions produced inside themselves. Therefore, 10B is selectively carried into tumours, being linked to a molecular vehicle. The tissues are then irradiated with thermal neutrons, and the boron neutron capture leads to the formation of alpha and 7Li particles which produce high levels of radiolytic damage along their range of 10 microns. Boron neutron capture therapy (BNCT) uses a thermal/epithermal neutron beam for irradiation, while boron neutron capture potentiation uses the addition of the captures in a fast neutron irradiation. A first trial, conducted in 1951 to 1961 in the USA to test BNCT on patients suffering of glioblastoma, was a failure, essentially because 10B was located in the cerebral capillaries rather than in the tumoral cells. Today, with great improvement in the boronated compounds which show an uptake preferentially inside the cells; the quality of neutron beams; and the knowledge of the microdosimetry of the technique, this technique may be clinically used to increase the local control of radioresistant tumours, like the high grade gliomas, cutaneous or uveal melanoma, and perhaps soft tissue sarcomas.

[Therapy by neutron capture of ocular melanoma: dosimetry and microdosimetry]

Neutron capture therapy (NCT) aims at destroying cancerous cells with the alpha and 7Li particles produced by the neutron capture reaction on 10B. This note reports on the study of the boron distribution in tissues on an animal model (nude mice) xenografted with a human ocular melanoma after an i.p.injection of 2g/kg of 10B-BPA and in cells cultured in the presence of 530 mumol/l of 10B-BPA. A concentration of 64 ppm of 10B in the active part of the tumour with a ratio of concentrations versus the skin of 3.7 are observed. Investigations on cells reveal the presence of boron in the cytoplasm. The biological, dosimetric and microdosimetric consequences of these findings are discussed.

[Morphological characterization of cell lines of human uveal melanoma]

Several cell lines have been derived from an ocular melanoma obtained from an enucleated patient. Three cell types are observed during the time in culture of all the cell lines under study. Two of them have epithelial and spindle shape respectively. A third cell type, having a spheroidal shape, is formed from spindle cells and may be transformed into epithelial cells upon re-seeding. Further experiments showed that the same cell may change of shape following the cycle: spheroidal-->epithelial-->fusiform-->spheroidal. Scanning microscopy shows the coexistence of the three cell shapes in the same culture and the presence of several filaments and processes protruding at the surface of the cells. Transmission electron microscopy shows that the cell lines, in general, contain melanosomes empty or fairly pigmented and several filaments and microtubules. The presence of melanin may be stimulated by seeding of melanoma cells over a "feeder layer" of fibroblasts.