Heterogeneity correction in the construction of optimized planning in radiotherapy using linear programming

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Periodontal changes in patients undergoing radiotherapy

Background: the purpose of this study was to evaluate changes in the periodontium in patients who received head and neck radiation therapy.Methods: Periodontal clinical parameters (probing depth, clinical attachment level, gingival recession, plaque index, and bleeding on probing) were assessed on 27 patients before and 6 to 8 months following radiation therapy in the head and neck area.Results: the greatest changes occurred in clinical attachment level: overall, 70.3% of the patients showed a loss, with 92% evincing loss in the mandible. Attachment loss was directly related to the field of radiation and was greater when the jaws were actually included in the irradiated area.Conclusion: Periodontal status should be evaluated prior to and following radiation therapy in the oral-maxillary-facial region to help ensure that periodontal health is maintained in oncology patients.

Developing new radiotherapy techniques using linac based gamma radiation sources

A major challenge in cancer radiotherapy is to deliver a lethal dose of radiation to the target volume while minimizing damage to the surrounding normal tissue. We have proposed a model on how treatment efficacy might be improved by interfering with biological responses to DNA damage using exogenous electric fields as a strategy to drastically reduce radiation doses in cancer therapy. This approach is demonstrated at this Laboratory through case studies with prokaryotes (bacteria) and eukaryotes (yeast) cells, in which cellkilling rates induced by both gamma radiation and exogenous electric fields were measured. It was found that when cells exposed to gamma radiation are immediately submitted to a weak electric field, cell death increases more than an order of magnitude compared to the effect of radiation alone. This finding suggests, although does not prove, that DNA damage sites are reached and recognized by means of long-range electric DNA-protein interaction, and that exogenous electric fields could destructively interfere with this process. As a consequence, DNA repair is avoided leading to massive cell death. Here we are proposing the use this new technique for the design and construction of novel radiotherapy facilities associated with linac generated gamma beams under controlled conditions of dose and beam intensity.

Effect of radiotherapy on the radiopacity and flexural strength of a composite resin.

The aim of this study was to evaluate the effect of radiotherapy on the radiopacity and flexural strength of composite resin. Forty Z250 composite resin specimens were polymerized using a halogen light-curing unit and divided into 5 groups, in accordance with the radiotherapy dose: G1- without irradiation, G2- 30 Gy, G3- 40 Gy, G4- 50 Gy and GS- 60 Gy Digital images were obtained using a GE 100 X-ray. Radiopacity values were obtained with the Digora digital imaging system and the flexural strength was evaluated with an EMIC universal testing machine. Data were submitted to ANOVA and Tukey 's test. G1 presented the highest radiopacity value, followed by G3, G5, G4 and G2. For flexural strength, G1 presented the lowest value, followed by G2, G5, G3 and G4. Differences were no significant (p>0.05). The commonly used dosage of radiotherapy treatment, did not cause alteration in the radiopacity and flexural strength of resin-based composites.

Nuclear data for proton beam radiotherapy

The need for a program of work focused on the nuclear data evaluation of chargedparticle reactions has arisen recently due to their increasing use in cancer therapy. This project, as part of that program, has as its main goal the selection and comparison of nuclear data for nuclear reactions induced by protons at low to intermediate energies (E < 250 MeV). The methodology of selection was based on the data base EXFOR and the compilations of radionuclide production cross sections of N. Sobolevsky. For the purpose of comparison and evaluation, theoretical calculations with the reaction model code EMPIRE-II are being used. © 2009 American Institute of Physics.

Influence of preventive dental treatment on mutans streptococci counts in patients undergoing head and neck radiotherapy

The aim of this study was to evaluate the influence of chlorhexidine gluconate, sodium fluoride and sodium iodine on mutans streptococci counts in saliva of irradiated patients. Forty-five patients were separated into three experimental groups and received chlorhexidine (0.12%), sodium fluoride (0.5%) or sodium iodine (2%), which were used daily during radiotherapy and for 6 months after the conclusion of the treatment. In addition, a fourth group, composed by 15 additional oncologic patients, who did not receive the mouthwash or initial dental treatment, constituted the control group. Clinical evaluations were performed in the first visit to dental clinic, after initial dental treatment, immediately before radiotherapy, after radiotherapy and 30, 60, 90 days and 6 months after the conclusion of radiotherapy. After clinical examinations, samples of saliva were inoculated on SB20 selective agar and incubated under anaerobiosis, at 37oC for 48 h. Total mutans streptococci counts were also evaluated by using real-time PCR, through TaqMan system, with specific primers and probes for S. mutans and S. sobrinus. All preventive protocols were able to reduce significantly mutans streptococci counts, but chlorhexidine gluconate was the most effective, and induced a significant amelioration of radiotherapy side effects, such as mucositis and candidosis. These results highlights the importance of the initial dental treatment for patients who will be subjected to radiotherapy for head and neck cancer treatment.

Pain and quality of life in patients undergoing radiotherapy for spinal metastatic disease treatment

Background: Radiotherapy is an important tool in the control of pain in patients with spinal metastatic disease. We aimed to evaluate pain and of quality of life of patients with spinal metastatic disease undergoing radiotherapy with supportive treatment. Methods. The study enrolled 30 patients. From January 2008 to January 2010, patients selection included those treated with a 20Gy tumour dose in five fractions. Patients completed the visual analogue scale for pain assessment and the SF-36 questionnaire for quality of life assessment. Results: The most frequent primary sites were breast, multiple myeloma, prostate and lymphoma. It was found that 14 spinal metastatic disease patients (46.66%) had restricted involvement of three or fewer vertebrae, while 16 patients (53.33%) had cases involving more than three vertebrae. The data from the visual analogue scale evaluation of pain showed that the average initial score was 5.7 points, the value 30days after the end of radiotherapy was 4.60 points and the average value 6months after treatment was 4.25 points. Notably, this final value was 25.43% lower than the value from the initial analysis. With regard to the quality of life evaluation, only the values for the functional capability and social aspects categories of the questionnaire showed significant improvement. Conclusion: Radiotherapy with supportive treatment appears to be an important tool for the treatment of pain in patients with spinal metastatic disease. © 2013 Valesin Filho et al; licensee BioMed Central Ltd.

Usefulness of computed tomography and magnetic resonance imaging in radiotherapy planning for the treatment of brain tumors

Advanced diagnostic techniques such as magnetic resonance imaging and computed tomography have become useful tools for confirmation of presumptive diagnosis of structural lesions in the brain such as encephalic neoplasms in small animal veterinary practice in Colombia, allowing an effective treatment planning that is more specific and less invasive for this type of pathology.

Salivary and serum proteomics in head and neck carcinomas before and after surgery and radiotherapy

Several body fluids have been evaluated as new sources for cancer biomarker discovery. In this context, salivary and serum proteomics seem promising diagnostic and predictive tools for head and neck diseases. In the present study, we performed a proteomic analysis of saliva and serum from patients presenting head and neck squamous cell carcinoma (HNSCC) and compared the results before and after therapy. In saliva of cancer patients, we observed an altered protein profile, including over-expression of PLUNC and zinc-alpha-2-glycoprotein. Both proteins may contribute to control tumor growth and, therefore, represent targets for new analysis. We also detected serotransferrin and a modified transthyretin form with altered levels in serum from patients. Comparing preoperative and postreatment samples, the results showed that the protein profile after treatment reverted to a pattern closer to those observed for controls. These results add information on the role of secreted proteins in the cancer process and emphasize the potential of saliva and serum analysis for diagnosis and monitoring of HNSCC.

A matheuristic for the selection of beam directions and dose distribution in radiotherapy planning

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Symptoms of depression in patients with cancer of the head and neck undergoing radiotherapy treatment: a prospective study

This study aimed to investigate the frequency of symptoms of depression in patients with cancer of the head and neck undergoing radiotherapy treatment, in the initial, middle and final stages of the treatment. This is a prospective exploratory quantitative study of 41 patients with head and neck cancer, undergoing radiotherapy treatment in the Oncology Outpatient Clinic of the Beneficencia Portuguese Hospital of Ribeirao Preto. Data were collected through the Beck Depression Inventory instrument, and analyzed quantitatively by means of the Statistical Package for the Social Sciences. Symptoms of dysphoria were found to increase throughout the treatment, as well as the number of patients with depression. The results show the importance for the healthcare professionals to detect the prevalence and the levels of the symptoms of depression, since these symptoms tend to increase and may lead to consequences such as a lack of adherence to treatment and a decrease in the quality of life of these patients.

Surrogate endpoints for prostate cancer-specific mortality after radiotherapy and androgen suppression therapy in men with localised or locally advanced prostate cancer: an analysis of two randomised trials

Background Androgen suppression therapy and radiotherapy are used to treat locally advanced prostate cancer. 3 years of androgen suppression confers a small survival benefit compared with 6 months of therapy in this setting, but is associated with more toxic effects. Early identification of men in whom radiotherapy and 6 months of androgen suppression is insufficient for cure is important. Thus, we assessed whether prostate-specific antigen (PSA) values can act as an early surrogate for prostate cancer-specific mortality (PCSM). Methods We systematically reviewed randomised controlled trials that showed improved overall and prostate cancer-specific survival with radiotherapy and 6 months of androgen suppression compared with radio therapy alone and measured lowest PSA concentrations (PSA nadir) and those immediately after treatment (PSA end). We assessed a cohort of 734 men with localised or locally advanced prostate cancer from two eligible trials in the USA and Australasia that randomly allocated participants between Feb 2, 1996, and Dec 27, 2001. We used Prentice criteria to assess whether reported PSA nadir or PSA end concentrations of more than 0.5 ng/mL were surrogates for PCSM. Findings Men treated with radiotherapy and 6 months of androgen suppression in both trials were significantly less likely to have PSA end and PSA nadir values of more than 0.5 ng/mL than were those treated with radiotherapy alone (p<0.0001). Presence of candidate surrogates (ie, PSA end and PSA nadir values >0.5 ng/mL) alone and when assessed in conjunction with the randomised treatment group increased risk of PCSM in the US trial (PSA nadir p=0.0016; PSA end p=0.017) and Australasian trial (PSA nadir p<0.0001; PSA end p=0.0012). In both trials, the randomised treatment group was no longer associated with PCSM (p >= 0.20) when the candidate surrogates were included in the model. Therefore, both PSA metrics satisfied Prentice criteria for surrogacy. Interpretation After radiotherapy and 6 months of androgen suppression, men with PSA end values exceeding 0.5 ng/mL should be considered for long-term androgen suppression and those with localised or locally advanced prostate cancer with PSA nadir values exceeding 0.5 ng/mL should be considered for inclusion in randomised trials investigating the use of drugs that have extended survival in castration-resistant metastatic prostate cancer.

Effects of 3-Dimensional Conformal or Intensity-modulated Radiotherapy on Dental Pulp Sensitivity during and after the Treatment of Oral or Oropharyngeal Malignancies

Introduction: Radiation therapy (RT) of malignant tumors in the head and neck area may have damaging effects on surrounding tissues. The aim of this investigation was to evaluate the effects of RI delivered by 3-dimensional conformal radiotherapy (3D-RT) or intensity-modulated radiotherapy (IMRT) on dental pulp sensitivity. Methods: Twenty patients with oral or oropharyngeal cancer receiving RT with 3D-RT or IMRT underwent cold thermal pulp sensitivity testing (PST) of 2 teeth each at 4 time points: before RT (TP1), the beginning of RT with doses between 30 and 35 Gy (TP2), the end of RT with doses between 60 and 70 Gy (TP3), and 4 to 5 months after the start of RT (TP4). Results: All 40 teeth showed positive responses to PST at TP1 (100%) and 9 at TP2 (22.5%; 3/16 [18.8%] for 3D-RT and 6/24 [25.0%] for IMRT). No tooth responded to PST at TP3 and TP4 (0%). A statistically significant difference existed in the number of positive pulp responses between different time points (TP1 through TP4) for all patients receiving RT (P <= .05), IMRT (P <= .05), and 3D-RT (P <= .05). No statistically significant differences in positive sensitivity responses were found between 3D-RT and IMRT at any time point (TP1, TP3, TP4, P = 1.0; TP2, P = .74). A statistically significant correlation existed between the location of the tumor and PST at TP2 for IMRT (P <= .05) but not for 3D-RT (P = .14). Conclusions: RT decreased the number of teeth responding to PST after doses greater than 30 to 35 Gy. The type of RT (3D-RT or IMRT) had no influence on the pulp responses to PST after the conclusion of RT. (J Endod 2012;38:148-152)