Antibiotics, cancer risk and oncologic treatment efficacy: a practical review of the literature.

Antibiotics have been extensively used to treat infectious diseases over the past century and have largely contributed to increased life expectancy over time. However, antibiotic use can impose profound and protracted changes to the diversity of the microbial ecosystem, affecting the composition of up to 30% of the bacterial species in the gut microbiome. By modifying human microbiota composition, antibiotics alter the action of several oncologic drugs, potentially leading to decreased efficacy and increased toxicities. Whether antibiotics interfere with cancer therapies or even increase the risk of cancer development has been under investigation, and no randomised trials have been conducted so far. The aim of the current review is to describe the possible effects of antibiotic therapies on different oncologic treatments, especially immunotherapies, and to explore the link between previous antibiotics use and the development of cancer.

Intensity modulated radiotherapy for localized prostate cancer: rigid compliance to dose-volume constraints as a warranty of acceptable toxicity?

BACKGROUND: To report the toxicity after intensity modulated radiotherapy (IMRT) for patients with localized prostate cancer, as a sole treatment or after radical prostatectomy. METHODS: Between August 2001 and December 2003, 132 patients with prostate cancer were treated with IMRT and 125 were evaluable to acute and late toxicity analysis, after a minimum follow-up time of one year. Clinical and treatment data, including normal tissue dose-volume histogram (DVH) constraints, were reviewed. Gastro-intestinal (GI) and genito-urinary (GU) signs and symptoms were evaluated according to the Radiation Therapy Oncology Group (RTOG) toxicity scales. Median prescribed dose was 76 Gy. Median follow-up time was of 26.1 months. RESULTS: From the 125 patients, 73 (58.4%) presented acute Grade 1 or Grade 2 GI and 97 (77.2%) presented acute Grade 1 or Grade 2 GU toxicity. Grade 3 GI acute toxicity occurred in only 2 patients (1.6%) and Grade 3 GU acute toxicity in only 3 patients (2.4%). Regarding Grade 1 and 2 late toxicity, 26 patients (20.8%) and 21 patients (16.8%) presented GI and GU toxicity, respectively. Grade 2 GI late toxicity occurred in 6 patients (4.8%) and Grade 2 GU late toxicity in 4 patients (3.2%). None patient presented any Grade 3 or higher late toxicity. Non-conformity to DVH constraints occurred in only 11.2% of treatment plans. On univariate analysis, no significant risk factor was identified for Grade 2 GI late toxicity, but mean dose delivered to the PTV was associated to higher Grade 2 GU late toxicity (p = 0.042). CONCLUSION: IMRT is a well tolerable technique for routine treatment of localized prostate cancer, with short and medium-term acceptable toxicity profiles. According to the data presented here, rigid compliance to DHV constraints might prevent higher incidences of normal tissue complication.

Radiosurgical boost for primary high-grade gliomas.

The purpose of this study was to retrospectively evaluate the survival of patients with high-grade gliomas treated with external beam radiotherapy with or without radiosurgical boost. From July 1993 to April 1998, 32 patients were selected, 15 of which received radiosurgery. Inclusion criteria were age > 18 years, histological confirmation of high-grade glioma, primary tumor treatment with curative intent, unifocal tumor and supratentorial location. All patients were found to be in classes III-VI, according to the recursive partitioning analysis proposed by the Radiation Therapy Oncology Group. The median interval between radiotherapy and radiosurgery was 5 weeks (range 1-13). Treatment volumes ranged from 2.9 to 70.3 cc (median 15.0 cc). Prescribed radiosurgery doses varied from 8.0 to 12.5 Gy (median 10.0 Gy). Radiosurgery and control groups were well balanced with respect to prognostic factor distributions. Median actuarial survival time in radiosurgery and control groups was 21.4 months and 11.6 months, respectively (p = 0.0254). Among patients with KPS > 80, median survival time was 11.0 months and 53.9 months in the control and radiosurgery groups, respectively (p = 0.0103). Radiosurgery was the single factor correlated with survival on Cox model analysis (p = 0.0362) and was associated with a 2.76 relative reduction in the risk of cancer death (95% confidence interval (CI) 1.07-7.13). Our results suggest that radiosurgery may confer a survival advantage for patients in RPA classes III-VI, especially for those with Karnofsky performance status >80. The definitive role of radiosurgical boost for patients with high-grade gliomas awaits the results of randomized trials.

Whole-pulmonary low-dose radiation therapy in agnogenic myeloid metaplasia with diffuse lung involvement.

Agnogenic myeloid metaplasia is a hematologic disorder accompanied by extramedullary hematopoiesis (EMH) affecting various organs. Lung involvement however is rare. We present the case of a 76-year-old woman with myelofibrosis, recurrent pleural effusions, pulmonary hypertension, and serious right cardiac failure. An open lung biopsy confirmed pulmonary EMH. She underwent low-dose (200 cGy) whole-lung radiotherapy in 4 fractions of 50 cGy each. Her clinical and hemodynamic parameters improved. We conclude that low-dose whole-lung radiation may be efficacious for the palliative treatment of pulmonary EMH.

Procedimentos para pacientes portadores de marcapasso e submetidos à radioterapia / Procedures for radiation therapy in patients using cardiac pacemarkers

Os modernos marcapassos cardíacos podem falhar quando submetidos a radiaçäo ionizante da ordem de 10 Gy e exibir alteraçös funcionais com doses täo baixas quanto 2 Gy. A interferência eletromagnética também pode afetar seu desempenho, mas este efeito näo é problema sério quando consideramos os equipamentos de radioterapia atuais. Devido ao aumento significativo de aceleradores lineares no Brasil e, com isto, um aumento da probabilidade de tratamento de pacientes portadores de marcapassos cardíacos permanentes com esses equipamentos, apresentamos uma revisäo e discussäo dos problemas em potencial associados e sugerimos alguns cuidados que adotamos e praticamos no Serviço de Radioterapia do Hospital Israelita Albert Einstein