Treatment of Retinoblastoma: The Role of External Beam Radiotherapy

The risk of radiotherapy-related secondary cancers in children with constitutional retinoblastoma 1 (RB1) mutations has led to reduced use of external beam radiotherapy (EBRT) for RB. Presently, tumor reduction with chemotherapy with or without focal surgery (chemosurgery) is most commonly undertaken; EBRT is avoided as much as possible and is considered only as the last treatment option prior to enucleation. Nevertheless, approximately 80% of patients are diagnosed at a locally advanced stage, and only 20-25% of early stage RB patients can be cured with a chemosurgery strategy. As a whole, chemotherapy fails in more than two-thirds of eyes with advanced stage disease, requiring EBRT or enucleation. Radiotherapy is still considered necessary for patients with large tumor(s) who are not candidates for chemosurgery but who have visual potential. When radiation therapy is indicated, the lowest possible radiation dose combined with systemic or local chemotherapy and focal surgery may yield the best clinical outcomes in terms of local control and treatment-related toxicity. Proton beam therapy is one EBRT method that can be used for treatment of RB and reduces the radiation dose delivered to the adjacent orbital bone while maintaining an adequate dose to the tumor. To maximize the therapeutic success of treatment of advanced RB, the possibility of integrating radiotherapy at early stages of treatment may need to be discussed by a multidisciplinary team, rather than considering EBRT as only a last treatment option.

Consideraciones clínicas, diagnósticas y de tratamiento en retinoblastoma / Clinical, diagnostic and therapeutic considerations in retinoblastoma

El retinoblastoma es el tumor intraocular primari o más frecuente en l a infancia. Su detección temprana y el inici o del tratamiento adecuado permi te mejorar dramáticamente l a sobrevida en estos niños. En este artícul o se hace una revisión general de l a enfermedad. Se empleó PubMed y se revisaron artículos representativos del tema, que permi tieran dar una idea general de los di ferentes avances alcanzados. Dada su cl ínica característica, el médico de atención primaria, es pieza fundamental en l a captación inicial del paciente. [Vi l lami l JF , Quintero LM, Serrano RA, Moreno IA. Consideraciones cl ínicas, diagnósticas y de tratamiento en retinoblastoma. MedUNAB 201 1; 14:180-187].

Retinoblastoma is the most common primary intraocular tumor in childhood. Its early detection and initiation of appropriate therapy , can dramatically improve the life expectancy in these children. This article is a general review of the disease. PubMed was employed and representative articles about the topic were selected in order to given us a general idea about the advances achieved. Due to clinical features, primary care physician is a fundamental part in the initial catchment of patient. [Villamil JF , Quintero LM, Serrano RA, Moreno IA. Clinical, diagnostic and therapeutic considerations in retinoblastoma. MedUNAB 2011; 14:180-187].

Carcinoma epidermoide de cuello uterino: anormalidades moleculares de los genes p53 y rb / Epidermoid carcinoma of the uterine cervix: molecular abnormalities of p53 and rb genes

The inactivation of p53 and rb genes has been implicated in the pathogenesis of cervix uteri carcinoma. Although this neoplasia presents high incidence and mortality rates in Chile, there are not studies about its molecular abnormalities. We investigated the frequency of loss of heterozygocity (LOH) at p53 and rb genes in 17 invasive aquamous cell carcinomas of the cervix uteri, using microdissection technique from microslides and microsatellite sequences amplification by PCR. Moreover, we investigated the immunohistochemical expression of p53 protein in 30 invasive squamous cell carcinomas. LOH was detected in 6/12 of informative cases (50 percent) at p53 gene and in 3/10 (30 percent) at rb gene. The p53 protein immunohistochemical expression was 47 percent (14/30 cases). LOH at p53 gene in cases without p53 protein immunohistochemical expression was observed. We concluded that p53 gene molecular abnormalities are important in the pathogenesis of squamous cell carcinoma of the cervix uteri in contrast than LOH at rb gene

PCR detection of Xbal polymorphism in the human Rb gene of retinoblastoma patients

Inactivation of the Rb (retinoblastoma) tumor suppressor gene is associated with hereditary and sporadic cases of retinoblastoma and other Rb-related tumors. Early diagnosis and genetic counseling heavily depend on practical methods for the detection of Rb deletions and mutations in high-risk families. Here we report on the use of a pair of primers in polymerase chain reaction (PCR) to amplify a 945-bp fragment from intron 17 of the Rb gene (T.L. McGee, G.S. Cowley, D.W. Yandell and T.P. Dryja, 1990, Nucleic Acid Research, 18: 207). Xbal digestion of the PCR product reveals 2 allelic versions: a single 945-bp fragment (allele 1) or 2 fragments of 315 and 630 bp (allele 2). We used total genomic DNA (blood and tumors) to investigate the power of this PCR-Rb-Xbal-RFLP in the identification of both segregation and loss of heterozygosity of the Rb gene. In one family studied (family 1A) in which 2 generations were affected, it was possible to localize the mutated Rb gene to Xbal-Rb allele 2. The assay of loss of heterozygosity of the Rb gene is available for all Xbal-Rb allele 1-2 individuals, so that analyses may be applied in large scale investigation of the participation of Rb gene in tumor development. We conclude that PCR-Rb-Xbal-RFLP is a practical and powerful tool for oncology research and genetic counseling