The role of para-aortic nodal irradiation in cervical cancer

The current standard of care for locally advanced cervical cancer is whole pelvis and para-aortic radiation when indicated, delivered concomitantly with chemotherapy and brachytherapy. Para-aortic node involvement is a predictor of survival in locally advanced disease but presence of metastases is difficult to determine because the currently available imaging methods lack enough sensitivity to be able to detect accurately para-aortic metastases when surgical staging is not feasible. The objective of this review is to describe the current status of para-aortic lymph node irradiation in locally advanced cervical cancer. It includes analysis of the diagnostic imaging and surgical approaches for assessment of para-aortic lymph node dissemination, together with indications for radiotherapy and radiotherapeutic techniques

Heuristic estimation of the α/β ratio for a cohort of Mexican patients with prostate cancer treated with external radiotherapy techniques

BACKGROUND: The aim of the study was to Estimate and compare the radiobiological ratio α/β with the heuristic method for a cohort of Mexican patients with prostate cancer (PCa) who were treated with external radiotherapy (RT) techniques at three Hospital Institutions in Mexico City. With the Kaplan-Meier technique and the Cox proportional hazards model, the biochemical relapse-free survival (bRFS) is determined and characterized for cohorts of Mexican patients with PCa who received treatment with external RT. Using these clinical outcomes, the radiobiological parameter α/β is determined using the heuristic methodology of Pedicini et. al. MATERIALS AND METHODS: The α/β is calculated from the survival curves for different treatment schemes implemented at three distinct hospitals. The Pedicini’s techniques allow to determine the parameters α/β, k and N0 when treatments are not radiobiologically equivalent, therefore, are built up of a set of curved pairs for the biologically effective dose (BED) versus the ratio α/β, where the ratio is given by the intersection for each pair of curves. RESULTS: Six different values of α/β were found: the first α/β = 2.46 Gy, the second α/β = 3.30 Gy, the third for α/β = 3.25 Gy, the fourth α/β = 3.24 Gy, the fifth α/β = 3.38 Gy and the last α/β = 4.08 Gy. These values can be explained as follows: a) The bRFS of the schemes presents a statistical variation; b) The absorbed doses given to the patient present uncertainties on the physical dosimetry that are not on the modeling; c) Finally, in the model for the bRFS of Eq. (3), there are parameters that have to be considered, such as: the number of clonogenic tumor cells N0, the overall treatment time (OTT), the kick-off time for tumor repopulation Tk and the repopulation doubling time. Therefore, the mean value to α/β for all schemes has an average value of 3.29 (± 0.52) Gy. CONCLUSIONS: The value of = 3.29 (± 0.52) Gy is determined from cohorts of Mexican patients with PCa treated with external radiotherapy using the time-dependent LQ model, which is a higher value with respect to the “dogma” value of α/β 1.5 Gy obtained with the LQ model without temporal dependence. Therefore, there is a possibility of optimizing treatments radiobiologically and improving the results of bRFS in Mexican patients with PCa treated with external radiotherapy

Mexican radiation dermatitis management consensus

Abstract Background: Radiotherapy (RT) is an essential element in cancer treatment: 50–70% of cancer patients receive RT at some time of the course of their disease. Of these, almost 95% experience some grade of radiation dermatitis (RD). RD can affect patient’s quality of life during and after treatment. Consequently, the management of RD is important. There are few randomized controlled clinical trials on interventions used to prevent and treat RD and no standardized consensus on RD management. A panel of opinion leaders of the Mexican Society of Radiotherapy (SOMERA) took part in a study of oncologic practice in Mexico. The following clinical guide is referenced both by the national practice reality and international evidence. Materials and methods: This RD management guide is based on input provided by 25 Mexican radiation oncologists, whose criteria were gathered using the Delphi Method and article review. Results: Twenty-one questions about experience in RD treatment were voted. More than 80% of the panel agreed with: the use of dermocosmetics/medical device in prevention and in treatment of RD grades 1–2. As for grade 3, they recommend individualizing each case and dermatologist evaluation. Topical steroids should be used when there is skin itching or pain. Consider the use of natural soaking elements. Skin care must be continued to avoid or reduce severity of late radiation skin lesions. Conclusion: This consensus was developed as a supportive educational tool that can be adapted to individual clinical needs, useful for professionals involved in the treatment of RT patients.  

Biochemical relapse free survival rate in patients with prostate cancer treated with external radiotherapy: outcomes obtained at the CMN Siglo XXI Hospital de Oncología, CMN 20 de Noviembre and Hospital General de México of the México City

AimBiochemical relapse-free survival (bRFS) rate is determined by a cohort of Mexican patients (n=595) with prostate cancer who received treatment with external radiotherapy.BackgroundPatients with prostate cancer were collected from CMN Siglo XXI (IMSS), CMN 20 de Noviembre (ISSSTE), and Hospital General de México (HGM). For the IMSS, 173 patients that are treated with three-dimensional conformal radiation therapy (3D-CRT) and 250 with SBRT, for the ISSSTE 57 patients are treated with 3D-CRT and on the HGM 115 patients are managed with intensity modulated radiation therapy (IMRT). The percentage of patients by risk group is: low 11.1%, intermediate 35.1% and high 53.8%. The average follow-up is 39 months, and the Phoenix criterion was used to determine the bRFS.Materials and methodsThe Kaplan–Meier technique for the construction of the survival curves and, the Cox proportional hazards to model the cofactors.Results(a) The bRFS rates obtained are 95.9% for the SBRT (7Gy fx, IMSS), 94.6% for the 3D-CRT (1.8Gy fx, IMSS), 91.3% to the 3D-CRT (2.65Gy fx, IMSS), 89.1% for the SBRT (7.25Gy fx, IMSS), 88.7% for the IMRT (1.8Gy fx, HGM) %, and 87.7% for the 3D-CRT (1.8Gy fx, ISSSTE). (b) There is no statistically significant difference in the bRFS rates by fractionation scheme, c) Although the numerical difference in the bRFS rate per risk group is 95.5%, 93.8% and 89.1% for low, intermediate and high risk, respectively, these are not statistically significant.ConclusionsThe RT techniques for the treatment of PCa are statistically equivalent with respect to the bRFS rate. This paper confirms that the bRFS rates of Mexican PCa patients who were treated with conventional vs. hypofractionated schemes do not differ significantly