Restricción de dosis a nichos de células madres en glándulas parótidas como optimización del tratamiento radiante definitivo en tumores de cabeza y cuello: análisis dosimétrico
Most cancer patients receive radiation therapy at some point during their\ntreatment. Irradiation of healthy tissues close to the tumor is virtually an unavoidable\nconsequence, which can lead to complications in these tissues. An example of this is\nsevere xerostomia as chronic irreversible toxicit...
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| Formato: | Tesis de maestría acceptedVersion |
| Lenguaje: | Español |
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Facultad de Farmacia y Bioquímica
2019
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| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=afamaster&cl=CL1&d=HWA_3169 http://repositoriouba.sisbi.uba.ar/gsdl/collect/afamaster/index/assoc/HWA_3169.dir/3169.PDF |
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| Sumario: | Most cancer patients receive radiation therapy at some point during their\ntreatment. Irradiation of healthy tissues close to the tumor is virtually an unavoidable\nconsequence, which can lead to complications in these tissues. An example of this is\nsevere xerostomia as chronic irreversible toxicity in patients diagnosed with head and\nneck tumors undergoing radiotherapy (Sciubba y Goldenberg, 2006).\nSalivary glands are very sensitive to the effect of radiation and their\ninvolvement is dependent on the dose of radiation they receive and on the volume of\ngland irradiated (Konings, Cotteleer, Faber et al., 2005). Once symptomatic\nxerostomia is established, there is no specific treatment. The most effective way to\npreserve salivary glandular function is prevention.\nCurrently, the most commonly used prevention strategy is radiant treatment\nplanning with highly conformed techniques such as IMRT or VMAT. However, even\nwith these conformal treatment techniques, taking care of the entire volume of the\nparotid glands is not always possible. Applying the dose restrictions currently in force\nto the entire volume of the parotid gland would, in many cases, mean neither\nresigning part of the coverage of the tumour volume with the correct prescription\ndose nor putting other healthier organs with higher priority at greater risk.\nIt is now known that not all salivary glandular tissue performs identical\nfunctions. Van Luijk and colleagues (2015, 2017, 2018) determined that different\nregions of the parotid gland have different regenerative capacity and that irradiation\nof areas with higher stem-cell content result in greater impairment of postradiotherapy\nglandular function. The stem-cells (stem-cells -SC-) contained in the\nparotid glands are responsible for tissue regeneration after radiant injury. These are\nlocated mainly in the area of the parotid gland adjacent to the dorsal end of the\nmandibular angle, where the first branches of the greater parotid duct (Steno duct)\nare born. The dose received in these rich areas of stem-cell is highly predictive of\npost-treatment glandular dysfunction.\nTo date, no dosimetric analysis results of treatment plans demonstrating the\nfeasibility of carrying out specific dose restriction planning in parotids have been\nreported. No specific dose restrictions were published for these niches of stem-cells\nin parotid glands.\nIn our work, we determined that the best radiant treatment planning strategy in\nterms of treatment volume coverage and parotid gland protection (both the complete\ngland volume and the stem-cell niches included in them) was obtained with VMAT\nplanning with specific parotid gland protection (protection of stem-cell niches of\nparotid glands). In addition, we were able to establish a correlation between the dose\nreceived in the parotid stem-cell niches and the xerostomia presented by the\npatients. Based on this, we proposed a maximum dose (Dmax) less than or equal to\n30 Gy as a new restriction for stem-cell niches in parotid glands.\nOur work sought to contribute to some extent to the current field of knowledge\nof radiant oncology and radiobiology, from a translational perspective. We consider\nthat the findings of our research should be validated in prospective trials with a\ngreater number of patients. |
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