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Papers by Alejandro González Motta

International Journal of Radiation Oncology*Biology*Physics

International Journal of Radiation Oncology*Biology*Physics, 2021

International Journal of Radiation Oncology*Biology*Physics, 2021

PURPOSE/OBJECTIVE(S) Cerebral arteriovenous malformations (AVM) are vascular lesions that include... more PURPOSE/OBJECTIVE(S) Cerebral arteriovenous malformations (AVM) are vascular lesions that include aberrant communication between arterial and venous systems. Treatment for AVM is still under debate. Surgery, embolization, observation, and radiosurgery are options for patients. Most data for radiosurgery came from the Gammaknife series. However, low middle-income countries have financial constraints to establish dedicated intracranial neurosurgery machines. We aimed to determine AVM obliteration rate in patients treated with linear accelerator stereotactic radiosurgery (SRS) guided by magnetic resonance imaging and panangiography fusion with computed tomography simulation at a quaternary care institution in Latin America. MATERIALS/METHODS We conducted an observational study with patients treated with SRS at our institution during 2011 and 2017. Exclusion criteria were age younger than 14 and a history of brain cancer. After IRB approval, data were collected retrospectively by reviewing medical records. Patients without available follow-up were contacted to gather missing information. Primary outcome was obliteration rate at 3 years, confirmed by diagnostic imaging (MRI or cerebral panangiography). Secondary outcomes were intracranial bleeding, headaches, epilepsy, and neurological deficits at clinical presentation and after SRS. Analysis included sociodemographic data, AVM characteristics (location and Spetzler-Martin grading), and treatment features. We used descriptive statistics, measures of central tendency and dispersion, and proportions. RESULTS We included 85 patients. The mean age at treatment was 40.8 (14-73), 49.4% of patients were male, and 50.6% female. The most common location was the frontal lobe in 25.9% (n = 22) and the parietal lobe in 24.7% (n = 21). At diagnosis, 44% of patients had a history of intracranial hemorrhage. 49 patients had received previous embolization. The mean dose of radiosurgery was 19.3 Gy (14-25). The mean isodose was 95.25 (80-98). 35.3% of the patients had an AVM Spetzler-Martin grade 2, 40% grade 3, and 12.9% grade 4. We obtained long-term follow-up data for 42 patients, with a median follow-up of 1366 days. The overall obliteration rate was 60%, based primarily on panangiography (59.1%). Symptoms after SRS included headaches (n = 30) and seizures (n = 10). 2 patients presented intracranial bleeding. We contacted all missing patients, but no follow-up data was available for analysis. Most missing patients lived outside the city. CONCLUSION Tri-modality image fusion SRS with linear accelerators for AVM could be a safe and accessible option in low-middle income countries. Health administrator issues, travel distances to access linear accelerators and multidisciplinary teams hinder timely follow-up and surveillance imaging. More prospective data are needed to define the role of SRS for AVMs. AUTHOR DISCLOSURE V. Rangel: None. J. Cure: None. M. Caicedo-Martinez: None. G. Borda: None. C. Lindado: None. E. Castro-Lombana: None. J. Puentes: None. O. Zorro: None. A. González-Motta: None.

La supervivencia global de los pacientes pediátricos con cáncer ha mejorado de manera constante e... more La supervivencia global de los pacientes pediátricos con cáncer ha mejorado de manera constante en los últimos 40 años; esto se ve reflejado en el aumento de la supervivencia a 5 años, la cual a mediados de los 70 era de un 58% y a principios del 2000 llegó a ser mayor del 80%.1 Esto se debe principalmente a avances en los diferentes esquemas de tratamientos, los cuales han permitido que una gran proporción de pacientes alcancen la adultez. Sin embargo, este aumento en la supervivencia implica una serie de complicaciones a largo plazo, de las cuales el desarrollo de segundas neoplasias es la más preocupante. Se realizó una revisión exploratoria de la literatura siguiendo los lineamientos del manual de PRISMA-ScP para revisiones exploratorias. Se redactó un protocolo inicial siguiendo los lineamientos establecidos en el manual de revisiones sistemáticas del JBI. Debido al tipo de revisión, no fue posible registrar el protocolo en la plataforma PROSPERO. Como resultados del proceso de...

Guillain-Barré Syndrome is the most common cause of acute, non-traumatic flaccid paralysis in the... more Guillain-Barré Syndrome is the most common cause of acute, non-traumatic flaccid paralysis in the world. It is a neurological emergency, causing a rapidly progressive polyneuropathy of sudden onset, generally with lower limb and lumbar pain, muscle weakness and paresthesias, progressing into an ascending symmetric paralysis with areflexia. Life-threatening consequences can occur if the respiratory muscles, cranial nerves or components of the autonomic system are compromised. Clinical presentation encompasses seven different subtypes associated with the immune agents involved in its pathophysiology. Diagnosis is based on clinical presentation, with electrophysiological findings comfirming a demyelinating pattern, F wave, and H reflex abnormalities. Cerebrospinal Fluid characteristic findings include albumino-cytological dissociation: an elevated protein level without an increase in cell count.

Revista Mexicana de Urología, 2020

Description: The COVID-19 pandemic poses an unprecedented challenge for urologic oncology and rad... more Description: The COVID-19 pandemic poses an unprecedented challenge for urologic oncology and radiotherapy Radiation oncology departments and international collaboration groups are sharing their management adaptations made in response to the pandemic The present narrative review summarizes the current recommendations Relevance: There is a need to define which patients are candidates for safe treatment delay until the pandemic is over or controlled, to reduce exposure to the virus in the healthcare personnel and patients Conclusions: Telemedicine is recommended for follow-up visits Active surveillance is the preferred treatment for patients with favorable intermediate risk In greater risk disease, hormone therapy safely postpones radiotherapy up to 7 months Radiosurgery is suggested in centers that have the necessary technology and previous experience A moderately hypofractionated regimen is recommended if radiosurgery/ultra-hypofractionation is not available Hypofractionation should...

SBRT may potentially replace HDR brachytherapy. Theoretical advantages include: (1) a shorter lea... more SBRT may potentially replace HDR brachytherapy. Theoretical advantages include: (1) a shorter learning curve; (2) similar radiobiological advantages to HDR; (3) the absence of a need for anesthesia; (4) patient convenience. However, there are limited long-term results and there may be subsets of patients for whom SBRT is contraindicated (e.g. men with a prominent median lobe, those with a neurologic movement disorder) and some insurance companies do not coverage for SBRT. Ideally randomized studies are needed to define the role of SBRT in High Risk patients and answer questions concerning the use of ADT and pelvic RT.

The overall survival of pediatric patients with cancer has steadily improved over the past 40 yea... more The overall survival of pediatric patients with cancer has steadily improved over the past 40 years; This is reflected in the increase in 5-year survival, which in the mid-1970s was 58% and in the early 2000s it became greater than 80% .1 This is mainly due to advances in the different schemes of treatments, which have allowed a large proportion of patients to reach adulthood. However, this increase in survival implies a series of long-term complications, of which the development of second malignancies is the most worrying. An exploratory review of the literature was carried out following the guidelines of the PRISMA-ScP manual for exploratory reviews. An initial protocol was drafted following the guidelines established in the JBI manual of systematic reviews. Due to the type of review, it was not possible to register the protocol on the PROSPERO platform. As a result of the search process, a total of 7696 articles reviewed were identified. After the review process of titles, summar...

Microsatellite instability is caused by an alteration of the mismatch repair systems, which can a... more Microsatellite instability is caused by an alteration of the mismatch repair systems, which can affect microsatellites within the entire human genome, causing errors in their replication. Published studies, mainly in the English literature, have found that some tumors, such as gastric ones, can express microsatellite instability. In this review, a description of the mismatch repair systems and their relationship with the presence of microsatellite instability in gastric tumors is presented, as well as its possible clinical utility, as an associated factor in the response to immunotherapy treatment, in patients with gastric cancer.

International Journal of Radiation Oncology*Biology*Physics

International Journal of Radiation Oncology*Biology*Physics, 2021

International Journal of Radiation Oncology*Biology*Physics, 2021

PURPOSE/OBJECTIVE(S) Cerebral arteriovenous malformations (AVM) are vascular lesions that include... more PURPOSE/OBJECTIVE(S) Cerebral arteriovenous malformations (AVM) are vascular lesions that include aberrant communication between arterial and venous systems. Treatment for AVM is still under debate. Surgery, embolization, observation, and radiosurgery are options for patients. Most data for radiosurgery came from the Gammaknife series. However, low middle-income countries have financial constraints to establish dedicated intracranial neurosurgery machines. We aimed to determine AVM obliteration rate in patients treated with linear accelerator stereotactic radiosurgery (SRS) guided by magnetic resonance imaging and panangiography fusion with computed tomography simulation at a quaternary care institution in Latin America. MATERIALS/METHODS We conducted an observational study with patients treated with SRS at our institution during 2011 and 2017. Exclusion criteria were age younger than 14 and a history of brain cancer. After IRB approval, data were collected retrospectively by reviewing medical records. Patients without available follow-up were contacted to gather missing information. Primary outcome was obliteration rate at 3 years, confirmed by diagnostic imaging (MRI or cerebral panangiography). Secondary outcomes were intracranial bleeding, headaches, epilepsy, and neurological deficits at clinical presentation and after SRS. Analysis included sociodemographic data, AVM characteristics (location and Spetzler-Martin grading), and treatment features. We used descriptive statistics, measures of central tendency and dispersion, and proportions. RESULTS We included 85 patients. The mean age at treatment was 40.8 (14-73), 49.4% of patients were male, and 50.6% female. The most common location was the frontal lobe in 25.9% (n = 22) and the parietal lobe in 24.7% (n = 21). At diagnosis, 44% of patients had a history of intracranial hemorrhage. 49 patients had received previous embolization. The mean dose of radiosurgery was 19.3 Gy (14-25). The mean isodose was 95.25 (80-98). 35.3% of the patients had an AVM Spetzler-Martin grade 2, 40% grade 3, and 12.9% grade 4. We obtained long-term follow-up data for 42 patients, with a median follow-up of 1366 days. The overall obliteration rate was 60%, based primarily on panangiography (59.1%). Symptoms after SRS included headaches (n = 30) and seizures (n = 10). 2 patients presented intracranial bleeding. We contacted all missing patients, but no follow-up data was available for analysis. Most missing patients lived outside the city. CONCLUSION Tri-modality image fusion SRS with linear accelerators for AVM could be a safe and accessible option in low-middle income countries. Health administrator issues, travel distances to access linear accelerators and multidisciplinary teams hinder timely follow-up and surveillance imaging. More prospective data are needed to define the role of SRS for AVMs. AUTHOR DISCLOSURE V. Rangel: None. J. Cure: None. M. Caicedo-Martinez: None. G. Borda: None. C. Lindado: None. E. Castro-Lombana: None. J. Puentes: None. O. Zorro: None. A. González-Motta: None.

La supervivencia global de los pacientes pediátricos con cáncer ha mejorado de manera constante e... more La supervivencia global de los pacientes pediátricos con cáncer ha mejorado de manera constante en los últimos 40 años; esto se ve reflejado en el aumento de la supervivencia a 5 años, la cual a mediados de los 70 era de un 58% y a principios del 2000 llegó a ser mayor del 80%.1 Esto se debe principalmente a avances en los diferentes esquemas de tratamientos, los cuales han permitido que una gran proporción de pacientes alcancen la adultez. Sin embargo, este aumento en la supervivencia implica una serie de complicaciones a largo plazo, de las cuales el desarrollo de segundas neoplasias es la más preocupante. Se realizó una revisión exploratoria de la literatura siguiendo los lineamientos del manual de PRISMA-ScP para revisiones exploratorias. Se redactó un protocolo inicial siguiendo los lineamientos establecidos en el manual de revisiones sistemáticas del JBI. Debido al tipo de revisión, no fue posible registrar el protocolo en la plataforma PROSPERO. Como resultados del proceso de...

Guillain-Barré Syndrome is the most common cause of acute, non-traumatic flaccid paralysis in the... more Guillain-Barré Syndrome is the most common cause of acute, non-traumatic flaccid paralysis in the world. It is a neurological emergency, causing a rapidly progressive polyneuropathy of sudden onset, generally with lower limb and lumbar pain, muscle weakness and paresthesias, progressing into an ascending symmetric paralysis with areflexia. Life-threatening consequences can occur if the respiratory muscles, cranial nerves or components of the autonomic system are compromised. Clinical presentation encompasses seven different subtypes associated with the immune agents involved in its pathophysiology. Diagnosis is based on clinical presentation, with electrophysiological findings comfirming a demyelinating pattern, F wave, and H reflex abnormalities. Cerebrospinal Fluid characteristic findings include albumino-cytological dissociation: an elevated protein level without an increase in cell count.

Revista Mexicana de Urología, 2020

Description: The COVID-19 pandemic poses an unprecedented challenge for urologic oncology and rad... more Description: The COVID-19 pandemic poses an unprecedented challenge for urologic oncology and radiotherapy Radiation oncology departments and international collaboration groups are sharing their management adaptations made in response to the pandemic The present narrative review summarizes the current recommendations Relevance: There is a need to define which patients are candidates for safe treatment delay until the pandemic is over or controlled, to reduce exposure to the virus in the healthcare personnel and patients Conclusions: Telemedicine is recommended for follow-up visits Active surveillance is the preferred treatment for patients with favorable intermediate risk In greater risk disease, hormone therapy safely postpones radiotherapy up to 7 months Radiosurgery is suggested in centers that have the necessary technology and previous experience A moderately hypofractionated regimen is recommended if radiosurgery/ultra-hypofractionation is not available Hypofractionation should...

SBRT may potentially replace HDR brachytherapy. Theoretical advantages include: (1) a shorter lea... more SBRT may potentially replace HDR brachytherapy. Theoretical advantages include: (1) a shorter learning curve; (2) similar radiobiological advantages to HDR; (3) the absence of a need for anesthesia; (4) patient convenience. However, there are limited long-term results and there may be subsets of patients for whom SBRT is contraindicated (e.g. men with a prominent median lobe, those with a neurologic movement disorder) and some insurance companies do not coverage for SBRT. Ideally randomized studies are needed to define the role of SBRT in High Risk patients and answer questions concerning the use of ADT and pelvic RT.

The overall survival of pediatric patients with cancer has steadily improved over the past 40 yea... more The overall survival of pediatric patients with cancer has steadily improved over the past 40 years; This is reflected in the increase in 5-year survival, which in the mid-1970s was 58% and in the early 2000s it became greater than 80% .1 This is mainly due to advances in the different schemes of treatments, which have allowed a large proportion of patients to reach adulthood. However, this increase in survival implies a series of long-term complications, of which the development of second malignancies is the most worrying. An exploratory review of the literature was carried out following the guidelines of the PRISMA-ScP manual for exploratory reviews. An initial protocol was drafted following the guidelines established in the JBI manual of systematic reviews. Due to the type of review, it was not possible to register the protocol on the PROSPERO platform. As a result of the search process, a total of 7696 articles reviewed were identified. After the review process of titles, summar...

Microsatellite instability is caused by an alteration of the mismatch repair systems, which can a... more Microsatellite instability is caused by an alteration of the mismatch repair systems, which can affect microsatellites within the entire human genome, causing errors in their replication. Published studies, mainly in the English literature, have found that some tumors, such as gastric ones, can express microsatellite instability. In this review, a description of the mismatch repair systems and their relationship with the presence of microsatellite instability in gastric tumors is presented, as well as its possible clinical utility, as an associated factor in the response to immunotherapy treatment, in patients with gastric cancer.