O6-methylguanine DNA methyltransferase(MGMT) gene promoter methylation plays an important role in colorectal carcinogenesis, occurring in about 30%-40% of metastatic colorectal cancer. Its prognostic role has not been...O6-methylguanine DNA methyltransferase(MGMT) gene promoter methylation plays an important role in colorectal carcinogenesis, occurring in about 30%-40% of metastatic colorectal cancer. Its prognostic role has not been defined yet, but loss of expression of MGMT, which is secondary to gene promoter methylation, results in an interesting high response to alkylating agents such as dacarbazine and temozolomide. In a phase 2 study on heavily pre-treated patients with MGMT methylated metastatic colorectal cancer, temozolomide achieved about 30% of disease control rate. Activating mutations of RAS or BRAF genes as well as mismatch repair deficiency may represent mechanisms of resistance to alkylating agents, but a dose-dense schedule of temozolomide may potentially restore sensitivity in RAS-mutant patients. Further development of temozolomide in MGMT methylated colorectal cancer includes investigation of synergic combinations with other agents such as fluoropyrimidines and research for additional biomarkers, in order to better define the role of temozolomide in the treatment of individual patients.展开更多
Exocrine pancreatic neoplasms represent up to 95%of pancreatic cancers(PCs)and are widely recognized among the most lethal solid cancers,with a very poor 5-year survival rate of 5%-10%.The remaining<5%of PCs are ne...Exocrine pancreatic neoplasms represent up to 95%of pancreatic cancers(PCs)and are widely recognized among the most lethal solid cancers,with a very poor 5-year survival rate of 5%-10%.The remaining<5%of PCs are neuroendocrine tumors that are usually characterized by a better prognosis,with a median overall survival of 3.6 years.The most common type of PC is pancreatic ductal adenocarcinoma(PDAC),which accounts for roughly 85%of all exocrine PCs.However up to 10%of exocrine PCs have rare histotypes,which are still poorly understood.These subtypes can be distinguished from PDAC in terms of pathology,imaging,clinical presentation and prognosis.Additionally,due to their rarity,any knowledge regarding these specific histotypes is mostly based on case reports and a small series of retrospective analyses.Therefore,treatment strategies are generally deduced from those used for PDAC,even if these patients are often excluded or not clearly represented in clinical trials for PDAC.For these reasons,it is essential to collect as much information as possible on the management of PC,as assimilating it with PDAC may lead to the potential mistreatment of these patients.Here,we report the most significant literature regarding the epidemiology,typical presentation,possible treatment strategies,and prognosis of the most relevant histotypes among rare PCs.展开更多
文摘O6-methylguanine DNA methyltransferase(MGMT) gene promoter methylation plays an important role in colorectal carcinogenesis, occurring in about 30%-40% of metastatic colorectal cancer. Its prognostic role has not been defined yet, but loss of expression of MGMT, which is secondary to gene promoter methylation, results in an interesting high response to alkylating agents such as dacarbazine and temozolomide. In a phase 2 study on heavily pre-treated patients with MGMT methylated metastatic colorectal cancer, temozolomide achieved about 30% of disease control rate. Activating mutations of RAS or BRAF genes as well as mismatch repair deficiency may represent mechanisms of resistance to alkylating agents, but a dose-dense schedule of temozolomide may potentially restore sensitivity in RAS-mutant patients. Further development of temozolomide in MGMT methylated colorectal cancer includes investigation of synergic combinations with other agents such as fluoropyrimidines and research for additional biomarkers, in order to better define the role of temozolomide in the treatment of individual patients.
文摘Exocrine pancreatic neoplasms represent up to 95%of pancreatic cancers(PCs)and are widely recognized among the most lethal solid cancers,with a very poor 5-year survival rate of 5%-10%.The remaining<5%of PCs are neuroendocrine tumors that are usually characterized by a better prognosis,with a median overall survival of 3.6 years.The most common type of PC is pancreatic ductal adenocarcinoma(PDAC),which accounts for roughly 85%of all exocrine PCs.However up to 10%of exocrine PCs have rare histotypes,which are still poorly understood.These subtypes can be distinguished from PDAC in terms of pathology,imaging,clinical presentation and prognosis.Additionally,due to their rarity,any knowledge regarding these specific histotypes is mostly based on case reports and a small series of retrospective analyses.Therefore,treatment strategies are generally deduced from those used for PDAC,even if these patients are often excluded or not clearly represented in clinical trials for PDAC.For these reasons,it is essential to collect as much information as possible on the management of PC,as assimilating it with PDAC may lead to the potential mistreatment of these patients.Here,we report the most significant literature regarding the epidemiology,typical presentation,possible treatment strategies,and prognosis of the most relevant histotypes among rare PCs.
