The incidence of CNS tumors is an important subject that could be affected of environmental and many other disparities which are inadequately understood [13]. Concerning to ethnic and racial consideration, brain tumors are less common in Asian Americans when compared with Whites in the USA and UK [1].
During this investigation, the overall PP for brain and other nervous system tumors was 20.9 per 100,000. This value is higher than the reported incidence of 15.5 cases per 100,000 in Gironde/France [13] and lower than the reported incidence of 22.4 cases per 100,000 in the USA [14].
In agreement with previous publication [14] that mentioned males not only develop more cancers but also they frequently have poorer responses to therapy as measured by event-free and overall survival, in this study, the PP for males was 1.4 times higher than females (24.5 versus 17.2 per 100,000). A study performed in the USA confirmed a higher incident for females when compared to males (24.5 versus 20 per 100,000) [14].
However, in this study there was an increase in incidence associated to both genders from 4.2 to 5.7 (35.7%) per 100,000 persons from 2011 to 2015, but related to each gender there was a 31.6% increase in females and 22% decrease in males’ tumors of the brain and other nervous system incidence.
In the 71% of the population studied in here, the highest incidence of CNS tumors was found in the age between 20 and 70 years old. This is in agreement with previous publication which confirms an incidence in most CNS tumors with age until the seventh decade [15,16,17,18,19,20,21,22,23,24,25,26,27].
Brain tumors are defined as neoplasms of the brain parenchyma [16, 17]; the results obtained from this study showed that the higher episode of brain and other nervous system tumors was associated to the brain (63%). Previous publication reported an overall incidence rate of all brain tumors as 10.82 per 100,000 person-years. The incidence proportion estimates were heterogeneous, even among the same tumor subtypes, and ranged from 0.051 per 100,000 (germ cell tumors) to 25.48 per 100,000 (all brain tumors) [4, 14].
As a previous publication confirmed that Iran is experiencing the increasing burden of cancers, which are currently the third leading cause of mortality in Iran [18], in this study, there was 56% recorded deaths due to tumors of the brain and other nervous system. The changing trend in mortality of cancer has also been studied in the UK. It seems that in 2011, the age-standardized mortality rate for cancer exceeded that of cardiovascular disease in both sexes [19].