From 2012 to 2016, the average annual incidence of primary CNS tumors for patients 19 years of age was 6.06 cases per 100,000 people in the USA [4]. Lower incidence rates were reported in other parts of the world, such as Japan (3.61 per 100,000 children) [5], Germany (2.6) [6], Italy (3.46) [7], and Taiwan (1.7) [8]. The reported incidence rate of CNS tumors increased slightly for those 0-19 years of age over the past 30 years in the USA [4, 9, 10]. This increase in the incidence is partly due to the improvements in diagnostic techniques, including magnetic resonance imaging (MRI), which has significantly enhanced the sensitivity of diagnosis [11,12,13]. Therefore, these findings illustrated the importance of the disease surveillance and registry system [11, 14] and reflected the demand for a registry system for CNS tumors among children (based on populations or hospitals) in China. Previous studies showed that pediatric intracranial tumors were more common in males [15,16,17,18]. We found a 1.47: 1 male-to-female ratio, indicating that male children were more likely to be affected, like previous literature reports. This predominance among male children was most evident in anaplastic ependymoma and medulloblastoma. However, there was a slightly higher incidence in female children in our study than in the study conducted in Beijing Tiantan Hospital from 2001 to 2005 [15].
Most of the pathological tumor types described in the 2016 WHO classification was observed in this retrospective study, demonstrating the diversity of CNS tumors among children. Studies have reported that the pathological types of intracranial tumors in children are different from those in adults. Meningiomas, pituitary tumors, and malignant gliomas are the most common types of adult intracranial tumors [19], whereas our study showed that craniopharyngioma was the most frequent type of intracranial tumor in children. Common intracranial tumors also included medulloblastoma, pilocytic astrocytoma, diffuse astrocytoma, and anaplastic ependymoma; the prevalence of these tumors herein was slightly different than those reported in other countries [4, 6, 7]. The most notable aspect of this study is the prevalence of GCTs, mostly observed in pediatric patients in Asia [20, 21]. However, during the period from 2015 to 2019, only 37 children were diagnosed with pure germinomas (1.16%) and treated with surgical resection. These data do not indicate a significant reduction in the prevalence of germinomas but rather improvements in the diagnosis and treatment of these tumors over the last two decades. Germinomas are extremely sensitive to radiotherapy, and a complete response could be achieved with radiotherapy alone in most cases [22, 23]; thus, pediatric patients with germinoma are more likely to avoid surgery except in emergency situations.
The overall data regarding age and tumor location showed that tumors were more commonly found in the supratentorial region than the infratentorial region in each age group. The largest difference was observed in the 13-15-year-old group. However, the most common intracranial tumors are found in the infratentorial region (except craniopharyngioma, which originates only in the sellar region). In the group aged 7-9 years old, infratentorial tumors accounted for the highest proportion, which may be due to the high incidence of medulloblastoma. An analysis of tumor grade and children’s age showed that most high-grade and low-grade tumors were found in children aged 4-6 years old, and the majority of tumors in each age group were low grade. This illustrated that the peak age of children with intracranial tumors is younger than in previous studies [15].
Regarding province and year distribution in childhood intracranial tumors, although the patients were from almost all the country’s provincial districts, they were not distributed evenly. Shandong Province and Hebei Province had the most pediatric patients, while Hong Kong and the Tibet Autonomous Region had the fewest patients. These results were related to the distance from Beijing, the level of medical care, and the economic level in the location of the patients. The overall trend over the 5-year period was not obvious. The number of patients was the largest in 2017, while there was a small decline in 2019. This trend may be related to the continuous development of medical criteria in various regions over recent years.
The research suggested that the CNS tumors are still one of the most important factors affecting children’s lives. Differences in age, region, and ethnicity may be potential factors affecting the pathological type and incidence rate of intracranial tumors in children [4, 10]. Among the top five most common types of intracranial tumors in this research, the majority were low-grade tumors, and the ratio of low-grade tumors to high-grade tumors was 1.94: 1 (1136/585). Among these intracranial tumors, craniopharyngioma, pilocytic astrocytoma, and diffuse astrocytoma are all low-grade tumors. This finding was related to the polymorphism of children’s tumor genes and the location of tumor origins [24]. Due to the popularization of neuroimaging technologies [13, 24], children with intracranial brain tumors can be diagnosed and treated earlier and more precisely; however, the prognosis and quality of life of children still need to be further analyzed.
Based on these findings, we are looking forward to multicenter and multidisciplinary collaborative research. Combining domestic regional characteristics to establish the disease surveillance and registry system and to improve epidemiological follow-up practices will be significant for the diagnosis and treatment of intracranial tumors among children in China.
