A total of 17,226 cases of primary CNS tumors were retrospectively included in this study. The potential relationship between the incidence of primary CNS tumors by age, gender, and anatomical site of both benign and malignant tumors reported from 2003 to 2019 was retrospectively analyzed.
The patients belonged to different regions, although the number of patients in some provinces was limited. The neurosurgery department of Tangdu Hospital has been ranked among the top ten in China for many years and is the largest neurosurgery center in the Northwest China. However, it still belongs to the category of a retrospective analysis with the largest number of cases among the Asian race, which has a certain reference value. The current study revealed that meningioma and tumors of neuroepithelial tissue are the most common primary tumors in the CNS. This is close to the incidence rate reported by many single centers, and CBTRUS [2, 3] which are based on demographic data.
At the same time, there is limited literature discussing the differences between different grades of gliomas as well as the associated biological properties of different anatomical sites [13]. Although the Wang X et al. study on the population in Southwest China described these conclusions, it did not describe the differences between different grades and tumor anatomical sites and the possible reasons [13]. For these reasons, we reviewed the CT/MRI data of all 3,325 cases of tumors of neuroepithelial tissue and noted the invaded anatomical sites. Interestingly, it was found that there were also differences in the sites according to the different grades of tumors of neuroepithelial tissue. Grade 1 tumors of neuroepithelial tissue are more common in the cerebellum, while the incidence rate is lower in the frontal lobe with the largest intracranial anatomy volume. The proportion of the frontal lobe increases with the grade. Further, we found that the most common site of grade 4 tumors of neuroepithelial tissue is the temporal lobe, where the incidence is slightly higher than that of the frontal lobe. Whether this result is related to the difference in neural function between different lobes, the microglia between different lobes, or other factors that may affect the occurrence and development of the tumor, is unknown and needs further detailed research and analysis.
The relationship between the primary CNS tumor and the age of the patients has been reported in many articles. In our data, the CNS tumors' onset age is close to that reported by the CBTRUS. With the passing of diagnosis age, the incidence rate of benign tumors showed a single peak distribution, mostly concentrated in middle-aged patients. This conclusion is consistent with previous reports [9, 19]. Further, we classified and analyzed all the tumor types. The results showed that while the incidence of other tumors increased with the age significantly, the embryonal tumors had a significantly high incidence at the age of 4–7 years. Whether this is related to the impact of development at different ages is unknown, but it is consistent with the data reported by some single centers [20].
Among all patients, there are also significant differences in high-risk tumor types at different age levels. We further divided all patients into children (0–14 years), adolescent and young adults (15–39 years), adults (40–65 years), and older adults (> 65 years). It was found that the incidence of tumors of neuroepithelial tissue increased with age. However, its proportion in different age groups gradually decreased, while the proportion of meningiomas gradually increased in different age groups. This phenomenon is consistent with that reported by the CBTRUS [2, 3].
According to previous reports, the incidence rate of CNS tumors is related to gender. Men are slightly more prone to CNS tumors than women [2, 3]. Our study found that the ratio of men to women was 0.84 in all patients. Further analysis revealed that among all our patients, meningiomas were significantly lower in males than in females, with a ratio of 0.35. Lymphomas, germ cell tumors, embryonal tumors, craniopharyngiomas, mesenchymal tumors, and pituitary adenomas were more frequently reported in males than females. Although there are some differences between this result and the previous literature [2, 3, 7, 8], the conclusion that meningiomas are more common in women is significant, and the proportion of men and women in malignant meningioma is 0.83, which is significantly higher compared to all meningioma patients.
However, there are few shortcomings in this study. First, this study is not based on demographic data;Second, the time span of the included patients is large. The diagnosis can include time-based errors, and the reclassification diagnosis cannot be carried out according to the current diagnostic criteria for various reasons, which has a certain impact on the study and conclusion of the results. Despite the limitations, our study still yielded reliable epidemiological data on CNS tumors in northwest China based on 17,226 samples.
In conclusion, we analyzed a large data set based on a single center and observed the different types, biological properties, and anatomical sites of the CNS tumors as well as the differences according to the patients’ age, gender, region, ethnic, and provided researchers, clinicians and medical insurance policy makers with information on the incidence rate of CNS tumors. As far as we know, this is the largest single-center report on the incidence of CNS tumors. At the same time, we call for more research to focusing on the histological aspects of CNS tumors and cooperation with different institutions to carry out multi-center and large sample size backtracking, and even establish and improve a demographic-based statistical analysis platform, which may have significant socio-economic significance for clarifying the etiology and characteristics of the CNS tumors reported in China.