Medulloblastoma (MB) is the most common embryonic tumor of the central nervous system, especially among children. Largely giving the credit to technology improvements in diagnosis and risk stratification which now integrate histology classification and molecular classification, MB has become one of the most rapidly advancing tumors in diagnosis and risk stratification. Despite these advances, the prognosis of MB patients has not been proven to be related to gender, race, ethnicity and unfavorable social environment such as low household income, low educational attainment, crowding, language isolation and being part of a new immigrant community. The initial aim of our study, therefore, was to understand these differences and address the issues that should be brought to the attention of health policy makers.
Brain tumors are a major disease that affects a large proportion of the population. At the same time, the brain tumor treatment environment and hospital facilities have put forward great demands, including high-resolution MRI, use of intraoperative monitoring and image guidance, and dedicated postoperative neurocritical ICU. This made the regions which were in poor SES and poor healthcare system could not offer an effective and standardized treatment for patients with brain tumors. In terms of brain tumors, many studies have shown that SES factors were associated with the prognosis of patients. Previous analysis has found a significant link between improved socioeconomic status and glioma, which could lead to different racial or ethnic differences in incidence. QT Ostrom et al’ study found that non-Hispanic whites who were diagnosed with glioblastoma had a poorer prognosis than the rest of the population. This pattern was found in both the era analysis before and after the STUPP protocol in patients receiving post-excision treatment. The potential impact of SES on cancer survival has been investigated for different tumor types in several countries, and community poverty levels have repeatedly been associated with cancer mortality. Higher SES was associated with greater likelihood of surgical resection and improved survival in patients with ovarian cancer. In Finland, the incidence of colon cancer in men with elementary education attainment has a steep increase. In China, SES is an important indicator of thyroid cancer in Hangzhou, and there are spatial differences in its influence.
In terms of gender, there had already reported that MB incidence was significantly higher in male than in female (about 60% male). Meanwhile, there were also differences in gender ratios among different molecular subtypes. However, the underlying relation of gender on the occurrence and prognosis of medulloblastoma has not been clearly studied. Although population-based studies are few, there does not appear to be any substantial difference in MB incidence across ethnic or geographic areas. Our cohort, obtained from the SEER database, had a larger sample size and was widely distributed, which reinforced the representation of individuals with medulloblastoma. Meanwhile, we used PSM to eliminate selection bias, leaving no difference in the baseline data we studied. Consistent with previous results, our multivariate analysis demonstrated that age was a significant factor affecting the prognosis of medulloblastoma in both male and female. For example, WNT-MB tumors rarely metastasized at the time of diagnosis, and patients younger than 16 years had a good prognosis, with 95% patients surviving for more than 5 years. In contrast, adults with WNT-MB may have poorer outcomes. The main reason is that the presence or absence of different molecular, genetic and clinical characteristics is closely related to prognosis. However, infant, childhood and adult MBs represent clinically and biologically distinct groups. Our results also failed to demonstrate an association between the prognosis of medulloblastoma and race. To date, germline mutations in six genes have been associated with a significantly increased risk of medulloblastoma. Nevertheless, germline mutation is closely related to family heredity and population. When genomic research is conducted, it may be necessary to redefine the differences in outcome of ethnic traditions. Yang et al observed that genomic variants co-isolated with native American ancestry were associated with a risk of recurrence of acute lymphoblastic leukemia, even after adjusting for known prognostic factors. Whether the same phenomenon applies to embryonic tumors, such as medulloblastoma, is unclear. Therefore, we could try to interrogate genome-wide germline single-nucleotide poly morphisms in a cohort of patients with MB to investigate the relationship between germline and race.
Survival inequality caused by socioeconomic factors, namely, educational attainment, poverty, unemployed, crowding, language isolation, immigration, insurance status, marital status, residence and median household income, has been well documented for many cancer types in literature. Our multivariate analysis demonstrated unemployed and marital status were important factors affecting the prognosis of medulloblastoma in male. Meanwhile, median household income, residence and insurance status were significant factors affecting the prognosis of medulloblastoma in female. As our study reflected, the downstream mechanisms through which SES influences medulloblastoma are not fully understood. But there is no denying that a country's SES is closely related to the establishment of the medical social security system. In addition to, our results do reflect that insurance status is associated with MB prognosis, regardless of gender. Our findings highlighted the potential gap between recommendations and the reality of access to primary health care, which may be even greater for more vulnerable populations. People living in relatively backward social and economic conditions were more vulnerable to being affected by MB. Children with limited support who face language, insurance, and financial barriers, and as a high incidence of MB, are at the greater risk for treatment failure. Last but not least, even if the child can be treated surgically, the following chemoradiotherapy also posed a great challenge to the economic conditions of the patients' families. Therefore, our study was not only focused on the impact of SES on MB. Moreover, we hoped to provide dedicated analyses and intervention advice to MB diagnosis and treatment through the establishment of a risk model.