Glioblastoma – or GBM – has long been known to differ in incidence and survival between sexes. A new study, however, provides evidence that sex also impacts how the tumor responds to treatment.
Women are less likely to develop brain cancer, and they live longer than men with the same type of tumor. This is a significant finding.
Incidence
There are a number of factors that influence brain tumor development. They include age, gender, and the type of brain tumor. The likelihood of developing a brain tumor increases with age. It is also more common in males than females, though this difference is not as great as it is for other diseases that affect men and women at different rates, such as heart disease or certain types of cancer.
The incidence of a brain tumor is also affected by a person’s location in the world and his or her socioeconomic status. For example, there are many regions of the world that have high incidence rates of brain tumors while others have lower rates. Some of these regions have lower human development indexes, which are determined by a country’s level of life expectancy, education, and standard of living. These countries may have difficulty providing adequate screening, accurate diagnosis, and proper treatment for people with brain tumors.
In addition to these factors, a person’s family history can influence the risk of a brain or other central nervous system (CNS) tumor. About 5% of brain tumor causes are linked to hereditary genetic conditions, such as Li-Fraumeni syndrome, neurofibromatosis, nevoid basal cell carcinoma syndrome, tuberous sclerosis, and von Hippel-Lindau disease. Some brain tumors have been found to occur in “clusters” within families, although the cause of these clusters is not known.
A new study, published in CA: A Cancer Journal for Clinicians, looked at incidence and survival data on malignant and non-malignant brain tumors in the United States over a 18-year period from 2000 to 2017. The researchers used information from the Central Brain Tumor Registry of the United States and the Surveillance, Epidemiology, and End Results program.
The findings of the study showed that the overall incidence rate for brain and other CNS tumors decreased 0.8% per year over the 18-year period. However, the researchers also noted that there was a modest increase in incidence for some tumor histologies, including oligodendroglioma, astrocytoma not otherwise specified, and anaplastic astrocytoma. The researchers speculate that this could be due to improved diagnostic technologies and ascertainment, but more research is needed.
Prognosis
Glial tumors are a diverse group of cancers that affect the brain, spinal cord and nerves. They can be benign or malignant, and they are found at any age from infants to the elderly. They typically arise when cells in the brain are damaged by chromosome mutations, which may be the result of inherited gene defects or environmental damage.
Glioblastoma multiforme, or glioblastoma (GBM), is the most common and fastest growing of these glial tumors. Researchers are investigating ways to improve diagnosis, treatment and prognosis for people with this type of brain tumor.
Scientists have found that people with a specific genetic variant are at higher risk for developing certain types of glial brain tumors, particularly GBM and anaplastic astrocytoma. Those with a higher genetic risk of developing these types of brain tumors have a more difficult time recovering from surgery and are more likely to die from the disease than people without the same variant.
A new study by researchers at City of Hope affiliate Translational Genomics Research Institute (TGen) and external collaborators examined the incidence and survival of almost 295,000 patients with primary brain and central nervous system cancers, including gliomas. The study, which was published Aug. 18 in Neurosurgery, analyzed data from the nation’s largest population-based cancer registry, the Central Brain Tumor Registry of the United States (CBTRUS), for a specific set of tumor subtypes that included all glioma types except meningioma and pituitary tumors.
TGen’s analysis demonstrated that both sex and age impact the incidence of glioma at different ages, depending on which glioma subtype is being studied. The sex-related impact is independent of the effects of circulating sex hormones, suggesting that there are biological factors at play.
The study also shows that sex, when taken into account with age, significantly impacts the prognosis of a patient with a glioma at any given age. This can help doctors identify which patients will do best with the standard of care, and provide individualized treatment for each patient. However, it’s important to remember that the 1- and 5-year figures are averages, and don’t tell us anything about a specific person’s chance of survival.
Treatment
The treatment options for brain tumors depend on the type and grade of the tumor; whether it has spread; your age, general health and other medical conditions; and what the tumor is caused by. The goal of treatment may be to cure the cancer or relieve symptoms (palliative care). Treatment often includes surgery, radiation therapy and chemotherapy.
Benign tumors are slow-growing and unlikely to spread, while malignant brain cancers can grow quickly and invade nearby structures in the brain and spinal cord. Secondary brain tumors, or metastases, are also common. They can be the result of primary cancers that have spread from other parts of the body, such as lung, breast, colorectal and kidney cancer. These cancers tend to affect younger people, and men more often than women.
Glioma is the most common malignant brain tumor, and researchers have found that its incidence and survival rates are affected by both age and sex. While previous studies have looked at sex and age separately, this study was the first to investigate their combined effect. The researchers from City of Hope affiliate Translational Genomics Research Institute (TGen) and other external collaborators examined MRI results, genetic profiles of tumors and survival data from patients with glioblastoma multiforme.
They found that the overall incidence of gliomas is higher in males, and that difference increases with age. Females have longer survival at almost every age, except for children up to 9 years old. The authors of this study are exploring why this is the case.
These findings are important for developing future strategies to reduce the impact of gliomas on people’s lives. They may help guide the development of more effective treatments for this difficult to treat disease.
Other factors that can affect the risk of brain tumors include a person’s lifestyle, the environment and socioeconomic developments. For example, the likelihood of brain tumors is much higher in developed countries than in low- and middle-income nations. This is likely due to higher levels of industrialization, which increase the exposure to biological hazards and toxins that can contribute to cancers such as brain tumors.
Prevention
The cause of most brain tumors isn’t known, but doctors have identified some factors that raise a person’s risk for developing one. These include age (most brain tumors happen in adults), a family history of hereditary genetic conditions and certain types of cancer that can spread to the brain, such as melanoma or lung cancer.
People of all ages can get brain tumors, but some occur mostly in older adults, while others happen most often in children. In general, malignant (cancerous) brain tumors grow more quickly and are more likely to spread to other parts of the body than benign (non-cancerous) brain tumors. Glioblastomas are the most common type of primary brain tumor. They begin in cells that support neurons and can lead to a mass that presses on and damages nearby brain tissue.
Researchers at City of Hope affiliate Translational Genomics Research Institute and external collaborators analyzed cancer registry data from 81 countries to better understand why the incidence of a brain tumor correlates with sex and age. The team compared the entire genetic code of thousands of people with brain tumors to similar numbers of healthy controls. This approach, called genomic epidemiology, increases the chances that researchers will find something in the genome of a tumor that could help prevent or treat it.
In this case, they looked at the genes of nearly 295,000 patients with a malignant tumor originating in the brain or central nervous system. The majority of these tumors were gliomas, which can also include pituitary tumors and craniopharyngiomas. Gliomas were more common in males than females at every age, and in both younger and older adults. Males were also more likely to die from these tumors than females, regardless of their age at diagnosis.
Meningiomas, a non-cancerous type of brain tumor, are twice as common in women as they are in men. These and other differences in the rates of different types of brain tumors can be explained by the fact that sex-specific proteins, such as retinoblastoma protein (RB), are less active in male brain cells than they are in female ones.
