Epidemiological studies are required to determine risk factors. Aside from exposure to vinyl chloride or ionizing radiation, there are no known environmental factors associated with brain tumors. Mutations and deletions of so-called tumor suppressor genes, such as P53, are thought to be the cause of some forms of brain tumor. Inherited conditions, such as Von Hippel–Lindau disease, multiple endocrine neoplasia, and neurofibromatosis type 2 carry a high risk for the development of brain tumors. People with celiac disease have a slightly increased risk of developing brain tumors.

Although studies have not shown any link between cell phone or mobile phone radiation and the occurrence of brain tumors, the World Health Organization has classified mobile phone radiation on the IARC scale into Group 2B – possibly carcinogenic. Discounting claims that current cell phone usage may cause brain cancer, modern, third-generation (3G) phones emit, on average, about 1% of the energy emitted by the GSM (2G) phones that were in use when epidemiological studies that observed a slight increase in the risk for glioma – a malignant type of brain cancer – among heavy users of wireless and cordless telephones were conducted.

Brain, other CNS or intracranial tumors are the ninth most common cancer in the UK (around 10,600 people were diagnosed in 2013), and it is the eighth most common cause of cancer death (around 5,200 people died in 2012).

An estimated 3% of pediatric brain tumors are AT/RTs, although this percentage may increase with better differentiation between PNET/medulloblastoma tumors and AT/RTs.

As with other CNS tumors, more males are affected than females (ratio 1.6:1). The ASCO study showed a 1.4:1 male to female ratio.

Metastatic spread is noted in roughly one-third of the AT/RT cases at the time of diagnosis, and tumors can occur anywhere throughout the CNS. The ASCO study of the 188 documented AT/RT cases prior to 2004 found 30% of the cases had metastasis at diagnosis. Metastatic spread to the meninges (leptomenigeal spread sometimes referred to as sugar coating) is common both initially and with relapse. Average survival times decline with the presence of metastasis. Primary CNS tumors generally metastasize only within the CNS.

One case of metastatic disease to the abdomen via ventriculoperitoneal shunt has been reported with AT/RT . Metastatic dissemination via this mechanism has been reported with other brain tumors, including germinomas, medulloblastomas, astrocytomas, glioblastomas, ependymomas, and endodermal sinus tumors. Guler and Sugita separately reported cases of lung metastasis without a shunt.

Papillary tumors of pineal region are extremely rare, constituting 0.4-1% of all central nervous system tumors. These tumors most commonly occur in adults with the mean age being 31.5. There have been cases reported for people between the ages 5 to 66 years. There is a slight predominance of females who have these tumors.

Pineoblastoma (also pinealoblastoma) is a malignant tumor of the pineal gland. A pineoblastoma is a supratentorial midline primitive neuroectodermal tumor.

Pineoblastoma may occur in patients with hereditary uni- or bilateral retinoblastoma. When retinoblastoma patients present with pineoblastoma this is characterized as "trilateral retinoblastoma". Up to 5% of patients with hereditary retinoblastoma are at risk of developing trilateral retinoblastoma. Prognosis of patients with trilateral retinoblastoma is dismal, only a few patients have survived more than 5 years after diagnosis; all survivors were diagnosed with small tumors in a subclinical stage. Recent advances in (high-dose) chemotherapy treatment regimens and early detection have improved survival of patients with trilateral retinoblastoma to up to 50%.

Primitive neuroectodermal tumor (PNET) is a malignant (cancerous) neural crest tumor. It is a rare tumor, usually occurring in children and young adults under 25 years of age. The overall 5 year survival rate is about 53%.

It gets its name because the majority of the cells in the tumor are derived from neuroectoderm, but have not developed and differentiated in the way a normal neuron would, and so the cells appear "primitive".

PNET belongs to the Ewing family of tumors.

A germinoma is a type of germ cell tumor, which is not differentiated upon examination. It may be benign or malignant.

Dysgerminoma is the most common type of malignant germ cell ovarian cancer. Dysgerminoma usually occurs in adolescence and early adult life; about 5% occur in pre-pubertal children. Dysgerminoma is extremely rare after age 50. Dysgerminoma occurs in both ovaries in 10% of patients and, in a further 10%, there is microscopic tumor in the other ovary.

Seminoma is the second most common testicular cancer; the most common is mixed, which may contain seminoma.

Abnormal gonads (due to gonadal dysgenesis and androgen insensitivity syndrome) have a high risk of developing a dysgerminoma. Most dysgerminomas are associated with elevated serum lactic dehydrogenase (LDH), which is sometimes used as a tumor marker.

Metastases are most often present in the lymph nodes.

It is classified into two types, based on location in the body: peripheral PNET and CNS PNET.

Trilateral retinoblastoma (TRb) is a malignant midline primitive neuroectodermal tumor occurring in patients with inherited uni- or bilateral retinoblastoma. In most cases trilateral retinoblastoma presents itself as pineoblastoma (pineal TRb). In about a fourth of the cases the tumor develops in another intracranial region, most commonly supra- or parasellar (non-pineal TRb), but there are reported cases with non-pineal TRb in the 3rd ventricle. In most cases pineal TRb is diagnosed before the age of 5, but after the diagnosis of retinoblastoma. Non-pineal TRb, however, is often diagnosed simultaneous with retinoblastoma. Prognosis of patients with trilateral retinoblastoma is dismal, only a few patients have survived more than 5 years after diagnosis; all survivors were diagnosed with small tumors in a subclinical stage. Recent advances in (high-dose) chemotherapy treatment regimens and early detection have improved survival of patients with trilateral retinoblastoma.

Because of the rarity of these tumors, there is still a lot of unknown information. There are many case studies that have been reported on patients who have been diagnosed with this specific type of tumor. Most of the above information comes from the findings resulting from case studies.

Since Papillary Tumors of the Pineal Region were first described in 2003, there have been seventy cases published in the English literature. Since there is such a small number of cases that have been reported, the treatment guidelines have not been established. A larger number of cases that contain a longer clinical follow-up are needed to optimize the management of patients with this rare disease.

Even though there is a general consensus on the morphology and the immunohistochemical characteristics that is required for the diagnosis, the histological grading criteria have yet to be fully defined and its biological behavior appears to be variable. This specific type of tumor appears to have a high potential for local recurrence with a high tumor bed recurrence rate during the five years after the initial surgery. This suggests the need for a tumor bed boost radiotherapy after surgical resection.

As stated above, the specific treatment guidelines have not yet been established, however, gross total resection of the tumor has been the only clinical factor associated overall and progression-free survival. The value of radiotherapy as well as chemotherapy on disease progression will need to be investigated in future trials. With this information, it will provide important insight into long-term management and may further our understanding of the histologic features of this tumor.

In the developed world, retinoblastoma has one of the best cure rates of all childhood cancers (95-98%), with more than nine out of every ten sufferers surviving into adulthood. In the UK, around 40 to 50 new cases are diagnosed each year.

Good prognosis depends upon early presentation of the child in health facility. Late presentation of the child in hospital is associated with poor prognosis.

Survivors of hereditary retinoblastoma have a higher risk of developing other cancers later in life.

Somatic amplification of the MYCN oncogene is responsible for some cases of non-hereditary, early-onset, aggressive, unilateral retinoblastoma. Although MYCN amplification accounted for only 1.4% of retinoblastoma cases, researchers identified it in 18% of infants diagnosed at less than 6 months of age. Median age at diagnosis for MYCN retinoblastoma was 4.5 months, compared with 24 months for those who had non-familial unilateral disease with two RB1 gene mutations.

Dysgerminomas, like other seminomatous germ cell tumors, are very sensitive to both chemotherapy and radiotherapy. For this reason, with treatment patients' chances of long-term survival, even cure, is excellent.

A dysgerminoma is a type of germ cell tumor; it usually is malignant and usually occurs in the ovary.

A tumor of the identical histology but not occurring in the ovary may be described by an alternate name: seminoma in the testis or germinoma in the central nervous system or other parts of the body.

Dysgerminoma accounts for less than 1% of ovarian tumors overall. Dysgerminoma usually occurs in adolescence and early adult life; about 5% occur in pre-pubertal children. Dysgerminoma is extremely rare after age 50. Dysgerminoma occurs in both ovaries in 10% of patients and, in a further 10%, there is microscopic tumor in the other ovary.

Abnormal gonads (due to gonadal dysgenesis and androgen insensitivity syndrome) have a high risk of developing a dysgerminoma. Most dysgerminomas are associated with elevated serum lactic dehydrogenase (LDH), which is sometimes used as a tumor marker.

Pineocytoma, also known as a pinealocytoma, is a benign, slowly growing tumor of the pineal gland. Unlike the similar condition pineal gland cyst, it is uncommon.

While cancer is generally considered a disease of old age, children can also develop cancer. In contrast to adults, carcinomas are exceptionally rare in children..

The two biggest risk factors for ovarian carcinoma are age and family history.

The 1997 International Germ Cell Consensus Classification is a tool for estimating the risk of relapse after treatment of malignant germ cell tumor.

A small study of ovarian tumors in girls reports a correlation between cystic and benign tumors and, conversely, solid and malignant tumors. Because the cystic extent of a tumor can be estimated by ultrasound, MRI, or CT scan before surgery, this permits selection of the most appropriate surgical plan to minimize risk of spillage of a malignant tumor.

Access to appropriate treatment has a large effect on outcome. A 1993 study of outcomes in Scotland found that for 454 men with non-seminomatous (non-germinomatous) germ cell tumors diagnosed between 1975 and 1989, 5-year survival increased over time and with earlier diagnosis. Adjusting for these and other factors, survival was 60% higher for men treated in a cancer unit that treated the majority of these men, even though the unit treated more men with the worst prognosis.

Choriocarcinoma of the testicles has the worst prognosis of all germ cell cancers

Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis. Others hypothesize a widespread distribution of germ cells to multiple sites during normal embryogenesis, with these cells conveying genetic information or providing regulatory functions at somatic sites.

Extragonadal germ cell tumors were thought initially to be isolated metastases from an undetected primary tumor in a gonad, but it is now known that many germ cell tumors are congenital and originate outside the gonads. The most notable of these is sacrococcygeal teratoma, the single most common tumor diagnosed in babies at birth.

Of all anterior mediastinal tumors, 15–20% are germ cell tumors of which approximately 50% are benign teratomas.

Spermatocytic seminomas are not considered a subtype of seminoma and unlike other germ cell tumours do not arise from intratubular germ cell neoplasia.

Seminoma (also known as "pure seminoma" or "classical seminoma") is a germ cell tumor of the testicle or, more rarely, the mediastinum or other extra-gonadal locations. It is a malignant neoplasm and is one of the most treatable and curable cancers, with a survival rate above 95% if discovered in early stages.

Testicular seminoma originates in the germinal epithelium of the seminiferous tubules. About half of germ cell tumors of the testicles are seminomas. Treatment usually requires removal of one testicle. However, fertility usually isn't affected. All other sexual functions will remain intact.

Sebaceous carcinoma is an uncommon and aggressive malignant cutaneous tumor. Most are typically about 10 mm in size at presentation. This neoplasm is thought to arise from sebaceous glands in the skin and, therefore, may originate anywhere in the body where these glands are found. Because the periocular region is rich in this type of gland, this region is a common site of origin. The cause of these lesions are, in the vast majority of cases, unknown. Occasional cases may be associated with Muir-Torre syndrome.

This type of cancer usually has a poor prognosis because of a high rate of metastasis.

Adenoid cystic carcinoma (sometimes referred to as adenocyst, malignant cylindroma, adenocystic, adenoidcystic, ACC or AdCC.) is a rare type of cancer that can exist in many different body sites. This tumor most often occurs in the salivary glands, but it can also be found in many anatomic sites, including the breast, lacrimal gland, lung, brain, bartholin gland, trachea, and the paranasal sinuses.

It is the third most common malignant salivary gland tumor overall (after mucoepidermoid carcinoma and polymorphous low grade adenocarcinoma). It represents 28% of malignant submandibular gland tumors, making it the single most common malignant salivary gland tumor in this region. Patients may survive for years with metastases because this tumor is generally well-differentiated and slow growing. In a 1999 study of a cohort of 160 ACC patients, disease specific survival was 89% at 5 years but only 40% at 15 years, reflecting deaths from late-occurring metastatic disease.

Pineocytomas are diagnosed from tissue, i.e. a brain biopsy.

They consist of:

- cytologically benign cells (with nuclei of uniform size, regular nuclear membranes, and light chromatin) and,

- have the characteristic pineocytomatous/neurocytic rosettes, which is an irregular circular/flower-like arrangement of cells with a large meshwork of fibers (neuropil) at the centre.

Pineocytomatous/neurocytic rosettes are superficially similar to Homer Wright rosettes; however, they differ from Homer Wright rosettes as they have (1) more neuropil at centre of the rosette and, (2) the edge of neuropil meshwork irregular/undulating.