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.

Regardless of location, all rhabdoid tumours are highly aggressive, have a poor prognosis, and tend to occur in children less than two years of age.

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.

Patients who have been diagnosed with ARMS often have poor outcomes. The four year survival rate without remission for local ARMS tumors is 65 percent, while the four year survival rate with metastatic ARMS is only 15 percent. Patients who have metastatic ARMS positive with PAX3-FOXO1 fusion often have a poorer outcome than patients positive with PAX7-FOXO1 fusion, with a four-year survival rate of 8 percent and 75 percent respectively. Other variables affect the four year survival rate, such as, primary tumor site, size of primary tumor, amount of local invasion, number of distal lymph nodes spread to, and whether metastasis has occurred. Prognosis for patients who have primary tumor sites within the bones often have higher survival rates and respond well to treatment options. While patients who have primary tumor sites within the nasopharynx region with metastases to the breast have very poor outcomes. Patients who are fusion protein negative with low risk clinical features should be treated with reduced therapy, while patients who are fusion protein positive with low risk clinical features should be treated as an intermediate risk and have more intensive therapy regimens.

Malignant rhabdoid tumour (MRT) is a very aggressive form of tumour originally described as a variant of Wilms' tumour, which is primarily a kidney tumour that occurs mainly in children.

MRT was first described as a variant of Wilms' tumour of the kidney in 1978. MRTs are a rare and highly malignant childhood neoplasm. Later rhabdoid tumours outside the kidney were reported in many tissues including the liver, soft tissue, and the central nervous system. Several cases of primary intracranial MRT have been reported since its recognition as a separate entity in 1978. The term "rhabdoid" was used due to its similarity with rhabdomyosarcoma under the light microscope. The exact pathogenesis of MRT is unknown.

The cerebellum is the most common location for primary intracerebral MRT (i.e., AT/RT). Biggs et al. were first to report a primary intracranial MRT around 1987.

Although the cell of origin is not known, cytogenetic studies have suggested a common genetic basis for rhabdoid tumours regardless of location with abnormalities in chromosome 22 commonly occurring.

Based on a series of 493 neuroblastoma samples, it has been reported that overall genomic pattern, as tested by array-based karyotyping, is a predictor of outcome in neuroblastoma:

- Tumors presenting exclusively with whole chromosome copy number changes were associated with excellent survival.

- Tumors presenting with any kind of segmental chromosome copy number changes were associated with a high risk of relapse.

- Within tumors showing segmental alterations, additional independent predictors of decreased overall survival were N-myc amplification, 1p and 11q deletions, and 1q gain.

Earlier publications categorized neuroblastomas into three major subtypes based on cytogenetic profiles:

- Subtype 1: favorable neuroblastoma with near triploidy and a predominance of numerical gains and losses, mostly representing non-metastatic NB stages 1, 2 and 4S.

- Subtypes 2A and 2B: found in unfavorable widespread neuroblastoma, stages 3 and 4, with 11q loss and 17q gain without N-myc amplification (subtype 2A) or with N-myc amplification often together with 1p deletions and 17q gain (subtype 2B).

Virtual karyotyping can be performed on fresh or paraffin-embedded tumors to assess copy number at these loci. SNP array virtual karyotyping is preferred for tumor samples, including neuroblastomas, because they can detect copy neutral loss of heterozygosity (acquired uniparental disomy). Copy neutral LOH can be biologically equivalent to a deletion and has been detected at key loci in neuroblastoma. ArrayCGH, FISH, or conventional cytogenetics cannot detect copy neutral LOH.

Neuroblastoma comprises 6–10% of all childhood cancers, and 15% of cancer deaths in children. The annual mortality rate is 10 per million children in the 0- to 4-year-old age group, and 4 per million in the 4- to 9-year old age group.

The highest incidence is in the first year of life, and some cases are congenital. The age range is broad, including older children and adults, but only 10% of cases occur in people older than 5 years of age. A large European study reported less than 2% of over 4000 neuroblastoma cases were over 18 years old.

Use of telomerase inhibitors such as Imetelstat seem to have very low toxicity compared to other chemotherapy. The only known side effect of most telomerase inhibitors is dose-induced neutropenia. Neuropsychological deficits can result from resection, chemotherapy, and radiation, as well as endocrinopathies. Additionally, an increase in gastrointestinal complications has been observed in survivors of pediatric cancers.

The age-standardized 5-year relative survival rate is 23.6%. Patients with this tumor are 46 times more likely to die than matched members of the general population. It is important to note that prognosis across age groups is different especially during the first three years post-diagnosis. When the elderly population is compared with young adults, the excess hazard ratio (a hazard ratio that is corrected for differences in mortality across age groups) decreases from 10.15 to 1.85 at 1 to 3 years, meaning that the elderly population are much more likely to die in the first year post-diagnosis when compared to young adults (aged 15 to 40), but after three years, this difference is reduced markedly.

Typical median survival for anaplastic astrocytoma is 2–3 years. Secondary progression to glioblastoma multiforme is common. Radiation, younger age, female sex, treatment after 2000, and surgery were associated with improved survival in AA patients.

Although reliable and comprehensive incidence statistics are nonexistent, LCLC-RP is a rare tumor, with only a few hundred cases described in the scientific literature to date. LCLC's made up about 10% of lung cancers in most historical series, equating to approximately 22,000 cases per year in the U.S. Of these LCLC cases, it is estimated that about 1% will eventually develop the rhabdoid phenotype during tumor evolution and progression. In one large series of 902 surgically resected lung cancers, only 3 cases (0.3%) were diagnosed as LCLC-RP. In another highly selected series of large-cell lung carcinoma cases, only 4 of 45 tumors (9%) were diagnosed as the rhabdoid phenotype using the 10% criterion, but another 10 (22%) had at least some rhabdoid cell formation. It appears likely, therefore, that LCLC-RP probably comprises between 0.1% and 1.0% of all lung malignancies.

Similar to nearly all variants of lung carcinoma, large cell lung carcinoma with rhabdoid phenotype appears to be highly related to tobacco smoking. It also appears to be significantly more common in males than in females.

Childhood rhabdomyosarcoma has been fatal. Recovery rates have increased by 50 percent since 1975. In children five years of age or younger survival rates are up to 65 percent. In adolescents younger than 15 years old, the survival rate has increased up to 30 percent.

The 5-year disease-free survival for age >5 years is 50-60%. Another report found a similar 5-year survival at about 65% with 51% progression-free survival. The 10-year disease-free survival is 40-50%. Younger ages showed lower 5 and 10-year survival rates. A 2006 study that observed 133 patients found 31 (23.3%) had a recurrence of the disease within a five-year period.

For low-grade tumors, the prognosis is somewhat more optimistic. Patients diagnosed with a low-grade glioma are 17 times as likely to die as matched patients in the general population.

The age-standardized 10-year relative survival rate was 47%. One study reported that low-grade oligodendroglioma patients have a median survival of 11.6 years; another reported a median survival of 16.7 years.

Fibrosarcoma occurs most frequently in the mouth in dogs . The tumor is locally invasive, and often recurs following surgery . Radiation therapy and chemotherapy are also used in treatment. Fibrosarcoma is also a rare bone tumor in dogs.

In cats, fibrosarcoma occurs on the skin. It is also the most common vaccine-associated sarcoma. In 2014, Merial launched Oncept IL-2 in Europe for the management of such feline fibrosarcomas.

Rhabdomyosarcoma is the most common soft-tissue sarcoma in children as well as the third most common solid tumor in children. Recent estimates place the incidence of the disease at approximately 4.5 case per 1 million children/adolescents with approximately 250 new cases in the United States each year. With the vast majority of cases of RMS occurring in children or adolescents, two-thirds of reported cases occur in youths under the age of 10. RMS also occurs slightly more often in males than in females, with a ratio of approximately 1.3–1.5:1. In addition, slightly lower prevalence of the disease has been reported in black and Asian children relative to white children. In most cases, there are no clear predisposing risk factors for the development of RMS. It tends to occur sporadically with no obvious cause. However, RMS has been correlated with familial cancer syndromes and congenital abnormalities including neurofibromatosis type 1, Beckwith-Wiedemann syndrome, Li–Fraumeni syndrome, cardio-facio-cutaneous syndrome, and Costello syndrome. It has also been associated with parental use of cocaine and marijuana.

Alveolar rhabdomyosarcoma (ARMS) is a sub-type of the rhabdomyosarcoma soft tissue cancer family whose lineage is from mesenchymal cells and are related to skeletal muscle cells. ARMS tumors resemble the alveoli tissue that can be found in the lungs. Tumor location varies from patient to patient, but is commonly found in the head and neck region, male and female urogenital tracts, the torso, and extremities. Two fusion proteins can be associated with ARMS, but are not necessary, PAX3-FKHR (now known as FOXO1). and PAX7-FKHR. In children and adolescents ARMS accounts for about 1 percent of all malignancies, has an incidence rate of 1 per million, and most cases occur sporadically with no genetic predisposition.

Esthesioneuroblastoma is a slow developing but malignant tumor with high reoccurrence rates because of its anatomical position. The tumor composition, location and metastatic characteristics as well as the treatment plan determine prognosis. Common clinical classification systems for esthesioneuroblastoma include the Kadish classification and the Dulguerov classfictation. Histopathological characteristics on top of Kadish classification can further determine cancer prognosis. In severe, Kadish class C tumors, Haym's grades of pathology are important for prognosis. Patients with low grade Kadish class C tumors have a 10-year survival rate of 86 percent compared to patients with high grade class C tumors who have a survival rate of 28 percent. Surgically treated patients with high grade tumors are more likely to experience leptomeningeal metastases or involvement of the cerebral spinal fluid unlike patients with low grade tumors who usually only see local recurrence. Survival rates for treated esthesioneuroblastoma are best for surgery with radiotherapy (65%), then for radiotherapy and chemotherapy (51%), just surgery (48%), surgery, radiotherapy and chemotherapy (47) and finally just radiotherapy (37%). From the literature, radiotherapy and surgery seem to boast the best outcome for patients. However, it is important to understand that to some degree, prognosis is related to tumor severity. More progressed, higher grade tumors would result in chemotherapy or radiotherapy as the only treatment. It is no surprise that the prognosis would be worse in these cases.

Individuals presenting with fibrosarcoma are usually adults aged thirty to fifty five years, often presenting with pain. In adults, males have a higher incidence for fibrosarcoma than females.

This group comprises anaplastic astrocytomas and glioblastoma multiforme. Whereas the median overall survival of anaplastic (WHO grade III) gliomas is approximately 3 years, glioblastoma multiforme has a poor median overall survival of ~15 months.

The prognosis for rhabdomyosarcoma has improved greatly in recent decades, with over 70% of patients surviving for five years after diagnosis.

LCLC-RP are considered to be especially aggressive tumors with a dismal prognosis. Many published cases have shown short survival times after diagnosis. Some studies suggest that, as the proportion of rhabdoid cells in the tumor increases, the prognosis tends to worsen, although this is most pronounced when the proportion of rhabdoid cells exceeds 5%. With regard to "parent" neoplasms other than LCLC, adenocarcinomas with rhabdoid features have been reported to have worse prognoses than adenocarcinomas without rhabdoid features, although an "adenocarcinoma with rhabdoid phenotype" tumor variant has not been specifically recognized as a distinct entity under the WHO-2004 classification system.

Interestingly, there are case reports of rhabdoid carcinomas recurring after unusually long periods, which is unusual for a fast-growing, aggressive tumor type. One report described a very early stage patient whose tumor recurred 6 years after initial treatment. Although rapidly progressive, fulminant courses seem to be the rule in this entity, long-term survival has also been noted, even post-metastectomy in late stage, distant metastatic disease.

Rhabdomyosarcoma, or RMS, is an aggressive and highly malignant form of cancer that develops from skeletal (striated) muscle cells that have failed to fully differentiate. It is generally considered to be a disease of childhood, as the vast majority of cases occur in those below the age of 18. It is commonly described as one of the "small, round, blue cell tumours of childhood" due to its appearance on an H&E stain. Despite being a relatively rare cancer, it accounts for approximately 40% of all recorded soft tissue sarcomas. RMS can occur in any site on the body, but is primarily found in the head, neck, orbit, genitourinary tract, genitals, and extremities. There are no clear risk factors for RMS, but the disease has been associated with some congenital abnormalities. Signs and symptoms vary according to tumor site, and prognosis is closely tied to the location of the primary tumor. Common site of metastasis include the lungs, bone marrow, and bones. There are many classification systems for RMS and a variety of defined histological types. Embryonal rhabdomyosarcoma is the most common type and comprises about 60% of cases. Patient outcomes vary considerably, with 5 years survival rates between 35% and 95% depending on the type of RMS involved, so clear diagnosis is critical for effective treatment and management. Unfortunately, accurate and quick diagnosis is often difficult due to the heterogeneity of RMS tumors and a lack of strong genetic markers of the disease. Treatment usually involves a combination of surgery, chemotherapy, and radiation. Sixty percent to 70% of newly diagnosed patients with nonmetastatic disease can be cured using this combined approach to therapy. Despite aggressive multimodality treatment, less than 20% of patients with metastatic RMS are able to be cured of their disease.

Ewing's sarcomas represent 16% of primary bone sarcomas. In the United States, they are most common in the second decade of life, with a rate of 0.3 cases per million in children under 3 years of age, and as high as 4.6 cases per million in adolescents aged 15–19 years. Internationally, the annual incidence rate averages less than 2 cases per million children. In the United Kingdom, an average of six children per year are diagnosed, mainly males in early stages of puberty. Due to the prevalence of diagnosis during teenage years, a link may exist between the onset of puberty and the early stages of this disease, although no research confirms this hypothesis.

The oldest known patient diagnosed was at age 76, from the Mercer County, New Jersey, area.

A grouping of three unrelated teenagers in Wake Forest, NC, have been diagnosed with Ewing's sarcoma. All three children were diagnosed in 2011 and all attended the same temporary classroom together while the school underwent renovation. A fourth teenager living nearby was diagnosed in 2009. The odds of this grouping are considered significant.

Ewing's sarcoma shows striking differences in incidence across human populations and is about 10- to 20-fold more common in populations from European descent as compared to Africans. Consistently, a genome-wide association study (GWAS) conducted in several hundreds European individuals with Ewing's sarcoma and genetically-matched healthy controls identified three susceptibility loci located on chromosomes 1, 10 and 15. A continuative study discovered that the Ewing's sarcoma susceptibility gene "EGR2", which is located within the chromosome 10 susceptibility locus, is regulated by the "EWSR1-FLI1" fusion oncogene via a GGAA-microsatellite.

Ewing's sarcoma is the second most common bone cancer in children and adolescents, with poor prognosis and outcome in ~70% of initial diagnoses and 10–15% of relapses.

Esthesioneuroblastoma accounts for 2% of all intranasal tumors with an incidence of 0.4 cases per million people. Fewer than 700 cases of esthesioneuroblastoma have been seen in the US since 1988. Fewer than 400 unique cases have been reported globally. Esthesioneuroblastoma can occur at any time, with peak occurrence reported in the second and sixth decade of life.

Sarcomas are quite rare with only 15,000 new cases per year in the United States. Sarcomas therefore represent about one percent of the 1.5 million new cancer diagnoses in that country each year.

Sarcomas affect people of all ages. Approximately 50% of bone sarcomas and 20% of soft tissue sarcomas are diagnosed in people under the age of 35. Some sarcomas, such as leiomyosarcoma, chondrosarcoma, and gastrointestinal stromal tumor (GIST), are more common in adults than in children. Most high-grade bone sarcomas, including Ewing's sarcoma and osteosarcoma, are much more common in children and young adults.