Pediatric soft tissue cancers at a glance

Five numbers that define pediatric soft tissue cancers

850–900

new U.S. soft tissue sarcoma cases in children and teens each year, roughly 350 rhabdomyosarcoma and 500 other subtypes

NCI PDQ · Cancer

of all childhood cancers

Cancer

50+

distinct subtypes of soft tissue sarcoma, each differing significantly in biology and behavior

PubMed

2subtypes

rhabdomyosarcoma alone splits into embryonal and alveolar, with very different relapse rates and survival odds

Cancer

71%

rhabdomyosarcoma survival today, up from 53% in 1975, though survival once the cancer has spread remains around 14%

NCI PDQ

When we talk about pediatric soft tissue cancers, we are really talking about many different rare diseases. That is exactly why research matters. Rarity should never be the reason a child has fewer treatment options or less hope for a cure.

Dean CroweFounder & CEO, Rally Foundation for Childhood Cancer Research
Strategic Perspectives in Nonprofit Management at Harvard Business School Executive Education

About 850 to 900 new U.S. soft tissue sarcoma cases are diagnosed in children and teens each year, roughly 350 rhabdomyosarcoma and 500 other soft tissue sarcoma types.

Sources: NCI PDQ · cancer.gov · Cancer · doi.org

Soft tissue sarcomas make up about 7% of all childhood cancers.

Source: Cancer · doi.org

This is not 1 but more than 50 distinct subtypes of soft tissue sarcoma, each differing significantly in biology and behavior.

Source: PubMed · pubmed.ncbi.nlm.nih.gov

Rhabdomyosarcoma alone splits into two biologically distinct subtypes, embryonal and alveolar, with very different relapse rates and survival odds.

Source: Cancer · doi.org

Rhabdomyosarcoma survival has risen from 53% in 1975 to about 71% today, though survival for cancer that has already spread remains around 14%.

Source: NCI PDQ · cancer.gov

Most common pediatric soft tissue cancers

Rhabdomyosarcoma is the most common soft tissue sarcoma in children, though dozens of other rare subtypes, including synovial sarcoma, infantile fibrosarcoma, and malignant peripheral nerve sheath tumor, also occur, especially in teens. Malignant rhabdoid tumor (MRT) is a related but extremely rare and aggressive soft tissue cancer of infants and very young children.

Rhabdomyosarcoma

The most common soft tissue cancer in children.

70%

of children with rhabdomyosarcoma survive at least 5 years

NCI PDQ

14%

survival if the cancer has already spread at diagnosis, versus about 69% for localized disease

NCI PDQ

63%vs 28%

relapse rate for the alveolar subtype versus the embryonal subtype

NCI PDQ

47%

survival for teens 15–19, versus about 70% for children 0–4

Cancer

About 70% of children with rhabdomyosarcoma survive at least 5 years.

Source: NCI PDQ · cancer.gov

Survival has improved a lot over time, from 53% in 1975 to 71% in 2017.

Source: NCI PDQ · cancer.gov

Survival depends heavily on whether cancer has spread: about 69% for localized disease, but only 14% if it has spread at diagnosis.

Source: NCI PDQ · cancer.gov

One subtype (alveolar) relapses much more often than another (embryonal), 63% versus 28%, reflecting its more aggressive biology, often driven by a gene fusion called PAX3::FOXO1 or PAX7::FOXO1.

Source: NCI PDQ · cancer.gov

Age matters too. Younger children (0 to 4) have notably better survival, about 70%, than teens (15 to 19) at about 47%. This reflects both a higher rate of aggressive tumor features in teens and an independent effect of age itself.

Source: Cancer · doi.org

Synovial Sarcoma

One of the more common soft tissue sarcomas outside of rhabdomyosarcoma, typically arising in adolescents and young adults.

5–10%

of all soft tissue sarcomas

Translational Pediatrics

90%+

of tumors carry the SS18-SSX gene fusion, which doctors use to confirm the diagnosis

American Journal of Surgical Pathology

73–89%

pediatric 5-year survival, notably better than the 43–76% typically seen in adults

Annals of Surgical Oncology

<13%

5-year survival once the cancer has already spread at diagnosis

PubMed Central

Synovial sarcoma makes up about 5 to 10% of all soft tissue sarcomas and is one of the more common non-rhabdomyosarcoma soft tissue sarcomas in children and adolescents.

Sources: Translational Pediatrics · doi.org · American Journal of Surgical Pathology · doi.org

It occurs mainly in adolescents and young adults and most often develops in an arm or leg, especially the thigh. In one pediatric cohort, 111 of 130 patients were between the ages of 10 and 19.

Source: Translational Pediatrics · doi.org

Nearly all cases are defined by a specific gene change called the SS18-SSX fusion, found in more than 90% of tumors, which doctors use to confirm the diagnosis.

Source: American Journal of Surgical Pathology · doi.org

Pediatric 5-year survival is roughly 73 to 89%, notably better than the 43 to 76% typically seen in adults. A tumor larger than 5 centimeters is the single strongest predictor of a worse outcome.

Source: Annals of Surgical Oncology · doi.org

Cancer that has already spread at diagnosis is a severe warning sign. Metastatic synovial sarcoma generally has a 5-year survival below 13%.

Source: NCBI PubMed Central · PMC10416854

The specific SS18-SSX2 gene fusion is linked to notably better survival than the SS18-SSX1 fusion, and complete surgical removal remains the most consistent predictor of a good outcome.

Sources: British Journal of Cancer · doi.org · Translational Pediatrics · doi.org

Infantile Fibrosarcoma

A rare tumor of infants with a genetic driver that is now directly targetable by modern drugs.

80%

are diagnosed within the first year of life, and about 40% are present at birth

PubMed Central

85%

of cases carry the ETV6-NTRK3 fusion, which makes the tumor highly responsive to targeted TRK inhibitors

PubMed Central · Annals of Oncology

89%

overall 5-year survival, far better than fibrosarcoma in adults

Journal of Clinical Oncology

45%

of children are cured by surgery alone

Journal of Clinical Oncology

Infantile fibrosarcoma is the most common soft tissue sarcoma in children under 1 year old. About 40% are present at birth and about 80% are diagnosed within the first year of life.

Source: NCBI PubMed Central · PMC10412926

About 85% of cases carry a specific gene change called the ETV6-NTRK3 fusion, which makes the tumor highly responsive to targeted drugs called TRK inhibitors such as larotrectinib and entrectinib.

Sources: NCBI PubMed Central · PMC10412926 · Annals of Oncology · doi.org

Overall 5-year survival is about 89%, far better than fibrosarcoma in adults.

Source: Journal of Clinical Oncology · doi.org

Treatment focuses on surgery first. About 45% of children are cured by surgery alone, while chemotherapy or targeted TRK-inhibitor therapy is used to shrink tumors that cannot be safely removed right away.

Source: Journal of Clinical Oncology · doi.org

Spread to distant parts of the body is uncommon, occurring in only about 8 to 15% of cases, and rare cases have even been documented to shrink on their own without treatment.

Source: Journal of Clinical Oncology · doi.org

Malignant Peripheral Nerve Sheath Tumor

MPNST

An aggressive nerve-tissue sarcoma strongly linked to the genetic condition neurofibromatosis type 1.

0.56per million

children under 15, versus about 1.46 per million people overall

PubMed Central

~50%

of pediatric and young adult cases occur in patients with neurofibromatosis type 1

PubMed Central

47–62%

pediatric 5-year overall survival

PubMed Central · PubMed

92%

5-year event-free survival for children whose tumors were completely removed before chemotherapy

PubMed

MPNST occurs at a rate of about 1.46 cases per million people overall but only about 0.56 per million in children under 15. About half of pediatric and young adult cases occur in patients with neurofibromatosis type 1, while roughly 40% are sporadic and about 10% follow radiation exposure.

Source: NCBI PubMed Central · PMC10775467

Most pediatric cases occur in adolescence, with a median age of about 13 years in one French cohort.

Source: ScienceDirect · sciencedirect.com

Pediatric 5-year overall survival is roughly 47 to 62%, and survival is significantly worse in patients with neurofibromatosis type 1 than in sporadic cases, about 32% versus 62% in one study.

Sources: NCBI PubMed Central · PMC9825640 · PubMed · pubmed.ncbi.nlm.nih.gov

Complete surgical removal is the strongest predictor of outcome. In one prospective study, children with completely resected tumors who had not yet received chemotherapy had a 92% 5-year event-free survival.

Source: PubMed · pubmed.ncbi.nlm.nih.gov

Most MPNSTs arise from the malignant change of an existing plexiform neurofibroma, and people with neurofibromatosis type 1 face an estimated 8 to 13% lifetime risk of developing this cancer.

Source: NCBI PubMed Central · PMC10775467

Malignant Rhabdoid Tumor

MRT

An extremely rare and aggressive tumor of infants and very young children, related to ATRT.

0.6per million

children, almost always infants and very young children

PubMed Central

10months

median age at diagnosis for kidney MRT, versus 18–26 months in other soft tissues

PubMed Central

17–36%

overall 5-year survival for MRT outside the brain, one of the deadliest childhood solid tumors

PubMed Central

83%

of kidney MRT cases have already spread by diagnosis, most often to the lungs

PubMed Central

MRT is extremely rare, about 0.6 cases per million children, and almost always affects infants and very young children.