Sarcoma accounts for roughly 1% of all adult cancers, making it one of the rarest broad categories of cancer. To put that in perspective, an estimated 13,520 new soft tissue sarcoma cases will be diagnosed in the United States in 2025, compared to nearly 300,000 new breast cancer cases in the same period. While sarcoma is uncommon at any age, its rarity varies significantly depending on the specific subtype, the patient’s age, and whether the tumor originates in soft tissue or bone.
Sarcoma by the Numbers
Soft tissue sarcomas occur at a rate of about 4.5 to 5 per 100,000 people per year. Bone sarcomas are even rarer, with incidence estimates ranging from 0.8 to 2.1 per 100,000 depending on the population studied. Together, sarcomas represent a small fraction of all cancer diagnoses in adults, though they play a larger role in childhood cancer, where they account for 12% to 15% of all cases.
That 1% figure in adults can be misleading, though, because it masks just how many different diseases fall under the sarcoma umbrella. The World Health Organization recognizes approximately 100 distinct sarcoma subtypes, many of which are individually so rare that most oncologists will see only a handful of cases in their careers.
The Most Common Subtypes
Even within a rare cancer group, some types appear far more often than others. The four most frequently diagnosed sarcoma subtypes, based on a large epidemiological study with centralized pathology review, are:
- Gastrointestinal stromal tumors (GIST): 18% of sarcomas, about 1.1 per 100,000 people per year
- Unclassified sarcoma: 16% of sarcomas, about 1.0 per 100,000
- Liposarcoma (arising from fat cells): 15% of sarcomas, about 0.9 per 100,000
- Leiomyosarcoma (arising from smooth muscle): 11% of sarcomas, about 0.7 per 100,000
Below these, the numbers drop sharply. A subtype like dermatofibrosarcoma occurs at a rate of roughly 0.3 per 100,000. And at the extreme end, angiosarcoma, a cancer of blood vessel walls, makes up only 1 to 2% of all soft tissue sarcomas. Thoracic angiosarcoma specifically occurs at rates as low as 0.25 to 1.5 per million people per year, meaning a large hospital system might see one or two cases annually.
How Age Affects Risk
Sarcoma’s rarity is not evenly distributed across age groups. Annual incidence rises steadily with age, from 0.9 per 100,000 in children under 10 to 18.2 per 100,000 in adults over 70. That’s a 20-fold increase. The sharpest jumps in risk occur around age 30 and again around age 70.
Interestingly, sarcoma makes up a larger share of total cancer diagnoses in younger people. In individuals under 40, soft tissue sarcomas account for more than 6% of all cancers. In those over 40, they represent fewer than 3%. This isn’t because sarcoma becomes less common with age. It’s because other cancers, like breast, lung, and colon cancers, become far more common in older adults, shrinking sarcoma’s relative share even as its absolute numbers climb.
Why Rarity Makes Diagnosis Harder
One of the real-world consequences of sarcoma’s rarity is that it often takes a long time to get a correct diagnosis. Because most primary care doctors and even many specialists rarely encounter sarcomas, these tumors are frequently mistaken for benign lumps, cysts, or muscle injuries. In a review of malpractice cases involving sarcoma, the median delay in diagnosis was 9.5 months for bone sarcomas and 12 months for soft tissue sarcomas. Some patients waited more than five years before receiving the correct diagnosis.
The problem is not always a lack of testing. In 36% of delayed-diagnosis cases, imaging or tissue samples had already produced findings suggestive of sarcoma, but the results were misinterpreted or not acted upon. In another 58% of cases, physicians did not pursue further workup based on the patient’s symptoms or physical exam alone. Many sarcomas were initially labeled as benign growths on both imaging and biopsy, a reflection of how difficult these tumors can be to identify without specialized pathology expertise.
This diagnostic challenge is a direct consequence of rarity. With roughly 100 subtypes, each with its own microscopic appearance and behavior, even experienced pathologists may struggle without access to specialized molecular testing. Sarcoma centers with dedicated expertise tend to have higher diagnostic accuracy, which is one reason referral to a specialized center matters when sarcoma is suspected.
Survival Rates Vary Widely by Stage
How well someone does after a sarcoma diagnosis depends heavily on how far the cancer has spread at the time it’s found. For soft tissue sarcomas diagnosed between 2015 and 2021, the American Cancer Society reports these five-year relative survival rates:
- Localized (confined to the original site): 83%
- Regional (spread to nearby tissues or lymph nodes): 60%
- Distant (spread to other parts of the body): 17%
The gap between localized and distant disease is enormous, which makes the diagnostic delays described above especially consequential. A soft tissue lump that sits undiagnosed for a year has more opportunity to grow and spread, potentially shifting a patient from a highly survivable stage to a far more dangerous one. An estimated 5,410 people will die from soft tissue sarcomas in the U.S. in 2025.
These survival figures are averages across all soft tissue sarcoma subtypes, which behave very differently from one another. A low-grade liposarcoma, for example, tends to grow slowly and carry a favorable prognosis, while an angiosarcoma is typically aggressive and harder to treat. Your specific subtype, grade, and tumor location all influence outcomes more than the broad “sarcoma” category alone.