A study led by Australian scientists has uncovered genetic risk factors for a rare type of cancer that mainly affects people aged under 50.

Pioneering work by Australian researchers has uncovered the complex genetic secrets of a rare type of cancer that predominantly strikes the young.

The discoveries transform the medical profession's understanding of sarcoma and have immediate implications for patients' treatment, says the Garvan Institutes Professor David Thomas, who led the study.

Sarcomas are cancers of connective tissue, like fat, muscle or bone, and disproportionately affect those aged under 50. They are one of the three leading causes of disease-related death among children and young adults in Australia.

Survivors of sarcoma are also at higher risk of developing a second cancer.

How our genetic make-up affects the risk of such cancer has been rudimentary until now, says Prof Thomas.

In a landmark study of more than 1000 sarcoma patients, scientists at the Garvan Institute discovered that almost half of the participants carried not just one gene mutation but several.

It is the first time - in any cancer - that anyone has quantified the effect of multiple rare genetic mutations on cancer risk.

Prof Thomas says the findings show the landscape of a person's risk of developing sarcoma is far more complex than carrying just one mutation, like the BRACA1 mutation that is linked to a high risk of breast cancer.

It was apparent the risk of developing sarcoma increased through the combined effect of several genes and that the more mutations someone carried the earlier the onset of cancer, Prof Thomas said.

The new mutations that significantly increase the risk of sarcoma include the genes ERCC2, ATR, BRCA2 and ATM.

It's hoped the findings, published in the medical journal The Lancet Oncology, will enable early detection of sarcoma, which hasn't before been possible.

Prof Thomas says many of the study's participants have had silent cancers detected through the use of whole body MRI as a result of their findings.

While the scientists may have only scratched the surface of understanding cancer's genetic underpinnings, he says it is a huge step forward to reducing the number of lives lost to the disease.