Scientists have pinpointed a key sequence of genes which appear to be active in rapidly developing cancers.
Stem cells may drive tumour growth
They believe activity among the 11 genes in the pathway is a potent sign that cancer will spread, and probably result in death.
It is thought the genes may control tumour stem cells that drive the development of the cancer.
The study, by the Sidney Kimmel Cancer Center, is published in the Journal of clinical Investigation.
The researchers evaluated 1,122 cancer patients diagnosed with 10 different types of cancer.
They examined tumours for signs of activity in an 11-gene sequence linked to the proliferation of normal stem cells in humans.
The same sequence has also been linked to the spread of cancer in mice, and secondary tumours in prostate cancer patients.
They found that a very consistent pattern of activity was present among tumours that spread quickly, and proved fatal - regardless of the type of cancer.
Tumour cell theory
The findings give weight to the theory that cancers contain a small population of tumour stem cells that are responsible for the growth of the tumour, and its spread around the body.
In an editorial in the same journal, experts from the University of Texas MD Anderson Cancer Center, say that previous research has identified other gene sequences thought to predict how a cancer is likely to develop.
Doubt has subsequently been cast over many of these efforts.
However, they say the latest study may be more significant, as the pattern of gene activity was seen over a range of different cancers, and not just one type.
More work is needed to corroborate the findings, they say, but potentially they could be highly significant.
"Such a 'magic marker' would, if validated, have a major impact on patient care."
Professor Bryan Young, of the charity Cancer Research UK said: "The results from this study show that some people will respond better to treatment than others.
"Understanding why some patients are resistant to treatment helps us explore ways to get round this.
"More research is needed to support this study, but in the future this may be useful when doctors plan a cancer patient's treatment."