Professor Saverio Alberti, from the University of Chieti Foundation, Italy, told delegates at the European Congress of Clinical Oncology (ECCO) in Barcelona, Spain, that he and his colleagues have found a widespread mechanism that stimulates tumour growth: Trop-2. The gene has now been found in the majority of human cancers, including breast, colon, stomach, lung, prostate, ovary, and pancreas.

Anticancer drug development programmes are increasingly devoted to finding targeted therapies - namely those where the drug attacks cancer cells in preference to normal cells. However, their effects are often modest and this is partly due to the fact that the targets are only over-expressed in limited numbers of tumours.

However, Trop-2 was found in between 65 per cent and 90 per cent of tumours types analysed, with an average of 74 per cent.

"These figures are high," explained Prof. Alberti. "In comparison...HER-2/NEU is a key determinant of breast cancer aggressiveness and is over-expressed in 25 per cent of the cancers. p53, possibly the most fundamental of tumour suppressors, is mutated and/or over-expressed in 50 per cent of tumours...So Trop-2 really stands out," he added.

Other oncogenes, such as epidermal growth factor receptor (EGFR) are also relatively infrequent in most cancers, such as 30 per cent of lung cancers.

The hope is that new therapies targeting Trop-2 could prove to be more effective than existing drugs. The more targeted therapies that exist, the more likely cancer treatment could be tailored towards a particular patient's gene 'signature' - the goal of personalised medicine. The gene itself is a product of the TACTD2 gene, which is expressed in placenta - an 'invasive' normal tissue.

"The function of Trop-2 was a mystery until now," said Prof. Alberti, "but knowing its expression in the trophoblast during pregnancy, we thought that it might well be involved in another invasive function - tumour growth."

This turned out to be the case and the scientists went on to develop antibodies for immunotherapy. The gene has also turned out to be a marker of metastasis in different tumours. The mechanisms through which Trop-2 induces these metastases are only just beginning to be unravelled. The team found that in the Trop-2 cytoplasmic tail, there are two sequence elements that act as an enhancer and silencer of metastases respectively.

The next step is to identify molecules that promote or inhibit the spread of cancer.

"If we can identify such molecules, we will be approaching a situation where we could influence their activity and hence either encourage or prevent it," he said.

"This could be an important step towards stopping cancer in its tracks."