Cancer spreads even before tumours form

NEW DELHI: In a new discovery that might challenge the existing knowledge of cancer and methods to treat it, researchers have found cancer cells spread to organs much earlier than was thought. In fact, cancer cells can spread even before a tumour develops, remain quiet for long periods of time and then awaken to form aggressive and fatal metastasis, show two new studies published recently in Nature, a leading international science journal.

The findings also offer an explanation for why some 5% of cancer patients have metastases but no original tumour.

In metastasis, cancer cells break away from where they first formed (primary cancer), travel through the blood or lymph system, and form new tumours (metastatic tumours). Metastases are responsible for over 90% of cancer deaths. However, the two new studies of breast cancer for the first time have identified the molecular mechanisms by which cancer cells spread and explains how even early detection such as with mammography or even advanced methods like breast MRI may fail to save lives. By the time tumours are detectable, cancer cells may have spread and formed fatal metastases at distant sites.

Furthermore, a clinical primary tumour may never develop, investigators say .However, how these early cancer lesions could spawn cells with traits of malignant tumours was unknown.

The two studies were conducted by researchers at Icahn School of Medicine at Mount Sinai and the University of Regensburg in Germany. “Biologically , this new model of early metastasis challenges everything we thought we knew about how cancer spreads and forms metastasis,“ said Dr Julio Aguirre-Ghiso of the Icahn School of Medicine at Mount Sinai in New York, who led one of the new studies.

The discovery might also explain why targeted drugs considered big successes in the fight against cancer often fail to keep patients alive much longer as compared to chemotherapy . These drugs disable the molecular mechanisms that spur proliferation, which is usually identified by biopsy of the tumour. But early spread cancer cells would escape these conventional therapies even if it kills a primary tumour, the findings explain.

Though the new findings are based on researches on breast cancer, researchers say the early departure of cancer cells to seed metastases can occur in other human cancers, including melanoma and pancreatic cancer.