NCRI Cancer Conference 2009: Larry Norton – Sowing the ‘seeds’ of cancer?

Dr Norton suggests that 'self-seeding' cancers are like a bed of weeds

Could cancer cells not only spread away from a tumour but also return to it from other distant parts of the body? That’s the theory presented on Sunday at the NCRI Cancer Conference by Dr Larry Norton of the Memorial Sloan-Kettering Cancer Center in New York, USA. The news has already hit the headlines, including the front page of the Daily Express.

This new concept could shed light on the way in which cancer spreads – a process called metastasis. Cancer cells can move away from a primary tumour to form new secondary tumours elsewhere in the body.

But Dr Norton thinks that wandering cancer cells could return to the site of the primary cancer and fuel its growth. And it could explain why – in some cases at least – secondary cancers turn up long after treatment has eliminated the main tumour.

Here’s a short interview with Dr Norton, explaining more about his ideas:

[youtube=http://www.youtube.com/watch?v=SlJXee2bT28]

Weeds and seeds

As Dr Norton explains in the video, we normally think of cancers as being a bit like oak trees – a single, large problem that produces small ‘acorns’ of growth in new places. But he paints cancer as being more like a bed of weeds, with ‘seeds’ drifting off to create new growth in the weed bed itself, as well as locations further afield.

This idea of a ‘self-seeding’ tumour could explain puzzling features of some cancers – for example the way in which breast cancer can return decades after it has been treated. And it may also help scientists to understand why some cancers seem to be more likely to spread soon after the main tumour has been removed. It could be that prodigal cells with no ‘home’ to go to once the primary tumour is gone are more likely to settle elsewhere.

New ideas for treatment

So far the research that backs up the theory has only been done in mice, but if it’s found to be relevant to human cancers then the consequences could be far-reaching. Work by Dr Norton and colleagues has already found that a gene called Src can allow breast cancer cells to lie dormant in the bone, suggesting this gene could be a target for future treatments.

The idea of self-seeding cancers also points towards entirely new ways of treating the disease. For example, if we can find what attracts the cancer cells back to the original tumour, perhaps we could design a ‘decoy’ to attract and trap returning cells. Dr Norton and his team have also designed some alternative chemotherapy schedules that take the self-seeding concept into account, and they hope to test them in clinical trials soon.

There’s a lot that scientists still don’t understand about cancer, and Dr Norton’s ideas challenge some of the assumptions that are made about this disease and how it spreads. Finding out more about wandering cells could lead to exciting new ways to tackle cancer in the future.

Nell