Sugars found in the small shellfish were “approximately as effective” as cancer drugs, biomedical scientists at the University of Salford in Manchester found.
“Cockle-chemo”, as they called the process, could be particularly suitable for children because it is less toxic and less likely to cause unhealthy side effects, they said.
Lower doses than some standard chemotherapy drugs could also be used to the same or better effect.
The results were published in the Marine Drugs journal after the scientists tested the mollusc sugars with positive results against leukaemia, breast, lung and colon cancer cells and tumours.
Lead researcher Dr David Pye, director of child cancer research charity Kidscan, said: “Polysaccharides (sugars) derived from mammals have long been a source of experimentation by cancer scientists but to date with inconclusive results.
“Certain applications have actually helped the cancer to grow.
“We opted to look at shellfish instead, not least because they are much cheaper and easier to source and well as being rich in sugars.
“They have a different structure from which we are starting to derive a number of potential drugs which with further refinement have the potential to work alongside more traditional treatments.”
He added that extracting the sugars from cockles was a “simple procedure” and he was encouraged by the impact on tumours.
Kidscan said two to three of every British child with cancer will not survive into adulthood.
Dr Pye added: “What is really significant about this is not so much the seafood source but that fact that sugars of this chemical structure work effectively at tolerable levels for children.
“A lot of children’s cancer drugs are watered down versions of adult ones, and they target and stop cell division.
“Clearly, as cell division is a central process of growth and development they hit children’s health disproportionately.
“The ‘Holy Grail’ of children’s cancer chemotherapy is to maximise the destruction of the cancer whilst minimising damage to normal cells and tissues.
“Sugars as therapeutic treatments should help to minimise harmful side-effects.”