A pill that 'wakes up' the immune system allowing it to kill spreading tumours could one day bring new hope to people with advanced cancer.
In tests on mice, scientists used a drug to activate natural killer (NK) cells, part of the innate immune system and the body's first line of cancer defence.
A major problem with progressing cancer is that it develops ways to 'turn off' NK cells so that they no longer recognise their enemy. As a result, cancer is permitted to spread around the body unchecked. The spread of disease to vital organs, or metastasis, is the chief cause of death in cancer patients.
The new molecule, known as a TAM kinase inhibitor, effectively removes the brakes from natural killer cells so they can destroy metastatic cancer.
Mice with spreading cancer responded well when given the treatment, either through injection or by mouth, and displayed no serious side effects.
Reporting their findings in the journal 'Nature', the scientists led by Dr Josef Penninger, from the Austrian Academy of Sciences in Vienna, wrote: "This novel . . . pathway shows that it might be possible to develop a 'pill' that awakens the innate immune system to kill cancer metastases." The blood-thinning drug warfarin, which targets the same TAM pathway, was also shown to combat metastasis in mice.
This finding could explain the long-standing puzzle of why cancer patients treated with warfarin sometimes show signs of improvement.
Meanwhile, being obese increases a man's risk of breast cancer by nearly a third, research has shown.
The Male Breast Cancer Pooling Project gathered together data on the disease from studies conducted around the world.
It found that obesity, and several other physical and hormone-related traits, were associated with increased breast cancer risk in men.
The results, published in the 'Journal of the National Cancer Institute', showed that breast cancer risk in men increases with weight.
Clinical obesity, meaning a Body Mass Index of 30 or above, increased the chances of a man developing breast cancer by around 30pc.
An association was also seen with gynecomastia, enlarged breast tissue in men, which appeared to be separate from the effect of obesity.
Klinefelter Syndrome, the presence of an extra X chromosome in men, was another confirmed risk factor.
Professor Anthony Swerdlow, from the Institute of Cancer Research in London – who led the UK arm of the study, said: "This research brings together data from studies of male breast cancer from around the world to clarify risk factors that have been uncertain.
"The results suggest that men who are overweight may be at increased risk of male breast cancer. We know that body size can be related to hormone levels.
"Also, hormonal factors may be the reason why patients with Klinefelter Syndrome, who have comparatively low levels of testosterone and high levels of oestrogen, have raised breast cancer risks compared with other men," he said.