A common blood test has shown to be just as accurate in predicting any type of cancer as a lump is for breast cancer, and researchers say it's the most promising detection method for cancer in 30 years.
A high number of platelets (tiny blood cells that help wounds clot) have been linked to an increased risk of all forms of cancer, and scientists are now urging doctors to consider thrombocytosis - a condition where too many platelets are produced in the body - as a detection method for patients who are yet to show symptoms.
"Our findings on thrombocytosis show a strong association with cancer, particularly in men - far stronger than that of a breast lump for breast cancer in women," says one of the team, Willie Hamilton from the University of Exeter in the UK.
"It is now crucial that we roll out cancer investigation of thrombocytosis. It could save hundreds of lives each year."
Thrombocytosis affects around 2 percent of people over the age of 40, and it's been linked to cancer before. What this new study does is establish a stronger link across all ages and genders, and with cancer in all areas of the body.
The researchers looked at 31,261 records of patients in the UK with a high platelet count (thrombocytosis), and 7,969 records of patients whose platelet count was normal.
They found that 11.6 percent of males with thrombocytosis went on to be diagnosed with cancer within a year, compared to 4.1 percent of those without. For females, cancer developed in 6.2 percent of those with thrombocytosis, compared to 2.2 percent without.
If a second high platelet count was recorded within six months, those risks went even higher: 18.1 percent for males and 10.1 percent for females.
A lump on the breast turns out to be cancerous in around 8.5 percent of cases for women aged 50 to 59 years, by comparison.
The researchers report that Lung and colorectal cancer were the types most commonly linked to thrombocytosis.
What's more, one-third of those with lung or colorectal cancer had no other symptoms of the disease apart from thrombocytosis - which means this could be a very important indicator in the future for cases when cancer wouldn't otherwise be spotted so soon.
The team says this the first new indicator of cancer to have been clearly identified in the last three decades, with the potential to identify thousands of cancers earlier and save hundreds of lives a year.
While early diagnosis is just one of many factors that affect the chances of someone getting better, it's known to improve survival rates across all types of cancer.
"We know that early diagnosis is absolutely key in whether people survive cancer," says one of the team, Sarah Bailey.
"Our research suggests that substantial numbers of people could have their cancer diagnosed up to three months earlier if thrombocytosis prompted investigation for cancer. This time could make a vital difference in achieving earlier diagnosis."
The research has been published in The British Journal of Medical Practice.