Blood sample
Blood sample Israel news photo: Flash 90

Tel Aviv University (TAU) researchers have discovered that routine blood tests can provide an early warning for colorectal cancer.

Anemia, a common blood disorder characterized by low hemoglobin levels, has long been associated with those suffering from colorectal cancer. It doesn't happen suddenly, however - and Tel Aviv University researchers say they have found that gradually decreasing hemoglobin levels can actually indicate a potential for colon cancer years in advance.

Graduate student Inbal Goldshtein, who works with Dr. Gabriel Chodick and Dr. Varda Shalev of TAU's School of Public Health and Maccabi Healthcare Services' Department of Medical Informatics, says that paying close attention to routine blood test results can be an effective screening system for colon cancer. Though some 50,000 Americans are expected to die from colon cancer in 2010, better screening leading to early diagnosis and effective treatment can significantly reduce those numbers, she says.

Up to Four Years in Advance
Goldshtein's study, recently published in the European Journal of Cancer Prevention, shows that most patients with colon cancer have a history of consistently declining hemoglobin levels up to four years before being diagnosed with the disease. Until now, only a sharp decrease in hemoglobin levels was sought out as an indicator of colon cancer. But Goldshtein and her fellow researchers have discovered that it's the continuous long-term decline that may announce the onset of the disease.

Specifically, a declining trend of more than 0.28 grams per deciliter every six months over a four-year period was observed - and as a result, may serve as a warning of illness on the horizon.

Over 3,000 patients suffering from colorectal cancer participated in the study, as did 10,000 control cases without colorectal cancer. Goldshtein and her fellow researchers looked at data from each participant's blood tests over a ten-year period, retrieved from the computerized database of Maccabi Healthcare Services.

Though hemoglobin levels may vary in everyone as a result of aging, a distinct trend was discovered among participants who had been diagnosed with colorectal cancer during the study period. Approximately four years prior to their diagnoses, their blood tests began to show a continuous decline in hemoglobin levels.

For the most part, Goldshtein says, these warning signs went unnoticed: "In practice, a doctor will look at the final results, and see if the hemoglobin levels are within a normal range. But this is not accurate enough. It is important to look at the continuing trend of each individual. If a person experiences a consistent decline relative to his own average level, it may be cause for concern."

No Need for Special Testing?
The benefit of this screening process is that it can be part of an routine physical exam. Current testing for colorectal cancer is often expensive and unpleasant – and many people who should undergo the test do not do so.

The next step, says Dr. Shalev, is to create an algorithm which will automatically detect suspicious declines in hemoglobin levels, advising physicians to send their patients for further testing.