Thrombocytopenia is a cancer

High cancer risk with thrombocytosis

EXETER. Elevated platelet counts are a marker of an increased risk of cancer. According to British doctors, the finding warrants tests for a possible underlying malignancy even in general practitioner patients without suspicious symptoms.

The doctors around Dr. Sarah E. R. Bailey of Exeter University used prospectively collected primary care registry data to determine that one in nine men and one in 16 women will be diagnosed with cancer in the year following thrombocytosis.

Cancer diagnoses were much less common in patients with normal platelet counts (Br J Gen Pract 2017, online May 23).

Data from over 30,000 patients

The data from 31,261 patients (median age 68 years, 70 percent women) with platelet counts> 400 x 10 were analyzed9/ l. 1098 men and 1355 women were diagnosed with cancer within a year of the laboratory finding.

For men it was 11.6 percent and for women 6.2 percent. In a control cohort of 7969 patients of the same age and sex with normal platelet counts, malignancy was found in 4.1 percent of men and 2.2 percent of women.

The risk of cancer increased with the platelet count. Patients with a second thrombocytosis test within six months had the highest risk. Men with the same or greater value than the first blood count were diagnosed with cancer in 18.1 percent, those with platelet counts that were still too high but decreased 19.1 percent. For women it was 10.1 and 7.3 percent.

Most cancers in the platelet cohort were found in the lungs or bowels (573 and 627 patients, respectively). The two types of cancer were thus much more common than in the general population. Breast and prostate cancer, on the other hand, was found below average.

Every third thrombocytosis patient with bronchial or colorectal cancer had no suspicious symptoms in the year prior to diagnosis. A median of 50 and 67 days elapsed between the abnormal blood count and the diagnosis of cancer.

Forecast values โ€‹โ€‹"very high"

The authors of the study rate the positive predictive values โ€‹โ€‹of thrombocytosis for malignant disease of 11.6 percent in men and 6.2 percent in women as "very high"; they are also well above the three percent that have been defined in a guideline of the National Institute for Health and Care Excellence as the threshold value for the urgent clarification of suspected cancer.

The greatest benefit of a further examination is likely to arise for those patients who do not have any other symptoms that trigger a cancer diagnosis. "This strongly suggests that cancer should be considered if thrombocytosis is found, even if there was no prior evidence of cancer," Bailey and colleagues point out.

According to their data, this could result in "a significant proportion of lung and colon cancer diagnoses being made at least two months earlier".