Thrombocytosis is defined as a platelet count over 400 x 109 / l for women and over 350 x 109 / l for men. It is often seen as a nonspecific sign of infections and chronic disease in the context of raised phase reactants (CRP, albumin, etc.)
With thrombocytosis the diagnostic value in cancer diagnostics is listed as below with likelihood ratio and risk (PPV) for cancer patients in general practice.
Pretest likelihood of cancer indicates the probability of the specific form of cancer among patients over 40 years old, seeking medical attention. For breast and uterine cancer are pretest probability of cancer designed for women over 40 years.
How useful is thrombocytosis in predicting an underlying cancer in primary care? a systematic review. Bailey SE, Ukoumunne OC, Shephard E, Hamilton W. Family Practice, 2016.