The platelet count, a component of the full blood count, has been identified as a useful diagnostic marker for cancer in primary care. The reference range for the platelet count is 150 to 400 or 450 × 109/L; this range does not account for natural variation in platelet count by age and sex. This study used three primary care cohorts from England, Canada, and Australia. Patients aged 40 years and over with a full blood count were included and stratified by age (in 10-year bands), sex, (male/female), and platelet count group. Cancer incidence within one year of the test date was estimated from linked registry data. In all three countries, there was a clear upwards trend in cancer incidence with increasing platelet count for both sexes and at all age groups. Lung and colorectal were the most common sites. These results have important implications for the international application of this work; analysis of local health datasets will be crucial to determining appropriate thresholds. Appropriate upper thresholds will depend on local populations, healthcare needs, and priorities. Further research is needed to assess the likely impact of new recommendations on the healthcare system, on cancer outcomes, and patient benefit.
血小板计数作为全血细胞计数的一部分，已被确定为初级诊疗中癌症诊断的有效标志物。血小板计数的参考范围为150至400或450×10⁹/L；该范围未考虑年龄和性别导致的血小板计数自然差异。本研究采用来自英格兰、加拿大和澳大利亚的三个初级诊疗队列，纳入40岁及以上接受全血细胞检测的患者，并按年龄（以10岁为区间）、性别（男/女）及血小板计数组进行分层分析。通过关联登记数据估算检测日期一年内的癌症发病率。在所有三个国家中，无论性别与年龄组别，癌症发病率均随血小板计数升高呈现明显上升趋势。肺癌和结直肠癌是最常见的发病部位。这些结果对本研究的国际应用具有重要意义；分析本地健康数据集对确定适宜阈值至关重要。合适的阈值上限需依据当地人群特征、医疗需求及优先事项而定。需开展进一步研究，评估新建议对医疗体系、癌症预后及患者获益可能产生的影响。
肿瘤(癌症)患者之家