Figure 3.

Decision thresholds and the probability of cancer. The observation threshold is the probability of cancer below which careful observation with serial CT is warranted. The surgical threshold is the probability of cancer above which surgery is warranted. Diagnostic testing with CT-FNA or PET is warranted for probabilities of cancer between these two extremes. Different factors that may alter these decision thresholds are shown. For example, increased comorbidities and surgical risk increase the surgical threshold. Improved detection of nodule growth with volumetric CT, thereby decreasing the hazard of delay, increases the observation threshold. The observation and surgical thresholds vary depending on individual patient comorbidities and surgical risk factors, patient preferences, and the availability of diagnostic tests and treatments. CT = computed tomography; CT-FNA = CT-guided fine-needle aspiration; PET = positron emission tomography.