Role of positron emission tomography in the treatment of occult disease in head-and-neck cancer: a modeling approach.

To determine under what conditions PET imaging will be useful in decisions regarding the use of radiation therapy for the treatment of clinically-occult lymph node metastases in head and neck cancer. A decision model of PET imaging and its downstream effects on radiation therapy outcomes was constructed using an influence diagram. This model included the sensitivity and specificity of PET as well as the type and stage of the primary tumor. These parameters were varied to determine the optimal strategy for imaging and therapy for different clinical situations. Maximum Expected Utility was the metric by which different actions were ranked. For primary tumors with a low probability of lymph node metastases, the sensitivity of PET should be maximized and 50 Gy should be delivered if PET is positive and 0 Gy if negative. As the probability for lymph node metastases increases, PET imaging becomes unnecessary in some situation and the optimal dose to the lymph nodes increases. The model needed to include the causes of certain health states in order to predict current clinical practice. The model demonstrated the ability to reproduce expected outcomes for a range of tumors and provided recommendations for different clinical situations. The differences between the optimal policies and current clinical practice is likely due to a disparity between stated clinical decision processes and actual decision making by clinicians.

确定在何种条件下，正电子发射断层成像（PET）在决定使用放射疗法治疗头颈部癌症临床隐匿性淋巴结转移方面将是有用的。 利用影响图构建了一个PET成像及其对放射治疗结果的下游影响的决策模型。该模型包括PET的敏感性和特异性以及原发肿瘤的类型和分期。改变这些参数以确定不同临床情况下成像和治疗的最佳策略。最大期望效用是对不同行动进行排序的指标。 对于淋巴结转移概率较低的原发肿瘤，应使PET的敏感性最大化，如果PET呈阳性则给予50戈瑞（Gy）的剂量，如果为阴性则给予0 Gy。随着淋巴结转移概率的增加，在某些情况下PET成像变得不必要，并且对淋巴结的最佳剂量增加。该模型需要包括某些健康状态的成因，以便预测当前的临床实践。 该模型展示了对一系列肿瘤重现预期结果的能力，并为不同临床情况提供了建议。最佳策略与当前临床实践之间的差异可能是由于所述临床决策过程与临床医生实际决策之间的差异所致。