Role of FLT PET in malignant pleural mesothelioma - prediction of response to chemotherapy

间皮瘤是一种肺内膜癌。化疗通常用于治疗病人，以减轻他们的症状，提高生活质量和延长寿命。然而，并非所有患者都能从化疗中获益，而且大多数患者都会出现一些副作用。目前，CT扫描被用来评估化疗的反应，然而间皮瘤的生长方式使得测量反应变得困难。CT扫描在早期检测反应方面也不是很敏感——通常需要3或4个治疗周期（3-4个月）才能看到效果。一项能够预测哪些患者在化疗1个周期（3-4周）后受益的测试将是一个巨大的优势，并可能使一些患者免于不必要的和潜在毒性的治疗。氟胸苷（FLT）是一种放射性示踪剂，注射到静脉后，被分裂的细胞吸收。肿瘤细胞通常比周围的正常细胞分裂得更活跃，因此当进行正电子发射断层扫描（PET）时，它会显示肿瘤是一个“热点”。FLT进入肿瘤的量取决于DNA合成（活跃细胞分裂）的发生。化疗后，如果肿瘤有反应，肿瘤内FLT的数量将会减少。这可以通过在第一个化疗周期后重复FLT PET扫描来评估。本研究旨在评估1个化疗周期后间皮瘤中FLT摄取变化的能力，以预测CT扫描测量的反应，以及患者的生活质量和生存等结果。如果成功的话，这种类型的扫描可以通过早期选择那些可能从化疗中受益的患者来改善患者的护理，并避免对无法从治疗中受益的患者产生不必要的毒性。

Mesothelioma is a cancer of the lining of the lung. Chemotherapy is often used to treat patients in order to reduce their symptoms and to improve quality and length of life. Not all patients however benefit from chemotherapy, and most patients will experience some side-effects. Currently CT scans are used to assess response to chemotherapy, however the way that mesothelioma grows makes measuring response difficult. CT scans also are not very sensitive in detecting response early - often 3 or 4 cycles of treatment (3-4 months) are required before benefit is seen. A test that could predict which patients were benefiting after only 1 cycle (3-4 weeks) of chemotherapy would be a great advantage, and may spare some patients unnecessary and potentially toxic treatment. Fluorothymidine (FLT) is a radioactive tracer that, after injection into a vein, is taken up by dividing cells. Tumour cells usually divide more actively than surrounding normal cells, and therefore when a positron emission tomography (PET) scan is performed it will demonstrate the tumour as a 'hot spot'. The amount of FLT uptake into the tumour depends on how much DNA synthesis (active cell division) is occurring. After chemotherapy, if the tumour responds it would be expected that the amount of FLT in the tumour will reduce. This can be assessed by repeating the FLT PET scan after the first cycle of chemotherapy. This study aims to assess the ability of the change in FLT uptake in mesothelioma after 1 cycle of chemotherapy to predict response, as measured on CT scans, and patient outcomes such as quality of life and survival. It is hoped that if successful this type of scan may improve patient care by selecting those who are likely to benefit from chemotherapy early and avoid unnecessary toxicity to patients who will not benefit from the treatment.