Prognostic Value Of The Ratio Of Positron Emission Tomography Uptake To Primary Tumor Size In Lung Cancer

Cancer is a major public health problem in the United States and also in china. One in4deaths in the United State s is due to cancer.in the article of Cancer Statistics, auhors provide the expected numbers of new cancer cases and deaths in2013nationally and by state, as well as an overview of current cancer statistics using data through2009, includ ing incidence, mortality, and survival rates and trends. They also estimate the number of deaths averted as a result of the decline in cancer death rates since the early1990s, and provide the actual reported numbers of deaths in2009by age for the10leadingcauses of death and the leading cancer types.Lung cancer is the leading cause of cancer-associated death in the world and accounts for28%of all cancer deaths in the United States [1]. Most non-small cell lung cancer(NSCLC)patients are diagnosed at a relatively late stage, platinum-based first line chemotherapy is prescribed as a part of standard treatment for advanced NSCLC patients.but, the treatment response are unclear.Accurate diagnosis and staging are important for the cancer patients. Positron emission tomography with2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) has used as a powerful imaging tool for the detection of many cancers. The combined acquisition of PET and CT has advantages over PET or CT alone and minimizes their individual limitations. It is a valuable technocal for staging and restaging of some tumors and has an great role in the detection of recurrence in patients with rising tumor marker levels and patients with negative findings on conventional imaging techniques. It also allows for monitoring response to therapy and permitting timely modification of therapeutic regimens. In some of the patients, the course of managment is changed. This review provides guidance for clinical specialists on the use of18F-FDG PET/CT in oncology [2,3];At present, in the role of PET/CT:Diagnosis and staging of tumors. Increased capacity utilization characteristics of tumor cells "capture" of FDG, not only can discover the tumor early and determine the malignant primary tumor site, can also be evaluated, the malignant degree of tumor;Monitoring of tumor recurrence and metastasis;Evaluation of the curative effect of early, mainly according to the changes of18F-FDG uptake in tumor tissue, through the analysis of visual and quantitative, predictive efficacy in early clinical or subclinical level;Guide the biopsy site, it can show the location of tumor metabolism, the most active site, especially in patients with lung lesions, which can guide the biopsy at the highest active pulmonary lumps, avoid biopsy when samples were taken from central necrosis, fibrous tissue and adjacent tissue, reduce false negative results;Looking for the primary lesion,cancer with unknown primary(CUP),about10%of all cancer patients.CUP failed to find the primary lesion may be:①primary tumor because of immune factors or vascular mechanism is destroyed; because of the specificity of gene changes, only the transfer occurs without promoting local primary tumor growth, so can not find the primary; the primary tumor disappeared automatically; check the equipment and inspection means to limit, difficult to find small primary tumor; lack of clinical experience in the doctor’s result in missed diagnosis; in some patients with primary not found on the dead from other diseases.Therefore, the primary tumor is the basis of suitable therapy and make prediction of malignant tumor behavior.PET is a reflection of the lesions, biochemical metabolism, due to the occurrence of disease progression, biochemical, metabolic abnormalities earlier than the morphological structure changes, so the detection of PET imaging has a unique rolevfor tumor function and metabolism. More recently,some researches have identified a high the Standardized Uptake Value (SUV) as a poor prognostic factor for treatment response and survival in patients with non-small cell lung cancer (NSCLC), no matter early-stage[4,5], or advanced-stage[6],because SUV in the primary site of a non-small-cell lung cancer (NSCLC), a semi-quantitative measurement of FDG uptake, has been correlated with proliferation[7,8]and aggressiveness[9,10]. But, not all studies did not control for tumor size or stage, it remains difficult to discern whether the SUV measurement is an independent predictor of survival or rather a surrogate marker for other poor prognostic factors.Based on these findings, we analyzed the first-line treatment response and survival of the patients who had pretreatment18F-FDG PET/CT in our center. The aim of the study was to clarify the pretreatment SUVmax or SUVmax to tumor size ratio could be used as independent prognostic variables to predict treatment response and survival in patients with advanced NSCLC.Purpose:In Surgically Resected Non-Small Cell Lung Cancer,a previous study has shown ratio of maximum standardized uptake value to primary tumor size is a more important indicator of prognosis than SUVmax alone. The objective of this study was to assess the prognostic value of patients with advanced non-small cell lung cancer (NSCLC). We have investigated whether SUVmax to tumor size ratio is associated with response to first-line therapy and survival in advanced Non-Small Cell Lung Cancer.Materials and methods1. Patient characteristicsPatients were included from January2007until july2011.241consecutive advanced NSCLC patients were registered. However,49patients that suspend therapy or transferred to another hospital or died in3months were excluded.Pretreatment FDG-PET/CT was performed in192patients. However, subsequently,5patients were excluded because had received concurrent chemoradiotherapy and1patient because with a second primary extrapulmonary cancer. Finally,186patients (118males and 68females; mean age:60.6years). The primary outcome measures were Response of first-line therapy and the duration of overall survival(OS). Response were evaluated by CT scans performed after treatment or emerge symptoms or relate to disease progression. OS was defined as the time in months between the pathological diagnosis and the date of death, PFS as time between pathological diagnosis and progression disease, and PPS as the time between progression disease and the date of death. Patients who were alive were censored at the time of the last clinical follow-up.2.18F-FDGPET/CTThe patients were injected with pyrogen-free [18F]FDG10to15mCi and were instructed previously to fast for at least6hours before scanning Scans performed by a dedicated16-slice whole-body PET/CT scanner.SUVmax values were obtained by correcting for the injected dose and the patient’s weight.For the purposes of this study, only uptake and tumor size in the primary site was analyzed.3Statistical AnalysisSurvival was calculated with the Kaplan-Meier method, and groups were compared with the log-rank test. Multivariate analysis was carried out with the Cox proportional hazards model. A significance level of0.05was used for covariate entry. P-values less than0.05considered to be statistically significant.Result:Total186patients were enrolled into the current study. Median OS was14.9m (range,3.1-64.0m), PFS was5.6m (range,0.8-41.1mo), and PPS was7.9m(range,0-51.3m). The statistical analysis data indicated that Low pretreatment SUV<7.9(P=0.026), and SUVmax to tumor size ratio<2.2(0.000) were associated with response to first-line therapy. Clinical response was independent prognostic factors for PFS (OR=3.152, P=0.000), low stage(Ⅲ) was associated with PPS independently, with OR=1.700, P=0.027,and for OS, low SUVmax to tumor size ratio(OR=1.764, P=0.027), tumor diameter (OR=1.743, P=0.013)and clinical response(OR=1.678, P=0.002) were all independent prognostic factors. ConclusionIn summary, Our results is first conclude that ratio of positron emission tomography uptake to primary tumor size can predict response and associate with survival, and compared with SUVmax, may be a more important indicator.SummaryIn current research, we found that, SUVmax were related with age, sex, smoke status, tumor diameter, histology, differentiation, and SUVmax to tumor size ratio is only affected by Age. SUVmax and SUVmax to tumor size ratio both may predict the response of first-line therapy.In survival analysis, SUVmax to tumor size ratio is an independent predictor of OS whereas SUVmax alone did not. and neither is an absolute independent predictor of PFS and PPS。So,compare with SUVmax,the ratio of SUVmax to tumor size may be a more important indicator of prognosis in patients with NSCLC.This study had certain limitations. First, it was retrospective reseach, and our study population was derived from just a single-center, Although our strict entry patients and take a larger sample as far as possible (n=186), there was some heterogeneity in the stage and histology between patients. as a result, a patient selection bias can not be avoided. Secondly, There is evidence in NSCLC that the use of EGFR-TKI are associated with survival []. However,.the TKIs too expensive to afford it for some patients,although as a benefit of pharmaceutical policy in China, and TKI was free once a patient had received it for5months[15]. In our study, in the whole course of treatment, only100patients use Iressa or Tarceva, which may affect the patient survival. Last,Chinese traditional medicine was used widely, in order to alleviate the adverse effects of treatment, may also have impact on survivalIn summary, Our results is first conclude that ratio of positron emission tomography uptake to primary tumor size can predict response and associate with survival, and compared with SUVmax, may be a more important indicator. Although this study was a respective study,it indicates the potential usefulness of a new predictor for advanced NSCLC patients.To confirm these findings, Additional larger,prospective and randomized studies are needed.