The importance of Pet in the diagnosis and response evaluation of esophageal cancer

Abstract

The major aims of imaging in esophageal cancer are to distinguish between locoregional and systemic disease (M-stage), to determine local tumor extension (T- and N-stage), to assess response to chemo- or chemoradiotherapy and to identify recurrence of cancer. The sensitivity of computed tomography (CT) for detection of distant metastases ranges between < 50% and > 90%. In esophageal cancer, F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) has been shown to detect metastatic disease in approximately 20% of patients who are considered as having only locoregional disease on CT. In locoregional pretherapeutic tumor staging, FDG-PET specificity of 80% is sufficient, but FDG-PET sensitivity of 50% is rather low. However, the initial staging of regional lymph nodes is less important because at the moment there is no pretherapeutic therapy stratification based on lymph node category. The accuracy for correct identification of recurrence in esophageal cancer is higher for FDG-PET than for CT scan. Unfortunately until today no reliable essays for prediction of response or prognosis exist for esophageal cancer in clinical practice for patients with neoadjuvant treatment. Thus the identification of parameters predicting response and/or prognosis is crucial for the future. Post-therapeutic assessment of tumor response by FDG-PET has been shown to correlate with histopathologic tumor regression and patient survival. Furthermore, quantitative measurements of tumor FDG-uptake may allow an early metabolic response evaluation after only 2 weeks of therapy. An association of metabolic response with histopathologic tumor regression and patient outcome 2 weeks after initiation of preoperative chemotherapy may be shown for esophageal cancer.

The clinical application of 18F‐fluorodeoxyglucose positron emission tomography to predict survival in patients with operable esophageal cancer

“…5,6,8,19,21,22 In general, a change in International Union Against Cancer (UICC) stage occurs in approximately 20% of the patients with esophageal cancer using FDG-PET compared with conventional imaging modalities. 23 Furthermore, changes in tumor metabolic activity during preoperative treatment have been shown to correlate with histopathologic response and patient survival. [24][25][26] Some researchers have suggested that FDG may be a predictive tool for patient outcome in esophageal cancer, as has already been demonstrated for other types of malignancies including lung cancer and head and neck cancer.…”

The higher the decrease in the standardized uptake value of positron emission tomography after chemoradiation, the better the survival of patients with gastroesophageal adenocarcinoma

“…16 The most interesting aspect is that percentage SUV changes in PET/CT seem to narrow these 3 categories into 2 categories prior to surgery: 1) some response (this includes complete pathologic response and 0% to 50% residual cancer cells) and 2) no response (>50% residual cancer cells). 23,28 This should be considered an advance; however, PET/CT changes have not been able to discriminate between those with pathologic complete response and those with some residual cancer. Unfortunately, PET/CT changes do not correlate with pathologic complete response.…”

“…Unfortunately, PET/CT changes do not correlate with pathologic complete response. 23,24,28,[44][45][46][47] Some limitations of our results must be considered. This is a retrospective analysis; the dichotomized cutoff value of >52% was chosen from a study of squamous cell carcinoma, but it certainly performed well for adenocarcinoma.…”

“…[15][16][17][18] However, the initial results and subsequent changes in positron emission tomography (PET) show promise. [19][20][21][22][23][24][25] Many investigators have demonstrated that decrease in metabolic activity as measured by the standardized uptake value (SUV) on PET/computed tomography (CT) as a result of therapy is of prognostic value. [25][26][27][28] In addition, PET/CT images obtained during therapy have been studied in a limited number of patients and seem to provide useful information regarding the response to therapy and prognosis of patients.…”

Radiology of Esophageal Cancer

“…Bu düşük duyarlılık büyük olasılıkla tekniğin uzaysal rezolüsyo-nunun düşük olmasına bağlıdır. Primer tümöre çok yakın olan metastatik lenf nodundaki FDG tutulumu primer tümördeki yoğun FDG tutulumundan ayırt edilememektedir (40). Bununla birlikte servikal ve abdominal uzak lenf nodu metastazını saptamadaki duyarlılığı oldukça yüksektir (Resim 7) (28).…”