Predictive value of 18F-FDG PET and somatostatin receptor scintigraphy in patients with metastatic endocrine tumors.

UNLABELLED: The treatment of metastatic neuroendocrine tumors depends on the aggressiveness of the disease. We wanted to know whether (18)F-FDG PET and somatostatin receptor scintigraphy (SRS) can predict early disease progression and patient survival. METHODS: We undertook a prospective study of patients with metastatic neuroendocrine tumor diagnosed between September 2003 and January 2006. After obtaining signed informed consent from the patients, we performed CT, SRS, and (18)F-FDG PET and reviewed histologic data. CT was repeated every 3 mo to assess the risk of early progressive disease (first 6 mo), progression-free survival, and overall survival. RESULTS: Thirty-eight patients (mean age, 60 +/- 15 y) were included. Histologically, 4 patients had a high-grade and 34 a low-grade tumor. The results of (18)F-FDG PET and SRS were positive in 15 and 27 patients. The 2-y overall survival and progression-free survival were 73% and 45%; 16 patients had early progressive disease. Most (18)F-FDG PET-positive patients had early progressive disease (14/15, vs. 2/23 (18)F-FDG PET-negative patients), and most SRS-negative patients had early progressive disease (9/11, vs. 7/27 SRS-positive patients); (18)F-FDG PET gave excellent negative and positive predictive values of 91% and 93%; (18)F-FDG PET results correlated with progression-free survival (P < 0.001) and overall survival (P < 0.001) even when only low-grade tumors were considered. SRS was associated with progression-free survival (P < 0.001) and overall survival (P < 0.03). At multivariate analysis, only (18)F-FDG PET was predictive of progression-free survival. CONCLUSION: (18)F-FDG PET exhibits excellent predictive values for early tumor progression. (18)F-FDG PET and SRS results correlate with progression-free survival and overall survival even for histologically low-grade tumors. These explorations could be included in the initial work-up for metastatic neuroendocrine tumor.

Impact of PET-FDG in the diagnosis and therapeutic care of patients presenting with metastases of unknown primary.

We carried out a study to evaluate the contribution of positron emission tomography with (18)F-fluorodeoxyglucose (PET-FDG) in the diagnosis and therapeutic care of patients presenting with metastases of unknown primary. PET-FDG was prospectively performed in 51 patients. The PET-FDG data were confirmed histologically or by a follow-up on average at 13 months. PET-FDG identified the primary in 24 percent of cases, and detected the presence of additional metastases in 41 percent of cases. PET-FDG led to a therapeutic modification for 12 patients (24 percent). Furthermore, the therapeutic impact seems more marked in localized forms than in the multifocal. This broad exploratory study confirms the important role of PET-FDG in the diagnosis and therapeutic management of patients with metastases of unknown primary.

Monitoring of early response to neoadjuvant chemotherapy in stage II and III breast cancer by [18F]fluorodeoxyglucose positron emission tomography.

PURPOSE: This study aimed to assess prospectively the efficacy of sequential [18F]fluorodeoxyglucose positron emission tomography (FDG PET) to evaluate early response to neoadjuvant chemotherapy in stage II and III breast cancer patients. PATIENTS AND METHODS: Images were acquired with a PET/computed tomography scanner in 64 patients after administration of FDG (5 MBq/kg) at baseline and after the first, second, third, and sixth course of chemotherapy. Ultrasound and mammography were used to assess tumor size. Decrease in the standardized uptake value (SUV) with PET was compared with the pathologic response. RESULTS: Surgery was performed after six courses of chemotherapy and pathologic analysis revealed gross residual disease in 28 patients and minimal residual disease in 36 patients. Although SUV data did not vary much in nonresponders (based on pathology findings), they decreased markedly to background levels in 94% (34 of 36) of responders. When using 60% of SUV at baseline as the cutoff value, the sensitivity, specificity, and negative predictive value of FDG PET were 61%, 96%, and 68% after one course of chemotherapy, 89%, 95%, and 85% after two courses, and 88%, 73%, and 83% after three courses, respectively. The same parameters with ultrasound (US) and mammography were 64%, 43%, and 55%, and 31%, 56%, and 45%, respectively. Assessment of tumor response with US or mammography was never significant whatever the cutoff. CONCLUSION: Pathologic response to neoadjuvant chemotherapy in stage II and III breast cancer can be predicted accurately by FDG PET after two courses of chemotherapy.