Biological imaging for selecting and monitoring cancer therapy; a pathway to individualised therapy

Can ¹⁸F-fluorodeoxyglucose positron emission tomography predict responses to neoadjuvant therapy in oesophageal cancer patients? A meta-analysis

OBJECTIVES

Neoadjuvant therapy for the treatment of oesophageal cancer was introduced in an effort to improve prognosis. Response assessment is crucial for the treatment of patients with oesophageal cancer. Currently, ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) seems to be the best available tool to assess neoadjuvant therapy response in patients with oesophageal cancer. The purpose of this study was to assess the diagnostic value of ¹⁸F-FDG PET for the evaluation of neoadjuvant therapy responses in patients with oesophageal cancer using a meta-analysis. A unified procedure and evaluation standard for ¹⁸F-FDG PET in the assessment of neoadjuvant therapy response should be established.

METHODS

All published English-language studies pertaining to the assessment of neoadjuvant therapy response in patients with oesophageal cancer using ¹⁸F-FDG PET in the MEDLINE and EMBASE databases were collected. The methodological quality of the included studies was evaluated according to the Quality Assessment of Diagnostic Accuracy Studies quality assessment tool. Pooled sensitivity, specificity, diagnostic odds ratios and summary receiver operating characteristic curves were obtained using statistical software.

RESULTS

Thirteen studies included in the meta-analysis fulfilled the inclusion criteria of the Quality Assessment of Diagnostic Accuracy Studies quality assessment tool. The pooled sensitivity, specificity and diagnostic odds ratios for F-¹⁸FDG PET in the evaluation of neoadjuvant therapy response in patients with oesophageal cancer were 70.3% [95% confidence interval (CI): 64.4-75.8], 70.1% (95% CI: 65.1-74.8) and 9.389 (95% CI: 3.482-25.319), respectively. The area under the curve and the Q value for the summary receiver operating characteristic curve were 0.8244 and 0.7575, respectively.

CONCLUSION

¹⁸F-FDG PET has some value in the assessment of neoadjuvant therapy response in patients with oesophageal cancer. A 50% reduction in standardized uptake value between pretherapy and posttherapy positron emission tomography scans performed in the first 2 weeks after the initiation of neoadjuvant therapy is the optimal condition for predicting a response to neoadjuvant therapy in patients with oesophageal cancer.

Is FDG-PET suitable for evaluating neoadjuvant therapy in non-small cell lung cancer? Evidence with systematic review of the literature

BACKGROUND

Neoadjuvant therapy response assessment is crucial in patients with non-small cell lung cancer (NSCLC). FDG-PET has emerged as a valuable tool for defining therapy response assessment in other tumours.

AIM

To systematically review publications appearing in the literature describing induction therapy response assessment with FDG-PET in NSCLC.

METHODS

We performed a bibliographic search and selected only prospective studies in order to include the highest levels of evidence.

RESULTS

Nine of 497 potentially relevant publications were selected. The ranges of sensitivity, specificity, positive predictive value and negative predictive value for primary tumour response assessment were 80-100%, 0-100%, 42.9-100%, and 66.7-100%, respectively. Pooling data for N2 restaging after neoadjuvant response the overall sensitivity was 63.8% (95% CI, 53.3-73.7%) and overall specificity was 85.3% (95% CI, 80.4-89.4%).

CONCLUSION

The results of the analysis do not support the use of FDG-PET as the only re-assessment tool for mediastinal lymph node evaluation for routine clinical use. FDG-PET seems to predict primary tumour response to induction therapy but it could not be shown by pooling analysis.

Assessing response to chemotherapy in metastatic melanoma with FDG PET: Early experience

OBJECTIVE

The management of metastatic melanoma remains challenging with only modest response rates to chemotherapy but the need to identify the best re-staging techniques remains paramount. This study evaluates our early experience in the use of FDG PET-CT in the assessment of early response to chemotherapy in metastatic melanoma.

METHODS

FDG PET-CT was performed at baseline and following two or three cycles of combination or single agent chemotherapy in seven patients. Response was assessed visually as complete, partial metabolic response or progressive disease.

RESULTS

There was intense FDG uptake in all metastases at baseline. Following two to three cycles of chemotherapy, there was a complete metabolic response (CMR) in one patient, partial metabolic response (PMR) in two patients and progressive metabolic disease (PMD) in the remaining three patients. Survival was 679 days in the single patient with a CMR, median of 206 and 129 days in the patients with PMR and PMD respectively.

CONCLUSION

This pilot study demonstrates the potential use of FDG PET as a biomarker in early response assessment to chemotherapy in metastatic melanoma. PET-CT already plays in integral role in staging high risk melanoma patients and it may also have a promising role in assessing response to current and novel therapies. Further larger studies examining specific therapies and optimal timing are required.