Positron emission tomography in assessing response to neoadjuvant chemotherapy for non-small-cell lung cancer

Early response evaluation and prediction in neoadjuvant-treated patients with esophageal cancer

Since the introduction of multimodal therapy regimens, the prognosis of esophageal cancer has improved. There is undoubtedly true for patients with surgically resected tumors in the case of a response to neoadjuvant chemotherapy or chemoradiation. Important conclusions can be drawn from this regarding the indication for perioperative therapies, the radicality of surgery, or the surgical indications. Thus, most of the current research in this field is aimed at the early identification of this subset of patients, at the beginning of, or even before, neoadjuvant treatment. Conventional staging tools have failed to predict responses to neoadjuvant therapy. However, molecular imaging methods, e.g. positron emission tomography (PET)-scans, have shown promising results in the early selection of responders and non-responders during the course of neoadjuvant therapy, allowing physicians to alter the treatment plan accordingly. Even more desirable is the identification of potential responders before the start of neoadjuvant therapy. Preliminary molecular data on biopsy specimens demonstrate the possibility of early response prediction in these patients. We present the current knowledge on response evaluation and prediction in esophageal cancer and draw conclusions for future clinical practice and studies in this review.

Predicting the response of localised oesophageal cancer to neo-adjuvant chemoradiation

BACKGROUND

A complete pathological response to neo-adjuvant chemo-radiation for oesophageal cancer is associated with favourable survival. However, such a benefit is seen in the minority. If one could identify, at diagnosis, those patients who were unlikely to respond unnecessary toxicity could be avoided and alternative treatment can be considered. The aim of this review was to highlight predictive markers currently assessed and evaluate their clinical utility.

METHODS

A systematic search of Pubmed and Google Scholar was performed using the following keywords; "neo-adjuvant", "oesophageal", "trimodality", "chemotherapy", "radiotherapy", "chemoradiation" and "predict". The original manuscripts were sourced for further articles of relevance.

RESULTS

Conventional indices including tumour stage and grade seem unable to predict histological response. Immuno-histochemical markers have been extensively studied, but none has made its way into routine clinical practice. Global gene expression from fresh pre-treatment tissue using cDNA microarray has only recently been assessed, but shows considerable promise. Molecular imaging using FDG-PET seems to be able to predict response after neo-adjuvant chemoradiation has finished, but there is a paucity of data when such imaging is performed earlier.

CONCLUSION

Currently there are no clinically useful predictors of response based on standard pathological assessment and immunohistochemistry. Genomics, proteomics and molecular imaging may hold promise.

Current status of positron emission tomography in oncology

Positron emission tomography (PET) has emerged as a powerful diagnostic tool in oncology patients. There is evidence of the superior utility over conventional imaging methods of the principal PET tracer 18F-fluoro-2-deoxy-glucose in the staging of a range of cancers and monitoring disease recurrence, as well as changing patient management to more appropriate therapy. The methods for evaluating the evidence for PET remain complex, particularly as the standard evidence-based approach of randomized controlled trials is not generally applicable to imaging technologies. PET has the potential to dramatically improve our ability to manage patients with cancer and is also making major contributions to the development of new therapies.

Current status of positron emission tomography in oncology

Positron emission tomography (PET) has emerged as a powerful diagnostic tool in oncology patients. There is evidence of the superior utility over conventional imaging methods of the principal PET tracer 18F-fluoro-2-deoxy-glucose in the staging of a range of cancers and monitoring disease recurrence, as well as changing patient management to more appropriate therapy. The methods for evaluating the evidence for PET remain complex, particularly as the standard evidence-based approach of randomized controlled trials is not generally applicable to imaging technologies. PET has the potential to dramatically improve our ability to manage patients with cancer and is also making major contributions to the development of new therapies.