Intraoperative staging by surgeons in patients with rectal cancer after preoperative chemoradiation: diagnostic accuracy and prognostic value

Clinical Tools for Rectal Cancer Response Assessment following Neoadjuvant Treatment in the Era of Organ Preservation

Local tumor response evaluation following neoadjuvant treatment(s) in rectal adenocarcinoma requires a multi-modality approach including physical and endoscopic evaluations, rectal protocoled MRI, and cross-sectional imaging. Clinical tumor response exists on a spectrum from complete clinical response (cCR), defined as the absence of clinical evidence of residual tumor, to near-complete response (nCR), which assumes a significant reduction in tumor burden but with increased uncertainty of residual microscopic disease, to incomplete clinical response (iCR), which incorporates all responses less than nCR that is not progressive disease. This article aims to review the clinical tools currently routinely available to evaluate treatment response and offers a potential management approach based on the extent of local tumor response.

Is it important to palpate lymph nodes in open surgery for colorectal cancer?

INTRODUCTION

In laparoscopic or robotic surgery, surgeons cannot directly palpate lymph nodes (LN), which could be considered a shortcoming in that procedure. This study was performed to evaluate the importance of palpation diagnosis of LN metastasis in colorectal cancer surgery.

METHODS

This study enrolled 408 patients who underwent curative resection for primary colorectal cancer in our department in 2014. The diameter of each manually dissected LN was measured, and the LN was then examined by palpation to determine whether it was metastatic based on its consistency. The palpation and pathological diagnoses of each LN were compared. Sensitivities, specificities, positive predictive values, negative predictive values, and accuracies were calculated for palpation diagnosis of LN metastasis in a node-by-node analysis, according to LN size.

RESULTS

Of the 13 750 dissected LN, 444 LN (3.2%) were metastatic. Overall, palpation diagnosis of LN metastasis revealed node-by-node sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 50%, 98%, 52%, 98%, and 97%, respectively. The sensitivity for LN 3 mm and smaller and for LN 15 mm and larger was 3% and 90%, respectively.

CONCLUSION

Palpation diagnosis of LN metastasis in colorectal cancer surgery was unreliable. Although poor haptics is considered to be a disadvantage in laparoscopic and robotic surgery, they are not inferior to open surgery in terms of LN dissection.

The role of diffusion-weighted MRI and (18)F-FDG PET/CT in the prediction of pathologic complete response after radiochemotherapy for rectal cancer: a systematic review

After neoadjuvant radiochemotherapy (RCT) for locally advanced rectal cancer, 15-27% of the patients experience a pathological complete response (pCR). This observation raises the question as to whether invasive surgery could be avoided in a selected cohort of patients who obtain a clinical complete response after preoperative RCT. In this respect, there has been growing interest in functional imaging techniques to improve clinical response assessment. This systematic review focuses on the role of diffusion-weighted imaging (DWI) and (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the prediction of pCR after RCT for rectal cancer. A total of 14 publications on DWI and 25 on (18)F-FDG PET/CT were retrieved. Pooled analysis of individual patient data shows both imaging modalities have a low positive predictive value in the prediction of pCR (mean PPV of 54% and 39% for DWI- and (18)F-FDG PET/CT-based parameters respectively). Especially pre-RCT imaging is unable to predict pCR with overall accuracies of 68-72% for DWI and 44% for (18)F-FDG PET/CT. Qualitative DWI assessment 5-10weeks after the end of RCT may outperform apparent diffusion coefficient (ADC)-based DWI-parameters (overall accuracy of 87% vs. 74-78%). Although few data are available, early changes in FDG-uptake seem promising in the prediction of pCR and the role of (18)F-FDG PET/CT during RCT should be further investigated. Quantitative and qualitative (18)F-FDG PET/CT measurements are equally effective in the assessment of pCR after RCT. The major strength of DWI and (18)F-FDG PET/CT lies in the identification of non-responders who are not candidates for organ preservation. Up to now, DWI and (18)F-FDG PET/CT are not accurate enough to safely select patients for organ-sparing strategies. Future research must focus on the integration of functional imaging with clinical data and molecular biomarkers.