¹⁸F‐FDG‐PET evaluation of treatment response to neo‐adjuvant therapy in patients with locally advanced rectal cancer: A meta‐analysis

Abstract

The purpose of this meta-analysis was to evaluate the utility of positron emission tomography (PET) using fluor-18-deoxyglucose (FDG) to predict the response of rectal cancer to neo-adjuvant therapy. All previously published studies on the role of FDG-PET in predicting the response of rectal cancer to neo-adjuvant therapy were collected. Pooled sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using statistical software. A total of 28 studies, comprising 1,204 patients with rectal cancer, were included in the meta-analysis. Pooled sensitivity, specificity, PPV and NPV for FDG-PET predicting the response to therapy was 78% [95% confidence interval (CI): 75-82%], 66% (95% CI: 62-69%), 70% (95% CI; 66-73%) and 75% (95% CI: 71-0.79%), respectively. The included studies were of a relatively high methodological quality according to the QUADAS (quality assessment of studies of diagnostic accuracy included in systematic reviews) criteria. Based on the subgroup analyses, there was no significant difference between the response index, the standardized uptake value and the visual response score in predicting the therapy response. However, the accuracy of the group that underwent PET scanning during therapy showed significantly higher values (sensitivity 86% and specificity 80%) than the group that was scanned after completion of the therapy. Therefore, FDG-PET is valuable for predicting the response of rectal carcinoma to neo-adjuvant therapy, and early evaluation of response during the therapy may be more promising. However, additional studies using prospective clinical trials will be required to assess the clinical benefit of this strategy.A standard treatment of locally advanced rectal cancer consists of neo-adjuvant therapy followed by surgery. The preoperative treatment is intended to control pelvic disease and to improve the chance of sphincter preservation during subsequent surgery, thereby improving overall survival and quality of life. Unfortunately, a complete response to neo-adjuvant therapy is noted in only 12-27% 1-3 of patients, while the remaining patients suffer from side effects without effective treatment. Therefore, early evaluation of therapy response is important because it may reduce morbidity and the cost of ineffective treatment as well as explore the feasibility of a response-guided early reorientation treatment in nonresponders. The first study using fluor-18-deoxyglucose-positron emission tomography (FDG-PET) to assess tumour response to

The predictive value of 18F-FDG PET/CT for assessing pathological response and survival in locally advanced rectal cancer after neoadjuvant radiochemotherapy

“…Our results are consistent with accumulating evidence, including a recent meta-analysis on the predictive role of metabolic response to preoperative RCT in LARC, that the early evaluation of response during treatment is more promising than evaluation after completion of therapy [39]. Previously reported results on the predictive value of 18 F-FDG PET/CT in patients with LARC after and during preoperative treatment are not uniform.…”

Early prediction of pathological response in locally advanced rectal cancer based on sequential 18F-FDG PET

“…A significant tumor downsizing and downstaging, as well as a reduction of the risk for local recurrence and longer survival have been observed as a result of PRCT [1–3]. Within this context, 18 F-FDG PET imaging has been demonstrated as an interesting predictive tool [4]. Indeed, correlations between the pathological tumor response after PRCT and the standard uptake value (SUV) decrease within the tumor have been demonstrated in several studies [5–9].…”

Is the Standardized Uptake Value of FDG-PET/CT Predictive of Pathological Complete Response in Locally Advanced Rectal Cancer Treated with Capecitabine-Based Neoadjuvant Chemoradiation?

“…Although early information on tumor response may be important for the choice of the most appropriate therapeutic strategy and was promising in a recent metanalysis [38], we did not find a useful role of early metabolic assessment as a possible surrogate biomarker of pathological response. On the contrary, in the posttherapy evaluation we found that both the final absolute value of SUVmax and the percentage reduction of the baseline value may predict pCR in LARC; in fact, SUV3 and RI (1–3) were significantly lower in patients with pCR as compared to non-pCR ones and, in univariate analysis, both parameters appeared to be significant predictive factors of pCR.…”