A Nomogram for Predicting Pathological Complete Response to Neoadjuvant Chemoradiotherapy Using Semiquantitative Parameters Derived From Sequential PET/CT in Locally Advanced Rectal Cancer

Abstract

We evaluated the predictive value of semiquantitative volumetric parameters derived from sequential PET/CT and developed a nomogram to predict pathological complete response (pCR) in patients with rectal cancer treated by neoadjuvant chemoradiotherapy (nCRT). From April 2008 to December 2013, among the patients who underwent nCRT, those who were taken sequential PET/CT before and after nCRT were included. MRI-based staging and semiquantitative parameters of PET/CT including standardized uptake value (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were evaluated before and after nCRT. Multivariable analysis was performed to select significant predictors to construct a nomogram. Sensitivity, specificity, accuracy, and area under the receiver operating characteristics curve (AUC) of the model were evaluated to determine its performance. Among 137 eligible patients, 17 (12.4%) had pCR. All post-PET/CT parameters showed significant differences between pCR and non-pCR groups. Patients were randomly assigned to a training group (91 patients) and a validation group (46 patients). In multivariable analysis with the training group, post-CEA, post-MRI T staging, post-SUVmax, and post-MTV were significantly associated with pCR. There was no significant pre-nCRT variable for predicting pCR. Using significant predictors, a nomogram was developed. Sensitivity, specificity, accuracy, and AUC of the nomogram were 0.882, 0.808, 0.848, and 0.884 with the training group and 0.857, 0.781, 0.783, and 0.828 with the validation group, respectively. This model showed the better performance than other predictive models that did not contain PET/CT parameters. A nomogram containing semiquantitative post-PET/CT could effectively select candidates for organ-sparing strategies.

Improving effectiveness using nimotuzumab (NTZ) in patients with nasopharyngeal carcinoma based on the 18F-FDG PET/CT maximum standardized uptake value

“…Their study assessed the SUVmax, TLG, and MTV before and after nCRT in 137 patients with rectal cancer which was locally advanced, and found that the post-SUVmax, post-TLG, and post-MTV values were smaller in the pCR group as compared to the non-pCR group. Multivariate analysis revealed that post-SUVmax, post-TLG, and post-MTV values were independent factors for pCR [31].…”

Associations between Response to Commonly Used Neo-Adjuvant Schedules in Rectal Cancer and Routinely Collected Clinical and Imaging Parameters

“…The predictive factors and the model also need to be validated in other large patient series, preferably prospective, and we will start with the RAPIDO [ 9 ] dataset. In this regard, other markers, serial examinations with MRI, PET-CT, and functional radiology measuring the tumour’s metabolic activity before and early during the treatment could improve the baseline model in the future [ 41 ].…”

The reduction of 18F-FDG uptake ability of tumor tissue after neoadjuvant chemoradiotherapy in locally advanced rectal cancer can effectively reflect the degree of tumor regression

“…In this study, we found that post-TLG had a negative predictive value of 92.59% for GR status in LARC patients, but did not show a predictive advantage in pCR status. In previous studies, there have been meaningful reports about MTV, ΔMTV and ΔTLG in predicting the responsiveness of LARC patients to nCRT ( 8 , 25 – 27 ). However, in our study, none of these three parameters was found to have meaningful predictive value in our study.…”