Abstract
Purpose
The aim of this multi-center study was to discover and validate radiomics classifiers as image-derived biomarkers for risk stratification of non-small-cell lung cancer (NSCLC).
Patients and methods
Pre-therapy PET scans from a total of 358 Stage I–III NSCLC patients scheduled for radiotherapy/chemo-radiotherapy acquired between October 2008 and December 2013 were included in this seven-institution study. A semi-automatic threshold method was used to segment the primary tumors. Radiomics predictive classifiers were derived from a training set of 133 scans using TexLAB v2. Least absolute shrinkage and selection operator (LASSO) regression analysis was used for data dimension reduction and radiomics feature vector (FV) discovery. Multivariable analysis was performed to establish the relationship between FV, stage and overall survival (OS). Performance of the optimal FV was tested in an independent validation set of 204 patients, and a further independent set of 21 (TESTI) patients.
Results
Of 358 patients, 249 died within the follow-up period [median 22 (range 0–85) months]. From each primary tumor, 665 three-dimensional radiomics features from each of seven gray levels were extracted. The most predictive feature vector discovered (FVX) was independent of known prognostic factors, such as stage and tumor volume, and of interest to multi-center studies, invariant to the type of PET/CT manufacturer. Using the median cut-off, FVX predicted a 14-month survival difference in the validation cohort (N = 204, p = 0.00465; HR = 1.61, 95% CI 1.16–2.24). In the TESTI cohort, a smaller cohort that presented with unusually poor survival of stage I cancers, FVX correctly indicated a lack of survival difference (N = 21, p = 0.501). In contrast to the radiomics classifier, clinically routine PET variables including SUVmax, SUVmean and SUVpeak lacked any prognostic information.
Conclusion
PET-based radiomics classifiers derived from routine pre-treatment imaging possess intrinsic prognostic information for risk stratification of NSCLC patients to radiotherapy/chemo-radiotherapy.
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To investigate the prevalence of memories of abuse being recovered in psychotherapy, Patihis and Pendergast surveyed patients about the duration and type of treatment they received, whether their therapists had discussed the possibility that they had repressed memories of abuse in childhood, and whether they had retrieved memories of being abused. Of 1,082 participants, 122 reported having recovered a memory of abuse. They were then asked how, where, and in what form they remember the abuse occurring, and whether they had cut off contact with family members. Twenty percent of the participants reported that their therapist had discussed the possibility of them repressing memories; this occurred in all types of therapies but mostly for those who started therapy in the 1990s. When the therapist had discussed the possibility of repressed memories, participants were 20 times more likely to report the recovery of such memories. The recovered memories most frequently reported involved emotional abuse, followed by physical abuse, and then sexual abuse, recalled as flashbacks both inside and outside of a therapy session. The recovered memory frequently resulted in cutting off contact with family members. The authors discuss the potential hazards of claimed memory recovery.
