Modeling strategies to improve parameter estimates in prognostic factors analyses with patient-reported outcomes in oncology

Purpose

The inclusion of patient-reported outcome (PRO) questionnaires in prognostic factor analyses in oncology has substantially increased in recent years. We performed a simulation study to compare the performances of four different modeling strategies in estimating the prognostic impact of multiple collinear scales from PRO questionnaires.

Methods

We generated multiple scenarios describing survival data with different sample sizes, event rates and degrees of multicollinearity among five PRO scales. We used the Cox proportional hazards (PH) model to estimate the hazard ratios (HR) using automatic selection procedures, which were based on either the likelihood ratio-test (Cox-PV) or the Akaike Information Criterion (Cox-AIC). We also used Cox PH models which included all variables and were either penalized using the Ridge regression (Cox-R) or were estimated as usual (Cox-Full). For each scenario, we simulated 1000 independent datasets and compared the average outcomes of all methods.

Results

The Cox-R showed similar or better performances with respect to the other methods, particularly in scenarios with medium–high multicollinearity (ρ?=?0.4 to ρ?=?0.8) and small sample sizes (n?=?100). Overall, the Cox-PV and Cox-AIC performed worse, for example they did not select one or more prognostic collinear PRO scales in some scenarios. Compared with the Cox-Full, the Cox-R provided HR estimates with similar bias patterns but smaller root-mean-squared errors, particularly in higher multicollinearity scenarios.

Conclusions

Our findings suggest that the Cox-R is the best approach when performing prognostic factor analyses with multiple and collinear PRO scales, particularly in situations of high multicollinearity, small sample sizes and low event rates.

     

Intraoperative radiotherapy during radical prostatectomy for intermediate‐risk to locally advanced prostate cancer: treatment technique and evaluation of perioperative and functional outcome vs standard radical prostatectomy,in a matched‐pair analysis

OBJECTIVE

To evaluate a novel approach with intraoperative radiotherapy (IORT) administered in the surgical field, after pelvic lymphadenectomy (PL) and before radical retropubic prostatectomy (RRP), evaluating acute and late toxicity, complications and biochemical progression‐free survival (bPFS), as the adequate treatment of locally advanced prostate cancer is still a controversial issue.

PATIENTS AND METHODS

Between June 2005 and October 2007, 33 consecutive patients with intermediate‐risk or locally advanced prostate cancer were selected for PL + IORT + RRP. IORT was delivered by a mobile linear accelerator in the operating room (electron beam, 12 Gy at 90% isodose). According to the pathological findings further adjuvant radio‐ or hormone therapy could be administered. The median follow‐up was 16 months. This group was compared retrospectively with a historical group of 100 patients who had undergone RRP and further adjuvant therapy, selected with equivalent criteria. The comparison was conducted as a matched‐pair analysis. The perioperative outcomes (surgical time, estimated blood loss, blood transfusions, days of catheterization, days of drainage, days of hospitalization), continence as the functional outcome, acute and late toxicity, rate of complications and bPFS were evaluated and compared.

RESULTS

The baseline characteristics of the two groups were equivalent but the node count and the number of positive lymph nodes was higher in the IORT group. The IORT group had longer surgery, and a shorter hospital stay and catheterization. There were no differences in continence rate, and no major complications in either group. The acute and late toxicity and bPFS were equivalent. A retrospective comparison and the short follow‐up were the major limitations.

CONCLUSIONS

IORT administered before RRP seems a feasible approach, with little effect on the variables evaluated.     

Asthma phenotypes in childhood

Introduction: Asthma is no longer thought of as a single disease, but rather a collection of varying symptoms expressing different disease patterns. One of the ongoing challenges is understanding the underlying pathophysiological mechanisms that may be responsible for the varying responses to treatment.

Areas Covered: This review provides an overview of our current understanding of the asthma phenotype concept in childhood and describes key findings from both conventional and data-driven methods.

Expert Commentary: With the vast amounts of data generated from cohorts, there is hope that we can elucidate distinct pathophysiological mechanisms, or endotypes. In return, this would lead to better patient stratification and disease management, thereby providing true personalised medicine.     

Part I—mechanism of adaptation: high nitric oxide adapted A549 cells show enhanced DNA damage response and activation of antiapoptotic pathways

Our previous studies demonstrate that A549, a human lung adenocarcinoma line, could be adapted to the free radical nitric oxide (NO^●). NO^● has been shown to be overexpressed in human tumors. The original cell line, A549 (parent), and the newly adapted A549-HNO (which has a more aggressive phenotype) serves as a useful model system to study the role of NO^● in tumor biology. It is well known that DNA damage response (DDR) is altered in cancer cells and NO^● is known to cause DNA damage. Modulations in molecular mechanisms involved in DNA damage response in A549-HNO cells can provide better insights into the enhanced growth behavior of these cells. Thus, here, we carried out a series of time course experiments by treating A549 and A549-HNO cells with NO^● donor and examining levels of proteins involved in the DDR pathway. We observed induced expression of key components of DDR pathway in A549-HNO cells. The HNO cells showed sustained expression of key proteins involved in both nonhomologous end joining (NHEJ) and homologous recombination pathways, whereas parent cells only expressed low levels of NHEJ pathway proteins. Further with prolonged NO^● exposure, ATR, Chk1, and p53 were activated and upregulated in HNO cells. Activation of p53 results in inhibition of apoptosis through induced Mcl1 expression. It also leads to cell cycle modulation. Interestingly, several reports show that cancer stem cells have enhanced expression of proteins involved in DNA damage response and also activated an antiapoptotic response. Our results here suggest that our HNO adapted A549 cells have increased activation of DNA damage response pathway proteins which can lead to better DNA repair function. Enhanced DDR leads to activation of antiapoptosis response and modulation in the cell cycle which may lead to better survival of these cells under harsh conditions. Thus, our present investigation further supports the hypothesis that HNO exposure leads to survival of these cells.     

Mechanisms of g protein-coupled estrogen receptor-mediated spinal nociception

Human and animal studies suggest that estrogens are involved in the processing of nociceptive sensory information and analgesic responses in the central nervous system. Rapid pronociceptive estrogenic effects have been reported, some of which likely involve G protein-coupled estrogen receptor (GPER) activation. Membrane depolarization and increases in cytosolic calcium and reactive oxygen species (ROS) levels are markers of neuronal activation, underlying pain sensitization in the spinal cord. Using behavioral, electrophysiological, and fluorescent imaging studies, we evaluated GPER involvement in spinal nociceptive processing. Intrathecal challenging of mice with the GPER agonist G-1 results in pain-related behaviors. GPER antagonism with G15 reduces the G-1-induced response. Electrophysiological recordings from superficial dorsal horn neurons indicate neuronal membrane depolarization with G-1 application, which is G15 sensitive. In cultured spinal sensory neurons, G-1 increases intracellular calcium concentration and induces mitochondrial and cytosolic ROS accumulation. In the presence of G15, G-1 does not elicit the calcium and ROS responses, confirming specific GPER involvement in this process. Cytosolic calcium concentration elevates faster and with higher amplitude following G-1 intracellular microinjections compared to extracellular exposure, suggesting subcellular GPER functionality. Thus, GPER activation results in spinal nociception, and the downstream mechanisms involve cytosolic calcium increase, ROS accumulation, and neuronal membrane depolarization. PERSPECTIVE: Our results suggest that GPER modulates pain processing in spinal sensory neurons via cytosolic calcium increase and ROS accumulation. These findings extend the current knowledge on GPER involvement in physiology and disease, providing the first evidence of its pronociceptive effects at central levels and characterizing some of the underlying mechanisms.     

Sensitivity and detection rate of a 12-core trans-perineal prostate biopsy: preliminary report

OBJECTIVES: The various prostate biopsy methods are usually compared in terms of the diagnosis rate of prostate cancer. However, the prevalence of cancer in patients with a negative prostatic biopsy is not usually known. We determined the sensitivity and detection rate of 12-core transperineal biopsies in patients not previously investigated for prostate cancer. METHODS: We performed prostate biopsy in 63 patients (median age 67 years) before radical cystoprostatectomy for high-grade bladder cancer. We then assessed the relationships between biopsy result, prostate cancer in the surgical specimen, and other variables. RESULTS: 17.2% of patients had a positive biopsy and 54% had prostate cancer on definitive histology. Biopsy sensitivity was 32.3% overall, 75% for clinically significant cancers, and 11% for non-significant cancers. Median PSA was 1.2ng/ml, PSA levels did not correlate with the presence of prostate cancer, the presence of clinically significant cancer, bioptic diagnosis, or prostate volume. Age correlated with risk of cancer. CONCLUSIONS: According to autopsy series, the prevalence of prostate cancer is greater than 50% in males older than 60, yet low PSA levels do not reliably indicate disease absence. The sensitivity of double sextant biopsy is unsatisfactory overall (32%), but acceptable (75%) for diagnosing clinically significant cancer.     

Adaptive learning algorithms to optimize mobile applications for behavioral health: guidelines for design decisions

ObjectiveProviding behavioral health interventions via smartphones allows these interventions to be adapted to the changing behavior, preferences, and needs of individuals. This can be achieved through reinforcement learning (RL), a sub-area of machine learning. However, many challenges could affect the effectiveness of these algorithms in the real world. We provide guidelines for decision-making.Materials and MethodsUsing thematic analysis, we describe challenges, considerations, and solutions for algorithm design decisions in a collaboration between health services researchers, clinicians, and data scientists. We use the design process of an RL algorithm for a mobile health study “DIAMANTE” for increasing physical activity in underserved patients with diabetes and depression. Over the 1.5-year project, we kept track of the research process using collaborative cloud Google Documents, Whatsapp messenger, and video teleconferencing. We discussed, categorized, and coded critical challenges. We grouped challenges to create thematic topic process domains.ResultsNine challenges emerged, which we divided into 3 major themes: 1. Choosing the model for decision-making, including appropriate contextual and reward variables; 2. Data handling/collection, such as how to deal with missing or incorrect data in real-time; 3. Weighing the algorithm performance vs effectiveness/implementation in real-world settings.ConclusionThe creation of effective behavioral health interventions does not depend only on final algorithm performance. Many decisions in the real world are necessary to formulate the design of problem parameters to which an algorithm is applied. Researchers must document and evaulate these considerations and decisions before and during the intervention period, to increase transparency, accountability, and reproducibility.Trial Registrationclinicaltrials.gov, {"type":"clinical-trial","attrs":{"text":"NCT03490253","term_id":"NCT03490253"}}NCT03490253.