More accurate cancer-related excess mortality through correcting background mortality for extra variables

Relative survival methods used to estimate the excess mortality of cancer patients rely on the background (or expected) mortality derived from general population life tables. These methods are based on splitting the observed mortality into the excess mortality and the background mortality. By assuming a regression model for the excess mortality, usually a Cox-type model, one may investigate the effects of certain covariates on the excess mortality. Some covariates are cancer-specific whereas others are variables that may influence the background mortality as well. The latter should be taken into account in the background mortality to avoid biases in estimating their effects on the excess mortality. Unfortunately, the available life table might not include such variables and, consequently, might provide inaccurate values of the background mortality. We propose a model that uses multiplicative parameters to correct potentially inaccurate background mortality. The model can be seen as an extension of the frequently used Estève model because we assume a Cox-type model for the excess mortality with a piecewise constant baseline function and introduce additional parameters that multiply the background mortality. The original and the extended model are compared, first in a simulation study, then in an application to colon cancer registry data.

Handling informative dropout in longitudinal analysis of health-related quality of life: application of three approaches to data from the esophageal cancer clinical trial PRODIGE 5/ACCORD 17

Background

Health-related quality of life (HRQoL) has become a major endpoint to assess the clinical benefit of new therapeutic strategies in oncology clinical trials. Typically, HRQoL outcomes are analyzed using linear mixed models (LMMs). However, longitudinal analysis of HRQoL in the presence of missing data remains complex and unstandardized. Our objective was to compare the modeling alternatives that account for informative dropout.

Methods

We investigated three alternative methods—the selection model (SM), pattern-mixture model (PMM), and shared-parameters model (SPM)—in relation to the LMM. We first compared them on the basis of methodological arguments highlighting their advantages and drawbacks. Then, we applied them to data from a randomized clinical trial that included 267 patients with advanced esophageal cancer for the analysis of four HRQoL dimensions evaluated using the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire.

Results

We highlighted differences in terms of outputs, interpretation, and underlying modeling assumptions; this methodological comparison could guide the choice of method according to the context. In the application, none of the four models detected a significant difference between the two treatment arms. The estimated effect of time on HRQoL varied according to the method: for all analyzed dimensions, the PMM estimated an effect that contrasted with those estimated by the SM and SPM; the LMM estimated effects were confirmed by the SM (on two of four HRQoL dimensions) and SPM (on three of four HRQoL dimensions).

Conclusions

The PMM, SM, or SPM should be used to confirm or invalidate the results of LMM analysis when informative dropout is suspected. Of these three alternative methods, the SPM appears to be the most interesting from both theoretical and practical viewpoints.

Trial registration

This study is registered with ClinicalTrials.gov, number NCT00861094.

GUIP1: a R package for dose escalation strategies in phase I cancer clinical trials

BACKGROUND

The main objective of phase I cancer clinical trials is to identify the maximum tolerated dose, usually defined as the highest dose associated with an acceptable level of severe toxicity during the first cycle of treatment. Several dose-escalation designs based on mathematical modeling of the dose-toxicity relationship have been developed. The main ones are: the continual reassessment method (CRM), the escalation with overdose control (EWOC) method and, for late-onset and cumulative toxicities, the time-to-event continual reassessment method (TITE-CRM) and the time-to-event escalation with overdose control (TITE-EWOC) methods. The objective of this work was to perform a user-friendly R package that combines the latter model-guided adaptive designs.

RESULTS

GUIP1 is an R Graphical User Interface for dose escalation strategies in Phase 1 cancer clinical trials. It implements the CRM (based on Bayesian or maximum likelihood estimation), EWOC and TITE-CRM methods using the dfcrm and bcrm R packages, while the TITE-EWOC method has been specifically developed. The program is built using the TCL/TK programming language, which can be compiled via R software libraries (tcltk, tkrplot, tcltk2). GUIP1 offers the possibility of simulating and/or conducting and managing phase I clinical trials in real-time using file management options with automatic backup of study and/or simulation results.

CONCLUSIONS

GUIP1 is implemented using the software R, which is widely used by statisticians in oncology. This package simplifies the use of the main model-based dose escalation methods and is designed to be fairly simple for beginners in R. Furthermore, it offers multiple possibilities such as a full traceability of the study. By including multiple innovative adaptive methods in a free and user-friendly program, we hope that GUIP1 will promote and facilitate their use in designing future phase I cancer clinical trials.

%TTD and %TUDD: New SAS macro programs to calculate the survival data of the time to deterioration for patient-reported outcomes data in oncology

BACKGROUND AND OBJECTIVE

Longitudinal analysis of patient-reported outcome (PRO) data remains challenging, as no standardization of statistical methods has been proposed, making comparison of PRO results between clinical trials difficult. In this context, the time to deterioration approach has recently been proposed and is regularly used as a modality of longitudinal PRO analysis in oncology.

METHODS

Two new SAS macro programs were developed, %TTD and %TUDD, which implement longitudinal analysis of PRO data according to the time to deterioration approach. These programs implement the recommended deterioration definitions. We described the programs with their different functionalities.

RESULTS

The %TTD macro calculates the time to first or transient deterioration, and the %TUDD macro calculates the time until definitive deterioration. These macros allow to obtain the survival variables from the time to deterioration approach. We illustrate our programs by presenting different applications on the randomized phase II AFUGEM GERCOR clinical trial.

CONCLUSION

The implementation of the deterioration definitions in SAS software allows the dissemination of this approach, in order to move toward the goal of standardization of longitudinal PRO analysis in oncology clinical trials.

Abstract P3-14-01: High-dose vitamin D supplementation for the correction of vitamin D insufficiency in patients undergoing adjuvant chemotherapy for breast cancer, a phase II multicenter study

Background:Vitamin D (VitD) insufficiency affects most of patients with early breast cancer (EBC). Breast cancer treatment may lead to bone loss, due to premature ovarian failure or direct chemotherapy (CT) cytotoxic effects. These increase the risk of skeletal morbidity as compared to women without breast cancer history. We previously published the persistence of VitD insufficiency at the end of adjuvant CT despite an adapted dose supplementation. We report here the safety and efficacy analysis of a phase II trial evaluating a high-dose oral VitD supplementation regimen for correction of VitD insufficiency in insufficient EBC patients treated with adjuvant CT.

Material and methods: EBC patients with VitD insufficiency for whom adjuvant CT was planned were eligible for this study. They received one dose of 100,000 IU 25OH-vitamin D every 3 weeks from day 1 of cycle 1 to day 1 of cycle 5, except in case of clinical or biological adverse event related to vitamin D and calcium metabolism, leading to early discontinuation. The primary endpoint was the percentage of serum 25OH-vitamin D level normalization at day 1 of cycle 6 (D1C6). Secondary endpoints were the safety, the Vitamin D and calcium parameters (blood calcium, phosphorus and parathormone [PTH] levels, urinary calcium excretion) at baseline and the description of their evolution during adjuvant CT, as well as the evaluation of the predictive value of these biomarkers and baseline clinical factors on the percentage of VitD normalization at D1C6.

Results: Among 45 eligible patients, 44 were evaluable for the primary endpoint. Among them, 21 (47.7%; 95%CI: 33.0-62.8) achieved a 25OH-Vitamin D correction at D1C6. No clinical toxicity linked to the VitD treatment was reported. However, 13 patients (29.5%) presented an asymptomatic grade 1 hypercalciuria, possibly linked to the VitD treatment, without concomitant change in the kidney function, but which lead to the interruption of the high dose oral VitD supplementation in 10 of the 13 patients. VitD normalization rates at 6, 12, 18 and 24 months were 50, 28.9, 80 and 60.9%, respectively. No clinical or biological marker was found to significantly predict the 6-month 25OH vitamin D normalization.

Conclusions: A high-dose 25OH-vitamin D regimen allowed a high percentage of serum 25OHD level normalization at D1C6 in EBC patients undergoing adjuvant CT. An asymptomatic increase in urinary calcium excretion was observed in one third of the patients, without clinical consequences. The physiopathology of this urinary calcium increase warrants further evaluation, since it is a classical reason for VitD treatment interruption, leading to a lower rate of correction in this highly requiring clinical setting.

Citation Format: Jacot W, D'Hondt V, Touraine C, Chapelle A, Legouffe E, Metge M, Rifai L, Roca L, Pouderoux S, Romieu G. High-dose vitamin D supplementation for the correction of vitamin D insufficiency in patients undergoing adjuvant chemotherapy for breast cancer, a phase II multicenter study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-14-01.

Abstract P3-14-03: Changes in vitamin D and calcium metabolism markers in patients undergoing adjuvant chemotherapy for breast cancer

Background:Vitamin D (VitD) insufficiency affects the majority of patients with early breast cancer (EBC). Breast cancer treatment may lead to bone loss, due to premature ovarian failure or direct chemotherapy (CT) cytotoxic effects. These increase the risk of skeletal morbidity compared to women without breast cancer history. However, even if these evidences are well described, the evolution of calcium metabolism under CT is unknown in this population with a high cure rate. We report the evolution of VitD and calcium metabolism markers in patients undergoing adjuvant CT for EBC.

Material and methods: We evaluated the VitD and calcium parameters (blood calcium, phosphorus and parathormone [PTH] levels, urinary calcium excretion) in EBC patients treated with 6 cycles of adjuvant CT without high dose calcium and VitD treatment. Variables of interest were recorded at inclusion, then every 3 weeks, at each chemotherapy cycle initiation. Primary endpoint was the occurrence of a hypercalciuria during the course of adjuvant CT (between Day 1, Cycle 1 [D1C1] and Day 1, Cycle 6 [D1C6]).

Results: 82 patients were evaluable for the primary endpoint. The median age was 53 years (range 20-71). CT consisted of a sequential anthracyclines and taxane regimen in 96.3% of the cases. Eleven (26.8%) patients received adjuvant trastuzumab. Most patients (66, 80.5%) presented with baseline VitD insufficiency (<30 ng/mL). Median baseline VitD level was 20.65ng/mL (range 2.9-55). Nine patients (8 VitD insufficient, 1 VitD sufficient [calcium only]) received low-dose VitD and/or calcium supplementation during the CT cycles. No baseline clinical parameter was statistically predictive of a VitD baseline insufficiency, while baseline blood calcium level was statistically predictive of a VitD baseline insufficiency (p=0.051). 94% of the patients presented with VitD insufficiency at D1C6 (median VitD level 20ng/mL; 9-39). No case of hypercalcemia was recorded. 29 patients (35.4%; 95%CI: 25.6-46.5) developed hypercalciuria between D1C1 and D1C6, none clinically significant. This percentage was not significantly different between VitD insufficient patients and the others (34.8% vs. 37.5%), nor between supplemented and not supplemented patients (37.5% vs. 34.5%). In multivariate analysis, weight and BMI were significantly associated with the occurrence of a hypercalciuria, while a trend was detected for baseline VitD (p=0.085) and albumin blood level (p=0.072). Baseline PTH level was elevated in 12.7% of the VitD insufficient patients vs. none of the patients with a normal VitD level. These percentages increased to 52.5% and 50% respectively at D1C6.

Conclusions: We report here, to our knowledge, the first comprehensive study of the kinetics of VitD and calcium biomarkers during EBC adjuvant CT. This population appears highly VitD insufficient, with a compensatory elevation in blood PTH levels during the course of treatment. Hypercalciuria, while asymptomatic, is a highly prevalent abnormality in this setting, and must not be a limitation for high dose VitD supplementation.

Citation Format: Jacot W, Firmin N, Touraine C, Pouderoux S, Viala M, Metge M, Rifai L, Romieu G, Roca L, Guiu S, D'Hondt V. Changes in vitamin D and calcium metabolism markers in patients undergoing adjuvant chemotherapy for breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-14-03.