Using splines to detect changes in PSA doubling times

Fermented Wheat Germ Extract (FWGE) as a Treatment Additive for Castration-Resistant Prostate Cancer: A Pilot Clinical Trial

Castration-resistant prostate cancer (CRPC) is a devastating and incurable disease. Combined therapy using conventional anticancer drugs and a proprietary medical nutriment, fermented wheat germ extract (FWGE), also known as Avemar, has been suggested as a treatment for progressing prostate cancer (PCa) patients, who have become resistant to first line hormonal therapy (gonadotropin releasing hormone, GnRH). The primary aim of this study was to test if this combined therapy would slow down disease progression in CRPC patients. We tested the nontoxic, readily available, inexpensive FWGE, together with the conventional treatment, GnRH analogue, in 36 CRPC patients. Although this is a pilot study, with the drawback of a statistically small sample size, some anticancer clinical activity of FWGE could be seen in the CRPC patients, as measured by prostate specific antigen doubling time (PSADT). We found that the intake of GnRH with FWGE for at least 4 months, improved the overall health as well as the quality of life (QOL) in 4 patients (11%) and was instrumental in extending the PSADT in about 17 (out of 26) patients (65.4%), six of whom were significant. Since no mentionable adverse events were noticed, this treatment may permit the postponement of chemotherapy for these patients.

Prostate cancer trajectory-map: clinical decision support system for prognosis management of radical prostatectomy

Purpose

Prostate cancer has a low mortality rate and requires persistent treatment; however, treatment decisions are challenging. Because prostate cancer is complex, the outcomes warrant thorough follow-up evaluation for appropriate treatment. Electronic health records (EHRs) do not present intuitive information. This study aimed to develop a Clinical Decision Support System (CDSS) for prognosis management of radical prostatectomy.

Methods

We used data from 5,199 prostate cancer patients from three hospitals' EHRs in South Korea, comprising laboratory results, surgery, medication, and radiation therapy. We used open source R for data preprocessing and development of web-based visualization system. We also used R for automatic calculation functionalities of two factors to visualize the data, e.g., Prostate-Specific Antigen Doubling Time (PSADT), and four Biochemical Recurrence (BCR) definitions: American Society of Therapeutic Radiology and Oncology (ASTRO), Phoenix, consecutive PSA > 0.2 ng/mL, and PSA > 0.2 ng/mL.

Results

We developed the Prostate Cancer Trajectory Map (PCT-Map) as a CDSS for intuitive visualization of serial data of PSA, testosterone, surgery, medication, radiation therapy, BCR, and PSADT.

Conclusions

The PCT-Map comprises functionalities for BCR and PSADT and calculates and visualizes the newly added patient data automatically in a PCT-Map data format, thus optimizing the visualization of patient data and allowing clinicians to promptly access patient data to decide the appropriate treatment.

Objective assessment of tumour response to therapy based on tumour growth kinetics

Background:

Current standards for assessment of tumour response to therapy (a) categorise therapeutic efficacy values, inappropriate for patient-specific and deterministic studies, (b) neglect the natural growth characteristics of tumours, (c) are based on tumour shrinkage, inappropriate for cytostatic therapies, and (d) do not accommodate integration of functional/biological means of therapeutic efficacy assessed with, for example, positron emission tomography or magnetic resonance imaging, with data from anatomical changes in tumour.

Methods:

A quantity for tumour response was formulated assuming that an effective treatment may decrease the cell proliferation rate (cytostatic) and/or increase the cell loss rate (cytotoxic) of the tumour. Tumour response values were analysed for 11 non-Hodgkin's lymphoma patients treated with ¹³¹I-labelled anti-B1 antibody and 12 prostate cancer patients treated with a nutritional supplement.

Results:

Tumour response was found to be equal to the logarithm of the ratio of post-treatment tumour volume to the volume of corresponding untreated tumour. Neglecting the natural growth characteristics of tumours results in underestimation of treatment effectiveness based on currently used methods. The model also facilitates the integration of data from tumour volume changes, with data from functional imaging.

Conclusion:

Tumour response to therapy can be assessed with a continuous dimensionless quantity for both cytotoxic and cytostatic treatments.

Quantitative analysis of tumor growth rate and changes in tumor marker level: specific growth rate versus doubling time

BACKGROUND

Doubling time (DT) of tumor volume has been widely used to estimate the growth rate of tumors. However, DT gives incorrect estimates of the average growth rate of tumors when the uncertainty of growth rate is considerable. Specific growth rate (SGR) is less affected by uncertainties and is a more relevant parameter. Optimized imaging techniques and prolonged interval between observations can reduce the uncertainty of growth rate estimation. DT is also used for defining changes in tumor marker level. The aim of this study was to compare DT and SGR as measures of growth rate when the uncertainty is negligible.

METHODS

Mathematical analysis and computer simulations were carried out assuming no uncertainty of growth rate estimation. Data from two previously published clinical studies were assessed by both variables.

RESULTS

Due to the non-linear relationship between DT and SGR, using these variables does not give similar results. The variation of DT is not uniformly indicating variations of the growth rate. DT largely overestimates the difference in growth rate of slowly growing tumors and underestimates the difference in growth rate of rapidly growing tumors. On the other hand, SGR uniformly indicates the difference between growth rates throughout all ranges. Quantitative analysis of clinical observations can lead to contradictory results depending on the variable used for growth rate.

CONCLUSION

The growth rate of tumor volume should be expressed by SGR, or percentage increase per unit time, regardless of the level of the uncertainty of growth rate estimation. This conclusion is also valid for changes in tumor marker level, whether it is correlated with the growth rate of tumor volume or not.

Hierarchical changepoint models for biochemical markers illustrated by tracking postradiotherapy prostate-specific antigen series in men with prostate cancer

PURPOSE

Biomarkers provide valuable information when detecting disease onset or monitoring disease progression; examples include bone mineral density (for osteoporosis), cholesterol (for coronary artery diseases), or prostate-specific antigens (PSA, for prostate cancer). Characteristics of markers series can then be used as prognostic factors of disease progression, such as the postradiotherapy PSA doubling time in men treated for prostate cancer. The statistical analysis of such data has to incorporate the within and between-series variabilities, the complex patterns of the series over time, the unbalanced format of the data, and the possibly nonconstant precision of the measurements.

METHODS

We base our analysis on a population-based cohort of 470 men treated with radiotherapy for prostate cancer; after treatment, the log(2)PSA concentrations follow a piecewise-linear pattern. We illustrate the flexibility of Bayesian hierarchical changepoint models by estimating the individual and population postradiotherapy log(2)PSA profiles; parameters such as the PSA nadir and the PSA doubling time were estimated, and their associations with baseline patient characteristics were investigated. The residual PSA variability was modeled as a function of the PSA concentration. For comparison purposes, two alternative models were briefly considered.

RESULTS

Precise estimates of all parameters of the PSA trajectory are provided at both the individual and population levels. Estimates suggest greater PSA variability at lower PSA concentrations, as well as an association between shorter PSAdts and greater baseline PSA levels, higher Gleason scores, and older age.

CONCLUSIONS

The use of Bayesian hierarchical changepoint models accommodates multiple complex features of longitudinal data, permits realistic modeling of the variability as a function of the marker concentration, and provides precise estimates of all clinically important parameters. This type of model should be applicable to the study of marker series in other diseases.

Modified citrus pectin (MCP) increases the prostate-specific antigen doubling time in men with prostate cancer: a phase II pilot study

This trial investigated the tolerability and effect of modified citrus pectin (Pecta-Sol) in 13 men with prostate cancer and biochemical prostate-specific antigen (PSA) failure after localized treatment, that is, radical prostatectomy, radiation, or cryosurgery. A total of 13 men were evaluated for tolerability and 10 for efficacy. Changes in the prostate-specific antigen doubling time (PSADT) of the 10 men were the primary end point in the study. We found that the PSADT increased (P-value<0.05) in seven (70%) of 10 men after taking MCP for 12 months compared to before taking MCP. This study suggests that MCP may lengthen the PSADT in men with recurrent prostate cancer.