Predicting the outcome of radiotherapy for prostate carcinoma: a model-building strategy

Outcome of ossiculoplasty in Kyoto University Hospital

CONCLUSION

We performed ossiculoplasty under conditions preventing inflammation by adopting a planned staged operation, which is suitable for ossiculoplasty using an artificial prosthesis. We identified the presence of chorda tympani nerve as a candidate predictive factor for successful ossiculoplasty.

OBJECTIVES

We aimed to summarize the outcome of ossiculoplasty and to find factors to improve the success rate.

METHODS

This was a retrospective chart review of 96 patients who underwent ossiculoplasty in Kyoto University Hospital from 2001 to 2008. Patients' backgrounds, hearing outcomes, and surgical procedures were analyzed. To find predictive factors for successful ossiculoplasty, we performed logistic regression analysis.

RESULTS

The improvement in the mean air conduction level was 12.9 dB. The mean postoperative air-bone gap (ABG) was 25.0 dB. The ABG decreased to within 20 dB in 40.7% of the cases. As a result of univariate logistic regression analysis, primary or planned second stage surgery, closed mastoid cavity, and presence of the chorda tympani nerve were identified as favorable factors for successful ossiculoplasty.

Predicting biochemical failure and overall survival through intratherapy PSA changes during definitive external beam radiotherapy

PURPOSE

To determine whether intratherapy prostate-specific antigen (itPSA) changes during radiotherapy (RT) predict prostate cancer outcomes.

METHODS AND MATERIALS

We retrospectively identified patients treated with definitive external beam RT without hormonal therapy who had at least two itPSA measurements. We calculated the adjusted ratio of rise (ARR) in itPSA relative to the pretreatment baseline PSA for each patient. This was defined as ln(maximal itPSA + 1)/ln(baseline PSA + 1). We stratified patients according to an ARR of <1 vs. >1.1. This corresponded to an approximately <30% vs. >30% increase in PSA during RT. Univariate and multivariate analyses were performed examining for biochemical failure-free survival (BFFS) and overall survival (OS).

RESULTS

At a median follow-up of 74 months, we identified 307 patients who met our criteria. Univariate analysis revealed that patients with an ARR of <1.1 (n = 182) had statistically significant inferior BFFS and OS compared with those with an ARR of >1.1 (n = 125). The median BFFS and OS for these two groups was 51 vs. 101 months (p = 0.001) and 96 vs. 128 months (p = 0.01), respectively. On multivariate analysis, the effect of ARR on the risk of biochemical failure for patients with an ARR of <1.1 was significant (p = 0.03) only during the first year after RT. In contrast, the effect of the ARR on OS remained significant for a full 5 years (p = 0.05).

CONCLUSION

The results of our study have shown that an ARR of <1.1 predicts for inferior BFFS and OS in patients treated with RT alone. PSA measurement during RT is a novel clinical tool that could be used to identify patients who might warrant more aggressive therapeutic intervention.

Automated Keratoconus Detection Using Height Data of Anterior and Posterior Corneal Surfaces

PURPOSE

To develop a keratoconus detection algorithm using the corneal topographic data of the anterior and posterior corneal surfaces.

METHODS

Topographic measurements of the cornea were made with a slit-scanning corneal topographer. We examined 120 subjects (165 eyes); keratoconus patients and keratoconus suspect patients comprised the keratoconus group, and post-photorefractive keratectomy patients, with-the-rule astigmatism patients, and controls without disease comprised the nonkeratoconus group. Two variables of the anterior corneal surface, two variables of the posterior corneal surface, and one corneal thickness variable were obtained by applying the Fourier harmonic decomposition formula. By performing a logistic regression analysis with a training set to differentiate the keratoconus group from the nonkeratoconus group, the Fourier-incorporated keratoconus detection Index (FKI) was created. The validity of the FKI was determined by using independent validation sets.

RESULTS

The FKI distinguished the keratoconus group from the nonkeratoconus group with 96.9% sensitivity and 95.4% specificity in the validation set.

CONCLUSIONS

A newly developed automated keratoconus classifier can be used to screen keratoconic patients. The index is based on information obtained by Fourier analysis from not only the anterior corneal surface but also from the posterior corneal surface and corneal thickness.

Increasing external beam dose for T1-T2 prostate cancer: effect on risk groups

PURPOSE

The aim of this study was to investigate effect of increasing dose on risk groups for clinical failure (CF: local failure or distant failure or hormone ablation or PSA>or=25 ng/ml) in patients with T1-T2 prostate cancer treated with external beam radiotherapy.

METHODS AND MATERIALS

Patients (n=4,537) were partitioned into nonoverlapping dose ranges, each narrow enough that dose was not a predictor of CF, and risk groups for CF were determined using recursive partitioning analysis (RPA). The same technique was applied to the highest of these dose ranges (70-76 Gy, 1,136 patients) to compare risk groups for CF in this dose range with the conventional risk-group classification.

RESULTS

Cutpoints defining low-risk groups in each dose range shifted to higher initial PSA levels and Gleason scores with increasing dose. Risk groups for CF in the dose range 70-76 Gy were not consistent with conventional risk groups.

CONCLUSIONS

The conventional classification of risk groups was derived in the early PSA era, when total doses<70 Gy were common, and it is inconsistent with risk groups for patients treated to doses>70 Gy. Risk-group classifications must be continuously re-examined whenever the trend is toward increasing total dose.

Prognostic value of PSA nadir ≤4 ng/mL within 4 months of high-dose radiotherapy for locally advanced prostate cancer

PURPOSE

To investigate early prostate-specific antigen (PSA) kinetics after high radiation doses of 85 Gy on locally advanced prostate cancer.

METHODS AND MATERIALS

A total of 201 patients were prospectively and consecutively treated with external beam radiotherapy and a brachytherapy boost. Of the 201 patients, 104 received concomitant hormonal therapy on the decision of the referring urologist and were excluded, yielding a study population of 97 patients. The first posttreatment PSA analysis was performed not earlier than 1 month after treatment completion but within the first 4 months, and then every 4 months. Analysis of PSA kinetics included the PSA nadir (nPSA) at values of < or =4 ng/mL to < or =0.5 ng/mL. The nPSA at < or =4 ng/mL within 4 months (nPSA < or =4/4m) was the variable of interest.

RESULTS

We established highly significant associations between an nPSA of < or =1 and < or =0.5 ng/mL and the nPSA < or =4/4m (p <0.0001). A hazard ratio of 0.33 (95% Confidence Interval (CI), 0.12-0.91) underlined the lower risk of recurrence related to nPSA < or =4/4m achievement (p = 0.033). Using time-dependent covariate models for patients who did not reach an nPSA < or =4/4m, an nPSA of < or =1 ng/mL remained without prognostic significance (p = 0.06). However, for patients who reached an nPSA < or =4/4m, an nPSA of < or =1 ng/mL did significantly improve the prognosis (p <0.001), but much later after treatment. The same analysis was repeated for nPSA < or =0.5 ng/mL with similar conclusions as when nPSA < or =4/4m was obtained (p <0.01).

CONCLUSION

The nPSA < or =4/4m has been demonstrated to be a significant predictor of biochemical no evidence of disease after high radiation doses of 85 Gy. Its major advantage is that it was available earlier than the other nadirs.

Group sequential clinical trials for longitudinal data with analyses using summary statistics

Longitudinal endpoints are used in clinical trials, and the analysis of the results is often conducted using within-individual summary statistics. When these trials are monitored, interim analyses that include subjects with incomplete follow-up can give incorrect decisions due to bias by non-linearity in the true time trajectory of the treatment effect. Linear mixed-effects models can be used to remove this bias, but there is a lack of software to support both the design and implementation of monitoring plans in this setting. This paper considers a clinical trial in which the measurement time schedule is fixed (at least for pre-trial design), and the scientific question is parameterized by a contrast across these measurement times. This setting assures generalizable inference in the presence of non-linear time trajectories. The distribution of the treatment effect estimate at the interim analyses using the longitudinal outcome measurements is given, and software to calculate the amount of information at each interim analysis is provided. The interim information specifies the analysis timing thereby allowing standard group sequential design software packages to be used for trials with longitudinal outcomes. The practical issues with implementation of these designs are described; in particular, methods are presented for consistent estimation of treatment effects at the interim analyses when outcomes are not measured according to the pre-trial schedule. Splus/R functions implementing this inference using appropriate linear mixed-effects models are provided. These designs are illustrated using a clinical trial of statin treatment for the symptoms of peripheral arterial disease.

What defines intermediate-risk prostate cancer? Variability in published prognostic models

PURPOSE

To assess the efficacy of a variety of prognostic models in the definition of intermediate-risk prostate cancer and to compare them to our own empiric model.

METHODS AND MATERIALS

Two hundred fifty-six consecutive men with prostate adenocarcinoma treated with external beam radiotherapy alone were studied. Biochemical failure (defined as 3 consecutive PSA rises or the initiation of androgen deprivation therapy) was examined using univariate, multivariate, and recursive partitioning analyses. The risk classification model used in our department was then compared to a number of published models to assess the relative performance of each in discriminating risk groups.

RESULTS

At a median follow-up of 62.4 months, the 5-year Biochemical failure-free survival (bFFS) was 46.8% for the overall group. This relates to 5-year bFFS of 77.8%, 51.1%, and 33.8% based on our institutional criteria for low-, intermediate-, and high-risk features, respectively. All the models examined showed an outcome group with a comparatively similar poor outcome when applied to our data. Large variation was seen in the intermediate-risk groups, with 5-year bFFS ranging from 38.1% to 51.1%. Good risk categories had similar large variations. All published models showed inability to delineate three significantly different outcome groups. Recursive partitioning analysis derived categories based on combinations of PSA (with cutpoints at 42.4, 20, and 10.6 ng/mL) and Gleason score (with cutpoints at 2-6 and 7-10) only.

CONCLUSIONS

Large variations in the relative performance of a number of prognostic models are shown when applied to our local data. The prognostic efficacy of PSA and biopsy Gleason score is reiterated, although other factors will need to be explored to further improve the performance of prognostic models, particularly in defining the intermediate-risk subset of prostate cancer.

A comparison of staging systems for localized extremity soft tissue sarcoma

BACKGROUND

Staging systems for soft tissue sarcoma (STS) are important to identify patients with similar systemic risk who might benefit from specific treatments. This study compared four commonly used staging systems for predicting systemic outcomes of patients with localized extremity STS, as proposed by the fourth and fifth editions of the American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) staging system, the Memorial Sloan-Kettering Cancer Center (MSK) system, and the Surgical Staging System (SSS) of the Musculoskeletal Tumor Society.

METHODS

Three hundred consecutive adult patients with newly diagnosed nonmetastatic STS of the lower extremity were treated at Memorial Sloan-Kettering Cancer Center between 1982 and 1989. Metastasis free survival was the end point of the study. The prognostic value of the four staging systems and their components were examined in univariate and multivariate analyses. The Akaike information criterion (AIC) was used to identify the system that best predicted the risk of systemic recurrence.

RESULTS

Compartment status, depth, grade, and size were all independent predictors of outcome within their respective staging systems. However, when compared with one another, only depth, grade, and size retained their prognostic significance. Of the four models, the AIC predicted that the MSK was the best predictor of systemic relapse, followed by the fifth edition of the AJCC/UICC staging system.

CONCLUSIONS

Staging systems such as the MSK system or the fifth edition of the AJCC/UICC system, which include tumor depth, grade, and size as prognostic factors, are the most predictive of systemic relapse in patients presenting with localized extremity STS. Both of these systems identify the same group of patients at the highest risk who would be the most suitable for adjuvant chemotherapy trials.

Prostate-specific antigen: effect of pelvic irradiation

PURPOSE

To study the effect of pelvic irradiation on the level of serum prostate-specific antigen (PSA).

MATERIALS AND METHODS

Of 33 patients treated with pelvic irradiation to the prostate and seminal vesicles for anal and rectal cancer, 26 received 50.4 Gy or more (1. 8 Gy per fraction), and seven received 25.0 Gy (5.0 Gy per fraction). PSA levels were measured before (n = 33), during (n = 26), and after radiation therapy (n = 33). In 24 patients, follow-up (mean, 15.7 months) PSA data were obtained. Actual and pretreatment PSA levels were compared (Wilcoxon rank test).

RESULTS

During the first 3 weeks in all patients, PSA levels rose steeply, culminating in a 3. 7-fold increase (P =.02). At the end of radiation therapy (7 weeks), the PSA level was no longer significantly different from the pretreatment value. In the long term, the PSA level decreased to 77% of the pretreatment value (P =.04).

CONCLUSION

Irradiation of the prostate initially elevates serum PSA levels. Apparently PSA release is determined by the duration of radiation therapy, while the accumulated dose has a minor effect. In the long term, PSA production is impaired after radical radiation therapy. PSA reference concentrations should be adjusted to these reduced levels.

Prevalence of chronic respiratory symptoms among Ohio cash grain farmers

BACKGROUND

The prevalence of chronic cough, chronic phlegm, dyspnea, and non-cold wheeze was estimated from a mixed-mode survey of Ohio cash grain farmers in 1993.

METHODS

Personal characteristics of the principal operators (POs) such as age and cigarette smoking, in addition to selected farm characteristics and relevant medical and work history factors potentially associated with both exposure to respiratory irritants and subsequent respiratory symptoms were considered.

RESULTS

The overall design-adjusted prevalences (and the corresponding 95% confidence intervals (CIs) were: 9.4% (7.6-11.1%) for chronic cough, 10.8% (9.0-12.6%) for chronic phlegm, 16.2% (14.1-18.3%) for dyspnea, and 8.1% (6.4-9.8%) for non-cold wheeze. In univariate and multivariate analyses, smoking status was found, not surprisingly, to be the strongest predictor of increased symptom prevalence compared to all other factors. Other non-occupational factors found associated with increased symptom prevalence include age (cough, phlegm, dyspnea) and pet allergy (non-cold wheeze). Occupational factors found at least weakly associated with increased symptom prevalence include lifetime hours of cab tractor operation (cough); percent time spent farming (phlegm); having livestock other than cattle, cows, and calves (dyspnea); acres of corn for silage or green chop (cough); acres of alfalfa hay (non-cold wheeze); and personal involvement with pesticides (cough).

CONCLUSIONS

Symptom prevalences reported here are consistent with previous findings from studies of other groups of farmers. Results pertaining to factors found associated with symptom prevalences should be interpreted in light of several sources of potential bias.