A population-level decline in serum testosterone levels in American men

CONTEXT: Age-specific estimates of mean testosterone (T) concentrations appear to vary by year of observation and by birth cohort, and estimates of longitudinal declines in T typically outstrip cross-sectional decreases. These observations motivate a hypothesis of a population-level decrease in T over calendar time, independent of chronological aging. OBJECTIVE: The goal of this study was to establish the magnitude of population-level changes in serum T concentrations and the degree to which they are explained by secular changes in relative weight and other factors. DESIGN: We describe a prospective cohort study of health and endocrine functioning in randomly selected men of age 45-79 yr. We provide three data collection waves: baseline (T1: 1987-1999) and two follow-ups (T2: 1995-1997, T3: 2002-2004). SETTING: This was an observational study of randomly selected men residing in greater Boston, Massachusetts. PARTICIPANTS: Data obtained from 1374, 906, and 489 men at T1, T2, and T3, respectively, totaling 2769 observations taken on 1532 men. MAIN OUTCOME MEASURES: The main outcome measures were serum total T and calculated bioavailable T. RESULTS: We observe a substantial age-independent decline in T that does not appear to be attributable to observed changes in explanatory factors, including health and lifestyle characteristics such as smoking and obesity. The estimated population-level declines are greater in magnitude than the cross-sectional declines in T typically associated with age. CONCLUSIONS: These results indicate that recent years have seen a substantial, and as yet unrecognized, age-independent population-level decrease in T in American men, potentially attributable to birth cohort differences or to health or environmental effects not captured in observed data.     

Optically guided patient positioning techniques

Optical tracking determines an object's position by measuring light either emitted or reflected from the object. The hallmark of optical tracking systems is their high spatial resolution and measurement in real time; such systems can resolve the position of a point source within a fraction of a millimeter and report at a rate of 10 Hz or faster. Several systems have been developed for radiation therapy, all of which track infrared markers attached to the patient's external surface. The positions of the optical markers relative to the target volume, together with the desired marker positions relative to treatment isocenter, are determined during computed tomography simulation. In the treatment room, the real marker positions are measured relative to isocenter; rigid-body mathematics then determine marker displacements from their desired positions and hence target displacement from isocenter. Real-time feedback allows one to correct the patient's position. The first systems were used for intracranial stereotaxis radiotherapy; rigid arrays of optical markers were attached to the patient via a biteplate linkage. Subsequent systems for extracranial radiotherapy tracked external markers to determine patient position and/or gate the radiation beam based on patient motion. Lastly, optical tracking has been integrated with ultrasound or stereoscopic x-ray imaging to determine the position of internal anatomy targets relative to isocenter.     

Seeking Help for Erectile Dysfunction After Treatment for Prostate Cancer

Prostate cancer survivors appear to have higher rates of seeking medical help for erectile dysfunction (ED) than other cohorts of sexually dysfunctional men; however, factors associated with help-seeking for ED after prostate cancer have not been investigated. A group of 1,188 men with ED after prostate cancer responded to a postal survey about their sexuality, including a new questionnaire developed to measure traditional masculine attitudes about sex that could inhibit help-seeking. Respondents had a mean age of 68 years and were an average of 4.3 years postdiagnosis of cancer. At the time of the survey, 46% had sought medical help for ED since their cancer treatment and 44% intended to seek help in the next year. A hierarchical backward selection logistic regression analysis was performed to determine factors correlated with seeking help for ED after prostate cancer. Blocks of factors were entered in to the analysis in order. Factors significant within each step were retained when calculating a final model. Out of 37 factors entered into the model, three retained significance: Men who sought help for ED were more likely to have had a prostate cancer treatment designed to spare sexual function and reported higher distress about postcancer ED. Even with all other factors taken into account, men who had more positive attitudes on the Help-Seeking Questionnaire were significantly more likely to have sought help for ED. A second logistic regression analysis examined correlates of intent to seek help for ED within the next year. Out of 38 factors entered into the analysis, six retained significance in the final model: Men intending to seek help had been treated more recently for their prostate cancer, were more dissatisfied with their sexual function, had higher levels of distress about postcancer ED and loss of sexual desire, and were more likely to have sought help for ED even before their prostate cancer was diagnosed. Even with these factors taken into account, positive attitudes on the Help-Seeking Questionnaire were significantly associated with help-seeking intentions. These results suggest that cognitive-behavioral interventions designed to challenge men's negative beliefs about seeking help for ED could potentially increase help-seeking behavior.     

Comparison of alternative biochemical failure definitions based on clinical outcome in 4839 prostate cancer patients treated by external beam radiotherapy between 1986 and 1995

PURPOSE: To assess the merit of the American Society for Therapeutic Radiology and Oncology (ASTRO) definition of biochemical failure after external beam radiotherapy for prostate cancer by testing alternative prostate-specific antigen (PSA) failure definitions against the "gold standard" of clinical failure and to study the effect of backdating the time of failure. METHODS AND MATERIALS: Nine participating institutions agreed to submit follow-up results for all patients with clinically localized prostatic cancer (Stage T1b, T1c, T2, N0M0) treated between 1986 and 1995 by external beam radiotherapy only, to doses of >or=60 Gy, with no androgen deprivation before treatment. A total of 4839 men met the study criteria, with a median follow-up time of 6.3 years. The prediction of clinical failure by 102 definitions of biochemical failure was assessed using various quantitative measures. RESULTS: Four definitions were superior as measured by the sensitivity, specificity, positive and negative predictive values, and hazard of clinical failure after biochemical failure: two rises of at least 0.5 ng/mL backdated, PSA level at or greater than the absolute nadir plus 2 ng/mL at the call date, and PSA level at or greater than the current nadir plus 2 or 3 ng/mL at the call date. The absolute nadir was the lowest measured PSA level during all of follow-up, and the current nadir was the lowest PSA measured previous to a particular PSA measurement during follow-up. With the possible exception of patients in the low-risk group, the likelihood of ultimate clinical failure decreased as the time of biochemical failure increased. Failure definitions based on PSA levels >0.2 or 0.5 ng/mL were inferior to other definitions. Backdating the failure time introduced bias into the estimate of freedom from biochemical failure, which was increasingly overestimated at shorter median follow-up times. This bias can be circumvented either by using a failure definition based on the call date or by backdating the censoring times of patients with one or two rises who could potentially have failure at a future (unobserved) time. A short follow-up time as such does not result in bias unless the failures are backdated; in the absence of backdating, it is the precision of failure-free survival that is increasingly compromised as the follow-up time is reduced. CONCLUSION: The ASTRO failure definition ended the confusion resulting from different failure definitions that had been in use, and it did so accurately enough that it is probably not necessary to recalculate previously published results. Nevertheless, for the current pooled analysis of outcome in 4839 men with a 6.3-year median follow-up, other definitions of biochemical failure were superior as assessed by various quantitative measures of concordance of biochemical and ultimate clinical failure. An additional disadvantage of the ASTRO definition is the bias introduced by backdating failures, as well as the necessarily retrospective nature of its application. Some "current" definitions, but not those based on the PSA level rising above a fixed threshold, have significantly higher sensitivity and specificity, do not lead to biased estimations of biochemical disease-free survival, and are directly applicable during patient counseling. These are all issues that would play a role in replacing the ASTRO consensus definition.