Donna K. Pauler

BACKGROUND: The optimal upper limit of the normal range for prostate-specific antigen (PSA) is unknown. We investigated the prevalence of prostate cancer among men in the Prostate Cancer Prevention Trial who had a PSA level of 4.0 ng per milliliter or less. METHODS: Of 18,882 men enrolled in the prevention trial, 9459 were randomly assigned to receive placebo and had an annual measurement of PSA and a digital rectal examination. Among these 9459 men, 2950 men never had a PSA level of more than 4.0 ng per milliliter or an abnormal digital rectal examination, had a final PSA determination, and underwent a prostate biopsy after being in the study for seven years. RESULTS: Among the 2950 men (age range, 62 to 91 years), prostate cancer was diagnosed in 449 (15.2 percent); 67 of these 449 cancers (14.9 percent) had a Gleason score of 7 or higher. The prevalence of prostate cancer was 6.6 percent among men with a PSA level of up to 0.5 ng per milliliter, 10.1 percent among those with values of 0.6 to 1.0 ng per milliliter, 17.0 percent among those with values of 1.1 to 2.0 ng per milliliter, 23.9 percent among those with values of 2.1 to 3.0 ng per milliliter, and 26.9 percent among those with values of 3.1 to 4.0 ng per milliliter. The prevalence of high-grade cancers increased from 12.5 percent of cancers associated with a PSA level of 0.5 ng per milliliter or less to 25.0 percent of cancers associated with a PSA level of 3.1 to 4.0 ng per milliliter. CONCLUSIONS: Biopsy-detected prostate cancer, including high-grade cancers, is not rare among men with PSA levels of 4.0 ng per milliliter or less--levels generally thought to be in the normal range.

The standard approach to early detection of disease with a quantitative marker is to set a population-based fixed reference level for making further individual screening or referral decisions. For many types of disease, including prostate and ovarian cancer, additional information is contained in the subject-specific temporal behavior of the marker, which exhibits a characteristic alteration early in the course of the disease. In this article we derive a Bayesian approach to screening based on calculation of the posterior probability of disease given longitudinal marker levels. The method is motivated by a randomized ovarian cancer screening trial in the United Kingdom comprising 22,000 women screened over 4 years with an additional 5 years of follow-up on average. Levels of the antigen CA125 were recorded annually in the screened arm. CA125 profiles of cases and controls from the U.K. trial are modeled using hierarchical changepoint and mixture models, posterior distributions are calculated using Markov chain Monte Carlo methods, and the model is used to calculate the Bayesian posterior risk of having ovarian cancer given a new subject's single or multiple longitudinal CA125 levels. A screening strategy based on the risk calculation is then evaluated using data from an independent screening trial of 5,550 women performed in Sweden. A longitudinal CA125 screening strategy based on calculation of the risk of ovarian cancer is proposed. Simulations of a prospective trial using a strategy based on the risk calculated from longitudinal CA125 values indicate potentially large increases in sensitivity for a given specificity compared to the standard approach based on a fixed CA125 reference level for all subjects.

The presentation and long-term therapeutic responses of PRL-secreting pituitary tumors in men have been only partially studied. Gender-specific differences in tumor size at clinical presentation and possible differences in tumor biology in men compared to women make it important to determine treatment outcomes of male patients with prolactinomas. We performed a retrospective review of men with prolactinomas medically managed at Massachusetts General Hospital between 1980 and 1997. We identified 46 male patients with prolactinomas managed with medical therapy alone. Twelve patients had microadenomas, defined as a serum PRL level greater than 15 ng/mL and a normal pituitary scan or a tumor smaller than 1 cm. Thirty-four patients had macroprolactinomas, defined by a serum PRL greater than 200 ng/mL and pituitary adenoma larger than 1 cm. Bromocriptine, quinagolide, and/or cabergoline were administered as medical therapy. All patients had at least one follow-up visit, and the most recent serum PRL measurement after initiating dopamine agonist therapy was reported. Baseline clinical characteristics for patients with macroprolactinomas and microprolactinomas showed a larger proportion of patients with macroprolactinomas reporting a history of headache (74% vs. 0%), whereas the prevalence of sexual dysfunction and testosterone deficiency was similar between the two groups. Median serum PRL at presentation was 99 ng/mL (range, 16-385 ng/mL) vs. 1,415 ng/mL (range, 387-67,900 ng/mL), in the microprolactinoma and macroprolactinoma groups, respectively. A normal PRL level was achieved in a similar percentage of men with microprolactinomas vs. macroprolactinomas (83% vs. 79%, respectively). Although the majority of patients in both groups were treated with bromocriptine, a comparable number of patients with microprolactinomas vs. macroprolactinomas achieved a normal PRL level with cabergoline therapy. The response rates for bromocriptine and cabergoline were similar in both groups. No patient with a microprolactinoma required hormone replacement therapy, in contrast to patients with macroprolactinomas, who required thyroid, testosterone, and/or glucocorticoid replacement therapy. No patient had evidence of an increase in tumor size during therapy. In summary, we investigated the clinical presentation and treatment outcome in men with prolactinomas. We found that normalization of serum PRL levels occurs in approximately 80% of men with prolactinomas. Of importance, dopamine agonist administration yielded similar biochemical remission rates in men with microprolactinomas and macroprolactinomas.

In this paper we derive Schwarz's information criterion and two modifications for choosing fixed effects in normal linear mixed models. The first modification allows an arbitrary, possibly informative, prior for the parameter of interest. Replacing this prior with the normal, unit-information, prior of Kass & Wasserman (1995) and the generalised Cauchy prior of Jeffreys (1961) yields the usual Schwarz criterion and a second modification, respectively. Under the null hypothesis, these criteria approximate Bayes factors using the corresponding priors to increased accuracy. In regression, the second modification also corresponds asymptotically to the Bayes factors of Zellner & Siow (1980) and O'Hagan (1995), and is similar to the Bayes factor of Berger & Pericchi (1996). In mixed models, the effective sample size term in Schwarz's formula is ambiguous because of correlation between observations. We propose an appropriate generalisation of Schwarz's approximation and apply our results to evaluate a large class of models for repeated neuron area measurements in alcoholic and suicidal patients.

Our objective was to identify factors that correlate with CA125 concentrations in healthy postmenopausal women and to introduce recommendations for reporting and interpreting individual CA125 assay results. We analyzed repeated serum CA125 levels, as measured by the CA125II assay, in 18,748 postmenopausal women who participated in the ST: Bartholomew's/Royal London Hospital Ovarian Cancer screening trial from 1986 to 1994 and were not diagnosed with ovarian cancer during the 12-year follow-up period. We found that race is a substantial predictor of normal levels of CA125, with average CA125II concentration from African (median, 9.0; 95% range, 4.0-26.0 units/ml) and Asian women (median, 13.0; range, 5.9-33.3 units/ml) lower than that in Caucasian women (median, 14.2; range, 6.0-41.0 units/ml; P < 0.001). Women with a hysterectomy have lower CA125II values (median, 13.6; range 5.5-39.0 units/ml; P < 0.001), and women with a prior cancer diagnosis other than ovarian cancer have higher levels of CA125 II (median, 16.0; range, 6.0-49.0 units/ml; P < 0.003). Regular smoking and caffeine consumption decrease CA125 levels (P < 0.001). A woman's age, age at menarche, age at menopause, and history of a previous ovarian cyst (P < 0.05) are also predictive of baseline CA125 levels. Parity, history of hormone replacement therapy or unilateral oopherectomy, and previous use of oral contraceptives or talcum powder are not significant predictors of CA125 concentrations (P > 0.05). We concluded that clinically significant differences in individual patient characteristics need to be reflected in the screening algorithms that use CA125II so that designed performance characteristics (sensitivity and specificity) are maintained in practice.