Low serum testosterone level predicts worse response to endocrine therapy in Japanese patients with metastatic prostate cancer

The role of the serum testosterone levels as a predictor of prostate cancer in patients with atypical small acinar proliferation at the first prostate biopsy

The current literature does not support the usefulness of clinical markers on predicting which patients with atypical small acinar proliferation (ASAP) are more likely to progress to prostate cancer (PCa). Androgens have long been considered to be the potential risk factors for PCa. However, the role of testosterone is controversial. The present study aims to analyze the relationship between serum testosterone (TS) levels and the diagnosis of PCa after a first prostate biopsy in patients affected by ASAP. This retrospective study included 143 patients diagnosed with ASAP in an initial transrectal ultrasound-guided prostate biopsy for suspicious PCa according to the European Association of Urology guidelines. Their TS levels, age, PSA, prostate volume, digital rectal examination, and prostate biopsy Gleason score (GS) were collected retrospectively for statistical analysis. All patients included in the study had a second biopsy and were suitable for further analysis. Re-biopsy was carried out 3-6 months after the first diagnosis of ASAP. Low and normal TS groups were composed of 29 (20.3%) and 114 (79.7%) patients, respectively. The diagnosis of the second biopsy was ASAP in 25.2% and PCa in 36.4% of patients. The comparison between patients with PCa and those with negative or an ASAP result in the second biopsy reported that men with cancer had significantly higher levels of TS (P < 0.001). However, there was no statistically significant association between GS postbiopsy and TS (P = 0.324). Our experience demonstrated that eugonadal patients may be a clinical risk factor for the diagnosis of PCa on re-biopsy after ASAP diagnosis than hypogonadal.

Low testosterone at first prostate-specific antigen failure and assessment of risk of death in men with unfavorable-risk prostate cancer treated on prospective clinical trials

BACKGROUND

Low testosterone at the time of diagnosis of prostate cancer has been associated with a worse prognosis. Whether this is true and how to define the best treatment approach at the time of first prostate-specific antigen (PSA) failure to the authors' knowledge has not been elucidated to date and was studied herein.

METHODS

Between 1995 and 2001, a total of 58 men with unfavorable-risk PC who were treated on clinical trials with radiotherapy and androgen deprivation therapy (ADT) had available testosterone levels at the time of PSA failure. Cox and Fine and Gray regressions were performed to ascertain whether low versus normal testosterone was associated with the risk of PC-specific mortality, other-cause mortality, and all-cause mortality adjusting for age, salvage ADT, and known PC prognostic factors.

RESULTS

After a median follow-up of 6.68 years after PSA failure, 31 men (53.4%) had died; 10 of PC (32.3%), of which 8 of 11 (72.7%) versus 2 of 47 (4.3%) deaths occurred in men with low versus normal testosterone at the time of PSA failure, respectively. A significant increase in the risk of all-cause mortality (adjusted hazard ratio [AHR], 2.54; 95% confidence interval [95% CI], 1.04-6.21 [P = .04]) and PC-specific mortality (AHR, 13.71; 95% CI, 2.4-78.16 [P = .003]), with a reciprocal trend toward a decreased risk of other-cause mortality (AHR, 0.18; 95% CI, 0.02-1.55 [P = .12]) was observed in men with low versus normal testosterone.

CONCLUSIONS

Low, but not necessarily castrate, testosterone levels at the time of PSA failure confer a very poor prognosis. These observations provide evidence to support testosterone testing at the time of PSA failure. Given prolonged survival when abiraterone or docetaxel is added to ADT in men with castrate-sensitive metastatic PC and possibly localized high-risk PC provides a rationale supporting their use with ADT in men with low testosterone in the setting of a phase 2 trial. Cancer 2018;124:1383-90. © 2017 American Cancer Society.

Low Testosterone Alters the Activity of Mouse Prostate Stem Cells

BACKGROUND

Low serum testosterone (low T) has been repeatedly linked to worse outcomes in men with newly diagnosed prostate cancer (PC). How low T contributes to these outcomes is unknown. Here we demonstrate that exposure to low T causes significant changes in the mouse prostate and prostate stem cells.

METHODS

Mice were castrated and implanted with capsules to achieve castrate, normal, or sub-physiological levels of T. After 6 weeks of treatment, LC-MS/MS was used to quantify the levels of T and dihydrotestosterone (DHT) in serum and prostate tissue. FACS was used to quantify the percentages of purported prostate stem and transit amplifying (TA) cells in mouse prostates. Prostate tissues were also stained for the presence of CD68+ cells and RNA was extracted from prostate tissue or specific cell populations to measure changes in transcript levels with low T treatment.

RESULTS

Despite having significantly different levels of T and DHT in the serum, T and DHT concentrations in prostate tissue from different T treatment groups were similar. Low T treatment resulted in significant alterations in the expression of androgen biosynthesis genes, which may be related to maintaining prostate androgen levels. Furthermore, the expression of androgen-regulated genes in the prostate was similar among all T treatment groups, demonstrating that the mouse prostate can maintain functional levels of androgens despite low serum T levels. Low T increased the frequency of prostate stem and TA cells in adult prostate tissue and caused major transcriptional changes in those cells. Gene ontology analysis suggested that low T caused inflammatory responses and immunofluorescent staining indicated that low T treatment led to the increased presence of CD68+ macrophages in prostate tissue.

CONCLUSIONS

Low T alters the AR signaling axis which likely leads to maintenance of functional levels of prostate androgens. Low T also induces quantitative and qualitative changes in prostate stem cells which appear to lead to inflammatory macrophage infiltration. These changes are proposed to lead to an aggressive phenotype once cancers develop and may contribute to the poor outcomes in men with low T. Prostate 77:530-541, 2017. © 2016 Wiley Periodicals, Inc.

Low serum testosterone is associated with tumor aggressiveness and poor prognosis in prostate cancer

Serum testosterone is a potential marker to distinguish between indolent and aggressive prostate cancer (PCa). The present study aimed to investigate whether low levels of total serum testosterone at diagnosis were associated with aggressive PCa and poor clinical outcomes. In total, 762 non-Hispanic Caucasian men with previously untreated PCa were recruited from The University of Texas MD Anderson Cancer Center (Houston, TX, USA). Patients were categorized into three groups based on their total serum testosterone levels according to clinical guidelines [low (<230 ng/dl), intermediate (230-350 ng/dl) and normal (>350 ng/dl)]. PCa aggressiveness (low-, intermediate- or high-risk, or metastatic) was compared using multinomial logistic regression. Rates of disease progression, mortality from any cause and PCa-specific mortality were compared using the multivariate Cox proportional hazards model. Testosterone levels significantly decreased as PCa aggressiveness increased (P<0.001). Compared with the normal testosterone group, the low testosterone group had 2.9-fold (OR, 2.92; 95% CI, 1.74-4.90; P<0.001), 5.6-fold (OR, 5.63; 95% CI, 3.14-10.12; P<0.001) and 72.4-fold (OR, 72.40; 95% CI, 20.89-250.89; P<0.001) increased risks of having intermediate-risk, high-risk and metastatic PCa, respectively. Furthermore, low levels of testosterone were significantly associated with a 10.7-fold (HR, 10.68; 95% CI, 1.35-84.44; P=0.03) increased risk of PCa-specific mortality. The results of the present study indicate that low levels of total serum testosterone at diagnosis are associated with aggressive PCa and predict poor PCa-specific survival.

Circulating steroid hormones in prostate carcinogenesis. Part 1 – Androgens

The aim of this review is to identify circulating steroids associated with prostate cancer (PCa) in bibliographic reports. First, we summarize chronological reports comparing circulating steroid levels in men with a high risk of PCa, such as African-Americans (AAs), with men having a lower risk. Higher testosterone plasma levels in young AA men have been reported. However, the difference between AAs and Caucasians decreases with age. When measured, dihydrotestosterone (DHT) was found to be higher in AAs; however, these results must be taken with caution, as immunological assay of this steroid is difficult. Second, we summarize chronological reports concerning circulating steroids assayed in blood samples drawn several years before a diagnosis of PCa was made, compared to controls. These nested case-control studies did not lead to straightforward conclusions regarding an increase in circulating testosterone. However, large collaborative studies showed a trend of a decrease in plasma sex hormone binding globulin, consequently an increase in bioavailable plasma testosterone in PCa. These nested case-control studies failed to associate plasma DHT levels with PCa risk. Third, we summarize numerous chronological publications relating plasma concentrations, measured at the time of PCa diagnosis. Numerous results showed a decrease in plasma testosterone levels in aggressive PCa (high Gleason score, advanced stage with positive surgical margins). Testosterone levels returned to normal several months after prostatectomy. All plasma hormone assay levels were always carried out using immunological methods. We recommend replacing this methodology by mass spectrometry coupled with gas chromatography or liquid chromatography in these epidemiologic studies.

Investigative clinical study on prostate cancer: on the role of the pretreatment total PSA to free testosterone ratio in selecting different biology groups of prostate cancer patients

OBJECTIVES

To show that prostate cancer biology is related to serum levels of both free testosterone (FT) and prostate-specific antigen (PSA), that PSA level is linearly related to FT and that the PSA to FT ratio may be considered as the growth rate parameter expressing cancer phenotype biology.

MATERIALS AND METHODS

The study includes 135 consecutive patients diagnosed with prostate cancer. Pretreatment simultaneous serum samples for analyzing total testosterone (TT), FT and total PSA levels were obtained. The study was assessed according to a multidimensional approach of the five continuous variables including TT, FT, PSA, AGE and percentage of positive biopsies (=P+). The all sets of data were considered as one--sample with no groupings among the observations. Multivariate analysis included factor analysis (FA) and principal component analysis (PCA). Multivariate inferential statistics for comparing different groups of patients according to the PSA to free testosterone ratio (PSA/FT) included Hotteling's multivariate two-sample T²-Test for comparing two mean vectors as well as Box's M-Test with the chi-square approximation for comparing multiple covariance matrices when patients were sampled in more than two groups.

RESULTS

Factor analysis showed the two natural grouping of variables, FT-TT and PSA-P+. PCA assessed FT and PSA as the two variables with large variances having a notable influence on the first two principal components. Multiple linear regression analysis showed that all the income variables, except age, significantly predicted the PSA/FT ratio. Patients were first sampled according to the PSA/FT ratio in group 1 (PSA/FT ≤ 0.20) and group 2 (PSA/FT > 0.20), and Hotteling's multivariate two sample T²-Test was significant (P < 0.01). Patients were then sampled according to the PSA/FT ratio in group 1 (PSA/FT ≤ 0.20), group 2 (PSA/FT > 0.20 and ≤ 0.40), and group 3 (PSA/FT > 0.40), and Box's M-Test comparing the covariance matrices of the 3 groups differed significantly (P < 0.001). Finally, patients were sampled according to the PSA/FT ratio in 6 groups, and Box's M-Test was again significant (P < 0.001).

CONCLUSIONS

The PSA to FT ratio is the growing rate parameter expressing different biology patterns and assessing different groups of prostate cancer patients. In our opinion, the results of the present study might have wide applications in understanding, assessing and planning prostate cancer studies including basic science, screening, assessing risk of the disease, predicting disease stage as well natural history after a planned treatment involving biochemical recurrence, progression, hormone refractory prostate cancer and disease-specific survival.

Prolonged exposure to reduced levels of androgen accelerates prostate cancer progression in Nkx3.1; Pten mutant mice

In this report, we have investigated the relationship between androgen levels and prostate tumorigenesis in Nkx3.1; Pten mutant mice, a genetically engineered mouse model of human prostate cancer. By experimentally manipulating serum levels of testosterone in these mice for an extended period (i.e., 7 months), we have found that prolonged exposure of Nkx3.1; Pten mutant mice to androgen levels that are 10-fold lower than normal (the "Low-T" group) resulted in a marked acceleration of prostate tumorigenesis compared with those exposed to androgen levels within the reference range (the "Normal-T" group). We found that prostate tumors from the Low-T mutant mice share a similar gene expression profile as androgen-independent prostate tumors from these mutant mice, which includes the deregulated expression of several genes that are up-regulated in human hormone-refractory prostate cancer, such as Vav3 and Runx1. We propose that exposure to reduced androgens may promote prostate tumorigenesis by selecting for molecular events that promote more aggressive, hormone-refractory tumors.

Inherited variation in hormone-regulating genes and prostate cancer survival

PURPOSE

Hormonal manipulation is the mainstay treatment of prostate cancer, notably in advanced stages. Despite initial favorably response, the cancer eventually develops hormone resistance resulting in disease progression and death. However, little is known about genetic determinants of disease progression and prostate cancer-specific death.

EXPERIMENTAL DESIGN

We analyzed a population-based cohort comprising 2,761 men diagnosed with prostate cancer from March 2001 to October 2003 and with complete follow-up through July 2006. During a median follow-up time of 3.8 years, a total of 300 men had died from prostate cancer. We genotyped 23 haplotype tagging single nucleotide polymorphisms in the genes AR, CYP17, and SRD5A2 and used Cox proportional hazards analyses to quantify associations between genotype and risk of dying from prostate cancer.

RESULTS

The variant 'A' allele of an AR promoter single nucleotide polymorphism, rs17302090, was borderline associated with a 50% increased risk of dying from prostate cancer (95% confidence interval, 1.0-2.3; P = 0.07). This finding was more pronounced in patients who received hormonal therapy as primary treatment at diagnosis (hazard ratio, 1.9; 95% confidence interval, 1.3-2.9; P = 0.007). We did not identify any associations between CYP17 or SRD5A2 variation and prostate cancer-specific death.

CONCLUSIONS

Our results suggest that inherited genetic variation in the androgen receptor gene affects hormonal treatment response and ultimately prostate cancer death.

Preoperative Serum Testosterone Level as an Independent Predictor of Treatment Failure following Radical Prostatectomy

OBJECTIVES

Preoperative low serum testosterone (TS) level has been reported to be associated with adverse pathologic results in patients with clinically localized prostate cancer (pCA) treated with radical prostatectomy (RP). However, prior studies failed to show prognostic impact of preoperative low TS in these patients. The aim of this study was to investigate the relationship between preoperative TS and prostate-specific antigen (PSA) failure in these patients.

METHODS

Of 304 patients diagnosed with clinically localized pCA who had been treated with RP alone, 272 patients whose preoperative TS level had been measured were eligible for this analysis. Postoperative TS levels were also available in 222 of the 272 patients. Cox proportional hazard model was used to elucidate factors predictive for PSA failure.

RESULTS

Of the 272 patients 49 had low (< 300 ng/dl) and 223 had normal preoperative TS level. In a stepwise multivariate analysis, preoperative TS (p = 0.021) was an independent and significant predictor of PSA failure along with RP Gleason score (p = 0.006), surgical margin status (p = 0.0001), and PSA (p = 0.0001). Five-year PSA failure-free survival rate of the patients with preoperative low TS (67.8%) was significantly worse than that with normal TS (84.9%) (p=0.035). Serum TS levels increased significantly after RP (p < 0.0001). The increment of TS level in preoperative low TS group was significantly greater than that in preoperative normal TS group (p = 0.0003).

CONCLUSIONS

The current results demonstrated that preoperative TS level is an independent and significant predictor of PSA failure after RP in patients with clinically localized pCA.

Testosterone replacement therapy and the risk of prostate cancer. Is there a link?

Substantial evidence supports the value of testosterone replacement therapy (TRT) in improving quality of life in men with proven aging male syndrome (AMS). Benefits of TRT include improved bone mineral density, reduced fracture risk, increased muscle mass, and improved mood, sense of well being, and libido, among others. There is currently a heated debate about the theoretical association between TRT and the initiation, progression, and aggressiveness of prostate cancer; however, this link has not been uniformly studied, and any results have been contradictory and nonconclusive. Although no clear evidence links TRT to prostate cancer, the possibility of increasing the risk of a clinical manifestation of a latent pre-existing malignancy can influence the decision about TRT use. Current recommendations are to exclude prostate cancer before initiating TRT in men over age 40 and to closely monitor men in the first year of testosterone replacement, followed by observation in subsequent years.

Castration triggers growth of previously static androgen-independent lesions in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model

BACKGROUND

Androgen-deprivation remains the standard of care for metastatic prostate cancer, yet its total impact on the course of disease is incompletely established.

METHODS

We have examined the long-term effects of castration upon the progression of established cancer in the TRAMP transgenic mouse model of prostate cancer. Mice castrated at 15-weeks of age, as well as intact littermates, were followed until spontaneous death from cancer.

RESULTS

Statistical analyses of age-at-death versus primary tumor mass revealed that mice segregate into two categories of response to androgen-deprivation. In Category One, the act of castration paradoxically triggers the growth of microscopic androgen-independent lesions, as evidenced by a statistical synchronization of primary tumor growth. Delaying castration until 20-weeks of age delays the synchronized growth of these tumors, as well as the deaths of the host mice. In Category Two, castration eliminates or substantially delays primary tumor growth, but fails to eliminate metastases. so that castration is found to impart no long-term survival advantage.

CONCLUSIONS

We propose a two-step model for the alteration of androgen signaling in prostate cancer capable of explaining the above paradoxical results, which is based upon the dualistic role of androgens as both survival and differentiation factors. This model makes specific predictions for clinical intervention that are discussed in light of published studies.

Preventing diseases of the prostate in the elderly using hormones and nutriceuticals

The prostate has only one function, namely to secrete fluid containing substances that are needed for reproduction. This requires an extremely high concentration of androgens in the tissues. Benign prostatic hypertrophy (BPH) seems to be related to the long-term exposure of the prostate to the strong androgen 5alpha-dihydrotestosterone (DHT) and, possibly, to estrogens. The relation between prostate cancer and androgens is suggested to be U-shaped, with both extremes of androgen concentrations being associated with increased risk of invasive cancer. In the treatment of patients with BPH, the lipidic liposterolic extracts of Serenoa repens were as effective as the pharmaceutical inhibitors of the 5alpha-reductase enzyme or alpha1-adrenergic blockers in relieving urinary symptoms. In addition to moderately inhibiting the 5alpha-reductase activity, Serenoa seems to exert anti-inflammatory and complementary cellular actions with beneficial effects on the prostate. Unlike the pharmaceutical 5alpha-reductase inhibitors, finasteride and dutasteride, Serenoa does not suppress serum PSA, facilitating the follow-up and the early detection of prostate cancer. We suggest a strategy to prevent prostate cancer that aims at providing men with partial androgen deficiency correct testosterone substitution with a sustained release buccal bio-adhesive tablet. In addition, food supplementation with extracts of Serenoa repens and a combination of the antioxidants selenium, (cis)-lycopene and natural vitamin E, together with fish oil rich in long-chain polyunsaturated essential fatty acids of the omega-3 group seems warranted. Clearly, a holistic approach including careful clinical and biological monitoring of the aging man and his prostate remains mandatory.