Undetectable serum prostate-specific antigen associated with metastatic prostate cancer: a case report and review of the literature

The U Shape of Prostate-specific Antigen and Prostate Cancer-specific Mortality in High-grade Metastatic Prostate Adenocarcinoma

BACKGROUND

Accumulated evidence suggests that metastatic prostate cancer (mPCa) with a low prostate-specific antigen (PSA) level may be a unique entity. However, its clinical features and prognosis have not been fully evaluated.

OBJECTIVE

To investigate the clinical features of low-PSA mPCa and the impact of low PSA level on overall survival (OS) and PCa-specific mortality (PCSM) of mPCa.

DESIGN, SETTING, AND PARTICIPANTS

A total of 8479 mPCa patients were retrieved from the Surveillance, Epidemiology, and End Results program (2010-2015). The median follow-up was 18 mo.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cox regression and Fine-Gray competing risk were used to calculate the hazard ratio (HR) and subdistribution hazard ratio (sHR) for OS and PCSM, respectively.

RESULTS AND LIMITATIONS

A higher rate of T4 stage disease (19.8%) and visceral metastasis (18.2%) and the shortest median OS (34 mo) were observed in mPCa patients with Gleason 8-10 and PSA ≤4ng/ml. In the Cox regression model, PSA ≤4ng/ml was a significant predictor of OS for Gleason 8-10 disease. The distribution of PCSM by PSA was U-shaped for Gleason score 8-10 (PSA 4.1-10ng/ml as the referent), with an adjusted sHR of 1.52 for PSA ≤4.0ng/ml (95% confidence interval: 1.17-1.96) versus 0.99 for PSA 10.1-20ng/ml and 1.35 for PSA >20ng/ml. In contrast, the distribution of PCSM by PSA was linear for Gleason 5-7. Sensitivity analyses showed similar results in Gleason 9-10 and Gleason 10 subgroup. The study is limited by its retrospective design.

CONCLUSIONS

Low PSA, high-grade mPCa has a higher proportion of T4 stage disease, visceral metastasis, and PCSM.

PATIENT SUMMARY

We found that 2.8% of high-grade metastatic prostate cancer has a prostate-specific antigen level ≤4ng/ml at diagnosis. This population has aggressive clinical features and a poor cancer-specific outcome. Our results highlighted this under-reported population, and the management of these patients warrants further research.

Solitary recurrence of castration-resistant prostate cancer with low or undetectable levels of prostate specific antigen salvaged with local ablative radiation therapy: A case report

Prostate cancer recurrences are usually first detected by increased levels of prostate specific antigen (PSA), and systemic therapy is often initiated if distant metastasis is confirmed. However, low or nearly undetectable levels of PSA in the modern era of ultrasensitive PSA assay may be difficult to interpret in patients with a history of prostate cancer. Deciding whether to initiate additional systemic therapy in limited indolent metastatic disease while balancing the quality of life of the patient and ensuring the oncologic control of the disease may be challenging. In the present study, the case of a biopsy-confirmed solitary spine recurrence of prostate cancer with nearly undetectable but persistent levels of PSA (0.05 ng/ml) is reported. Treatment of the recurrence with local ablative radiotherapy improved the pain experienced by the patient, and reduced his levels of PSA to undetectable limits (<0.05 ng/ml). Repeated imaging analysis, PSA assay and clinical assessment demonstrated durable control of the disease without the requirement for additional systemic treatments. The present case highlighted the importance of initiating appropriate work-up according to the clinical scenario. Local treatment for solitary or oligometastatic recurrence of prostate cancer may enhance the effectiveness of current therapeutic strategies and benefit certain patients.

Prostate cancer

Prostate cancer is biologically and clinically a heterogeneous disease and its imaging evaluation will need to be tailored to the specific phases of the disease in a patient-specific, risk-adapted manner. We first present a brief overview of the natural history of prostate cancer before discussing the role of various imaging tools, including opportunities and challenges, for different clinical phases of this common disease in men. We then review the preclinical and clinical evidence on the potential and emerging role of positron emission tomography with various radiotracers in the imaging evaluation of men with prostate cancer.

Osteoblasts can stimulate prostate cancer growth and transcriptionally down-regulate PSA expression in cell line models

INTRODUCTION

To investigate the effect of bone environment on cellular proliferation, mature prostate-specific antigen (PSA) production and secretion, and PSA transcriptional regulation of prostate cancer cells.

MATERIALS AND METHODS

Androgen-independent C4-2 prostate cancer cells were co-cultured with various osteoblastic cells in a transwell system. Proliferation was measured via cell counting and MTT assay. Lactate and PSA were determined in the conditioned media (CM). Transcriptional activity of the full-length PSA promoter (6.1 kilobases) and of 3 deletion constructs was determined via luciferase reporter assay upon exposure to CM from various osteoblastic cell lines.

RESULTS

Osteoblastic bone cells and CM, but not control cells (fibroblast) or CM, reproducibly stimulated the proliferation of C4-2 cells. The co-culture system, PSA production by C4-2 cells transiently decreased when in co-culture with osteoblastic, but not with control cells. After abundant prostate cell proliferation, the secreted PSA levels rose exponentially. Addition of CM from osteoblastic cells, but not control cells, consistently decreased (about 3-fold) the transcriptional activity of the PSA promoter in C4-2 cells. Deletion construct analysis of the PSA promoter revealed that the transcriptional down-regulation is dually controlled by elements close to the TATA and upstream androgen responsive (ARE(III)) components.

CONCLUSIONS

The osteoblastic environment stimulates prostate cancer cell proliferation but reduces PSA production initially. The mechanism of PSA down-regulation is transcriptional, most likely in response to soluble factors present in the osteoblastic bone stromal cell CM. Transcriptional down-regulation appears to be mediated by elements near both the TATA box and the ARE(III) component.

Inappropriate treatment of prostate cancer caused by heterophilic antibody interference

BACKGROUND

A 58-year-old man, without any personal or familial risk factors for prostate cancer, visited his primary care physician for a first routine prostate cancer screening with a serum PSA test.

INVESTIGATIONS

Serum PSA test, digital rectal examination, prostate biopsy and pathological analysis, repeat serum PSA tests and pathological re-evaluation, abdominal tomodensitometry, whole-body bone scan and prostatic MRI.

DIAGNOSIS

Highly elevated serum PSA indicative of advanced prostate cancer at high risk for metastasis.

MANAGEMENT

The patient was started on androgen deprivation therapy with goserelin acetate and bicalutamide. At 3 months, he was asymptomatic, his prostate was atrophic on digital rectal examination and he had suppressed serum testosterone. However, his serum PSA level remained highly elevated in the absence of any radiographic evidence of advanced cancer. A repeat PSA test using a different assay returned a negligible PSA concentration; evaluation with blocker agents revealed the presence of heterophilic antibody interference with the original PSA assay. The patient was rediagnosed as having a likely low-grade prostate adenocarcinoma; androgen deprivation therapy was stopped, and he was deemed a candidate for watchful waiting. At 15 months, his serum PSA level remained stable at a low level, and prostatic dynamic MRI showed no sign of tumor in the prostate or in the pelvis.

Molecular imaging of prostate cancer with 18F-fluorodeoxyglucose PET

Prostate cancer poses a major public health problem, particularly in the US and Europe, where it constitutes the most common type of malignancy among men, excluding nonmelanoma skin cancers. The disease is characterized by a wide spectrum of biological and clinical phenotypes, and its evaluation by imaging remains a challenge in view of this heterogeneity. Imaging in prostate cancer can be used in the initial diagnosis of the primary tumor, to determine the occurrence and extent of any extracapsular spread, for guidance in delivery and evaluation of local therapy in organ-confined disease, in locoregional lymph node staging, to detect locally recurrent and metastatic disease in biochemical relapse, to predict and assess tumor response to systemic therapy or salvage therapy, and in disease prognostication (in terms of the length of time taken for castrate-sensitive disease to become refractory to hormones and overall patient survival). Evidence from animal-based translational and human-based clinical studies points to a potential and emerging role for PET, using F-fluorodeoxyglucose as a radiotracer, in the imaging evaluation of prostate cancer.

Prostate cancer: radical prostatectomy

Today, more men than ever before are being followed after radical prostatectomy. Prognosis and follow-up should be based on the pathologic specimen. Measurable prostate-specific antigen (PSA) after surgery defines failure, with time to detectable PSA and rate of PSA rise being useful prognostic factors. The natural history of untreated biochemical failure is protracted, a fact to be considered in discussions of adjuvant treatment. Early in disease recurrence, imaging studies to locate residual disease rarely are useful clinically. Both adjuvant and salvage radiation to the prostate bed have benefits and risks, but neither is superior in overall prostate cancer survival. The timing of hormone therapy remains largely empiric. The promise of effective cytotoxic chemotherapy still is greater than its actual benefits, although novel cytostatic agents are being developed. The future management of this disease will improve with better molecular definition of risk and therapeutic response.

Phase II study of epirubicin, mitomycin C, and 5-fluorouracil in hormone-refractory prostatic carcinoma

Management of metastatic prostatic carcinoma when it becomes refractory to hormonal therapy is controversial, and no standard treatment exists. Nevertheless, chemotherapy for hormone-refractory prostatic carcinoma (HRPC) has shown some advantages compared with the best supportive care. In a prospective phase II study, we evaluated the combination of epirubicin (E), mitomycin C (MMC), and 5-fluorouracil (5-FU) in patients with HRPC. Twenty-eight patients with HRPC were treated with a combination of E (30 mg/m2), 5-FU (750 mg/m2), and MMC (5 mg/m2) day 1 and 2, every 4 weeks. Treatment was continued until evidence of disease progression or excessive toxicity. Patients were monitored with serial measurements of prostate-specific antigen (PSA). Forty-seven percent of the patients exhibited a reduction of serum PSA concentration and an objective response; 38% exhibited disease stability, and 15% had disease progression. Toxicity was substantial. The median time to progression was 7.3 months (range, 1.7-16.8 months) and median survival was 14.5 months (range, 1.6-38.4 months). Performance status improved in 80% of patients, and bone pain was relieved in 70%. Thus the combination of E, MMC, and 5-FU shows activity in the treatment of HRPC, giving substantial palliation of symptoms. In one patient, PSA values remained low even when the tumor had progressed.