Background

Metastatic lesions in prostate cancer beyond the bone have prognostic importance and affect clinical therapeutic decisions. Few data exist regarding the prevalence of soft-tissue metastases at the initial diagnosis of metastatic castration-resistant prostate cancer (mCRPC).

Methods

This study analyzed 232 men with nonmetastatic (M0) castration-resistant prostate cancer (CRPC) who developed metastases detected by a bone scan or computed tomography (CT). All bone scans and CT scans within the 30 days before or after the mCRPC diagnosis were reviewed. The rate of soft-tissue metastases among those undergoing CT was determined. Then, predictors of soft-tissue metastases and visceral and lymph node metastases were identified.

Results

Compared with men undergoing CT (n = 118), men undergoing only bone scans (n = 114) were more likely to have received primary treatment (P = .048), were older (P = .013), and less recently developed metastases (P = .018). Among those undergoing CT, 52 (44%) had soft-tissue metastases, including 20 visceral metastases (17%) and 41 lymph node metastases (35%), whereas 30% had no bone involvement. In a univariable analysis, only prostate-specific antigen (PSA) predicted soft-tissue metastases (odds ratio [OR], 1.27; P = .047), and no statistically significant predictors of visceral metastases were found. A higher PSA level was associated with an increased risk of lymph node metastases (OR, 1.38; P = .014), whereas receiving primary treatment was associated with decreased risk (OR, 0.36; P = .015).

Conclusions

The data suggest that there is a relatively high rate of soft-tissue metastasis (44%) among CRPC patients undergoing CT at the initial diagnosis of metastases, including some men with no bone involvement. Therefore, forgoing CT during a metastatic evaluation may lead to an underdiagnosis of soft-tissue metastases and an underdiagnosis of metastases in general. Cancer 2015. © 2015 American Cancer Society. Cancer 2016;122:222-229. © 2015 American Cancer Society.

Objectives

To test the external validity of a previously developed risk table, designed to predict the probability of a positive bone scan among men with non-metastatic (M0) castration-resistant prostate cancer (CRPC), in a separate cohort.

Patients and methods

We retrospectively analysed 429 bone scans of 281 patients with CRPC, with no known previous metastases, treated at three Veterans Affairs Medical Centers. We assessed the predictors of a positive scan using generalized estimating equations. Area under the curve (AUC), calibration plots and decision-curve analysis were used to assess the performance of our previous model to predict a positive scan in the current data.

Results

A total of 113 scans (26%) were positive. On multivariable analysis, the only significant predictors of a positive scan were log-transformed prostate-specific antigen (PSA): hazard ratio (HR) 2.13; 95% confidence interval (CI) 1.71-2.66 (P < 0.001) and log-transformed PSA doubling time (PSADT): HR 0.53; 95% CI 0.41-0.68 (P < 0.001). Among men with a PSA level <5 ng/mL, the rate of positive scans was 5%. The previously developed risk table had an AUC of 0.735 to predict positive bone scan with excellent calibration, and provided additional net benefit in the decision-curve analysis.

Conclusion

We have validated our previously developed table to predict the risk of a positive bone scan among men with M0/Mx CRPC. Use of this risk table may allow better tailoring of patients' scanning to identify metastases early, while minimizing over-imaging. Regardless of PSADT, positive bone scans were rare in men with a PSA <5 ng/mL.

Objective

To review follow-up imaging after equivocal bone scans in men with castration resistant prostate cancer (CRPC) and examine the characteristics of equivocal bone scans that are associated with positive follow-up imaging.

Methods

We identified 639 men from five Veterans Affairs Hospitals with a technetium-99m bone scan after CRPC diagnosis, of whom 99 (15%) had equivocal scans. Men with equivocal scans were segregated into "high-risk" and "low-risk" subcategories based upon wording in the bone scan report. All follow-up imaging (bone scans, computed tomography [CT], magnetic resonance imaging [MRI], and X-rays) in the 3 months after the equivocal scan were reviewed. Variables were compared between patients with a positive vs. negative follow-up imaging after an equivocal bone scan.

Results

Of 99 men with an equivocal bone scan, 43 (43%) received at least one follow-up imaging test, including 32/82 (39%) with low-risk scans and 11/17 (65%) with high-risk scans (p = 0.052). Of follow-up tests, 67% were negative, 14% were equivocal, and 19% were positive. Among those who underwent follow-up imaging, 3/32 (9%) low-risk men had metastases vs. 5/11 (45%) high-risk men (p = 0.015).

Conclusion

While 19% of all men who received follow-up imaging had positive follow-up imaging, only 9% of those with a low-risk equivocal bone scan had metastases versus 45% of those with high-risk. These preliminary findings, if confirmed in larger studies, suggest follow-up imaging tests for low-risk equivocal scans can be delayed while high-risk equivocal scans should receive follow-up imaging.

Objective

To identify the predictors of time from initial diagnosis of metastatic castration-resistance prostate cancer (mCRPC) to all-cause death within the Shared Equal Access Regional Cancer Hospital cohort.

Patients and methods

We performed a retrospective analysis of 205 mCRPC men. Overall survival was estimated and plotted using the Kaplan-Meier method. The uni- and multivariable overall survival predictors were evaluated with the Cox proportional hazards model. A nomogram was generated to predict overall survival at 1, 2, 3, and 5 years after mCRPC. Concordance index and calibration plot were obtained.

Results

A total of 170 men (83%) died over a median follow-up of 41 months. In univariable analysis, older age, more remote year of mCRPC, nonblack race, greater number of bone metastasis, higher prostate-specific antigen (PSA) levels, shorter PSA doubling time, and faster PSA velocity at mCRPC diagnosis were significantly associated with shorter overall survival (all P < .05). In multivariable analysis, older age, more remote year of mCRPC, greater number of bone metastasis, higher PSA levels, and shorter PSA doubling time at mCRPC diagnosis remained significantly associated with shorter overall survival (all P < .05). On the basis of these variables, a nomogram was generated yielding a concordance index of 0.67 and good calibration.

Conclusion

The use of clinical parameter such as age, disease burden, and PSA levels and kinetics can be used to estimate overall survival in mCRPC patients.

Purpose

We investigated imaging practice patterns in men with nonmetastatic (M0) castration resistant prostate cancer.

Materials and methods

We analyzed data on 247 patients with documented M0 CRPC from the SEARCH database. Patients were selected regardless of primary treatment modality and all had a negative bone scan after a castration resistant prostate cancer diagnosis. Cox models were used to test associations of time to a second imaging test with several demographic and clinical factors.

Results

During a median followup of 29.0 months (IQR 12.9-43.5) after a post-castration resistant prostate cancer bone scan was negative, 190 patients (77%) underwent a second imaging test. On univariable analysis patients with higher prostate specific antigen (HR 1.13, p = 0.016), shorter prostate specific antigen doubling time (HR 0.79, p < 0.001) and faster prostate specific antigen velocity (HR 1.01, p < 0.001) were more likely to undergo a second imaging test. Treatment center was also a significant predictor of a second imaging test (p = 0.010). No other factor was a significant predictor. Results were similar on multivariable analysis. It was estimated that approximately 20% of men with a prostate specific antigen doubling time of less than 3 months did not undergo an imaging test in the first year after a post-castration resistant prostate cancer negative bone scan. However, 50% of patients with prostate specific antigen doubling time 15 months or greater underwent a second imaging test in the first year.

Conclusions

Clinicians use some known predictors of positive imaging tests to determine which patients with M0 castration resistant prostate cancer undergo a second imaging test . However, there may be under imaging in those at high risk and over imaging in those at low risk. Further studies are needed to identify risk factors for metastasis and form clear imaging guidelines in patients with M0 castration resistant prostate cancer.

Objective

To investigate predictors of time to metastasis among men treated with androgen deprivation therapy for nonmetastatic prostate cancer who developed castration-resistant prostate cancer (CRPC) within the Shared Equal Access Regional Cancer Hospital cohort.

Methods

This is a retrospective analysis of 458 nonmetastatic CRPC men. Metastases were detected in routine bone scans or other imaging tests. Predictors of time to metastasis were analyzed using proportional hazards model with CRPC as time zero.

Results

A total of 256 (56%) men were diagnosed with metastatic disease over a median follow-up of 36 months. Metastasis-free survival was 79%, 65%, 52%, 47%, and 41% at 1, 2, 3, 4, and 5 years after CRPC, respectively. In multivariable analysis, Gleason score 8-10 (hazard ratio [HR] = 1.61; P = .026), receiving primary localized treatment (HR = 1.38; P = .028), higher prostate-specific antigen (PSA) levels at CRPC diagnosis (logPSA HR = 1.64; P < .001), and PSA doubling time ≤6 months (HR = 1.42; P = .040) were independently associated with shorter time to metastasis. Race, year of CRPC, age, and time from androgen deprivation therapy to CRPC were not associated with metastasis.

Conclusion

Among nonmetastatic CRPC men, nearly 60% developed metastatic disease during the first 5 years, with most of the metastasis occurring within the first 3 years. Higher Gleason score, receiving primary treatment, higher PSA, and shorter PSA doubling time were independently associated with shorter time to metastasis. Therefore, these variables can be used to stratify patients according to metastasis risk.