Prostate-specific antigen density: a new prognostic indicator for prostate cancer

Prostate-specific antigen versus prostate-specific antigen density as predictor of tumor volume, margin status, pathologic stage, and biochemical recurrence of prostate cancer

OBJECTIVES

To compare prostate-specific antigen (PSA) and PSA density (PSAD) calculated by transrectal ultrasound (TRUS) volume (TRUS PSAD), pathologic volume (Path PSAD), and weight (Weight PSAD) for their ability to predict pathologic characteristics and biochemical recurrence of prostate cancer. We also compared all PSAD derivatives to determine consistency.

METHODS

Between 1993 and 2002, 306 patients were retrospectively identified who had had PSAD determined preoperatively by TRUS and subsequently underwent radical prostatectomy with whole mounting and close step sectioning. The determination of stage, margin status, tumor number, individual tumor volume, and total tumor volume was obtained from the pathologic evaluation. Clinical follow-up was available for 265 patients.

RESULTS

The mean patient age was 62 years, the median Gleason score was 7, the median PSA level was 5.80 ng/mL, and the median TRUS PSAD was 0.16. The percentages of concordance for PSA, TRUS PSAD, Path PSAD, and Weight PSAD were similar in predicting margin status and extracapsular extension. Using linear regression analysis, PSA was more efficacious than TRUS PSAD, Path PSAD, or Weight PSAD in predicting the total tumor volume (R2 0.11, 0.08, 0.04, and 0.06, respectively). A significant positive correlation was found among TRUS PSAD, Path PSAD, and Weight PSAD. PSA was significantly better in predicting biochemical recurrence than TRUS, Path, or Weight PSAD (concordance 75.5%, 66.6%, 66.5%, and 70.4%, respectively).

CONCLUSIONS

PSA and TRUS PSAD are significant and equivalent predictors of margin status and extracapsular extension. A marked difference may exist between PSA and TRUS PSAD in predicting the total tumor volume and biochemical recurrence.

A comparison of the single and double factor high-risk models for risk assignment of prostate cancer treated with 3D conformal radiotherapy

PURPOSE

Two models for stratification of prostate cancer aggressiveness predominate for the purposes of daily treatment decision making. This study investigates the relationships between these two clinically popular models.

METHODS

Both risk stratification models use the same definition for low risk: Gleason score (GS) <or=6, pretreatment initial prostate specific antigen (iPSA) <or=10 ng/mL, and stage T1c-T2c. For the single factor high risk model (SF), intermediate risk (IR) is defined as the presence of GS 7 or PSA > 10-20 ng/mL, without the presence of any high-risk feature; high risk (HR) was defined as the presence of GS 8-10, iPSA >20, or palpation stage T3. For the double factor high risk (DF) model, IR and HR were defined as one and more than one of the following: GS >or=7, iPSA >10, or stage T3. Between April 1989 and October 2001, 1,597 patients were treated definitively with 3D conformal radiation therapy (3D-CRT) alone for prostate cancer at our institution. The main clinical endpoint was freedom from biochemical failure (FFBF).

RESULTS

The 5-year actuarial FFBF rate for the low-risk group was 83%. The SF model resulted in FFBF rates of 76% and 47% for IR and HR patients respectively. The DF model resulted in FFBF rates of 70% and 52% for IR and HR patients, respectively. The FFBF rate for patients defined as IR and HR by both models was 76% and 40%, respectively. Those classified as IR by the DF model and then further subdivided into IR and HR by the SF model had a 76% and 52% 5-year FFBF rate (p = 0.0004). Those classified as HR by the DF model and then further subdivided into IR and HR by the SF model had a 71% and 40% 5-year FFBF (p = 0.0014).

CONCLUSIONS

The SF model created prognostic groups with a greater internal consistency than the DF model. The SF was also better at identifying patients with high-risk prostate cancer who may benefit from a more aggressive approach.

Predicting time to prostate cancer recurrence based on joint models for non-linear longitudinal biomarkers and event time outcomes

Biological markers that are both sensitive and specific for tumour regrowth or metastasis are increasingly becoming available and routinely monitored during the regular follow-up of patients treated for cancer. Obtained by a simple blood test, these markers provide an inexpensive non-invasive means for the early detection of recurrence (or progression). Currently, the longitudinal behaviour of the marker is viewed as an indicator of early disease progression, and is applied by a physician in making clinical decisions. One marker that has been studied for use in both population screening for early disease and for detection of recurrence in prostate cancer patients is PSA. The elevation of PSA levels is known to precede clinically detectable recurrence by 2 to 5 years, and current clinical practice often relies partially on multiple recent rises in PSA to trigger a change in treatment. However, the longitudinal trajectory for individual markers is often non-linear; in many cases there is a decline immediately following radiation therapy or surgery, a plateau during remission, followed by an exponential rise following the recurrence of the cancer. The aim of this article is to determine the multiple aspects of the longitudinal PSA biomarker trajectory that can be most sensitive for predicting time to clinical recurrence. Joint Bayesian models for the longitudinal measures and event times are utilized based on non-linear hierarchical models, implied by unknown change-points, for the longitudinal trajectories, and a Cox proportional hazard model for progression times, with functionals of the longitudinal parameters as covariates in the Cox model. Using Markov chain Monte Carlo sampling schemes, the joint model is fit to longitudinal PSA measures from 676 patients treated at Massachusetts General Hospital between the years 1988 and 1995 with follow-up to 1999. Based on these data, predictive schemes for detecting cancer recurrence in new patients based on their longitudinal trajectory are derived.

Chemical disease-free survival in localized carcinoma of prostate treated with external beam irradiation: comparison of American Society of Therapeutic Radiology and Oncology Consensus or 1 ng/mL as endpoint

PURPOSE

To compare postirradiation biochemical disease-free survival using the American Society of Therapeutic Radiology and Oncology (ASTRO) Consensus or elevation of postirradiation prostate-specific antigen (PSA) level beyond 1 ng/mL as an endpoint and correlate chemical failure with subsequent appearance of clinically detected local recurrence or distant metastasis.

METHODS AND MATERIALS

Records of 466 patients with histologically confirmed adenocarcinoma of the prostate treated with irradiation alone between January 1987 and December 1995 were analyzed; 339 patients were treated with bilateral 120 degrees arc rotation and, starting in 1992, 117 with three-dimensional conformal irradiation. Doses were 68--77 Gy in 1.8 to 2 Gy daily fractions. Minimum follow-up is 4 years (mean, 5.5 years; maximum, 9.6 years). A chemical failure was recorded using the ASTRO Consensus or when postirradiation PSA level exceeded 1 ng/mL at any time. Clinical failures were determined by rectal examination, radiographic studies, and, when clinically indicated, biopsy.

RESULTS

Six-year chemical disease-free survival rates using the ASTRO Consensus according to pretreatment PSA level for T1 tumors were: < or = 4 ng/mL, 100%; 4.1--20 ng/mL, 80%; and > 20 ng/mL, 50%. For T2 tumors the rates were: < or = 4 ng/mL, 91%; 4.1--10 ng/mL, 81%; 10.1--20 ng/mL, 55%; 20.1--40 ng/mL, 63%; and > 40 ng/mL, 46%. When postirradiation PSA levels higher than 1 ng/mL were used, the corresponding 6-year chemical disease-free survival rates for T1 tumors were 92% for pretreatment PSA levels of < or = 4 ng/mL, 58--60% for levels of 4.1--20 ng/mL, and 30% for levels > 20 ng/mL. For T2 tumors, the 6-year chemical disease-free survival rates were 78% in patients with pretreatment PSA levels of 4--10 ng/mL, 45% for 10.1--40 ng/mL, and 25% for > 40 ng/mL. Of 167 patients with T1 tumors, 30 (18%) developed a chemical failure, 97% within 5 years from completion of radiation therapy; no patient has developed a local recurrence or distant metastasis. In patients with T2 tumors, overall 45 of 236 (19%) had chemical failure, 94% within 5 years of completion of radiation therapy; 4% have developed a local recurrence, and 10%, distant metastasis. In patients with T3 tumors, overall, 24 of 65 (37%) developed a chemical failure, 100% within 3.5 years from completion of radiation therapy; 4% of these patients developed a local recurrence within 2 years, and 12% developed distant metastasis within 4 years of completion of irradiation. The average time to clinical appearance of local recurrence or distant metastasis after a chemical failure was detected was 5 years and 3 years, respectively.

CONCLUSION

There was a close correlation between the postirradiation nadir PSA and subsequent development of a chemical failure. Except for patients with T1 tumors and pretreatment PSA of 4.1--20 ng/mL, there is good agreement in 6-year chemical disease-free survival using the ASTRO Consensus or PSA elevations above 1 ng/mL as an endpoint. Although the ASTRO Consensus tends to give a higher percentage of chemical disease-free survival in most groups, the differences with longer follow-up are not statistically significant (p > 0.05). It is important to follow these patients for at least 10 years to better assess the significance of and the relationship between chemical and clinical failures.

PSA-based outcome analysis after radiation therapy for prostate cancer: a new definition of biochemical failure after intervention

OBJECTIVES

To examine pretreatment variables that influence biochemical failure, and to describe and test a new definition of prostate-specific antigen (PSA)-based biochemical failure.

METHODS

We introduce and describe a new definition of biochemical failure, which is based on quadratic fitting of the logarithm of the follow-up PSA profile curve. From a data base of 449 patients with prostate cancer treated with definitive radiation therapy, 230 patients who had at least five follow-up PSA observations were chosen for analysis. The new definition of failure was applied to this cohort, as was the conventional definition of two consecutive PSA rises. Univariate and multivariate analyses were performed using established pretreatment prognostic factors as covariates. Also, the association of both definitions of failure with clinical outcome (local recurrence and any recurrence) was examined.

RESULTS

Application of the new definition of biochemical failure resulted in smoothing of the "noise" that is inherent in using definitions based on successive PSA rises. This smoothing was verified by smaller P values for the statistically significant covariates in the univariate analysis. Furthermore, the new definition correlated better with clinical outcome, as demonstrated by the statistically significant P values on regression analysis when using the quadratic fitted nadir compared with using the observed nadir.

CONCLUSIONS

We devised a new criterion based on quadratic curve fitting for PSA-based biochemical failure. This definition is based on all available PSA information, correlates with both pretreatment factors and post-treatment clinical outcome, is relatively insensitive to noise, and allows for prediction of time of failure.

Is prostate specific antigen density an important prognostic indicator for patients with prostate cancer treated with external beam therapy?

The purpose of this study was to determine if prostate specific antigen density (PSAD) is a predictor of outcome following external beam radiotherapy for prostate cancer, and to compare it with other prognostic factors. Between January 1990 and December 1993, 205 patients with T1-T3 adenocarcinoma of the prostate received a radical course of external beam irradiation, with no prior or adjuvant hormonal therapy. All patients had pre- and post-treatment serum prostate specific antigen (PSA) evaluation. They were followed up for at least 24 months. PSAD was defined as the ratio of pre-treatment serum PSA to the prostate volume, as determined from CT treatment planning scans. Prostate volumes were calculated using the prostate ellipse formula. Median PSA density was 0.37, with a range 0.01-6.7. Biochemical failure was defined as three consecutive rises in serum PSA, regardless of the magnitude of elevation. 4-year biochemical disease-free survival (BDFS) for patients with PSAD < or = 0.3 was 60%, compared with 22% for patients with PSAD > 0.3 (p = < 0.001). In a multivariate analysis, pre-treatment PSA (p = < 0.001), Gleason score (p = 0.002), and stage (p = 0.03) were independent predictors of BDFS, while PSAD was not an important prognosticator (p = 0.62). Pre-treatment serum PSA is the most important prognosticator of BDFS, following external beam radiotherapy, for patients with prostate cancer. PSA density did not predict treatment outcome.

Changes in biochemical disease-free survival rates as a result of adoption of the consensus conference definition in patients with clinically localized prostate cancer treated with external-beam radiotherapy

PURPOSE

The optimal definition of biochemical recurrence of prostate cancer after definitive radiotherapy remains elusive. Different institutions have developed their own definitions, and a consensus conference (CC) sponsored by the American Society for Therapeutic Radiology and Oncology has recently proposed another definition. This study compares the definition previously used at our institution with the definition proposed by the CC.

METHODS

Two hundred and eight patients were treated for localized prostate cancer with conformal external-beam radiotherapy between 1989-1993 at our institution and followed for at least 24 months. Patients were categorized as failures according to our institutional definition and the CC definition. Our definition (CPMC) required two increases in serum prostate specific antigen (PSA) over at least a 3-month period with a final value of at least 1 ng/ml or a single value resulting in clinical intervention. The CC definition required three consecutive increases in PSA. This was modified to also consider those patients with one or two increases leading to clinical intervention as failures. Differences in the failure rates between the two definitions were evaluated and factors influencing these differences were explored. In an additional analysis, CC was modified such that patients with one or two PSA increases were censored at the time of the PSA prior to the increases (CC-II), rather than at the last PSA (CC). The median follow-up time was 31 months.

RESULTS

There were 36 fewer failures according to CC (n = 96) compared with CPMC (n = 132) (p < 0.001). Twenty cases called failures by CPMC subsequently had a decrease in PSA ("false failures"). The other 16 patients have had two increases in PSA, but are awaiting their next follow-up visit to obtain a third PSA ("pending failures"). Analysis of factors predicting "pending failures" showed Gleason score to be the sole predictor of this change in status in multivariate analysis (p = 0.03) with patients with lower-grade tumors being more likely to change status (Gleason 2-6: 15% vs. Gleason 7-10: 1%). On the other hand, "false failures," compared to true failures, had a lower mean PSA nadir (1.7 ng/ml vs. 7.0 ng/ml, p < 0.001) and significantly smaller mean increases in PSA (1st increase: 0.6 ng/ml vs. 3.4 ng/ml, p = 0.006; 2nd increase: 0.4 ng/ml vs. 4.8 ng/ml, p = 0.002). In 85% (17 of 20) of these patients, at least one of the increases was < or = 0.3 ng/ml compared with 44% (42 of 96) of the true failures (p = 0.0008). CC-II resulted in a small decrease in BDFS rates compared with CC, but did not affect the overall difference between CC and CPMC. A modified definition that defines failure as two consecutive increases in PSA over 3 months, with a final value greater than 1.0 ng/ml and each increase being at least 0.3 ng/ml, or three consecutive increases would result in a "false" failure rate of only 3% (3 of 99) and identify 56% (54 of 96) of the true failures after only two PSA increases.

CONCLUSION

The CPMC definition of two PSA increases can falsely identify patients as failures, particularly if the increases in PSA are small (i.e., < or = 0.3 ng/ml). The CC definition requiring three increases in PSA can falsely identify patients as disease-free when the time to failure is long relative to the follow-up time. We propose a that a definition that combines aspects of both definitions (two consecutive increases in PSA over 3 months, with a final value greater than 1.0 ng/ml and each increase being at least 0.3 ng/ml, or three consecutive increases) may be a better definition of biochemical failure.

Radiotherapy options for localized prostate cancer based upon pretreatment serum prostate-specific antigen levels and biochemical control: a comprehensive review of the literature

PURPOSE

To review all the available radiotherapy (RT) literature on localized prostate cancer treatment where serum prostate-specific antigen (PSA) levels were used to both stratify patients and evaluate outcome and determine if any conclusions can be reached regarding an optimal radiotherapeutic management for this disease.

METHODS AND MATERIALS

A MEDLINE search was conducted to obtain all articles in English on prostate cancer treatment employing RT from 1986-1997. Studies were considered eligible for review only if they met all the following criteria: 1) pretreatment PSA values were recorded and grouped for subsequent evaluation, 2) posttreatment PSA values were continuously monitored, 3) definitions of biochemical control were stated, and 4) the median follow-up was given.

RESULTS

Of the 246 articles identified, only 20 met the inclusion criteria; 4 using conformal external beam RT, 8 using conventional external beam RT, and 8 using interstitial brachytherapy (4 using a permanent implant alone, 3 combining external beam RT with a permanent implant, and 1 combining a conformal temporary interstitial implant boost with external beam RT). No studies using neutrons (with or without external beam RT) or androgen deprivation (combined with external beam RT) were identified where patients were stratified by pretreatment PSA levels. Results for all therapies were extremely variable with the 3-5-year rates of biochemical control for patients with pretreatment PSA levels < or = 4 ng/ml ranging from 48 to 100%, for PSA levels >4 and < or = 10 ng/ml ranging from 44 to 90%, for PSA levels >10 and < or = 20 ng/ml ranging from 27 to 89%, and for PSA levels >20 ranging from 14 to 89%. The median Gleason score, T-stage, definition of biochemical control, and follow-up were substantially different from series to series. No RT option consistently produced superior results.

CONCLUSIONS

When data are reviewed from studies using serum PSA levels to stratify patients and to evaluate treatment outcome, no consistently superior RT technique was identified. These data suggest that standard definitions of disease stage (combining clinical, pathologic, and biochemical criteria) and a common definition of biochemical cure (as developed by the American Society for Therapeutic Radiology and Oncology Consensus Panel) need to be adopted to evaluate treatment efficacy and advise patients on the most appropriate radiotherapeutic option for their disease.

Biologic classification as an alternative to anatomic staging for clinically localized prostate cancer: a proposal based on patients treated with external beam radiotherapy

OBJECTIVES

The prognostic significance of clinical stage in patients with prostate cancer who are treated with external beam radiotherapy is unclear. This study evaluates multiple pretreatment factors, including clinical stage, to determine which are the best prognostic factors, and develops a classification system based on these factors.

METHODS

All 249 evaluable patients with clinically localized adenocarcinoma of the prostate treated with definitive conformal external beam radiotherapy without androgen deprivation at our institution between 1989 and 1993 were analyzed. Clinical stage, serum PSA level, Gleason score, race, and history of transurethral resection of the prostate (TURP) were evaluated for their ability to predict biochemical disease-free survival (BDFS). Factors predictive of BDFS were then used to construct a classification system. The classification system was then analyzed for its ability to predict BDFS, distant metastases, local recurrence, and clinical disease free survival in univariate and multivariate analyses. Median follow-up was 27 months.

RESULTS

Gleason score and PSA predicted BDFS in multivariate analysis (both P <0.0001), whereas clinical stage, race, and history of a TURP did not. These two biologic factors were combined into a four-level classification system. This classification system was analyzed together with Gleason score and PSA and was found to be the only predictor of BDFS on multivariate analysis (P <0.0001). In addition, this classification system was the only predictor of distant metastases in multivariate analysis (P <0.0001).

CONCLUSIONS

The classification system derived herein based on the biologic factors of Gleason score and serum PSA levels is the sole predictor of distant metastases and biochemical recurrence for patients treated with definitive conformal external beam radiotherapy for clinically localized prostate cancer. This classification system may be useful when comparing competing therapies and stratifying patients in clinical trials, but requires validation from other institutions and other therapies prior to its widespread use.

Re-examining the role of prostate-specific antigen density in predicting outcome for clinically localized prostate cancer

OBJECTIVES

To evaluate the prognostic significance of prostate-specific antigen density (PSAD) in clinically localized prostate cancer and determine whether this index is independent of or superior to prostate-specific antigen (PSA) in predicting outcome of patients treated with external beam radiotherapy.

METHODS

Between January 1989 and December 1993, 175 evaluable patients with clinically localized prostate cancer received definitive radiotherapy using computed tomography (CT)-guided conformal techniques. PSAD was defined as the ratio of the pretreatment serum PSA to the prostate volume measured from CT treatment planning scans by one investigator. All PSA values were determined using the Hybritech assay. Biochemical failure was defined as two consecutive elevations in PSA separated by at least 3 months and a final PSA value greater than 1 ng/mL.

RESULTS

Multivariate analysis including PSA and Gleason score revealed both to be statistically significant predictors of biochemical disease-free survival (P = 0.048 and P < 0.001, respectively). PSAD did not achieve significance on regression analysis. A direct multivariate analysis including PSA and PSAD required dichotomization in order to reduce high correlation. This analysis demonstrated a relative risk (RR) for failure of 1.27 (NS) for high PSA versus low PSA compared with a RR of 1.20 (NS) for high PSAD versus low PSAD. A regression model containing all three variables indicated only the Gleason score as significant in predicting biochemical failure.

CONCLUSIONS

These data do not suggest that PSAD is either an independent prognostic factor or a stronger discriminant of outcome than PSA in patients with clinically localized prostate cancer treated with definitive external beam radiotherapy. Larger patient numbers with longer follow-up data, use of a clinical end point, or an analysis restricted to the appropriate subgroup may demonstrate the utility of PSAD in the future.

Prostate-specific antigen density

Nearly 20 years have passed since PSA was definitively identified. Throughout this period, its clinical application as a tumor marker has expanded significantly. Today, besides monitoring prostate cancer therapy, PSA is being used extensively in mass screening programs for early detection of adenocarcinoma of the prostate and has become the most important tumor marker in urologic oncology. Although of unquestionable importance, PSA is not the perfect marker because of its lack of efficacy in discriminating BPH from prostate cancer. In order to enhance its sensibility, specificity, and predictive value, a series of variables influencing PSA levels have been studied and new parameters developed to correct discrepancies or confounding factors. Recognition of the relationship between PSA, prostate volume, and their interference with serum PSA levels made possible the development of the PSAD concept. Its wide application in different sets of patients for diagnostic and staging purposes resulted in enough data to demonstrate its usefulness and cost effectiveness as a second-line screening parameter, helping to distinguish BPH from prostate cancer in patients with PSA levels in the intermediate area, and avoiding some unnecessary biopsies. Even though PSAD does not offer a definitive solution for prostate cancer screening or management, its association with all the other diagnostic methods may offer the best way to assess the population at risk and assure their well-being (Fig. 5).

Prostate-specific antigen cancer volume: a significant prognostic factor in prostate cancer patients at intermediate risk of failing radiotherapy

PURPOSE

Although the pretreatment serum prostate-specific antigen level (PSAL) is the single-most significant predictor of local and biochemical control in prostate cancer patients treated with radiotherapy, it is relatively insensitive for patients with a PSAL in the intermediate range (4-20 ng/ml). PSA density (PSAD) has been shown to be slightly more predictive of outcome than PSAL for this intermediate risk group; however, this improvement is small and of little use clinically. PSA cancer volume (PSACV), an estimate of cancer volume based on PSA, has recently been described and has been purported to be more significant than PSAL in predicting early biochemical failure after radiotherapy. We report a detailed comparison between this new prognostic factor, PSAL, and PSAD.

METHODS AND MATERIALS

The records of 356 patients treated with definitive external beam radiotherapy for regionally localized (T1-4,Nx,M0) adenocarcinoma of the prostate were reviewed. Each patient had a PSAL, biopsy Gleason score, and pretreatment prostate volume by transrectal ultrasonography. The median PSAL was 9.3 ng/ml and 66% had Gleason scores in the 2-6 range. The median radiation dose was 66.0 Gy and the median follow-up for those living was 27 months. PSACV was calculated using a formula which takes into account PSAL, pretreatment prostate ultrasound volume, and Gleason score. The median PSACV was 1.43 cc. Biochemical failure was defined as increases in two consecutive follow-up PSA levels, one increase by a factor > 1.5, or an absolute increase of > 1 ng/ml. Local failure was defined as a cancer-positive prostate biopsy, obtained for evidence of tumor progression.

RESULTS

The distributions of PSACV and PSAL were similar and, when normalized by log transformation, were highly correlated (p < 0.0001, linear regression). There was a statistically significant relationship between PSACV and several potential prognostic factors including PSAL, PSAD, stage, Gleason score, and pretreatment prostatic acid phosphatase (PAP). In univariate analyses, PSACV, PSAL, and PSAD proved to be the most significant predictors of both biochemical and local control. In multivariate analyses using Cox proportional hazards models with PSAL, PSAD, PSACV, and PAP as continuous variables, PSAL, PSACV, and Gleason score were significant in predicting biochemical control. Only PSAL was significantly correlated with local control. However, when these analyses were restricted to patients with intermediate PSALs (4-20 ng/ml), only PSACV was significant for predicting both biochemical and local control.

CONCLUSION

PSACV was highly correlated with actuarial local and biochemical control and was superior to both PSAL and PSAD in predicting these outcomes in patients with PSALs between 4 and 20 ng/ml.

Prostate specific antigen density as a prognostic factor for patients with prostate carcinoma treated with radiotherapy

BACKGROUND

The pretreatment serum prostate specific antigen level (PSAL) is the most significant predictor of biochemical and local failure in patients treated with definitive radiotherapy. The role of prostate specific antigen (PSA) density (PSAD) relative to PSAL for such patients is controversial. In this article, we describe a comparative analysis of the prognostic value of PSAL and PSAD.

METHODS

The study was comprised of 365 patients who were treated with external beam radiotherapy for regionally localized (T1-T4, Nx, M0) adenocarcinoma of the prostate between 1987-1993 and in whom PSAL and pretreatment prostate volume by transrectal ultrasound were available. The mean and median doses were 66.8 Gy and 66 Gy. Median follow-up for those patients living was 27 months. The mean PSAL was 12.7 ng/mL with a median of 9.1 ng/mL. PSAD was calculated by dividing the PSAL by the pretreatment prostate transectal ultrasound volume (in cc). The mean PSAD was 0.44 and the median was 0.31. Biochemical failure was defined as two consecutive increases in follow-up PSAs, one increase by a factor of greater than 1.5 of an absolute increase of greater than 1 ng/mL.

RESULTS

The distributions of PSAD and PSAL were similar and were positively skewed. When log-transformed, the distributions of both parameters were normalized and linear regression revealed a high correlation (P < 0.0001). PSAD was significantly associated with several potential prognostic factors, including stage, Gleason score, PSAL, and pretreatment prostatic acid phosphatase. Univariate analyses of PSAD and PSAL revealed that these were the most significant correlates of local and biochemical control. By contrast, stage and Gleason score were the only factors predictive of freedom from distant metastasis. Multivariate analyses using Cox proportional hazards models were then performed to determine if PSAD provided prognostic information independent of PSAL. The manner in which PSAD and PSAL were categorized (four, three, of two groups) dramatically influenced the significance of these covariates. Optimization of these groups for significance showed grouped PSAD to be the stronger predictor of the local control and grouped PSAL to be the stronger predictor of biochemical control. However, when PSAD and PSAL were used as continuous variables, PSAL was the only independently significant prognostic factor for local or biochemical control.

CONCLUSIONS

PSAD was highly correlated with actuarial patient outcome in the univariate analyses and appeared to provide independent information when PSAL was between 4 and 20 ng/mL. However, the differences based on PSAD were relatively small and, therefore, not clinically useful.

Serum prostate specific antigen and prostate specific antigen density in patients receiving radical prostatectomy

OBJECTIVE

To study the significance of prostate specific antigen (PSA) and prostate specific antigen density (PSAD) for predicting the risk of occult metastatic disease and extra-prostatic invasion of prostate cancer in patients receiving radical prostatectomy.

PATIENTS AND METHODS

The cases of 41 consecutive patients who underwent radical prostatectomy were reviewed. Relations of PSA and PSAD using Markit M PATM assay for grade, preoperative clinical stage, postoperative pathological stage, capsular penetration, seminal vesicle invasion, resection margins and lymph node metastasis are discussed.

RESULTS

Although serum PSA was correlated with PSAD and PSA was correlated with preoperative prostate volume, PSAD was not influenced by prostate volume. PSA correlated only with the grade, while PSAD was correlated with grade, preoperative clinical stage, postoperative pathological stage, capsular penetration, seminal vesicle invasion, resection margins and lymph node metastasis. In addition, sixty-two percent (8/13) of margin positive patients showed a PSAD value of more than 0.4, while 93% (26/28) of margin negative patients showed less than 0.4. Sixty-seven percent (6/9) of lymph node positive patients showed a PSAD of more than 0.4, while 91% (29/32) of lymph node negative patients showed less than 0.4.

CONCLUSION

We concluded that PSAD was useful for predicting extra-prostatic involvement of prostatic cancer.

Prostate specific antigen and prostate specific antigen density. Roles in patient evaluation and management

Prostate specific antigen (PSA) is the most accurate serum marker for prostate cancer. However, sensitivity and specificity are suboptimal, especially at the intermediate levels between 4.1 and 10.0 ng/ml (monoclonal). For intermediate PSA levels, PSA density (PSAD) provides unique information regarding the need for biopsy and the likelihood of prostate cancer. The authors prospectively used PSAD to determine the need for biopsy in 68 patients with PSAD values below 0.150 and normal results from a digital rectal examination. Ten patients have undergone biopsy secondary to a rising serum PSA. Three were found to harbor prostate cancer and have undergone therapy. The remaining 65 patients continue on surveillance. PSAD can predict treatment outcomes for patients with clinically localized prostate cancer treated with radical prostatectomy. PSADs at low values are 90% accurate in predicting operative success. PSADs at high values are 67% accurate in predicting failure. Cancer 1994; 74: 1667-73.