Practical application of biochemical failure definitions: what to do and when to do it

Comparison of biochemical failure rates between permanent prostate brachytherapy and radical retropubic prostatectomy as a function of posttherapy PSA nadir plus 'X'

Background

Prostate-specific antigen (PSA) nadir + 2 ng/mL, also known as the Phoenix definition, is the definition most commonly used to establish biochemical failure (BF) after external beam radiotherapy for prostate cancer management. The purpose of this study is to compare BF rates between permanent prostate brachytherapy (PPB) and radical retropubic prostatectomy (RRP) as a function of PSA nadir plus varying values of X and examine the associated implications.

Methods and materials

We retrospectively searched for patients who underwent PPB or RRP at our institution between 1998 and 2004. Only primary patients not receiving androgen-deprivation therapy were included in the study. Three RRP patients were matched to each PPB patient on the basis of prognostic factors. BF rates were estimated for PSA nadirs + different values of X.

Results

A total of 1,164 patients were used for analysis: 873 in the RRP group and 291 in the PPB group. Patients were equally matched by clinical stage, biopsy Gleason sum, primary Gleason grade, and pretherapy PSA value. Median follow-up was 3.1 years for RRP patients and 3.6 years in the PPB group (P = .01). Using PSA nadir + 0.1 ng/mL for the definition of BF, the 5-year BF rate was 16.3% for PPB patients and 13.5% for RRP patients (P = .007), whereas at nadir + 2 ng/mL or greater, the BF rates were less than 3% and were indistinguishable between PPB and RRP patients.

Conclusions

In a cohort of well-matched patients who had prostatectomy or brachytherapy, we examined BF as a function of nadir + X, where X was treated as a continuous variable. As X increases from 0.1 to 2.0 ng/mL, the BF curves converge, and above 2.0 ng/mL they are essentially indistinguishable. The data presented are of interest as BF definitions continue to evolve.

Management of patients with biochemical recurrence after local therapy for prostate cancer

Nearly three-quarters of a million American men who have been treated with prostatectomy and/or radiation therapy experience an increasing prostate-specific antigen level known as biochemical recurrence. Although androgen-deprivation therapy remains a reasonable option for some men with biochemical recurrence, deferring androgen ablation or offering nonhormonal therapies may be appropriate in patients in whom the risk of clinical or metastatic progression and prostate cancer-specific death is low. A risk-stratified approach informed by the patient's prostate-specific antigen kinetics, comorbidities, and personal preferences is recommended to determine the best management approach.

Clinical outcome of patients treated with 3D conformal radiation therapy (3D-CRT) for prostate cancer on RTOG 9406

PURPOSE

Report of clinical cancer control outcomes on Radiation Therapy Oncology Group (RTOG) 9406, a three-dimensional conformal radiation therapy (3D-CRT) dose escalation trial for localized adenocarcinoma of the prostate.

METHODS AND MATERIALS

RTOG 9406 is a Phase I/II multi-institutional dose escalation study of 3D-CRT for men with localized prostate cancer. Patients were registered on five sequential dose levels: 68.4 Gy, 73.8 Gy, 79.2 Gy, 74 Gy, and 78 Gy with 1.8 Gy/day (levels I-III) or 2.0 Gy/day (levels IV and V). Neoadjuvant hormone therapy (NHT) from 2 to 6 months was allowed. Protocol-specific, American Society for Therapeutic Radiation Oncology (ASTRO), and Phoenix biochemical failure definitions are reported.

RESULTS

Thirty-four institutions enrolled 1,084 patients and 1,051 patients are analyzable. Median follow-up for levels I, II, III, IV, and V was 11.7, 10.4, 11.8, 10.4, and 9.2 years, respectively. Thirty-six percent of patients received NHT. The 5-year overall survival was 90%, 87%, 88%, 89%, and 88% for dose levels I-V, respectively. The 5-year clinical disease-free survival (excluding protocol prostate-specific antigen definition) for levels I-V is 84%, 78%, 81%, 82%, and 82%, respectively. By ASTRO definition, the 5-year disease-free survivals were 57%, 59%, 52%, 64% and 75% (low risk); 46%, 52%, 54%, 56%, and 63% (intermediate risk); and 50%, 34%, 46%, 34%, and 61% (high risk) for levels I-V, respectively. By the Phoenix definition, the 5-year disease-free survivals were 68%, 73%, 67%, 84%, and 80% (low risk); 70%, 62%, 70%, 74%, and 69% (intermediate risk); and 42%, 62%, 68%, 54%, and 67% (high risk) for levels I-V, respectively.

CONCLUSION

Dose-escalated 3D-CRT yields favorable outcomes for localized prostate cancer. This multi-institutional experience allows comparison to other experiences with modern radiation therapy.

Validating the interval to biochemical failure for the identification of potentially lethal prostate cancer

PURPOSE

To validate the interval to biochemical failure (IBF) as a prognostic factor at the time of biochemical failure for prostate cancer mortality (PCM) following radiotherapy (RT).

PATIENTS AND METHODS

From a collaborative data set of men with clinically localized prostate cancer treated with RT from four institutions in three countries, we identified 1,722 men with biochemical failure (BF; prostate-specific antigen nadir + 2 ng/mL). The IBF was defined as the time interval from completion of treatment to the date of BF. The primary outcome measure was discriminatory power in the form of the concordance index (c-index).

RESULTS

Seventeen percent of men had an IBF ≤ 18 months. Median potential follow-up beyond the time of BF was 67 months. There were 290 deaths from prostate cancer. The IBF was the most discriminating individual prognostic factor overall, with a sensitivity of IBF ≤ 18 months to predict PCM within 10 years of 48.4% (95% CI, 43.3% to 54.1%); the specificity was 86.1% (95% CI, 84.5% to 87.7%), equating to a c-index of 0.611 (95% CI, 0.578 to 0.647). The 5-year cumulative incidence of PCM for IBF more than 18 months versus IBF ≤ 18 months was 9.4% (95% CI, 7.7% to 11.5%) versus 26.3% (95% CI, 21.2% to 31.8%); corresponding 10-year estimates were 26.2% (95% CI, 21.5% to 30.8%) versus 55.9% (95% CI, 48.9% to 63.0%), respectively (P < .001 for both). IBF exhibited minimal change in performance across various follow-up durations.

CONCLUSION

IBF is the single most robust prognostic factor for PCM following RT without androgen deprivation therapy. This external validation demonstrates that patients and clinicians can use this information to make decisions about subsequent treatments.

PKA knockdown enhances cell killing in response to radiation and androgen deprivation

The therapeutic efficacy of Gem®231, a second generation antisense molecule targeted to the RIα subunit of PKA(RIα) (AS-PKA), administered in combination with androgen deprivation (AD) and radiation therapy (RT), was examined in androgen sensitive (LNCaP) and insensitive (PC3) cell lines. Apoptosis was assayed by Caspase 3 + 7 activity and Annexin V binding. AS-PKA significantly increased apoptosis in vitro from RT (both lines), with further increases in LNCaP cells grown in AD medium. In LNCaP cells, AD increased phosphorylated mitogen activated protein-kinase (pMAPK), which was reduced by AS-PKA relative to the mismatch (MM) controls. AS-PKA also reduced pMAPK levels in PC3 cells. Cell death was measured by clonogenic survival assays. In vivo, LNCaP cells were grown orthotopically in nude mice. Tumor kinetics were measured by magnetic resonance imaging and serum prostate-specific antigen. PC3 cells were grown subcutaneously and tumor volume assessed by caliper measurements. In PC3 xenografts, AS-PKA caused a significant increase in tumor doubling time relative to MM controls as a monotherapy or in combination with RT. In orthotopic LNCaP tumors, AS-PKA was ineffective as a monotherapy; however, it caused a statistically significant increase in tumor doubling time relative to MM controls when used in combination with AD, with or without RT. PKA(RIα) levels in tumors were quantified via immunohistochemical (IHC) staining and image analysis. IHC measurements in LNCaP cells exhibited that AS-PKA reduced PKA(RIα) levels in vivo. We demonstrate for the first time that AS-PKA enhances cell killing androgen sensitive prostate cancer cells to AD ± RT and androgen insensitive cells to RT.

Assessment of response to radiotherapy for prostate cancer: value of diffusion-weighted MRI at 3 T

OBJECTIVE

The objective of our study was to investigate the changes of apparent diffusion coefficient (ADC) values in prostate cancers before and after radiotherapy at 3 T using a phased-array coil.

MATERIALS AND METHODS

Forty-nine patients with biopsy-proven prostate cancer who received radiotherapy underwent diffusion-weighted imaging (DWI) at 3 T and were included in the study. Biopsies in all patients were performed before the initial MRI examination (range, 15-35 days before MRI; mean, 23.4 days). All 49 patients underwent DWI (b values = 0 and 1,000 s/mm(2)) before and 1-5 months after the completion of radiotherapy. The changes in ADC values were measured for cancers and benign tissues before and after therapy. Additionally, the changes in serum prostate-specific antigen (PSA) levels were evaluated before and after therapy.

RESULTS

A total of 57 cancers (peripheral zone, n = 45; transition zone, n = 12) were found in 46 patients. For the tumors, the mean ADC value after therapy (1.61 x 10(-3) mm(2)/s) was increased compared with the mean ADC value before therapy (1.0 x 10(-3) mm(2)/s) (p < 0.001). After radiotherapy, the mean ADC values of benign peripheral zones and of benign transition zones were statistically significantly decreased compared with those before radiotherapy (p < 0.05). Before treatment, a significant difference of ADC values between the tumors and benign tissues was found (p < 0.001), whereas there was no significant difference of ADC values between them after treatment (p > 0.1). The median PSA level after therapy (0.49 ng/mL) was decreased compared with the median PSA level before therapy (20.0 ng/mL).

CONCLUSION

With the use of a 3-T MR scanner, our preliminary results suggest that ADC values may be useful as an imaging biomarker for monitoring therapeutic response of prostate cancer to radiotherapy.

Predictors of androgen deprivation therapy efficacy combined with prostatic irradiation: the central role of tumor stage and radiation dose

PURPOSE

To evaluate the response of clinically localized prostate cancer to various durations of planned androgen deprivation therapy (ADT) and to investigate subgroups predicting response.

METHODS AND MATERIALS

Data of 3,666 prostate cancer patients treated with either combined ADT and external beam radiotherapy (EBRT) or EBRT alone at four institutions were examined. ADT consisted of neoadjuvant, concurrent, or adjuvant ADT or combinations of these regimens. The primary endpoint was time to biochemical failure (nadir plus 2 ng/ml), assessed from the end of therapy. Factors predictive for the need for ADT were examined with interaction analyses.

RESULTS

The impact of increasing ADT duration was nonlinear with, on average, 6 months of adjuvant ADT resulting in a reduction of the risk of biochemical failure by 38% (95% confidence interval [CI], 29%-46%), while 12, 24, and 36 months of ADT resulted in a 58% (95% CI, 47%-67%), 66% (95% CI, 55%-75%), and 66% (95% CI, 51%-77%) relative failure reduction, respectively. Patients with higher T stage cancers and those treated with lower radiation doses had a significantly greater benefit for increasing ADT duration (interaction, p=0.016 and p=0.007, respectively). Pretreatment prostate-specific antigen values, Gleason score, age, and risk group did not modify the response to ADT.

CONCLUSIONS

The known ADT efficacy derived from randomized studies can be generalized to patients with different features, and individual predictions of potential benefit from ADT use and duration may be calculated to aid patient and physician decision making. Tumor stage and radiation dose variations were related to significantly different ADT duration effects. The validity of these predictive factors requires prospective evaluation.

[Prostate specific antigen: utilization modalities and interpretation]

The prostate specific antigen test has become one of the most popular blood test. However, its result should be analyzed with caution due to physiologic variability. The PSA test is performed for prostate cancer (PC) screening or for post-treatment PC surveillance. According to the applied treatment (surgery or radiation therapy with or without hormonal therapy), PSA analysis can confirm biochemical control or relapse. New PSA data regarding the evolution of this biomarker during the surveillance (PSA doubling time and PSA velocity) are now important to consider in case of biochemical relapse.

Update of Dutch multicenter dose-escalation trial of radiotherapy for localized prostate cancer

PURPOSE

To update the analysis of the Dutch dose-escalation trial of radiotherapy for prostate cancer.

PATIENTS AND METHODS

A total of 669 patients with localized prostate cancer were randomly assigned to receive 68 or 78 Gy. The patients were stratified by age, institution, use of neoadjuvant or adjuvant hormonal therapy, and treatment group. The primary endpoint was freedom from failure (FFF), with failure defined as clinical or biochemical failure. Two definitions of biochemical failure were used: the American Society for Therapeutic Radiology and Oncology definition (three consecutive increases in prostate-specific antigen level) and the Phoenix definition (nadir plus 2 microe secondary endpoints were freedom from clinical failure, overall survival, and genitourinary and gastrointestinal toxicity.

RESULTS

After a median follow-up of 70 months, the FFF using the American Society for Therapeutic Radiology and Oncology definition was significantly better in the 78-Gy arm than in the 68-Gy arm (7-year FFF rate, 54% vs. 47%, respectively; p = 0.04). The FFF using the Phoenix definition was also significantly better in the 78-Gy arm than in the 68-Gy arm (7-year FFF rate, 56% vs. 45%, respectively; p = 0.03). However, no differences in freedom from clinical failure or overall survival were observed. The incidence of late Grade 2 or greater genitourinary toxicity was similar in both arms (40% and 41% at 7 years; p = 0.6). However, the cumulative incidence of late Grade 2 or greater gastrointestinal toxicity was increased in the 78-Gy arm compared with the 68-Gy arm (35% vs. 25% at 7 years; p = 0.04).

CONCLUSION

The results of our study have shown a statistically significant improvement in FFF in prostate cancer patients treated with 78 Gy but with a greater rate of late gastrointestinal toxicity.

Post-treatment prostate biopsies in the era of three-dimensional conformal radiotherapy: what can they teach us?

BACKGROUND

The ability to discriminate between therapeutic success and failure after radiotherapy (RT) for prostate cancer (PCa) remains a clinical challenge. Post-treatment biopsies would seem ideal for evaluating innovations such as dose escalation protocols or combination treatments involving brachytherapy or hormones.

OBJECTIVE

Correlate post-treatment biopsy results with prostate-specific antigen (PSA) and clinical outcome in PCa patients treated with three-dimensional conformal radiotherapy (3DCRT) in a dose-escalation study.

DESIGN, SETTING, AND PARTICIPANTS

This study included 160 patients with clinical stage T1c to T3b PCa treated between 1995 and 2005 in Hospital Universitario la Princesa with 3DCRT who consented to and underwent a transrectal ultrasound (TRUS)-guided prostate biopsy 24-36 mo after RT. The median follow-up was 78 mo (range 27-171 mo).

INTERVENTION

The median radiation dose was 74 gray (Gy; range 66.0-84.1). Risk-adapted short-term androgen deprivation (STAD) and long-term androgen deprivation (LTAD) were associated in 25 and 106 patients, respectively. Right and left systematic biopsies were carried out by the same urologist and were examined by a genitourinary pathologist.

MEASUREMENTS

Biochemical disease-free survival (bDFS) according to American Society for Therapeutic Radiology and Oncology (ASTRO) 1997 and Phoenix definition criteria as well as histologic control using post-treatment prostate biopsies.

RESULTS

Twenty-one percent of patients (34 of 160) had post-treatment-positive biopsies (PB). The 5-yr bDFS according to the Phoenix definition was 87%, 65%, and 92% for the whole series (PB and negative biopsies [NB] patients, respectively [p<0.001]). Multivariate analysis showed that biopsy status at 24-36 mo was an independent predictor of bDFS (p<0.0005) and of clinical failure-free survival (p=0.043).

CONCLUSION

The results of the present study show a strong correlation between a post-treatment PB and the 5-yr probability of bDFS, confirming that PSA control can be an adequate surrogate for local control, as assessed by post-treatment biopsies.

The Phoenix definition of biochemical failure predicts for overall survival in patients with prostate cancer

BACKGROUND

The American Society for Therapeutic Radiology and Oncology (ASTRO) definition of biochemical failure (BF) incorporates backdating, resulting in an artificial flattening of Kaplan-Meier curves and overly favorable estimates when follow-up is short. The nadir + 2 ng/mL (Nadir + 2; Phoenix) definition reduces these artifacts. The objective of the current study was to compare ASTRO and Phoenix BF estimates as determinants of distant metastasis (DM), cause-specific mortality (CSM), and overall mortality (OM).

METHODS

A total of 1831 patients with T1-4N0M0 prostate cancer were treated with external beam radiotherapy (RT) using conventional or three-dimensional conformal methods to at least 60 grays (Gy). The median follow-up was 71 months and the median RT dose was 72 Gy (range, 60-79 Gy). Cox regression models incorporating BF as a time-dependent covariate were used for both univariate and multivariate analyses. Other covariates included in the analyses were T classification, Gleason score, neoadjuvant/adjuvant androgen deprivation, age, RT dose, and pretreatment prostate-specific antigen.

RESULTS

BF was observed in 389 men (21%) using the Phoenix definition and 460 men (25%) using the ASTRO definition. DM was observed in 84 patients (5%), 48 patients (3%) patients died of prostate cancer, and 404 patients (22%) died of any cause. The Phoenix definition of BF was found to be a significant predictor of DM, CSM, and OM, after controlling for other significant covariates. The ASTRO definition was found to be associated with CSM and DM, but not OM.

CONCLUSIONS

The Phoenix definition of BF is a more robust determinant of patient outcome compared with the ASTRO definition. The correlation with mortality, including OM, and the independence of this correlation from the use of neoadjuvant/adjuvant androgen deprivation, supports the use of Nadir + 2 in prostate cancer clinical trials of RT with or without androgen deprivation.

Evidence-based radiation oncology: Definitive, adjuvant and salvage radiotherapy for non-metastatic prostate cancer

The standard treatment options based on the risk category (stage, Gleason score, PSA) for localized prostate cancer include surgery, radiotherapy and watchful waiting. The literature does not provide clear-cut evidence for the superiority of surgery over radiotherapy, whereas both approaches differ in their side effects. The definitive external beam irradiation is frequently employed in stage T1b-T1c, T2 and T3 tumors. There is a pretty strong evidence that intermediate- and high-risk patients benefit from dose escalation. The latter requires reduction of the irradiated normal tissue (using 3-dimensional conformal approach, intensity modulated radiotherapy, image-guided radiotherapy, etc.). Recent data suggest that prostate cancer may benefit from hypofractionation due to relatively low alpha/beta ratio; these findings warrant confirmation though. The role of whole pelvis irradiation is still controversial. Numerous randomized trials demonstrated a clinical benefit in terms of biochemical control, local and distant control, and overall survival from the addition of androgen suppression to external beam radiotherapy in intermediate- and high-risk patients. These studies typically included locally advanced (T3-T4) and poor-prognosis (Gleason score >7 and/or PSA >20 ng/mL) tumors and employed neoadjuvant/concomitant/adjuvant androgen suppression rather than only adjuvant setting. The ongoing trials will hopefully further define the role of endocrine treatment in more favorable risk patients and in the setting of the dose escalated radiotherapy. Brachytherapy (BRT) with permanent implants may be offered to low-risk patients (cT1-T2a, Gleason score <7, or 3+4, PSA <or=10 ng/mL), with prostate volume of <or=50 ml, no previous transurethral prostate resection and a good urinary function. Some recent data suggest a benefit from combining external beam irradiation and BRT for intermediate-risk patients. EBRT after radical prostatectomy improves disease-free survival and biochemical and local control rates in patients with positive surgical margins or pT3 tumors. Salvage radiotherapy may be considered at the time of biochemical failure in previously non-irradiated patients.

Timing of biochemical failure and distant metastatic disease for low-, intermediate-, and high-risk prostate cancer after radiotherapy

BACKGROUND

The relation of prostate cancer risk-group stratification and the timing of biochemical failure (BF) and distant metastasis (DM) is not well defined. The authors hypothesized that early failures due to subclinical micrometastasis at presentation could be differentiated from late failures due to local persistence.

METHODS

A total of 1833 men with clinically localized prostate cancer treated with 3D-conformal radiotherapy with or without short-term androgen deprivation were retrospectively analyzed. By using American Society for Therapeutic Radiology and Oncology (ASTRO) and Phoenix (Nadir+2) definitions (developed at the ASTRO-RTOG [Radiation Therapy Oncology Group] consensus meeting, Phoenix, Arizona, January 21, 2005), the interval hazard rates of BF and DM were determined for men with low-risk, intermediate-risk, and high-risk disease.

RESULTS

Median follow-up was 67 months. Multivariate analysis showed that increasing risk group was independently associated with higher ASTRO BF (P < .0001) and Nadir+2 BF (P < .0001). The preponderance (87%) of ASTRO BF occurred 4 years. The hazard of Nadir+2 BF persisted in Years 8-12 in all risk groups. The interval hazard function for DM appeared to be biphasic (early peak followed by a drop and late increase) for intermediate-risk and high-risk patients, but no distinct early wave was evident for low-risk patients.

CONCLUSIONS

Because of backdating, ASTRO BF underestimates late BF. Local persistence of disease is suggested by delayed Nadir+2 BF and subsequent late DM in every risk group. The paucity of early DM among those with low-risk tumors supports the hypothesis that occult micrometastases contributed to the early wave.

An update of the phase III trial comparing whole pelvic to prostate only radiotherapy and neoadjuvant to adjuvant total androgen suppression: updated analysis of RTOG 94-13, with emphasis on unexpected hormone/radiation interactions

PURPOSE

This trial was designed to test the hypothesis that total androgen suppression and whole pelvic radiotherapy (WPRT) followed by a prostate boost improves progression-free survival (PFS) by > or =10% compared with total androgen suppression and prostate only RT (PORT). This trial was also designed to test the hypothesis that neoadjuvant hormonal therapy (NHT) followed by concurrent total androgen suppression and RT improves PFS compared with RT followed by adjuvant hormonal therapy (AHT) by > or =10%.

METHODS AND MATERIALS

Patients eligible for the study included those with clinically localized adenocarcinoma of the prostate and an elevated prostate-specific antigen level of <100 ng/mL. Patients were stratified by T stage, prostate-specific antigen level, and Gleason score and were required to have an estimated risk of lymph node involvement of >15%.

RESULTS

The difference in overall survival for the four arms was statistically significant (p = 0.027). However, no statistically significant differences were found in PFS or overall survival between NHT vs. AHT and WPRT compared with PORT. A trend towards a difference was found in PFS (p = 0.065) in favor of the WPRT + NHT arm compared with the PORT + NHT and WPRT + AHT arms.

CONCLUSIONS

Unexpected interactions appear to exist between the timing of hormonal therapy and radiation field size for this patient population. Four Phase III trials have demonstrated better outcomes when NHT was combined with RT compared with RT alone. The Radiation Therapy Oncology Group 9413 trial results have demonstrated that when NHT is used in conjunction with RT, WPRT yields a better PFS than does PORT. It also showed that when NHT + WPRT results in better overall survival than does WPRT + short-term AHT. Additional studies are warranted to determine whether the failure to demonstrate an advantage for NHT + WPRT compared with PORT + AHT is chance or, more likely, reflects a previously unrecognized biologic phenomenon.

Prostate-specific antigen nadir within 12 months of prostate cancer radiotherapy predicts metastasis and death

BACKGROUND

The nadir prostate-specific antigen (PSA) at 1 year (nPSA12) was investigated as an early estimate of biochemical and clinical outcome after radiotherapy (RT) alone for localized prostate cancer.METHODS.From May 1989 to November 1999, 1000 men received 3D conformal RT alone (median, 76 Gy) with minimum and median follow-up periods of 26 and 58 months, respectively, from the end of treatment. The calculation of PSA doubling time (PSADT) was possible in 657 patients. Multivariate analyses (MVAs) via Cox proportional hazards regression were used to determine the association of nPSA12 to biochemical failure (BF; ASTRO definition), distant metastasis (DM), cause-specific mortality (CSM), and overall mortality (OM). Dichotomization of nPSA12 was optimized by evaluating the sequential model likelihood ratio and P-values.RESULTS.In MVA, nPSA12 as a continuous variable was independent of RT dose, T-stage, Gleason score, pretreatment initial PSA, age, and PSADT in predicting for BF, DM, CSM, and OM. Dichotomized nPSA12 (2 versus >2 ng/mL) was independently related to DM and CSM. Kaplan-Meier 10-year DM rates for nPSA12 2 versus >2 ng/mL were 4% versus 19% (P<.0001).CONCLUSIONS.nPSA12 is a strong independent predictor of outcome after RT alone for prostate cancer and should be useful in identifying patients at high risk for progression to metastasis and death.

Radiation dose and late failures in prostate cancer

PURPOSE

To quantify the impact of radiation dose escalation on the timing of biochemical failure (BF) and distant metastasis (DM) for prostate cancer treated with radiotherapy (RT) alone.

METHODS

The data from 667 men with clinically localized intermediate- and high-risk prostate cancer treated with three-dimensional conformal RT alone were retrospectively analyzed. The interval hazard rates of DM and BF, using the American Society for Therapeutic Radiology and Oncology (ASTRO) and Phoenix (nadir + 2) definitions, were determined. The median follow-up was 77 months.

RESULTS

Multivariate analysis showed that increasing radiation dose was independently associated with decreased ASTRO BF (p < 0.0001), nadir + 2 BF (p = 0.001), and DM (p = 0.006). The preponderance (85%) of ASTRO BF occurred at < or =4 years after RT, and nadir + 2 BF was more evenly spread throughout Years 1-10, with 55% of BF in < or =4 years. Radiation dose escalation caused a shift in the BF from earlier to later years. The interval hazard function for DM appeared to be biphasic (early and late peaks) overall and for the <74-Gy group. In patients receiving > or =74 Gy, a reduction occurred in the risk of DM in the early and late waves, although the late wave appeared reduced to a greater degree.

CONCLUSION

The ASTRO definition of BF systematically underestimated late BF because of backdating. Radiation dose escalation diminished and delayed BF; the delay suggested that local persistence may still be present in some patients. For DM, a greater radiation dose reduced the early and late waves, suggesting that persistence of local disease contributed to both.

Unification of a common biochemical failure definition for prostate cancer treated with brachytherapy or external beam radiotherapy with or without androgen deprivation

PURPOSE

Minimal data are available regarding selection of an optimal biochemical failure (BF) definition for patients treated with brachytherapy, external beam radiotherapy (EBRT), and combinations of these treatments with or without androgen deprivation (AD). We retrospectively analyzed our institution's experience treating localized prostate cancer in an attempt to determine a BF definition that could be applied for these various treatment modalities.

METHODS AND MATERIALS

A total of 2376 patients with clinical stage T1-T3 N0 M0 prostate cancer were treated with conventional dose (median, 66.6 Gy) EBRT (n = 1201), high-dose (median, 75.6 Gy) adaptive radiation therapy (n = 465), EBRT + high-dose-rate brachytherapy boost (n = 416), or brachytherapy alone (n = 294) between 1987 and 2003. A total of 496 patients (21%) received neoadjuvant AD with radiation therapy. There were 21924 posttreatment prostate-specific antigen (PSA) measurements. Multiple BF definitions were tested for their sensitivity, specificity, positive predictive value (+PV), and negative PV (-PV) in predicting subsequent clinical failure (CF) (any local failure or distant metastasis), overall survival (OS), and cause-specific survival (CSS). Median follow-up was 4.5 years. The date of BF was the date BF criteria were met (e.g., date of third rise).

RESULTS

A total of 290 patients (12%) experienced CF at a median interval of 3.6 years (range, 0.2-15.2 years). The 5- and 10-year CF rates were 12% and 26%, respectively. Three consecutive rises yielded a 46% sensitivity and 84% specificity for predicting CF. The 10-year CF for those 475 patients who experienced three rises (BF) was 37% vs. 17% for those patients who did not meet these criteria (biochemically controlled [BC]). For all patients, the following definitions were superior to three rises for predicting CF for both +PV, and -PV: n + 1 (> or =1 ng/mL above nadir), n + 2, n + 3, threshold 2 (any PSA > or =2.0 ng/mL at or after nadir), threshold 3, threshold 4, and threshold 5. For the subset of patients treated with EBRT alone, the n + k definitions and threshold k definitions maintained superior predictive capacity. However, the threshold k definitions seemed to maintain a slightly greater separation in 10-year CF rates (43% for BF vs. 13% for BC = 30% difference for threshold 3). Surprisingly, all definitions generally had better predictive capacity for those patients who received brachytherapy or neoadjuvant AD vs. EBRT alone. The endpoints appeared similar for n + 1 vs. threshold 3 and n + 2 vs. threshold 4 in EBRT alone patients, but for brachytherapy or neoadjuvant AD patients, there were similarities for n + 2 vs. threshold 3 and n + 3 vs. threshold 4. This may be a reflection of the lower nadir levels in patients receiving AD (median <0.1 ng/mL vs. 0.2 ng/mL for brachytherapy vs. 0.8 ng/mL for EBRT alone, p < 0.01). When examining CF correlation for the various classes of BF definitions, the threshold k definitions clearly demonstrated the greatest area under the receiver operating characteristic curve, followed by the n + k definitions. For OS, the threshold k definitions again demonstrated the greatest area under the curve, followed by definitions based on specific nadir cutoffs (nadir > or =k ng/mL).

CONCLUSIONS

Biochemical failure definitions applying a PSA threshold at or after the nadir (e.g., threshold 3) demonstrated the highest association with CF, OS, and CSS for all assessed treatment modalities. Definitions incorporating a PSA increase above the nadir value (e.g., nadir + 2 ng/mL) were also superior for all modalities. In general, BF definitions have greater predictive capacity for clinical outcome with brachytherapy or neoadjuvant AD than EBRT alone, possibly because of less "noise" from production of background PSA.

Radiation dose escalation combined with hormone therapy improves outcome in localised prostate cancer

We present the impact of systematic radiation dose escalation from 64 Gy to 66 Gy to 70 Gy on the outcome after radiation therapy (RT) alone or combined with hormonal treatment (HT) in a series of 494 consecutive localised prostate cancer patients treated during 1990-1999. Prognostic factors for prostate-specific antigen (PSA) failure, overall survival (OS) and prostate cancer specific survival (CSS) were investigated using multivariate analysis. T stage, pre-treatment PSA, grade, radiation dose and HT were found to be independent predictors of PSA failure. T stage, grade and HT were also independent predictors of both OS and CSS, while radiation dose was a significant predictor for OS and indicated a trend (p = 0.07) for CSS. A dose of 70 Gy combined with hormonal treatment improves PSA failure free survival and survival in localised prostate cancer compared with doses of 64-66 Gy.

Use of different definitions of biochemical failure after external beam radiotherapy changes conclusions about relative treatment efficacy for localized prostate cancer

OBJECTIVES

To report biochemical relapse-free survival (bRFS) after radiotherapy (RT) for localized prostate cancer with two separate failure definitions and compare the results with those after radical prostatectomy (RP).

METHODS

The study sample comprised 2516 patients with a median follow-up of 78 months. Biochemical relapse after RT was defined as either the American Society for Therapeutic Radiology Oncology definition (definition A [DefA]) or a prostate-specific antigen elevation of more than 2 ng/mL greater than the nadir prostate-specific antigen level (definition N [DefN]). Failure after RP was defined as a prostate-specific antigen level greater than 0.2 ng/mL.

RESULTS

Compared with DefA, DefN resulted in a 13% greater bRFS rate at 5 years and a 12% lower bRFS rate at 10 years. On multivariate analysis, the treatment modality (RP versus RT) was a significant predictor of bRFS using DefA in favor of RP (P <0.001), but was not with DefN (P = 0.87). Higher radiation doses were independently associated with a better outcome with either definition.

CONCLUSIONS

Compared with DefA, DefN resulted in better outcomes for up to 7 years after RT, but worse outcomes thereafter. The use of DefA versus DefN resulted in opposite conclusions about the relative efficacies of RT and RP, with DefN suggesting RT is equivalent to RP and DefA that it is worse than RP. Different definitions of biochemical failure after RT can result in differences in the conclusions about treatment efficacy in men with localized prostate cancer, thereby potentially affecting clinical decisions.

Comparison of biochemical failure definitions for permanent prostate brachytherapy

PURPOSE

To assess prostate-specific antigen (PSA) failure definitions for patients with Stage T1-T2 prostate cancer treated by permanent prostate brachytherapy.

METHODS AND MATERIALS

A total of 2,693 patients treated with radioisotopic implant as solitary treatment for T1-T2 prostatic adenocarcinoma were studied. All patients had a pretreatment PSA, were treated at least 5 years before analysis, 1988 to 1998, and did not receive hormonal therapy before recurrence. Multiple PSA failure definitions were tested for their ability to predict clinical failure.

RESULTS

Definitions which determined failure by a certain increment of PSA rise above the lowest PSA level to date (nadir + x ng/mL) were more sensitive and specific than failure definitions based on PSA doubling time or a certain number of PSA rises. The sensitivity and specificity for the nadir + 2 definition were 72% and 83%, vs. 51% and 81% for 3 PSA rises. The surgical type definitions (PSA exceeding an absolute value) could match this sensitivity and specificity but only when failure was defined as exceeding a PSA level in the 1-3 ng/mL range and only when patients were allowed adequate time to nadir. When failure definitions were compared by time varying covariate regression analysis, nadir + 2 ng/mL retained the best fit.

CONCLUSIONS

For patients treated by permanent radioisotopic implant for prostate cancer, the definition nadir + 2 ng/mL provides the best surrogate for failure throughout the entire follow-up period, similar to patients treated by external beam radiotherapy. Therefore, the same PSA failure definition could be used for both modalities. For brachytherapy patients with long-term follow-up, at least 6 years, defining failure as exceeding an absolute PSA level in the 0.5 ng/mL range may be reasonable.

A multicenter study demonstrating discordant results from electronic prostate-specific antigen biochemical failure calculation systems

PURPOSE

To evaluate the interobserver variation of four electronic biochemical failure (bF) calculators using three bF definitions.

METHODS AND MATERIALS

The data of 1200 men were analyzed using the electronic bF calculators of four institutions. Three bF definitions were examined for their concordance of bF identification across the centers: the American Society for Therapeutic Radiology and Oncology consensus definition (ACD), the lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L2), and a threshold of 3 ng/mL (T3).

RESULTS

Unanimous agreement regarding bF status using the ACD, L2, and T3 definitions occurred in 87.3%, 96.4%, and 92.7% of cases, respectively. Using the ACD, 63% of the variation was from one institution, which allowed the bF status to be reversed if a PSA decline was seen after bF (PSA "bounce"). A total of 270 men had an ACD bF time variation of >2 months across the calculators, and the 5-year freedom from bF rate was 49.8-60.9%. The L2 definition had a 20.5% rate of calculated bF times; which varied by >2 months (median, 6.4; range, 2.1-75.6) and a corresponding 5-year freedom from bF rate of 55.9-61.0%. The T3 definition had a 2.0% range in the 5-year freedom from bF. Fifteen definition interpretation variations were identified.

CONCLUSION

Reported bF results vary not only because of bF definition differences, but because of variations in how those definitions are written into computer-based calculators, with multiple interpretations most prevalent for the ACD. An algorithm to avoid misinterpretations is proposed for the L2 definition. A verification system to guarantee consistent electronic bF results requires development.

The Effect of Age on Prostate Implantation Results

PURPOSE

The current study was undertaken to determine the effect of young age (60 years or younger) on the 5-year biochemical disease-free survival rate following ultrasound-guided transperineal prostate implantation.

PATIENTS AND METHODS

The radiation therapy charts of 330 patients who underwent ultrasound-guided transperineal prostate implantation who were treated from 1992 through 2004 were retrospectively reviewed. Follow-up ranged from 12 to 120 months, with a mean of 48 months. A total of 63 patients were 60 years of age or younger, and 267 patients were over 60 years of age. Prostate-specific antigen (PSA) recurrence was defined as three successive increases following ultrasound-guided transperineal prostate implantation. Biochemical disease-free survival was determined using the life-table method.

RESULTS

There were no statistically significant differences in the 5-year biochemical disease-free survival rates for the younger versus the older group. On univariate analysis, age was not a statistically significant factor in predicting PSA failure. Univariate analysis revealed that Gleason score, PSA at diagnosis, and clinical T stage were significant in predicting for PSA failure. Patients with Gleason score<7, PSA<10, and clinical stage T1c disease had statistically significant lower PSA failure rates than patients with Gleason score>or=7, PSA>or=10, and clinical stage T2 disease, respectively.

CONCLUSIONS

Patients who are 60 years of age or younger who are treated with ultrasound-guided transperineal prostate implantation can expect 5-year biochemical disease-free survival rates similar to those of older patients treated with ultrasound-guided transperineal prostate implantation therapy.

Outcome analysis of 300 prostate cancer patients treated with neoadjuvant androgen deprivation and hypofractionated radiotherapy

PURPOSE

Neoadjuvant androgen deprivation and radical radiotherapy is an established treatment for localized prostate carcinoma. This study sought to analyze the outcomes of patients treated with relatively low-dose hypofractionated radiotherapy.

METHODS AND MATERIALS

Three hundred patients with T1-T3 prostate cancer were treated between 1996 and 2001. Patients were prescribed 3 months of neoadjuvant androgen deprivation before receiving 5250 cGy in 20 fractions. Patients' case notes and the oncology database were used to retrospectively assess outcomes. Median follow-up was 58 months.

RESULTS

Patients presented with prostate cancer with poorer prognostic indicators than that reported in other series. At 5 years, the actuarial cause-specific survival rate was 83.2% and the prostate-specific antigen (PSA) relapse rate was 57.3%. Metastatic disease had developed in 23.4% of patients. PSA relapse continued to occur 5 years from treatment in all prognostic groups. Independent prognostic factors for relapse included treatment near the start of the study period, neoadjuvant oral anti-androgen monotherapy rather than neoadjuvant luteinizing hormone releasing hormone therapy, and diagnosis through transurethral resection of the prostate rather than transrectal ultrasound.

CONCLUSION

This is the largest reported series of patients treated with neoadjuvant androgen deprivation and hypofractionated radiotherapy in the United Kingdom. Neoadjuvant hormonal therapy did not appear to adequately compensate for the relatively low effective radiation dose used.

Dose-Response in Radiotherapy for Localized Prostate Cancer: Results of the Dutch Multicenter Randomized Phase III Trial Comparing 68 Gy of Radiotherapy With 78 Gy

Purpose

To determine whether a dose of 78 Gy improves outcome compared with a conventional dose of 68 Gy for prostate cancer patients treated with three-dimensional conformal radiotherapy.

Patients and Methods

Between June 1997 and February 2003, stage T1b-4 prostate cancer patients were enrolled onto a multicenter randomized trial comparing 68 Gy with 78 Gy. Patients were stratified by institution, age, (neo)adjuvant hormonal therapy (HT), and treatment group. Four treatment groups (with specific radiation volumes) were defined based on the probability of seminal vesicle involvement. The primary end point was freedom from failure (FFF). Failure was defined as clinical failure or biochemical failure, according to the American Society of Therapeutic Radiation Oncology definition. Other end points were freedom from clinical failure (FFCF), overall survival (OS), and toxicity.

Results

Median follow-up time was 51 months. Of the 669 enrolled patients, 664 were included in the analysis. HT was prescribed for 143 patients. FFF was significantly better in the 78-Gy arm compared with the 68-Gy arm (5-year FFF rate, 64% v 54%, respectively), with an adjusted hazard ratio of 0.74 (P = .02). No significant differences in FFCF or OS were seen between the treatment arms. There was no difference in late genitourinary toxicity of Radiation Therapy Oncology Group and European Organisation for Research and Treatment of Cancer grade 2 or more and a slightly higher nonsignificant incidence of late gastrointestinal toxicity of grade 2 or more.

Conclusion

This multicenter randomized trial shows a significantly improved FFF in prostate cancer patients treated with a higher dose of radiotherapy.

An international multicenter study evaluating the impact of an alternative biochemical failure definition on the judgment of prostate cancer risk

PURPOSE

To evaluate the impact of an alternative biochemical failure (bF) definition on the performance of existing plus de novo prognostic models.

METHODS AND MATERIALS

The outcomes data of 1,458 Australian and 703 Canadian men treated with external-beam radiation monotherapy between 1993 and 1997 were analyzed using a lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L + 2) bF definition. Two existing prognostic models were scrutinized using discrimination (Somers Dxy [SDxy]) and calibration indices. Alternative prognostic models were also created using recursive partitioning analysis (RPA) and multivariate nomogram methods for comparison.

RESULTS

Discrimination of bF was improved using the L + 2 definition compared with the American Society for Therapeutic Radiology and Oncology (ASTRO) definition using both the three-level risk model (SDxy 0.30 and 0.22, respectively) or the nomogram (SDxy 0.35 and 0.27, respectively). Both existing prognostic models showed only modest calibration accuracy. Using RPA, five distinct risk groups were identified based primarily on Gleason score (GS) and all subsequent divisions based on PSA. All GS 7-10 tumors were intermediate or high risk. This model and the developed nomogram showed improved discrimination over the existing models as well as accurate calibration against the Canadian data, apart from the 30-50% failure region.

CONCLUSIONS

The L + 2 definition of bF provides improved capacity for discrimination of failure risk. New prognostic models based on this endpoint have overall statistical performance superior to those based on the ASTRO consensus definition but continue to have unreliable discrimination in the intermediate-risk region.

Defining biochemical failure after radiotherapy with and without androgen deprivation for prostate cancer

PURPOSE

To compare several characteristics of alternative definitions of biochemical failure (BF) in men with extended follow-up after radiotherapy (RT) with or with androgen deprivation therapy (ADT) for prostate cancer.

METHODS AND MATERIALS

From December 1, 1991, to April 30, 1998, 688 men with Stage T1c-T3NX-N0M0 prostate cancer received RT alone (n = 586) or RT plus ADT (n = 102) with a minimal follow-up of 4 years and five or more "ADT-free" posttreatment prostate-specific antigen levels. BF was defined by three methods: (1) the ASTRO definition (three consecutive rises in prostate-specific antigen level); (2) a modified American Society for Therapeutic Radiology Oncology (ASTRO) definition requiring two additional consecutive rises when a decline immediately subsequent to three consecutive rises occurred; and (3) the "Houston" or nadir plus 2-ng/mL definition (a rise of at least 2 ng/mL greater than the nadir). The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy were determined for each using clinical progression as the endpoint. Furthermore, the misclassification rates for a steadily rising prostate-specific antigen level, ability to satisfy the proportional hazards (RT with or without ADT), effects of short follow-up, and intervals to the diagnosis of BF were compared.

RESULTS

The misclassification rate for BF using the nadir plus 2-ng/mL definition was 2% for RT alone and 0% for RT plus ADT compared with 0% and 0% for the modified ASTRO definition, and 5% and 23% for the ASTRO definition, respectively. The hazard rates for RT alone and RT plus ADT were proportional only for the nadir plus 2 ng/mL definition and seemingly unaffected by the length of follow-up. For RT with or without ADT, the nadir plus 2 ng/mL definition was the most specific (RT, 80% vs. RT plus ADT, 75%) with the greatest positive predictive value (RT, 36% vs. RT plus ADT, 25%) and overall accuracy (RT, 81% vs. RT plus ADT, 77%). A greater proportion of BF was diagnosed in the first 2 years of follow-up with the nadir plus 2 ng/mL definition compared with the ASTRO definition (13% vs. 5%, p = 0.0138, chi-square test).

CONCLUSION

The nadir plus 2 ng/mL definition was the best predictor of sustained, true, biochemical, and clinical failure, and was not affected by the use of ADT or follow-up length.

When Prostate Brachytherapy Fails: A Case Report and Discussion

For appropriately selected brachytherapy patients, prostate-specific antigen failure is uncommon. Our patient experienced biochemical failure after 125I brachytherapy treatment for low-risk prostate adenocarcinoma. We suggest neoadjuvant/adjuvant hormonal therapy combined with pelvic external-beam radiation therapy as a reasonable salvage treatment. At the 2-year follow-up, he is apparently doing well. With limited data available, salvage management for this situation is presently investigational.

Characterization of the behavior of three definitions of prostate-specific antigen-based biochemical failure in relation to detection and follow-up biases: comparison with the American Society for Therapeutic Radiology and Oncology consensus definition

PURPOSE

To examine the impact of detection biases on three prostate cancer biochemical failure (bF) definitions in comparison with the existing American Society for Therapeutic Radiology and Oncology Consensus Definition (ACD).

METHODS AND MATERIALS

Three alternative bF definitions were tested against the ACD: three rises in prostate-specific antigen (PSA) level without backdating, nadir plus 2 ng/mL, and a threshold PSA level of >3 ng/mL, according to data from 1050 men. The mean time between PSA tests (MTBT), regularity of collection, and calendar year of analysis were examined in each bF definition.

RESULTS

The MTBT produced a statistically significant difference in the derived hazard ratio for identification of bF in all definitions. The influence of test regularity was statistically significant beyond the median level of regularity in all definitions. The year of analysis impacted greatly on the ACD, whereas the three alternative definitions exhibited minor follow-up duration variations by comparison. The alternative definitions had reliable follow-up when the crude median time to censoring was at least 1.6 times greater than that of failure.

CONCLUSIONS

Detection biases will always be a significant issue in defining bF. A number of alternative failure definitions have more predictable interactions with these biases than the existing ACD.

PSA bounces after neoadjuvant androgen deprivation and external beam radiation: Impact on definitions of failure

PURPOSE

To determine the characteristics of prostate specific antigen (PSA) bounces after external beam radiation therapy (EBRT) with neoadjuvant androgen deprivation and their impact on definitions of biochemical failure.

METHODS AND MATERIALS

Characteristics of bounce were calculated for all patients treated by EBRT with neoadjuvant androgen deprivation at our institution between 1992 and 1998 (preexclusion analysis). Calculations were repeated for the subgroup that satisfied additional inclusion/exclusion criteria (postexclusion analysis). The percentage of bounces scoring as false positives according to the ASTRO definition of biochemical failure was compared with those for three alternative definitions (Vancouver, Nadir-plus-two, and Nadir-plus-three) using McNemar's tests.

RESULTS

Thirty-nine percent (preexclusion cohort) and 56% (postexclusion cohort) of patients demonstrated a PSA bounce. Twenty percent (preexclusion analysis) and 25% (postexclusion analysis) of these bounces scored as biochemical failure according to the ASTRO definition. The Nadir-plus-three definition scored the smallest percentage of bounces as failure, but the difference between this definition and the ASTRO definition reached statistical significance in neither preexclusion nor postexclusion analyses (p >/= 0.070).

CONCLUSIONS

A substantial proportion of patients treated by EBRT with neoadjuvant deprivation experienced a PSA bounce. A large percentage of these bounces scored as biochemical failure according to the ASTRO definition. The Nadir-plus-three definition is less vulnerable to this bias.

DEFINING RECURRENCE AFTER RADIATION FOR PROSTATE CANCER

PURPOSE

We reviewed prostate specific antigen (PSA) definitions of recurrence after external beam radiation for prostatic cancer and related them to the definitions used for other treatment modalities.

MATERIALS AND METHODS

The literature on defining recurrence after external beam radiation, brachytherapy and prostatectomy for prostate cancer was reviewed through a MEDLINE search to ensure completeness and the inclusion of all pertinent information.

RESULTS

Although the definition, which is the current standard for estimating recurrence after external beam radiation, has proved to be a reasonable measure, alternative options that are more sensitive and specific have now been defined. Similar statistical testing and comparison must also be done for other treatment modalities since the choice of failure definitions has not been evaluated nearly as thoroughly for these therapies. As much as possible, outcome reporting should be done according to the same method to ensure fairness when comparisons are made. However, inherent differences between treatment modalities and their effect on PSA production must also be considered.

CONCLUSIONS

With the latest available information from patients with long-term followup PSA definitions of tumor recurrence after external beam radiation for prostatic cancer must again be reviewed in a consensus conference format. The application of a universal PSA definition of tumor recurrence across multiple treatment modalities should also be explored.

LIMITATIONS IN THE USE OF SERUM PROSTATE SPECIFIC ANTIGEN LEVELS TO MONITOR PATIENTS AFTER TREATMENT FOR PROSTATE CANCER

PURPOSE

We reviewed the literature to help clarify the benefits and/or hazards associated with monitoring serum prostate specific antigen (PSA) after treatment with surgery or radiation therapy (RT) for nonmetastatic prostate cancer.

MATERIALS AND METHODS

A search was performed for 1990 to 2004 using the MEDLINE database, CancerLit database and reference lists of relevant studies to obtain articles addressing the use of serum PSA to follow patients after treatment for prostate cancer. Studies were reviewed to determine 1) if serial PSA monitoring provides an early and accurate surrogate assessment of cancer cure or treatment failure, 2) if any pattern in the PSA profile after treatment provides conclusive evidence of early local vs systemic failure, 3) the magnitude of the lead time to clinical failure that serial PSA monitoring may provide and 4) if the early identification of biochemical failure (BF) with earlier intervention improves outcome.

RESULTS

Although a lower PSA nadir after treatment with RT has been associated with cancer cure, 5% to 25% of patients ultimately have failure (beyond 5 years) even with the most optimal biochemical response. The most appropriate BF definitions to use after treatment for prostate cancer with RT remains controversial due to substantial differences in their accuracy, sensitivity, specificity and positive predictive value for clinical outcome. No pattern of PSA kinetics after treatment has conclusively been associated with a specific recurrence site. Biochemical failure definitions in patients treated with RT appear to provide a 6 to 18 month lead time to clinical failure but there are only limited published data to suggest that early intervention of any type (androgen deprivation, RT, surgery, etc) impacts survival.

CONCLUSIONS

The overall benefit of monitoring serum PSA after treatment for prostate cancer remains controversial. Considering the potential dangers associated with incorrectly assuming the efficacy of new forms of treatment, the toxicity of administering salvage therapies of uncertain efficacy after BF has been identified and the anxiety associated with tracking posttreatment serum PSA, additional studies must be done to determine the appropriate use of this marker in properly treating patients after therapy.

Definitions of biochemical failure that best predict clinical failure in patients with prostate cancer treated with external beam radiation alone: a multi-institutional pooled analysis

PURPOSE

Pooled data on 4,839 patients with T1-2 prostate cancer treated with external beam radiation therapy (RT) alone at 9 institutions have previously provided long-term biochemical failure (BF) and clinical outcomes using the American Society for Therapeutic Radiology and Oncology (ASTRO) definition. In this report we determined the sensitivity and specificity of several BF definitions using distant failure (DF) alone or clinical failure (CF), defined as local failure (LF) and/or DF.

MATERIALS AND METHODS

The pooled cohort was treated between 1986 and 1995 with external beam RT (60 Gy or greater) without pre-RT androgen suppression or planned post-RT adjuvant androgen suppression. Median followup was 6.3 years. The sensitivity and specificity of 102 definitions of BF relative to DF and LF were assessed.

RESULTS

The BF definitions with higher sensitivity and specificity than the ASTRO definition for DF only and CF are reported. The sensitivity and specificity of the ASTRO definition to predict DF alone was 55% and 68%, respectively. Three definitions had higher sensitivity and specificity, namely prostate specific antigen (PSA) greater than current nadir (lowest PSA prior to current measurement) plus 3 ng/ml (sensitivity 76% and specificity 72%), dated at the call (failure date as the date when the criterion was met), PSA greater than absolute nadir plus 2 ng/ml (sensitivity 72% and specificity 70%), dated at the call, or 2 consecutive increases of at least 0.5 ng/ml, back dated (sensitivity 69% and specificity 73%). The sensitivity and specificity of the ASTRO definition to predict CF was 60% and 72%, respectively. Three definitions had higher sensitivity and specificity, namely PSA greater than current nadir plus 3 ng/ml (sensitivity 66% and specificity 77%), dated at the call, PSA greater than absolute nadir plus 2 ng/ml (sensitivity 64% and specificity 74%), dated at the call, or 2 consecutive increases of at least 0.5 ng/ml, back dated (sensitivity 67% and specificity 78%).

CONCLUSIONS

Using what is to our knowledge the largest data set of patients with prostate cancer treated with RT alone we correlated multiple definitions of BF with the strict clinical end points of DF alone and CF (DF or local failure). Defining BF as PSA greater than absolute nadir plus 2 ng/ml, dated at the call, PSA greater than current nadir plus 3 ng/ml, dated at the call, or 2 consecutive increases of at least 0.5 ng/ml, back dated, had higher sensitivity and specificity for DF alone or CF compared with the ASTRO definition. This information should contribute to the discussion regarding suggested modifications to the ASTRO definition of biochemical failure.

Failure definition–dependent differences in outcome following radiation for localized prostate cancer: Can one size fit all?

PURPOSE

To compare long-term outcome using alternative failure definitions after external beam radiation for localized prostate cancer.

METHODS AND MATERIALS

Data from 4839 patients with stage T1b, T1c, and T2 adenocarcinoma of the prostate who were treated solely with external beam radiation between 1986 and 1995 at nine U.S. institutions were analyzed. Outcome using the following prostate-specific antigen (PSA) failure definitions was compared: (1) three consecutive PSA rises backdated (American Society for Therapeutic Radiology and Oncology [ASTRO]), (2) two PSA rises of at least 0.5 ng/mL each, backdated (0.5 x 2), (3) three consecutive PSA rises with failure recorded at the call date (ASTRO call date), (4) PSA > or =current PSA nadir + 2 ng/mL (Houston + 2), (5) PSA > or =current PSA nadir + 3 ng/mL (Houston + 3), (6) PSA >0.2 ng/mL, or (7) PSA >0.5 ng/mL. For definitions 3-7, the failure date was recorded as the date the criterion was met, without backdating.

RESULTS

PSA disease-free survival (PSA-DFS) varied according to the failure definition used with differences of up to 13% with PSA rise definitions and up to 44% with absolute nadir value surgical-type definitions within the first 5 years post-therapy as compared with the ASTRO definition. PSA-DFS was 66%, 66%, 68%, 72%, 15%, and 25% at 5 years postradiation for definitions 2-7, respectively, vs. 59% for the ASTRO definition. Sensitivity and specificity of definitions 2, 4, and 5 were better than for the ASTRO definition, whereas, for definitions 6 and 7, the sensitivity was at least 90% but the specificity was only 9% and 26%, respectively. This analysis shows that the ASTRO definition does not overestimate outcome, particularly in the first 5 years after therapy, as compared with other definitions appropriate to irradiated patients.

CONCLUSION

There are notable differences in both short- and long-term outcomes after definitive radiation for prostate cancer depending on the failure definition applied. Failure definitions must be tested objectively for sensitivity and specificity in predicting clinical outcome, and it is only in this manner that reasonable choices can be made. Although traditional surgical-type failure definitions do not seem applicable to patients treated with external beam radiation, further analysis of definitions across multiple therapeutic modalities is necessary to determine whether a universal failure definition might be feasible, at least for research and comparative purposes.

Undetectable prostate specific antigen at 6-12 months

BACKGROUND

The concept of a prostate-specific antigen (PSA) "nadir" has been used as a predictive marker for treatment success in patients treated with radiotherapy for localized prostate carcinoma. However, this approach is not applicable in patients who are concomitantly treated with short-term hormonal therapies. To address this, the authors sought to develop a new predictive marker in such patients after prostate brachytherapy (BT).

METHODS

Between March 1997 and November 2002, 194 men with clinical Stage T1A-T3N0M0 prostate carcinoma (according to the 1992 International Union Against Cancer/American Joint Committee on Cancer TNM classification system) were treated with interstitial palladium (103Pd3) BT and androgen ablation therapy with or without external beam radiotherapy (EBRT). Based on tumor characteristics, 127 patients received an antiandrogen, finasteride, and BT whereas 67 received an antiandrogen, leuprolide, and EBRT followed by a BT boost. Hormonal therapy was initiated 2-3 months before any radiotherapy for a total duration of 8-9 months. Follow-up included physical examination and determining the PSA level at 3-month intervals. Postoperative serum testosterone was evaluated in preoperatively potent patients with erectile dysfunction > 6 months after therapy. A PSA level < or = 0.06 ng/mL or < or = 0.20 ng/mL detected during a 6-12-month window after the implant were evaluated as predictors of biochemically disease-free survival (DFS), defined as the time to a PSA level > or = 1.0 ng/mL.

RESULTS

Of the 194 patients, 163 were available for analysis. The median length of follow-up was 48 months. In those patients with a PSA level < or = 0.20 ng/mL at 6-12 months, the DFS at 48 months after the implant was 96% (95% confidence interval [95% CI], 91-99%) compared with the remainder of the patients, whose DFS decreased to 80% (95% CI, 65-89%) (P < 0.001). When a PSA level < or = 0.06 ng/mL was used as an indicator, the 48-month DFS was 99% (95% CI, 91-100%) compared with that for patients with a PSA level > 0.06 ng/mL, in whom the DFS was 85% (95% CI, 74-92%) (P = 0.004). Furthermore, because testosterone levels may occasionally remain low after the cessation of luteinizing hormone-releasing hormone agonist therapy and result in erectile dysfunction and an artificially low PSA level, the authors reviewed the serum testosterone levels in 23 patients who were so treated and were experiencing erectile dysfunction. None had PSA values below the lower limit of normal.

CONCLUSIONS

A PSA level < or = 0.20 ng/mL or < or = 0.06 ng/mL measured at 6-12 months after BT appears to be a useful predictive marker for detecting early success in patients with prostate carcinoma who are treated with neoadjuvant androgen ablation and BT. These markers may be used to identify those patients who are at an increased risk of biochemical failure and may be useful in stratifying patients for closer follow-up, long-term adjuvant therapies, or clinical trials. A longer follow-up period will be needed to verify whether these are predictive of long-term cancer control.

PSA failure and the risk of death in prostate cancer patients treated with radiotherapy

PURPOSE

To determine the relationship between prostate-specific antigen (PSA) failure and cause-specific and overall survival in prostate cancer patients treated with radical radiotherapy.

METHODS AND MATERIALS

Patients with and without PSA failure were compared with respect to overall survival and cause-specific survival in a cohort of 1786 patients. The relationship between PSA failure and survival was further investigated among six subgroups defined by three tumor risk groups (high, intermediate, and low risk based on T stage, Gleason score, and presenting PSA) and two age groups (<75 years and >/=75 years).

RESULTS

The 5-year overall survival among patients who had PSA failure was 79.5% vs. 87.5% among patients who had not failed (p = 0.0003). The corresponding 5-year cause-specific survival was 84.4% vs. 99.0% (p <0.0001). When the six subgroups are considered separately, PSA failure was associated with a worse cause-specific survival in the groups with intermediate- and high-risk disease. PSA failure was only associated with a worse overall survival in one subgroup: patients younger than 75 with high-risk disease. Deaths from nonprostate causes made the survival curves of patients with and without PSA failure in the other subgroups almost identical.

CONCLUSION

PSA failure in prostate cancer patients treated with radiotherapy was associated with a poorer overall survival, which is seen mainly in younger patients with high-risk disease.

Both pretreatment prostate-specific antigen level and posttreatment biochemical failure are independent predictors of overall survival after radiotherapy for prostate cancer

PURPOSE

To assess the impact of pretreatment prognostic factors plus subsequent biochemical failure on overall survival after radiotherapy for prostate cancer.

METHODS AND MATERIALS

We analyzed the prostate-specific antigen (PSA) and survival records of 1571 men with clinically localized prostate cancer treated with external beam radiotherapy monotherapy at the former Queensland Radium Institute between 1990 and 1997. The pretreatment PSA level, biopsy Gleason score, clinical stage, patient age, and the development of biochemical failure were assessed in relationship to overall survival and cause-specific survival, using fixed, as well as time-dependent, statistics.

RESULTS

The median follow-up was 88.1 months (95 months for those still alive). The actuarial overall survival, cause-specific survival, and biochemical failure-free survival rate at 10 years was 61.1%, 80.9%, and 25.9% respectively. Cause-specific survival was independently influenced by the pretreatment PSA level, Gleason score, clinical stage, and the development of biochemical failure (relative risk, 19.1). Using the overall survival endpoint, multivariate analysis showed age, pretreatment PSA level, Gleason score, and biochemical failure (relative risk 1.27) to be statistically significant variables.

CONCLUSION

In addition to previously identified factors, the pretreatment PSA level and occurrence of biochemical failure after radiotherapy for prostate cancer are associated with an increased overall mortality risk. Both pretreatment PSA level and posttreatment biochemical failure are independent predictors of overall survival after radiotherapy for prostate cancer.

Potential survival advantage with early androgen deprivation for biochemical failure after external beam radiotherapy: The importance of accurately defining biochemical disease status

PURPOSE

We analyzed our experience treating localized prostate cancer to determine the impact of androgen deprivation (AD) on clinical outcome if administered at the time of isolated biochemical failure (BF) vs. after clinical failure (clinical failure), and the associated impact of various BF definitions.

METHODS

A total of 1,201 patients with stage T1-T3N0M0 prostate cancer were treated with external beam radiotherapy (EBRT) to a median dose of 66.6 Gy. Early AD was defined as administration of AD after BF, without evidence of clinical failure. Delayed AD was defined as administration of AD after clinical failure. Multiple BF definitions were tested for capacity to predict subsequent clinical failure. For each BF definition, outcome was compared for BF patients receiving early AD vs. no or delayed AD.

RESULTS

Five-year clinical failure (from date of BF) was 60% for patients who experienced a prostate-specific antigen rise to >/=3 ng/mL above nadir. For these patients, early AD was associated with decreased 5-year local failure (4% vs. 33%), distant metastasis (13% vs. 44%), cause-specific death (9% vs. 24%), and death due to any cause (32% vs. 48%), despite poorer prognostic factors in patients receiving early AD. On multivariate analysis, early AD remained independently significant for each of these end points.

CONCLUSION

The efficacy of AD after BF varies depending on the BF definition. When an optimal BF definition is applied, early AD decreases distant metastasis and improves survival. Prostate-specific antigen elevation to >/=2 or >/=3 ng/mL above nadir seems optimal in establishing clinically significant BF and the timing of AD intervention.

Clinical results of combined treatment conformal high-dose-rate iridium-192 brachytherapy and external beam radiotherapy using staging lymphadenectomy for localized prostate cancer

PURPOSE

To report the first long-term biochemical control rate of patients treated with two protocols using a combination of external beam radiotherapy (EBRT) and high-dose-rate (HDR) brachytherapy for localized prostate cancer in Japan.

METHODS AND MATERIALS

Between October 1997 and July 2001, 71 patients with localized prostatic adenocarcinoma were treated with a combination of EBRT and HDR brachytherapy. Patient age ranged from 58 to 81 years (mean 70.5). Of the 71 patients, 12, 41, and 18 had Stage T1c, T2, and T3, respectively, according to the International Union Against Cancer classification system (1997). The mean initial prostate-specific antigen (PSA) level was 24.2 ng/mL (median, 11.9 ng/mL); 30% of the patients had an initial PSA level >20 ng/mL. Of the 71 patients, 31 had received neoadjuvant hormonal therapy. Hormonal therapy before treatment was stopped at the beginning of RT in all cases. Patients in this series were treated on two protocols. In the initial protocol, patients were treated with whole pelvis EBRT to 45.0 Gy in 25 fractions and three HDR fractions of 5.5 Gy each (35 patients). In the second protocol, patients were treated with prostatic EBRT to 41.8 Gy in 19 fractions, with an added staging lymphadenectomy to rule out lymph node metastasis for patients with high-risk factors, and four HDR fractions of 5.5 Gy each (36 patients). The American Society for Therapeutic Radiology and Oncology consensus definition for biochemical failure was used. Acute and chronic toxicities were scored using the Radiation Therapy Oncology Group guidelines. Follow-up ranged from 24 to 65 months (median, 44 months).

RESULTS

Of the 71 patients, 69 were alive at the last follow-up. Two patients had died of hepatocellular carcinoma and gastric cancer at 3.5 and 4.0 years after treatment with no biochemical failure. Sixty-six patients (93%), including the two who had died of intercurrent disease, showed a tendency for a PSA decline after treatment and had no biochemical or clinical evidence of disease at the last follow-up visit. Sixty patients (85%) achieved PSA nadir levels of < or =1.0 ng/mL. The biochemical/clinical failure-free control rate at 3 and at 5 years was 93% and 93%, respectively. The bladder and rectal complications were minimal.

CONCLUSION

Despite the high frequency of high-risk patients in the present patient population, the actuarial biochemical control rate was 93% at 5 years. Acute and chronic toxicity with this method was acceptable. Additional long-term follow-up is required to assess this treatment, because the median survival is not likely to be reached for several years.

LDR vs. HDR brachytherapy for localized prostate cancer: the view from radiobiological models

PURPOSE

Permanent LDR brachytherapy and temporary HDR brachytherapy are competitive techniques for clinically localized prostate radiotherapy. Although a randomized trial will likely never be conducted comparing these two forms of brachytherapy, a comparative radiobiological modeling analysis proves useful in understanding some of their intrinsic differences, several of which could be exploited to improve outcomes.

METHODS AND MATERIALS

Radiobiological models based upon the linear quadratic equations are presented for fractionated external beam, fractionated (192)Ir HDR brachytherapy, and (125)I and (103)Pd LDR brachytherapy. These models incorporate the dose heterogeneities present in brachytherapy based upon patient-derived dose volume histograms (DVH) as well as tumor doubling times and repair kinetics. Radiobiological parameters are normalized to correspond to three accepted clinical risk factors based upon T-stage, PSA, and Gleason score to compare models with clinical series. Tumor control probabilities (TCP) for LDR and HDR brachytherapy (as monotherapy or combined with external beam) are compared with clinical bNED survival rates. Predictions are made for dose escalation with HDR brachytherapy regimens.

RESULTS

Model predictions for dose escalation with external beam agree with clinical data and validate the models and their underlying assumptions. Both LDR and HDR brachytherapy achieve superior tumor control when compared with external beam at conventional doses (<70 Gy), but similar to results from dose escalation series. LDR brachytherapy as boost achieves superior tumor control than when used as monotherapy. Stage for stage, both LDR and current HDR regimens achieve similar tumor control rates, in agreement with current clinical data. HDR monotherapy with large-dose fraction sizes might achieve superior tumor control compared with LDR, especially if prostate cancer possesses a high sensitivity to dose fractionation (i.e., if the alpha/beta ratio is low).

CONCLUSIONS

Radiobiological models support the current clinical evidence for equivalent outcomes in localized prostate cancer with either LDR or HDR brachytherapy using current dose regimens. However, HDR brachytherapy dose escalation regimens might be able to achieve higher biologically effective doses of irradiation in comparison to LDR, and hence improved outcomes. This advantage over LDR would be amplified should prostate cancer possess a high sensitivity to dose fractionation (i.e., a low alpha/beta ratio) as the current evidence suggests.

Analysis of Prostate-Specific Antigen Rebound Interval in Patients with Prostate Cancer Receiving Hormonal Therapy and External-Beam Radiation Therapy

The goal of this investigation is to characterize the clinical significance of the rebound interval (RI) after neoadjuvant short-course hormonal therapy (HT) and external-beam radiation therapy (RT), during which the prostate-specific antigen (PSA) may rise because of hormone withdrawal prior to full RT efficacy. The charts of 257 consecutive patients with localized prostate cancer who received short-course neoadjuvant HT and RT were reviewed. A piecewise-linear log PSA versus time curve was generated for each patient and averaged over the population to facilitate identification of the RI start and end dates. Existing definitions of biochemical failure--American Society for Therapeutic Radiology and Oncology (ASTRO), Vancouver and Houston--were applied, as were these same definitions modified to exclude failures during the RI. Sensitivity and specificity were analyzed, using no evidence (by digital rectal examination or radiology) of disease failure as the gold standard. The 5-year biochemical survival with different failure definitions were ASTRO versus ASTRO-modified: 81.6% versus 86.7%; Houston versus Houston-modified: 71.4% versus 76.7%; and Vancouver versus Vancouver-modified: 83.5% versus 85.6%. The sensitivity and specificity comparisons were ASTRO versus ASTRO-modified 58.3% versus 33.3%; 91.4% versus 94.3%, Vancouver versus Vancouver-modified: 50% versus 50%; 92.7% versus 95.5%, Houston versus Houston-modified: 100% versus 66.7%; 90.6% versus 92.2%. The RI after HT and RT is likely not merely an artifact of hormone withdrawal but is correlated with ultimate clinical outcome. Excluding RI failures can marginally improve specificity but may possibly have an unacceptable risk of lowering sensitivity. Further work is needed to design and validate definitions of failure, which account for the RI.

Iodine 125 Versus Palladium 103 Implants for Prostate Cancer

PURPOSE

The purpose of this study was to evaluate the clinical outcomes and compare complication rates for patients with prostate cancer treated with iodine 125 ((125)I) and palladium 103 ((103)Pd) prostate brachytherapy at a single institution.

PATIENTS AND METHODS

Between 1992 and 2002, 272 patients with prostate cancer were treated with ultrasound-guided transperineal implantation incorporating (125)I (107 patients) or (103)Pd (165 patients). Three months of hormonal therapy was incorporated into the treatment program in 33% of the patients in both groups. Nineteen percent of those treated with (125)I were treated with a combination of implantation plus external-beam radiation therapy. Only 6% of the group receiving (103)Pd implants were treated with such a combination. For those treated with (125)I implantation alone, the minimum tumor dose was 145 Gy. The minimum tumor dose for those treated with (103)Pd alone was 125 Gy. Those treated with a combination of external-beam radiation therapy and (125)I received 45 Gy via 1.8-Gy fractions followed by implantation with a minimum tumor dose of 110 Gy. For those treated with external-beam radiation therapy and (103)Pd, the doses were 45 Gy via 1.8-Gy fractions followed by implantation with minimum tumor dose of 98 Gy. Outcomes were evaluated based on radionuclide used, T stage, Gleason score, prostate-specific antigen, and prognostic group. Complications were also evaluated for each radionuclide. The mean follow-up for the (125)I group was 55 months, and the range was 12-108 months. The mean follow-up for the (103)Pd group was 44 months, and the range was 12-72 months.

RESULTS

The 5-year biochemical disease-free survival rates for those in the favorable group (clinical stage T1c or T2, prostate-specific antigen level <10, Gleason score <7) were 92% for the (125)I group and 92% for the patients treated with (103)Pd. The 5-year disease-free survival rates for those in the intermediate and poor prognostic groups, which were combined, was 72% and 74%, respectively, for (125)I and (103)Pd. There was no statistically significant difference for either modality for any treatment group tested. In those treated with implantation alone, patients treated with (125)I had higher complication rates than those treated with (103)Pd (15% vs 4%). (125)I-treated patients had a grade 2 complication rate of 8% and a grade 3-4 complication rate of 7%, compared with 3% and 1%, respectively, for the (103)Pd-treated patients.

CONCLUSION

Despite the different management recommendations that evolved during the study period, the clinical outcome for patients treated with either radionuclide were similar with respect to biochemical disease-free survival. Although specific dosimetric comparisons are not valid given differences in imaging over the study course, the complication rate appears to be somewhat higher for (125)I, which is consistent with a radiobiologic model.

Ambiguities within the astro consensus definition of biochemical failure: never assume all is equal

PURPOSE

To quantitate the impact of a number of variables within the American Society of Therapeutic Radiology and Oncology consensus definition (ACD) of biochemical failure (bF) for prostate cancer.

METHODS AND MATERIALS

The prostate-specific antigen (PSA) data of 1050 men with prostatic adenocarcinoma treated between 1990 and 1997 with external beam radiotherapy monotherapy was examined. A total of 10,872 PSA results were examined for the effect of backdating, stable values, possible nadir date variations, assay resolution, and assay lower limit. Test timing was analyzed according to attendance frequency (mean time between tests [MTBT]) and regularity (using a derived "Irregularity Index" [II]).

RESULTS

Median biochemical follow-up was 76 months. Nadir date alterations varied the rate of bF beyond 5 years between 0.8% and 5.3%. The bF rate of all MTBT and II quartiles subgroups differed significantly except between the two most regular and the two most infrequent quartiles. Multivariate analysis showed PSA, MTBT, and II to be statistically significant independent predictors of bF (p < 0.0001 for all).

CONCLUSIONS

Many variables exist within the ACD that can produce inconsistencies in bF determination or alter the calculated date of bF. Detection bias issues, especially related to test timing, play a significant role in the derived outcomes.

Salvage prostatectomy in patients who have failed radiation therapy or cryotherapy as primary treatment for prostate cancer

Asymptomatic prostate-specific antigen (PSA) recurrence after radiation therapy for prostate carcinoma poses a diagnostic and therapeutic dilemma for clinicians. Patients with locally recurrent disease can consider treatment options of salvage surgery, cryotherapy, watchful waiting, or androgen deprivation. Of these options, only salvage surgery has been shown to result in long-term disease-free survival for selected patients. However, salvage surgery is associated with significant morbidity, including urinary incontinence and rectal injuries. Ideally, salvage surgery outcomes can be optimized with careful patient selection according to clinical stage, serum PSA levels before radiation and surgery, the medical condition of the patient, and clear expectations of the physician and patient. Among patients with locally recurrent disease, those with localized prostate carcinoma amenable to radical prostatectomy before radiation or cryotherapy would be the most suitable candidates for salvage surgery.

Comparison of alternative biochemical failure definitions based on clinical outcome in 4839 prostate cancer patients treated by external beam radiotherapy between 1986 and 1995

PURPOSE

To assess the merit of the American Society for Therapeutic Radiology and Oncology (ASTRO) definition of biochemical failure after external beam radiotherapy for prostate cancer by testing alternative prostate-specific antigen (PSA) failure definitions against the "gold standard" of clinical failure and to study the effect of backdating the time of failure.

METHODS AND MATERIALS

Nine participating institutions agreed to submit follow-up results for all patients with clinically localized prostatic cancer (Stage T1b, T1c, T2, N0M0) treated between 1986 and 1995 by external beam radiotherapy only, to doses of >or=60 Gy, with no androgen deprivation before treatment. A total of 4839 men met the study criteria, with a median follow-up time of 6.3 years. The prediction of clinical failure by 102 definitions of biochemical failure was assessed using various quantitative measures.

RESULTS

Four definitions were superior as measured by the sensitivity, specificity, positive and negative predictive values, and hazard of clinical failure after biochemical failure: two rises of at least 0.5 ng/mL backdated, PSA level at or greater than the absolute nadir plus 2 ng/mL at the call date, and PSA level at or greater than the current nadir plus 2 or 3 ng/mL at the call date. The absolute nadir was the lowest measured PSA level during all of follow-up, and the current nadir was the lowest PSA measured previous to a particular PSA measurement during follow-up. With the possible exception of patients in the low-risk group, the likelihood of ultimate clinical failure decreased as the time of biochemical failure increased. Failure definitions based on PSA levels >0.2 or 0.5 ng/mL were inferior to other definitions. Backdating the failure time introduced bias into the estimate of freedom from biochemical failure, which was increasingly overestimated at shorter median follow-up times. This bias can be circumvented either by using a failure definition based on the call date or by backdating the censoring times of patients with one or two rises who could potentially have failure at a future (unobserved) time. A short follow-up time as such does not result in bias unless the failures are backdated; in the absence of backdating, it is the precision of failure-free survival that is increasingly compromised as the follow-up time is reduced.

CONCLUSION

The ASTRO failure definition ended the confusion resulting from different failure definitions that had been in use, and it did so accurately enough that it is probably not necessary to recalculate previously published results. Nevertheless, for the current pooled analysis of outcome in 4839 men with a 6.3-year median follow-up, other definitions of biochemical failure were superior as assessed by various quantitative measures of concordance of biochemical and ultimate clinical failure. An additional disadvantage of the ASTRO definition is the bias introduced by backdating failures, as well as the necessarily retrospective nature of its application. Some "current" definitions, but not those based on the PSA level rising above a fixed threshold, have significantly higher sensitivity and specificity, do not lead to biased estimations of biochemical disease-free survival, and are directly applicable during patient counseling. These are all issues that would play a role in replacing the ASTRO consensus definition.