External beam radiotherapy dose response characteristics of 1127 men with prostate cancer treated in the PSA era

Value of 18F-fluorocholine PET/CT in predicting response to radical radiotherapy in patients with localized prostate cancer

PURPOSE

This study aims to establish whether metabolic parameters obtainable from FCH PET/CT can predict long-term response to radical radiotherapy (rRT) in patients with localized prostate cancer (PCa).

METHODS

Drawing on a single-center database, we retrospectively reviewed the pre-treatment FCH PET/CT scans of 50 patients who underwent rRT between 2012 and 2017. Patients were enrolled if they had a follow-up of at least 3 years after rRT. Various metabolic parameters were considered for each PET/CT, including FCH multifocality. rRT was administered to all patients for a total equivalent dose of 76-80 Gy, using a standard or hypofractionated schedule. Patients were classified as disease-free (DF) if their PSA levels after rRT rose by <2 ng/mL vis-à-vis their PSA nadir, or as not disease free (NDF) if their PSA levels rose by more than 2 ng/ml.

RESULTS

A multifocal FCH uptake in the prostate gland was identified in 27 patients (54%). At 3-year follow-up, 37 patients (74%) were judged DF, and 13 (26%) were NDF. The SUVmax and SUVmean, and the sum of the two values in all FCH foci in the prostate gland were significantly higher for NDF patients than for DF patients (all p < 0.005). The sum of the TLCKA levels in all FCH foci was likewise significantly higher in patients who were NDF than in those found DF (median 54.5 vs. 29.4; p < 0.05). At univariate analysis, the most of PET-metrics and Gleason Score were predictors of biochemical relapse after 3-year follow-up (all p < 0.05).

CONCLUSION

Higher SUVs seems predict a worse outcome for patients with multifocal intraprostatic lesions who are candidates for rRT.

Optimizing External Beam Radiotherapy as per the Risk Group of Localized Prostate Cancer: A Nationwide Multi-Institutional Study (KROG 18-15)

PURPOSE

This nationwide multi-institutional study analyzed the patterns of care and outcomes of external beam radiotherapy (EBRT) in localized prostate cancer patients. We compared various risk classification tools and assessed the need for refinements in current radiotherapy (RT) schemes.

METHODS AND MATERIALS

We included non-metastatic prostate cancer patients treated with primary EBRT from 2001 to 2015 in this study. Data of 1573 patients from 17 institutions were analyzed and re-grouped using a risk stratification tool with the highest predictive power for biochemical failure-free survival (BCFFS). We evaluated BCFFS, overall survival (OS), and toxicity rates.

RESULTS

With a median follow-up of 75 months, 5- and 10-year BCFFS rates were 82% and 60%, and 5- and 10-year OS rates were 95% and 83%, respectively. NCCN risk classification revealed the highest predictive power (AUC = 0.556, 95% CI 0.524-0.588; p < 0.001). Gleason score, iPSA < 12 ng/mL, intensity-modulated RT (IMRT), and ≥179 Gy1.5 (EQD2, 77 Gy) were independently significant for BCFFS (all p < 0.05). IMRT and ≥179 Gy1.5 were significant factors in the high-risk group, whereas ≥170 Gy1.5 (EQD2, 72 Gy) was significant in the intermediate-risk group and no significant impact of dose was observed in the low-risk group. Both BCFFS and OS improved significantly when ≥179 Gy1.5 was delivered using IMRT and hypofractionation in the high-risk group without increasing toxicities.

CONCLUSIONS

With NCCN risk classification, dose escalation with modern high-precision techniques might increase survivals in the high-risk group, but not in the low-risk group, although mature results of prospective studies are awaited.

Low-/high-dose-rate brachytherapy boost in patients with intermediate-risk prostate cancer treated with radiotherapy: long-term results from a single institution team experience

Purpose

To compare brachytherapy (BT) boost of low-dose-rate (LDR) and high-dose-rate (HDR) techniques in patients diagnosed with intermediate-risk prostate cancer.

Material and methods

Between January 2005 and February 2018, 142 patients (50 LDR and 92 HDR) with intermediate-risk prostate cancer were treated with a BT boost, and retrospectively analyzed. Prescribed dose was 45 Gy with external beam radiotherapy (EBRT) plus 100-108 Gy with LDR-BT, and 60 Gy with EBRT plus one fraction of 10 Gy with HDR-BT. 99% of patients received androgen deprivation therapy (ADT) for 6 months. Primary endpoint was to compare LDR and HDR boosts in terms of biochemical progression-free survival (bPFS). Secondary endpoint, after re-classifying patients into "favorable" and "unfavorable" sub-groups, was to analyze differences with a similar treatment intensity.

Results

Median overall follow-up for the total cohort was 66.5 months (range, 16-185 months). There were no significant differences in bPFS, overall survival, cause specific survival, local failure, lymph node failure, or distant failure when LDR or HDR was employed. bPFS at 90 months was 100% for favorable, and 89% and 85% for unfavorable patients at 60 months and 90 months, respectively (log-rank test, p = 0.017). The crude incidence of genitourinary acute and chronic toxicity grade 3 was 0.7% and 4%, respectively. Twelve patients (8%) had chronic rectal hemorrhage grade 2, in whom argon was applied (4 LDR and 8 HDR).

Conclusions

Combined treatment is an excellent therapeutic option in patients with intermediate-risk prostate carcinoma, with similar results in both LDR and HDR approaches and very low toxicities. Importantly, the current literature has indicated that unfavorable-risk patients belong to a different category, and should be treated as patients with high-risk factors. Therefore, the stratification and identification of both risk groups is extremely relevant.

Dose Escalation for Prostate Adenocarcinoma: A Long-Term Update on the Outcomes of a Phase 3, Single Institution Randomized Clinical Trial

PURPOSE

To determine the long-term outcomes for prostate adenocarcinoma when escalating radiation dose from 70 Gy to 78 Gy.

METHODS AND MATERIALS

Between 1993 and 1998, 301 patients with biopsy-proven clinical stage T1b-T3 prostate adenocarcinoma, any prostate-specific antigen level, and any Gleason score were randomized to 70 Gy in 35 fractions versus 78 Gy in 39 fractions of photon radiation therapy using a 4-field box technique without hormone deprivation therapy. The primary outcome was powered to detect a 15% difference in biochemical or clinical failure. Secondary outcomes included survival, prostate cancer mortality, biochemical failure, local failure, nodal failure, distant failure, and secondary malignancy rates.

RESULTS

With a median follow-up of 14.3 years, the cumulative incidence of 15-year biochemical or clinical failure was 18.9% versus 12.0% in the 70 Gy versus 78 Gy arms, respectively (subhazard ratio [sHR], 0.61; 95% confidence interval [CI], 0.38-0.98; Fine-Gray P = .042). The 15-year cumulative incidence of distant metastasis was 3.4% versus 1.1%, respectively (sHR, 0.33; 95% CI, 0.13-0.82; Fine-Gray P = .018). The 15-year cumulative incidence of prostate cancer-specific mortality was 6.2% versus 3.2%, respectively, (sHR, 0.52; 95% CI, 0.27-0.98; Fine-Gray P = .045). There were no differences in overall survival (HR, 1.10; 95% CI, 0.84-1.45; log rank P = .469) or other-cause survival (sHR, 1.33; 95% CI, 0.99-1.79; Fine-Gray P = .061). Salvage therapy was more common in the 70 Gy arm, at 38.7% versus 21.9% in the 78 Gy arm (P = .002). There was a 2.3% secondary solid malignancy rate (1 bladder, 6 rectal) within the radiation treatment field, which was not significantly different between treatment arms.

CONCLUSIONS

Dose escalation by 8 Gy (78 Gy vs 70 Gy) provided a sustained improvement in biochemical and clinical failure, which translated into lower salvage rates and improved prostate cancer-specific mortality, but not overall survival. Long-term follow-up demonstrated a low incidence of potential solid tumor secondary malignancies.

Three-Dimensional Conformal External Beam Radiotherapy versus the Combination of External Radiotherapy with High-Dose Rate Brachytherapy in Localized Carcinoma of the Prostate: Comparison of Acute Toxicity

Aims and background

Radiotherapy represents one of the basic therapeutic methods in treatment of localized carcinoma of the prostate. Optimal irradiation dose is the cornerstone of a successful treatment. Along with local control of the disease and overall survival of the patient, possible acute and long-term side effects need to be monitored very closely.

Methods

A non-randomized prospective study comparing the acute genitourinary and gastrointestinal toxicity in patients irradiated for localized carcinoma of the prostate. Fifty-seven patients were treated with three-dimensional conformal external beam radiotherapy alone, and in the second treatment arm a combination of external beam radiotherapy and high-dose rate brachytherapy was employed in 40 patients.

Results

Three-dimensional conformai external beam radiotherapy. Acute G1 genitourinary toxicity was recorded in 35.1% of patients, G2 in 22.8%, and G2-3 in one patient (1.7%). Acute gastrointestinal toxicity was experienced by 54.4% of patients, G1 in 28.1%, G2 in 17.5%, and G3 in 8.8%. Three-dimensional conformal external beam radiotherapy + brachytherapy. Acute G1 genitourinary toxicity was recorded in 37.5% and grade 2 in 15% of the patients. Only G1 acute gastrointestinal toxicity was recorded in 40% of the patients.

Conclusions

Acute G1 genitourinary toxicity was experienced by a similar percentage of patients in both treatment arms. Acute G2 genitourinary toxicity was more frequent in the three-dimensional conformal radiotherapy arm. Higher acute genitourinary toxicity, G3 or G4, was recorded only in one patient per treatment arm. Acute gastrointestinal toxicity was more frequent in the three-dimensional conformal radiotherapy arm. Higher acute gastrointestinal toxicity, G2 and G3, was only observed in the three-dimensional conformal radiotherapy arm. The acute toxicity observed was of a low grade. The combination of external beam radiotherapy with brachytherapy resulted in a lower incidence of gastrointestinal toxicity than external beam radiotherapy alone.

Localized prostate cancer treated with external beam radiation therapy: Long-term outcomes at a European comprehensive cancer centre

AIMS AND BACKGROUND

To present survival and toxicity outcomes in patients with clinically localized, non-metastatic prostate cancer (PCa) treated with external beam radiotherapy (EBRT) combined with androgen deprivation therapy (ADT).

MATERIALS AND METHODS

Retrospective study of 849 PCa patients (pts) treated from 1996 to 2005. Until August 2000, all patients (281) were treated with conventional dose EBRT (<76 Gy); subsequent pts received ≥76 Gy (565 pts). Median age was 70 years (range, 39-82). Most pts were intermediate (353; 42.8%) or high-risk (344; 41.7%). Mean PSA was 10.1 ng/ml. Median dose to the prostate was 75 Gy. Complete ADT was administered to 525 pts (61.8%).

RESULTS

Median follow-up was 109.6 months (range, 68.3-193.4). Overall survival (OS) was 92.5% and 81.1% at 5 and 10 years; by risk group (low, intermediate, high), 5- and 10-year OS rates were 94.3% and 85.9%, 92.3% and 79.2%, and 91.9% and 80.2% (p = 0.728). Five- and 10-year BRFS was 94.1% and 80.6% (low risk), 86.4% and 70.9% (intermediate), and 85.2% and 71.4% (high) (p = 0.0666). Toxicity included rectitis: grade 1 (G1) (277 pts; 32.6%), G2 (108; 12.7%), and G3 (20; 2.6%) and urethritis: G1 (294; 34.6%); G2 (223; 26.2%), and G3 (11; 1.3%). By dose rate (<76 Gy vs. ≥76 Gy), 5 and 10-year BRFS rates were 83.1% and 68.3% vs. 88.4% and 74.8% (p = 0.038).

CONCLUSIONS

Our results are comparable to other published series in terms of disease control and toxicity. These findings confirm the need for dose escalation to achieve better biochemical control and the benefits of ADT in high-risk PCa patients.

Up-to-date results of carbon-ion radiotherapy for prostate cancer

Carbon ion radiotherapy (C-ion RT) for prostate cancer was started in 1995 using the Heavy-Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS), Japan. After preceding phase I/II dose-escalation studies of 20 fractions over 5 weeks, a phase II study was initiated in April 2000 using the treatment techniques and the recommended dose fractionations established by the phase I/II studies. This study was also successfully completed in October 2003 when the C-ion RT for solid tumors, including the prostate cancer, was approved as ‘Advanced Medicine’ by the Ministry of Health, Labor, and Welfare. Since then, more than 1400 patients have been treated with C-ion RT as of February 2012, and advancement of hypofractionation has also been achieved. In this paper, the treatment outcomes in 1144 patients who underwent the established C-ion RT between April 2000 and July 2012 were analyzed.

Out of 1144 patients, 585 patients were categorized as high-risk group, which includes patients having at least one of the following conditions: T3 clinical stage, Gleason's score of 8 or higher and PSA of 20 or higher. One hundred and ninety-seven patients who met the conditions such as clinical stage of T2a or lower, Gleason's score of 6 or lower and PSA of <20 were categorized as low-risk group. Three hundred and sixty-two patients who were not included in either high- or low-risk group were categorized as intermediate-risk group. All patients were pathologically proven to have adenocarcinoma of the prostate, and Gleason's score was determined by the chief pathologist of our study group. Written consent was obtained from all patients included in the clinical study. Patients with the following conditions were not registered in the clinical trial: having distant metastases, having synchronous primary malignancy, not histologically proven cancer, without informed consent, post-operative/post-irradiation recurrence.

All patients were treated with three field irradiations (vertical one field and horizontal opposing two fields). The prostate and proximal part of the seminal vesicle were contoured as clinical target volume (CTV), and planning target volume (PTV) was set with 5–10 mm margins around the CTV. On the way of radiotherapy, a part of irradiation field of the posterior side was cut to reduce the rectal dose. The 197 patients in the low-risk group did not undergo androgen deprivation therapy (ADT), whereas the 947 patients of intermediate- and high-risk groups underwent ADT. The patients of intermediate-risk group underwent about 6 months of neoadjuvant ADT, and the patients of high-risk group also underwent about 6 months of neoadjuvant ADT and sequential adjuvant ADT for more than 18 months. The median age of all patients was 68 years, and the median follow-up time was 48.7 months (range: 3.6–151.1 months).

The 5-year overall survival rate and biochemical relapse-free rate of the entire groups was 95.7% and 91.0%, respectively. T-stage and Gleason's score were significant prognostic factors for both the biochemical control and patient survival and initial PSA was also a predictive factor for survival. Regarding the late radiation toxicity, the incidence of rectal toxicity of grade 2 or worse was 1.1% and that of genitourinary toxicity was 6.5%. These outcomes seemed to be better than those of the past publications [ 1 – 4 ]. In addition, the incidence of toxicity in patients treated with more hypofractionated C-ion RT of 16 fractions over 4 weeks was lower than those of 20 fraction treatment. These favorable outcomes can be thought as apparent evidence of physical and biological advantages of the hypofractionated C-ion RT.

Feasibility of prostate robotic radiation therapy on conventional C-arm linacs

PURPOSE

Significant dosimetric improvement for radiation therapy using optimized noncoplanar fields has been previously demonstrated. The purpose here is to study the feasibility of optimized robotic noncoplanar radiation therapy, termed 4π therapy, for prostate cancer treatments on a conventional C-arm linac.

METHODS AND MATERIALS

Twelve low-risk prostate cancer patients previously treated by 2-arc volumetric modulated arc therapy (VMAT) were selected. Forty gray in 5 fractions were prescribed to cover 95% of the prostate planning target volume (PTV). To replan by 4π therapy, a column generation method was used to optimize beam orientations and fluence. A total of 30 beams were selected for each patient.

RESULTS

Both planning methods provided adequate PTV coverage. Compared against VMAT plans, the 4π plan reduced the rectum V50%, V80%, V90%, D1cc, and the penile bulb maximum doses by 50%, 28%, 19% 11%, and 9% (P < .005), respectively, and the mean body dose was reduced from 2.07 Gy to 1.75 Gy (P = .0001). The bladder dose was only slightly reduced.

CONCLUSIONS

By optimizing beam angles and fluences in the noncoplanar solution space, superior prostate treatment plan quality was achieved compared against state of the art VMAT plans. The dosimetric potential for 4π therapy is established on an existing C-arm linac platform.

Prostate alpha/beta revisited -- an analysis of clinical results from 14 168 patients

PURPOSE

To determine the dose response parameters and the fractionation sensitivity of prostate tumours from clinical results of patients treated with external beam radiotherapy.

MATERIAL AND METHODS

The study was based on five-year biochemical results from 14 168 patients treated with external beam radiotherapy. Treatment data from 11 330 patients treated with conventional fractionation have been corrected for overall treatment time and fitted with a logit equation. The results have been used to determine the optimum α/β values that minimise differences in predictions from 2838 patients treated with hypofractionated schedules.

RESULTS

Conventional fractionation data yielded logit dose response parameters for all risk groups and for all definitions of biochemical failures. The analysis of hypofractionation data led to very low α/β values (1-1.7 Gy) in all mentioned cases. Neglecting the correction for overall treatment time has little impact on the derivation of α/β values for prostate cancers.

CONCLUSIONS

These results indicate that the high fractionation sensitivity is an intrinsic property of prostate carcinomas and they support the use of hypofractionation to increase the therapeutic gain for these tumours.

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.

The feasibility and safety of high-intensity focused ultrasound combined with low-dose external beam radiotherapy as supplemental therapy for advanced prostate cancer following hormonal therapy

The aim of this study was to investigate the feasibility and safety of high-intensity focused ultrasound (HIFU) combined with (+) low-dose external beam radiotherapy (LRT) as supplemental therapy for advanced prostate cancer (PCa) following hormonal therapy (HT). Our definition of HIFU+LRT refers to treating primary tumour lesions with HIFU in place of reduced field boost irradiation to the prostate, while retaining four-field box irradiation to the pelvis in conventional-dose external beam radiotherapy (CRT). We performed a prospective, controlled and non-randomized study on 120 patients with advanced PCa after HT who received HIFU, CRT, HIFU+LRT and HT alone, respectively. CT/MR imaging showed the primary tumours and pelvic lymph node metastases visibly shrank or even disappeared after HIFU+LRT treatment. There were significant differences among four groups with regard to overall survival (OS) and disease-specific survival (DSS) curves (P = 0.018 and 0.015). Further comparison between each pair of groups suggested that the long-term DSS of the HIFU+LRT group was higher than those of the other three groups, but there was no significant difference between the HIFU+LRT group and the CRT group. Multivariable Cox's proportional hazard model showed that both HIFU+LRT and CRT were independently associated with DSS (P = 0.001 and 0.035) and had protective effects with regard to the risk of death. Compared with CRT, HIFU+LRT significantly decreased incidences of radiation-related late gastrointestinal (GI) and genitourinary (GU) toxicity grade ≥ II. In conclusion, long-term survival of patients with advanced PCa benefited from strengthening local control of primary tumour and regional lymph node metastases after HT. As an alternative to CRT, HIFU+LRT showed good efficacy and better safety.

Comparison of dose volume histograms for supine and prone position in patients irradiated for prostate cancer-A preliminary study

AIM

To compare DVHs for OARs in two different positions - prone and supine - for prostate cancer patients irradiated with a Tomotherapy unit.

BACKGROUND

In the era of dose escalation, the choice of optimal patient immobilization plays an essential role in radiotherapy of prostate cancer.

MATERIALS AND METHODS

The study included 24 patients who were allocated to 3 risk groups based on D'Amico criteria; 12 patients represented a low or intermediate and 12 a high risk group. FOR EACH PATIENT TWO TREATMENT PLANS WERE PERFORMED: one in the supine and one in the prone position. PTV included the prostate, seminal vesicles and lymph nodes for the high risk group and the prostate and seminal vesicles for the intermediate or low risk groups. DVHs for the two positions were compared according to parameters: Dmean, D70, D50 and D20 for the bladder and rectum and Dmean, D10 for the intestine. The position accuracy was verified using daily MVCT.

RESULTS

Prone position was associated with lower doses in OARs, especially in the rectum. Despite the fact that in the entire group the differences between tested parameters were not large, the Dmean and D10 for the intestine were statistically significant. In the case of irradiation only to the prostate and seminal vesicles, the prone position allowed for substantial reduction of all tested DVH parameters in the bladder and rectum, except D20 for bladder. Moreover, the Dmean and D50 parameter differences for the bladder were statistically significant. No significant differences between positions reproducibility were demonstrated.

CONCLUSION

In patients irradiated to prostate and seminal vesicles, the prone position may support sparing of the rectum and bladder. The reproducibility of position arrangement in both positions is comparable.

Long-term failure patterns and survival in a randomized dose-escalation trial for prostate cancer. Who dies of disease?

PURPOSE

To report long-term failure patterns and survival in a randomized radiotherapy dose escalation trial for prostate cancer.

MATERIALS AND METHODS

A total of 301 patients with Stage T1b-T3 prostate cancer treated to 70 Gy versus 78 Gy now have a median follow-up of 9 years. Failure patterns and survival were compared between dose levels. The cumulative incidence of death from prostate cancer versus other causes was examined and regression analysis was used to establish predictive factors.

RESULTS

Patients with pretreatment prostate-specific antigen (PSA) >10 ng/mL or high-risk disease had higher biochemical and clinical failures rates when treated to 70 Gy. These patients also had a significantly higher risk of dying of prostate cancer. Patients <70 years old at treatment died of prostate cancer nearly three times more frequently than of other causes when they were radiated to 70 Gy, whereas those treated to 78 Gy died of other causes more frequently. Patients age 70 or older treated to 70 Gy died of prostate cancer as often as other causes, and those receiving 78 Gy never died of prostate cancer within 10 years of follow-up. In regression analysis, factors predicting for death from prostate cancer were pretreatment PSA >10.5 ng/mL, Gleason score 9 and 10, recurrence within 2.6 years of radiation, and doubling time of <3.6 months at the time of recurrence.

CONCLUSIONS

Moderate dose escalation (78 Gy) decreases biochemical and clinical failure as well as prostate cancer death in patients with pretreatment PSA >10 ng/mL or high-risk disease.

A new method for synthesizing radiation dose-response data from multiple trials applied to prostate cancer

PURPOSE

A new method is presented for synthesizing dose-response data for biochemical control of prostate cancer according to study design (randomized vs. nonrandomized) and risk group (low vs. intermediate-high).

METHODS AND MATERIALS

Nine published prostate cancer dose escalation studies including 6,539 patients were identified in the MEDLINE and CINAHL databases and reviewed to assess the relationship between dose and biochemical control. A novel method of analysis is presented in which the normalized dose-response gradient, gamma(50), is estimated for each study and subsequently synthesized across studies. Our method does not assume that biochemical control rates are directly comparable between studies.

RESULTS

Nonrandomized studies produced a statistically significantly higher gamma(50) than randomized studies for intermediate- to high-risk patients (gamma(50) = 1.63 vs. gamma(50) = 0.93, p = 0.03) and a borderline significantly higher (gamma(50) = 1.78 vs. gamma(50) = 0.56, p = 0.08) for low-risk patients. No statistically significant difference in gamma(50) was found between low- and intermediate- to high-risk patients (p = 0.31). From the pooled data of low and intermediate- to high-risk patients in randomized trials, we obtain the overall best estimate of gamma(50) = 0.84 with 95% confidence interval 0.54-1.15.

CONCLUSIONS

Nonrandomized studies overestimate the steepness of the dose-response curve as compared with randomized trials. This is probably the result of stage migration, improved treatment techniques, and a shorter follow-up in higher dose patients that were typically entered more recently. This overestimation leads to inflated expectations regarding the benefit from dose-escalation and could lead to underpowered clinical trials. There is no evidence of a steeper dose response for intermediate- to high-risk compared with low-risk patients.

A prediction study on radiation-induced second malignancies for IMRT treatment delivery

Low-level peripheral organ dose and its effect on second malignancies for patients undergoing radiation therapy have been reported in the literature. However, a comprehensive database outlining the treatment modalities, the tumor location, and a quantification of the overall relative risk of second malignancies is rather limited. In this work, we quantify the relative risks or percent likelihood of second malignancies for patients undergoing IMRT and conventional radiotherapy for four different tumor sites: breast, head and neck, lung, and prostate. We utilize Monte Carlo methods based on actual patient plans to compute the whole body effective dose equivalent for each plan and then deduce the percent likelihood of the occurrence of second malignancy. Based on an evaluation of over 30 actual patient plans and Monte Carlo simulations using 6, 10, and 18MV photon beam energies, we observed that the IMRT patients treated for head and neck cancer showed a 40% increase in risk for developing a second malignancy compared to those treated with conventional radiotherapy. The increase in risk for prostrate patients was 30% while the IMRT lung patients gave the highest relative risk almost tripling that observed in their conventionally treated counterparts. There was negligible difference in risk between breast patients undergoing IMRT treatment versus conventional therapy. The overall relative risk of radiation induced malignancy observed was below 6% in all treatment plans considered.

Comparison of rectal volume definition techniques and their influence on rectal toxicity in patients with prostate cancer treated with 3D conformal radiotherapy: a dose-volume analysis

BACKGROUND

To evaluate the impact of four different rectum contouring techniques and rectal toxicities in patients with treated with 3D conformal radiotherapy (3DCRT).

METHODS

Clinical and dosimetric data were evaluated for 94 patients who received a total dose 3DCRT of 70 Gy, and rectal doses were compared in four different rectal contouring techniques: the prostate-containing CT sections (method 1); 1 cm above and below the planning target volume (PTV) (method 2); 110 mm starting from the anal verge (method 3); and from the anal verge to the sigmoid flexure (method 4). The percentage of rectal volume receiving RT doses (30-70 Gy) and minimum, mean rectal doses were assessed.

RESULTS

Median age was 69 years. Percentage of rectal volume receiving high doses (>or= 70 Gy) were higher with the techniques that contoured smaller rectal volumes. In methods 2 and 3, the percentage of rectal volume receiving >or= 70 Gy was significantly higher in patients with than without rectal bleeding (method 2: 30.8% vs. 22.5%, respectively (p = 0.03); method 3: 26.9% vs. 18.1%, respectively (p = 0.006)). Mean rectal dose was significant predictor of rectal bleeding only in method 3 (48.8 Gy in patients with bleeding vs. 44.4 Gy in patients without bleeding; p = 0.02).

CONCLUSION

Different techniques of rectal contouring significantly influence the calculation of radiation doses to the rectum and the prediction of rectal toxicity. Rectal volume receiving higher doses (>or= 70 Gy) and mean rectal doses may significantly predict rectal bleeding for techniques contouring larger rectal volumes, as was in method 3.

Reduced rectal toxicity with ultrasound-based image guided radiotherapy using BAT (B-mode acquisition and targeting system) for prostate cancer

PURPOSE

To evaluate the effect of image guided radiotherapy with stereotactic ultrasound BAT (B-mode acquisition and targeting system) on rectal toxicity in conformal radiotherapy of prostate cancer.

PATIENTS AND METHODS

42 sequential patients with prostate cancer undergoing radiotherapy before and after the introduction of BAT were included. Planning computed tomography (CT) was performed with empty rectum and moderately filled bladder. The planning target volume (PTV) included the prostate and seminal vesicles with a safety margin of 1.5 cm in anterior and lateral direction. In posterior direction the anterior 1/3 of the rectum circumference were included. Total dose was 66 Gy and a boost of 4 Gy excluding the seminal vesicles. 22 patients (BAT group) were treated with daily stereotactic ultrasound positioning, for the other 20 patients (NoBAT group) an EPID (electronic portal imaging device) was performed once a week. Acute and late genito-urinary (GU) and rectal toxicity and PSA values were evaluated after 1.5, 3, 6, 9 and 12 months. The total median follow up of toxicity was 3 years in the BAT group and 4 years in the NoBAT group.

RESULTS

In the NoBAT group significant more rectal toxicity occurred, while in GU toxicity no difference was seen. Two patients in the NoBAT group showed late rectal toxicity grade 3, no toxicity>grade 2 occurred in the BAT group. There was no significant difference in PSA reduction between the groups.

CONCLUSION

Without BAT significant more acute and a trend to more late rectal toxicity was found. With regard to dose escalation this aspect is currently evaluated with a larger number of patients using intensity-modulated radiotherapy (IMRT).

Late rectal and urinary toxicity from conformal, dose-escalated radiation therapy for prostate cancer: a prospective study of 402 patients

This study investigates the rate of late rectal and urinary toxicity from three-dimensional conformal radiation therapy (3DCRT) for localized prostate cancer. The influence of neoadjuvant androgen deprivation (AD) on toxicity rates was also examined. A total of 402 men at Liverpool and Westmead hospitals received radical 3DCRT for localized prostate cancer between 1999 and 2003. Patients received either 70 Gy or 74 Gy, according to their prognostic risk grouping and or date of commencing radiation therapy (RT). Late rectal and urinary toxicity data were collected prospectively using Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer criteria. The median follow up of this cohort was 43.5 months. At 36 months, the cumulative incidence of >or=grade 2 rectal and urinary toxicities was 6.7 and 17.5%, respectively. Peak prevalence of late urinary toxicity occurred at 36 months (9.5%), although late rectal toxicity was highest at 12 months (2.9%) from completion of 3DCRT. The use of AD did not cause additional late toxicities. Patients receiving 74 Gy did not experience significantly worse toxicities than the group receiving 70 Gy.

Phase II Trial of Hypofractionated Image-Guided Intensity-Modulated Radiotherapy for Localized Prostate Adenocarcinoma

PURPOSE

To assess in a prospective trial the feasibility and late toxicity of hypofractionated radiotherapy (RT) for prostate cancer.

METHODS AND MATERIALS

Eligible patients had clinical stage T1c-2cNXM0 disease. They received 60 Gy in 20 fractions over 4 weeks with intensity-modulated radiotherapy including daily on-line image guidance with intraprostatic fiducial markers.

RESULTS

Between June 2001 and March 2004, 92 patients were treated with hypofractionated RT. The cohort had a median prostate-specific antigen value of 7.06 ng/mL. The majority had Gleason grade 5-6 (38%) or 7 (59%) disease, and 82 patients had T1c-T2a clinical staging. Overall, 29 patients had low-risk, 56 intermediate-risk, and 7 high-risk disease. Severe acute toxicity (Grade 3-4) was rare, occurring in only 1 patient. Median follow-up was 38 months. According to the Phoenix definition for biochemical failure, the rate of biochemical control at 14 months was 97%. According to the previous American Society for Therapeutic Radiology and Oncology definition, biochemical control at 3 years was 76%. The incidence of late toxicity was low, with no severe (Grade > or =3) toxicity at the most recent assessment.

CONCLUSIONS

Hypofractionated RT using 60 Gy in 20 fractions over 4 weeks with image guidance is feasible and is associated with low rates of late bladder and rectal toxicity. At early follow-up, biochemical outcome is comparable to that reported for conventionally fractionated controls. The findings are being tested in an ongoing, multicenter, Phase III trial.

Monte Carlo determination of radiation-induced cancer risks for prostate patients undergoing intensity- modulated radiation therapy

The application of intensity‐modulated radiation therapy (IMRT) has enabled the delivery of high doses to the target volume while sparing the surrounding normal tissues. The drawbacks of intensity modulation, as implemented using a computer‐controlled multileaf collimator (MLC), are the larger number of monitor units (MUs) and longer beam‐on time as compared with conventional radiotherapy. Additionally, IMRT uses more beam directions—typically 5 – 9 for prostate treatment—to achieve highly conformal dose and normal‐tissue sparing. In the present work, we study radiation‐induced cancer risks attributable to IMRT delivery using MLC for prostate patients.

Whole‐body computed tomography scans were used in our study to calculate (according to report no. 116 from the National Council on Radiation Protection and Measurements) the effective dose equivalent received by individual organs. We used EGS4 and MCSIM to compute the dose for IMRT and three‐dimensional conformal radiotherapy. The effects of collimator rotation, distance from the treatment field, and scatter and leakage contribution to the whole‐body dose were investigated. We calculated the whole‐body dose equivalent to estimate the increase in the risk of secondary malignancies.

Our results showed an overall doubling in the risk of secondary malignancies from the application of IMRT as compared with conventional radiotherapy. This increase in the risk of secondary malignancies is not necessarily related to a relative increase in MUs. The whole‐body dose equivalent was also affected by collimator rotation, field size, and the energy of the photon beam. Smaller field sizes of low‐energy photon beams (that is, 6 MV) with the MLC axis along the lateral axis of the patient resulted in the lowest whole‐body dose. Our results can be used to evaluate the risk of secondary malignancies for prostate IMRT patients.

PACS: 87.53.wz, 87.53.‐j

Long-term results of the M. D. Anderson randomized dose-escalation trial for prostate cancer

PURPOSE

To report the long-term results of a randomized radiotherapy dose escalation trial for prostate cancer.

METHODS AND MATERIALS

From 1993 to 1998, a total of 301 patients with stage T1b to T3 prostate cancer were accrued to a randomized external beam dose escalation trial using 70 Gy versus 78 Gy. The median follow-up is now 8.7 years. Kaplan-Meier analysis was used to compute rates of prostate-specific antigen (PSA) failure (nadir + 2), clinical failure, distant metastasis, disease-specific, and overall survival as well as complication rates at 8 years post-treatment.

RESULTS

For all patients, freedom from biochemical or clinical failure (FFF) was superior for the 78-Gy arm, 78%, as compared with 59% for the 70-Gy arm (p = 0.004, and an even greater benefit was seen in patients with initial PSA >10 ng/ml (78% vs. 39%, p = 0.001). The clinical failure rate was significantly reduced in the 78-Gy arm as well (7% vs. 15%, p = 0.014). Twice as many patients either died of prostate cancer or are currently alive with cancer in the 70-Gy arm. Gastrointestinal toxicity of grade 2 or greater occurred twice as often in the high dose patients (26% vs. 13%), although genitourinary toxicity of grade 2 or greater was less (13% vs. 8%) and not statistically significantly different. Dose-volume histogram analysis showed that the complication rate could be significantly decreased by reducing the amount of treated rectum.

CONCLUSIONS

Modest escalation in radiotherapy dose improved freedom from biochemical and clinical progression with the largest benefit in prostate cancer patients with PSA >10 ng/ml.

Failure to achieve a PSA level <or=1 ng/mL after neoadjuvant LHRHa therapy predicts for lower biochemical control rate and overall survival in localized prostate cancer treated with radiotherapy

PURPOSE

To investigate whether failure to suppress the prostate-specific antigen (PSA) level to <or=1 ng/mL after >or=2 months of neoadjuvant luteinizing hormone-releasing hormone agonist therapy in patients scheduled to undergo external beam radiotherapy for localized prostate carcinoma is associated with reduced biochemical failure-free survival.

METHODS AND MATERIALS

A retrospective case note review of consecutive patients with intermediate- or high-risk localized prostate cancer treated between January 2001 and December 2002 with neoadjuvant hormonal deprivation therapy, followed by concurrent hormonal therapy and radiotherapy was performed. Patient data were divided for analysis according to whether the PSA level in Week 1 of radiotherapy was <or=1.0 ng/mL. Biochemical failure was determined using the American Society for Therapeutic Radiology and Oncology (Phoenix) definition.

RESULTS

A total of 119 patients were identified. The PSA level after neoadjuvant hormonal deprivation therapy was <or=1 ng/mL in 67 patients and >1 ng/mL in 52. At a median follow-up of 49 months, the 4-year actuarial biochemical failure-free survival rate was 84% vs. 60% (p = 0.0016) in favor of the patients with a PSA level after neoadjuvant hormonal deprivation therapy of <or=1 ng/mL. The overall survival rate was 94% vs. 77.5% (p = 0.0045), and the disease-specific survival rate at 4 years was 98.5% vs. 82.5%.

CONCLUSIONS

The results of our study have shown that patients with a PSA level >1 ng/mL at the beginning of external beam radiotherapy after >or=2 months of neoadjuvant luteinizing hormone-releasing hormone agonist therapy have a significantly greater rate of biochemical failure and lower survival rate compared with those with a PSA level of <or=1 ng/mL. Patients without adequate PSA suppression should be considered a higher risk group and considered for dose escalation or the use of novel treatments.

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.

Demethylation-linked activation of urokinase plasminogen activator is involved in progression of prostate cancer

Increased expression of urokinase plasminogen activator (uPA) has been reported in various malignancies including prostate cancer. However, the mechanism by which uPA is abnormally expressed in prostate cancer remains elusive. Here, we show that uPA is aberrantly expressed in a high percentage of human prostate cancer tissues but rarely expressed either in tumor-matched nonneoplastic adjacent tissues or benign prostatic hyperplasia samples. This aberrant expression is associated with cancer-linked demethylation of the uPA promoter. Furthermore, treatment with demethylation inhibitor S-adenosylmethionine or stable expression of uPA short hairpin RNA significantly inhibits uPA expression and tumor cell invasion in vitro and tumor growth and incidence of lung metastasis in vivo. Collectively, these findings strongly suggest that DNA demethylation is a common mechanism underlying the abnormal expression of uPA and is a critical contributing factor to the malignant progression of human prostate tumors.

The proportion of prostate biopsy tissue with Gleason pattern 4 or 5 predicts for biochemical and clinical outcome after radiotherapy for prostate cancer

PURPOSE

To investigate the prognostic utility of the proportion of prostate biopsy tissue containing Gleason pattern 4 or 5 (GP4/5) after definitive radiotherapy (RT) for prostate cancer.

METHODS AND MATERIALS

A total of 568 patients with T1c-3 Nx/0 prostate cancer who received three-dimensional conformal RT alone between May 1989 and August 2001 were studied. There were 161 men with Gleason score 7-10 disease. The GP4/5 was defined as the percentage of biopsy tissue containing Gleason pattern 4 or 5. A Cox proportional hazards model was used for univariate and multivariate analyses (MVA) for biochemical failure (BF) (American Society of Therapeutic Radiology and Oncology definition) and distant metastasis (DM). A recursive partitioning analysis was done using the results of the MVA to identify a cutpoint for GP4/5.

RESULTS

The median follow-up was 46 (range, 13-114) months and median RT dose was 76 (range, 65-82) Gy. On MVA, increasing initial prostate-specific antigen (p = 0.0248) decreasing RT dose (continuous, p = 0.0022), T stage (T1/2 vs. T3), (p = 0.0136) and GP4/5 (continuous, p < 0.0001) were significant predictors of BF in a model also containing GS. GP4/5 was the only significant predictor of DM in the same model (p < 0.0001).

CONCLUSION

The GP4/5 in prostate biopsy specimens is a predictor of BF and DM after RT independent of Gleason score. This parameter should be reported by the pathologist when reviewing prostatic biopsy specimens.

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.

Clinicopathologic analysis of extracapsular extension in prostate cancer: Should the clinical target volume be expanded posterolaterally to account for microscopic extension?

PURPOSE

We performed a complete pathologic analysis examining extracapsular extension (ECE) and microscopic spread of malignant cells beyond the prostate capsule to determine whether and when clinical target volume (CTV) expansion should be performed.

METHODS AND MATERIALS

A detailed pathologic analysis was performed for 371 prostatectomy specimens. All slides from each case were reviewed by a single pathologist (N.S.G.). The ECE status and ECE distance, defined as the maximal linear radial distance of malignant cells beyond the capsule, were recorded.

RESULTS

A total of 121 patients (33%) were found to have ECE (68 unilateral, 53 bilateral). Median ECE distance=2.4 mm [range: 0.05-7.0 mm]. The 90th-percentile distance = 5.0 mm. Of the 121 cases with ECE, 55% had ECE distance>or=2 mm, 19%>or=4 mm, and 6%>or=6 mm. ECE occurred primarily posterolaterally along the neurovascular bundle in all cases. Pretreatment prostrate-specific antigen (PSA), biopsy Gleason, pathologic Gleason, clinical stage, bilateral involvement, positive margins, percentage of gland involved, and maximal tumor dimension were associated with presence of ECE. Both PSA and Gleason score were associated with ECE distance. In all 371 patients, for those with either pretreatment PSA>or=10 or biopsy Gleason score>or=7, 21% had ECE>or=2 mm and 5%>or=4 mm beyond the capsule. For patients with both of these risk factors, 49% had ECE>or=2 mm and 21%>or=4 mm.

CONCLUSIONS

For prostate cancer with ECE, the median linear distance of ECE was 2.4 mm and occurred primarily posterolaterally. Although only 5% of patients demonstrate ECE>4 to 5 mm beyond the capsule, this risk may exceed 20% in patients with PSA>or=10 ng/ml and biopsy Gleason score>or=7. As imaging techniques improve for prostate capsule delineation and as radiotherapy delivery techniques increase in accuracy, a posterolateral CTV expansion should be considered for patients at high risk.

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.

Cluster model analysis of late rectal bleeding after IMRT of prostate cancer: a case-control study

PURPOSE

Cluster models are newly developed normal-tissue complication probability models in which the spatial aspects of radiation-induced injury are taken into account by considering the size of spatially contiguous aggregates of damaged tissue units. The purpose of this study was to test the validity of a two-dimensional cluster model of late rectal toxicity based on maximum cluster size of damage to rectal surface.

METHODS AND MATERIALS

A paired case-control study was performed in which each of 9 patients experiencing Grade 2 or higher late rectal toxicity after intensity-modulated radiation therapy of localized prostate cancer was paired with a patient having a similar rectal dose-surface histogram but free of rectal toxicity. Numeric simulations were performed to determine the distribution of maximum cluster size on each rectal surface for each of many different choices of possible model parameters.

RESULTS

Model parameters were found for which patients with rectal toxicity were consistently more likely to have a significantly larger mean maximum cluster size than their matched controls. These parameter values correspond to a 50% probability of tissue-unit damage at doses near 30 Gy.

CONCLUSIONS

This study suggests that a cluster model based on maximum cluster size of damage to rectal surface successfully incorporates spatial information beyond that contained in the rectal dose-surface histogram and may therefore provide a useful new tool for predicting rectal normal-tissue complication probability after radiotherapy.

Locally advanced prostate cancer treated with radiotherapy and androgen deprivation

BACKGROUND

A 60-year-old man, with a 2-year history of lower-urinary-tract symptoms (frequency and reduced flow) and perineal discomfort, presented with a serum PSA level of 42 ng/ml.

INVESTIGATIONS

Digital rectal examination, transrectal ultrasound, prostate biopsy (8 cores), prostate and pelvic MRI, renal ultrasound and bone scan.

DIAGNOSIS

cT3b, N0, M0 prostate cancer (Gleason score 7 [4 + 3]).

MANAGEMENT

Hormonal down-staging with bicalutamide 150 mg/day for 3 months, then conformal radiotherapy (70 Gy over 7 weeks) with adjuvant bicalutamide 150 mg/day, to be continued until disease progression. Breast radiotherapy administered over a 5-day period at a dose of 15 Gy to reduce nonsteroidal antiandrogen-associated gynecomastia and breast pain.

Radiotherapeutic techniques for prostate cancer, dose escalation and brachytherapy

There is evidence to confirm a dose-response relationship in prostate cancer. The relative benefit is dependent on the clinical prognostic risk factors (T stage, Gleason score and presenting prostate-specific antigen [PSA]) being more favourable for intermediate-risk patients. Refinement of prognostic groups and clinical threshold parameters is ongoing. Escalation of dose in prostate radiotherapy using conventional techniques is limited by rectal tolerance. Substantial advances have been made in radiotherapy practice, such as the development of conformal radiotherapy (CFRT) and intensity-modulated radiotherapy (IMRT). Randomised data support the value of CFRT in reducing rectal toxicity. IMRT can permit higher-dose escalation while still respecting known rectal tolerance thresholds. Brachytherapy is a recognised alternative for low-risk prostate cancer subgroups. New radiotherapeutic strategies for prostate cancer include pelvic nodal irradiation, exploiting the presumed low alpha/beta ratio in prostate cancer for hypofractionation and combining external beam with high-dose-rate brachytherapy boosts. New image-guided methodologies will enhance the therapeutic ratio of any radiotherapy technique or dose escalation programme by enabling more reliable and accurate treatment delivery for improved patient outcomes.

Targeted elimination of prostate cancer by genetically directed human T lymphocytes

The genetic transfer of antigen receptors is a powerful approach to rapidly generate tumor-specific T lymphocytes. Unlike the physiologic T-cell receptor, chimeric antigen receptors (CARs) encompass immunoglobulin variable regions or receptor ligands as their antigen recognition moiety, thus permitting T cells to recognize tumor antigens in the absence of human leukocyte antigen expression. CARs encompassing the CD3zeta chain as their activating domain induce T-cell proliferation in vitro, but limited survival. The requirements for genetically targeted T cells to function in vivo are less well understood. We have, therefore, established animal models to assess the therapeutic efficacy of human peripheral blood T lymphocytes targeted to prostate-specific membrane antigen (PSMA), an antigen expressed in prostate cancer cells and the neovasculature of various solid tumors. In vivo specificity and antitumor activity were assessed in mice bearing established prostate adenocarcinomas, using serum prostate-secreted antigen, magnetic resonance, computed tomography, and bioluminescence imaging to investigate the response to therapy. In three tumor models, orthotopic, s.c., and pulmonary, we show that PSMA-targeted T cells effectively eliminate prostate cancer. Tumor eradication was directly proportional to the in vivo effector-to-tumor cell ratio. Serial imaging further reveals that the T cells must survive for at least 1 week to induce durable remissions. The eradication of xenogeneic tumors in a murine environment shows that the adoptively transferred T cells do not absolutely require in vivo costimulation to function. These results thus provide a strong rationale for undertaking phase I clinical studies to assess PSMA-targeted T cells in patients with metastatic prostate cancer.

PSA nadir predicts biochemical and distant failures after external beam radiotherapy for prostate cancer: a multi-institutional analysis

PURPOSE

To determine the significance of prostate-specific antigen (PSA) nadir (nPSA) and the time to nPSA (T(nPSA)) in predicting biochemical or clinical disease-free survival (PSA-DFS) and distant metastasis-free survival (DMFS) in patients treated with definitive external beam radiotherapy (RT) for clinical Stage T1b-T2 prostate cancer.

METHODS AND MATERIALS

Nine participating institutions submitted data on 4839 patients treated between 1986 and 1995 for Stage T1b-T2cN0-NxM0 prostate cancer. All patients were treated definitively with RT alone to doses > or =60 Gy, without neoadjuvant or planned adjuvant androgen suppression. A total of 4833 patients with a median follow-up of 6.3 years met the criteria for analysis. Two endpoints were considered: (1) PSA-DFS, defined as freedom from PSA failure (American Society for Therapeutic Radiology and Oncology definition), initiation of androgen suppression after completion of RT, or documented local or distant failure; and (2) DMFS, defined as freedom from clinically apparent distant failure. In patients with failure, nPSA was defined as the lowest PSA measurement before any failure. In patients without failure, nPSA was the lowest PSA measurement during the entire follow-up period. T(nPSA) was calculated from the completion of RT to the nPSA date.

RESULTS

A greater nPSA level and shorter T(nPSA) were associated with decreased PSA-DFS and DMFS in all patients and in all risk categories (low [Stage T1b, T1c, or T2a, Gleason score < or =6, and PSA level < or =10 ng/mL], intermediate [Stage T1b, T1c, or T2a, Gleason score < or =6, and PSA level >10 but < or =20 ng/mL, or Stage T2b or T2c, Gleason score < or =6, and PSA level < or =20 ng/mL, or Gleason score 7 and PSA level < or =20 ng/mL], and high [Gleason score 8-10 or PSA level >20 ng/mL]), regardless of RT dose. The 8-year PSA-DFS and DMFS rate for patients with nPSA <0.5 ng/mL was 75% and 97%; nPSA > or =0.5 but <1.0 ng/mL, 52% and 96%; nPSA > or =1.0 but <2.0 ng/mL, 40% and 91%; and nPSA > or =2.0 ng/mL, 17% and 73%, respectively. The 8-year PSA-DFS and DMFS rate for patients with T(nPSA) <6 months was 27% and 66%; T(nPSA) > or =6 but <12 months, 31% and 85%; T(nPSA) > or =12 but <24 months, 42% and 94%; and T(nPSA) > or =24 months, 75% and 99%, respectively. A shorter T(nPSA) was associated with decreased PSA-DFS and DMFS, regardless of the nPSA. Both nPSA and T(nPSA) were significant predictors of PSA-DFS and DMFS in multivariate models incorporating clinical stage, Gleason score, initial PSA level, and RT dose. The significance of nPSA and T(nPSA) was supported by landmark analysis, as well as by analysis of nPSA and T(nPSA) as time-dependent covariates. A dose > or =70 Gy was associated with a lower nPSA level and longer T(nPSA) in all risk categories, and a greater dose was significantly associated with greater PSA-DFS and DMFS in multivariate analysis. Regression analysis confirmed that higher clinical stage, Gleason score, and initial PSA were associated with a greater nPSA level.

CONCLUSION

The results of this large, multi-institutional analysis of 4833 patients have provided important evidence that nPSA and T(nPSA) after definitive external beam RT are not only predictive of a predominantly PSA endpoint (PSA-DFS), but are also predictive of distant metastasis in all clinical risk categories. Greater RT doses were associated with lower nPSA, longer T(nPSA), and improved PSA-DFS and DMFS.