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

The Journey of Radiotherapy Dose Escalation in High Risk Prostate Cancer; Conventional Dose Escalation to Stereotactic Body Radiotherapy (SBRT) Boost Treatments

High risk prostate cancer (HR-PrCa) is a subset of localized PrCa with significant potential for morbidity and mortality associated with disease recurrence and metastasis. Radiotherapy combined with Androgen Deprivation Therapy has been the standard of care for many years in HR-PrCa. In recent years, dose escalation, hypo-fractionation and high precision delivery with immobilization and image-guidance have substantially changed the face of modern PrCa radiotherapy, improving treatment convenience and outcomes. Ultra-hypo-fractionated radiotherapy delivered with high precision in the form of stereotactic body radiation therapy (SBRT) combines delivery of high biologically equivalent dose radiotherapy with the convenience of a shorter treatment schedule, as well as the promise of similar efficacy and reduced toxicity compared to conventional radiotherapy. However, rigorous investigation of SBRT in HR-PrCa remains limited. Here, we review the changes in HR-PrCa radiotherapy through dose escalation, hypo- and ultra-hypo-fractionated radiotherapy boost treatments, and the radiobiological basis of these treatments. We focus on completed and on-going trials in this disease utilizing SBRT as a sole radiation modality or as boost therapy following pelvic radiation.

Targeting Radiation-Resistant Prostate Cancer Stem Cells by B7-H3 CAR T Cells

Radiotherapy (RT) is a key treatment for prostate cancer. However, RT resistance can contribute to treatment failure. Prostate cancer stem cells (PCSCs) are radioresistant. We recently found that fractionated irradiation (FIR) upregulates expression of the immune checkpoint B7-H3 (CD276) on PCSCs and bulk cells in each prostate cancer cell line tested. These findings prompted us to investigate whether B7-H3 targeting chimeric antigen receptor (CAR) T cells, which may abrogate function of an immune checkpoint and mediate lysis of targeted cells, can target RT-resistant PCSCs in vitro and in vivo. B7-H3 expression is naturally higher on PCSCs than bulk prostate cancer cells and cytotoxicity of B7-H3 CAR T cells to PCSCs is more potent than to bulk prostate cancer cells. Furthermore, FIR significantly upregulates B7-H3 expression on PCSCs and bulk prostate cancer cells. The duration of FIR or single-dose irradiation-induced further upregulation of B7-H3 on bulk prostate cancer cells and PCSCs lasts for up to 3 days. B7-H3 CAR T-cell cytotoxicity against FIR-resistant PCSCs at a low effector to target ratio of 1:1 was assessed by flow cytometry and sphere formation assays. Further upregulation of B7-H3 expression by FIR made PCSCs even more sensitive to B7-H3 CAR T-cell-mediated killing. Consequently, the FIR and B7-H3 CAR T-cell therapy combination is much more effective than FIR or CAR T cells alone in growth inhibition of hormone-insensitive prostate cancer xenografts in immunodeficient mice. Our work provides a sound basis for further development of this unique combinatorial model of RT and B7-H3 CAR T-cell therapy for prostate cancer. SIGNIFICANCE: We demonstrate that FIR significantly upregulates B7-H3 expression by RT-resistant PCSCs and bulk cells; cytotoxicity of B7-H3 CAR T cells to FIR-treated PCSCs is potent and results in significantly improved antitumor efficacy in mice.

Patterns of Lymph Node Failure in Patients With Recurrent Prostate Cancer Postradical Prostatectomy and Implications for Salvage Therapies

PURPOSE

There is increasing use of radical prostatectomy to treat patients with high-risk prostate cancer. This has contributed toward a pathologic stage migration, and a greater number of patients are subsequently being diagnosed with biochemical failure. There is increasing use of advanced imaging techniques in the setting of biochemical failure, including positron emission tomography-computed tomography (PET-CT).

METHODS AND MATERIALS

This critical literature review highlights the evidence for PET-CT in postprostatectomy biochemical failure and identifies sites of pelvic lymph node relapse in the setting of biochemical failure and the potential implications that the locations of these relapses may have for salvage therapies. Potential future directions are then considered.

RESULTS

The optimal PET-CT tracer remains uncertain but there is increasing use of prostate-specific membrane antigen PET-CT for investigating sites of nodal metastasis at low prostate-specific antigen levels, and this is leading to a blurring of the biochemical and radiologic recurrence phases. The optimal therapeutic approach remains undefined, with current trials investigating postoperative radiation therapy to the whole pelvis in addition to the prostatic fossa, the use of PET-CT in the setting of biochemical recurrence to guide delivery of salvage radiation therapy, and, for patients with node-only relapsed prostate cancer, the addition of whole pelvis radiation therapy to metastasis-directed therapies such as stereotactic ablative radiotherapy.

CONCLUSIONS

The most appropriate target volume for salvage radiation therapy remains uncertain, and the findings of studies using PET-CT to map nodal recurrences suggest that there could be a role for extending whole pelvis radiation therapy volumes to increase coverage of superior nodal regions. The emerging fields of radiomics and radiogenomics could provide important prognostic information and aid decision making for patients with relapsed prostate cancer.

Efficacy and toxicity outcomes for patients treated with focal salvage high dose rate brachytherapy for locally recurrent prostate cancer

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Local recurrence of prostate cancer may be treated with salvage therapies.

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Focal salvage high dose rate brachytherapy provides good biochemical control.

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Severe genitourinary and gastrointestinal toxicities are low.

Introduction

Isolated local recurrence of prostate cancer following primary radiotherapy or brachytherapy may be treated with focal salvage high dose rate brachytherapy, although there remains an absence of high quality evidence to support this approach.

Methods

Men with prostate cancer treated consecutively between 2015 and 2018 using 19 Gy in a single fraction high dose rate brachytherapy (HDR) for locally recurrent prostate cancer were identified from an institutional database. Univariable analysis was performed to evaluate the relationship between patient, disease and treatment factors with biochemical progression free survival (bPFS).

Results

43 patients were eligible for evaluation. Median follow up duration was 26 months (range 1–60). Median bPFS was 35 months (95% confidence interval 25.6–44.4). Kaplan-Meier estimates for bPFS at 1, 2 and 3 years post salvage were 95.2%, 70.6% and 41.8% respectively. On univariable Cox regression analysis, only nadir PSA was significantly associated with bPFS although the majority of patients were also treated with androgen deprivation therapy. Only one late grade 3 genitourinary toxicity was observed.

Conclusion

Focal salvage HDR brachytherapy may provide good biochemical control with a low risk of severe toxicity. Further evaluation within clinical trials are needed to establish its role in the management of locally recurrent prostate cancer.

Phase I Trial of MRI-Guided Prostate Cancer Lattice Extreme Ablative Dose (LEAD) Boost Radiation Therapy

PURPOSE

A phase I clinical trial was designed to test the feasibility and toxicity of administering high-dose spatially fractionated radiation therapy to magnetic resonance imaging (MRI)-defined prostate tumor volumes, in addition to standard treatment.

METHODS AND MATERIALS

We enrolled 25 men with favorable to high-risk prostate cancer and 1 to 3 suspicious multiparametric MRI (mpMRI) gross tumor volumes (GTVs). The mpMRI-GTVs were treated on day 1 with 12 to 14 Gy via dose cylinders using a lattice extreme ablative dose technique. The entire prostate, along with the proximal seminal vesicles, was then treated to 76 Gy at 2 Gy/fraction. For some high-risk patients, the distal seminal vesicles and pelvic lymph nodes received 56 Gy at 1.47 Gy/fraction concurrently in 38 fractions. The total dose to the lattice extreme ablative dose cylinder volume(s) was 88 to 90 Gy (112-123 Gy in 2.0 Gy equivalents, assuming an α-to-β ratio of 3).

RESULTS

Dosimetric parameters were satisfactorily met. Median follow-up was 66 months. There were no grade 3 acute/subacute genitourinary or gastrointestinal adverse events. Maximum late genitourinary toxicity was grade 1 in 15 (60%), grade 2 in 4 (16%), and grade 4 in 1 (4%; sepsis after a posttreatment transurethral resection). Maximum late gastrointestinal toxicity was grade 1 in 11 (44%) and grade 2 in 4 (16%). Two patients experienced biochemical failure.

CONCLUSIONS

External beam radiation therapy delivered with an upfront spatially fractionated, stereotactic high-dose mpMRI-GTV boost is feasible and was not associated with any unexpected events. The technique is now part of a follow-up phase II randomized trial.

Increased EZH2 expression in prostate cancer is associated with metastatic recurrence following external beam radiotherapy

BACKGROUND

Enhancer of zeste 2 (EZH2) promotes prostate cancer progression. We hypothesized that increased EZH2 expression is associated with postradiotherapy metastatic disease recurrence, and may promote radioresistance.

METHODS

EZH2 expression was investigated using immunohistochemistry in diagnostic prostate biopsies of 113 prostate cancer patients treated with radiotherapy with curative intent. Associations between EZH2 expression in malignant and benign tissue in prostate biopsy cores and outcomes were investigated using univariate and multivariate Cox regression analyses. LNCaP and PC3 cell radiosensitivity was investigated using colony formation and γH2AX assays following UNC1999 chemical probe-mediated EZH2 inhibition.

RESULTS

While there was no significant association between EZH2 expression and biochemical recurrence following radiotherapy, univariate analysis revealed that prostate cancer cytoplasmic and total EZH2 expression were significantly associated with metastasis development postradiotherapy (P = 0.034 and P = 0.003, respectively). On multivariate analysis, the prostate cancer total EZH2 expression score remained statistically significant (P = 0.003), while cytoplasmic EZH2 expression did not reach statistical significance (P = 0.053). No association was observed between normal adjacent prostate EZH2 expression and biochemical recurrence or metastasis. LNCaP and PC3 cell treatment with UNC1999 reduced histone H3 lysine 27 tri-methylation levels. Irradiation of LNCaP or PC3 cells with a single 2 Gy fraction with UNC1999-mediated EZH2 inhibition resulted in a statistically significant, though modest, reduction in cell colony number for both cell lines. Increased γH2AX foci were observed 24 hours after ionizing irradiation in LNCaP cells, but not in PC3, following UNC1999-mediated EZH2 inhibition vs controls.

CONCLUSIONS

Taken together, these results reveal that high pretreatment EZH2 expression in prostate cancer in diagnostic biopsies is associated with an increased risk of postradiotherapy metastatic disease recurrence, but EZH2 function may only at most play a modest role in promoting prostate cancer cell radioresistance.

Long-term oncological results of treatment for high-risk prostate cancer using radical prostatectomy in a cancer hospital

OBJECTIVES

To analyse the most relevant oncologic results of treatment using radical prostatectomy (RP) for high-risk prostate cancer (HRPC) in a specialist cancer hospital.

MATERIAL AND METHODS

A descriptive retrospective study of RP was conducted at our centre from 1986 to 2017 on HRPC whose primary objective was to determine overall survival (OS) and cancer-specific survival (CSS). The study's secondary objectives were to determine biochemical progression-free survival (BPFS), metastasis-free survival (MFS), rescue therapy-free survival (RTFS), hormone therapy-free survival (HTFS) and the development of castration-resistant prostate cancer. We performed a Cox regression analysis to establish predictive models and to better understand the weight of each variable that defines high risk.

RESULTS

A total of 2093 RPs were performed, 480 (22.9%) of which were for HRPC. The median follow-up for the overall series was 79.57 months (P_25-75 37.92-135.16). Lymphadenectomy was not performed in 6.5% of the cases. The lymphadenectomy was of the obturator type in 51.2% of the cases and extended in 42.3%. Overall survival at 5, 10 and 15 years was 89.8% (95% CI 86.7-92.9%), 73.3% (95% CI 68-78.6%) and 51.4% (95% CI 43.8-59%), respectively. CSS at 5, 10 and 15 years was 94.8% (95% CI 92.4-97.2%), 84.0% (95% CI 79.3-88.7%) and 75.5% (95% CI 68.8-82.2%), respectively. MFS at 5, 10 and 15 years was 87.4% (95% CI 84.1-90.7%), 72.2% (95% CI 66.7-77.7%) and 61.7% (95% CI 54.3-69.1%), respectively. A total of 120 patients of 477 analysed (25.1%) required rescue radiation therapy, and 293/477 never required hormone therapy (61.4%). Of the 93 pN1 patients, 33 (35.5%) did not require hormone therapy. The time from RP to biochemical progression was the variable with the greatest prognostic weight for MFS, CSS and overall survival.

CONCLUSIONS

RP plus extended lymphadenectomy should be the first therapeutic manoeuvre when feasible within a multimodal strategy. A longer follow-up of the series is needed to validate the hypothesis of better oncologic results based on the earlier implementation of rescue radiation therapy, extended lymphadenectomy and drugs that prolong survival in the CRPC phase.

IGF-1R associates with adverse outcomes after radical radiotherapy for prostate cancer

BACKGROUND

Activated type 1 insulin-like growth factor receptors (IGF-1Rs) undergo internalisation and nuclear translocation, promoting cell survival. We previously reported that IGF-1R inhibition delays DNA damage repair, sensitising prostate cancer cells to ionising radiation. Here we tested the clinical relevance of these findings.

METHODS

We assessed associations between IGF-1R and clinical outcomes by immunohistochemistry in diagnostic biopsies of 136 men treated with 55-70 Gy external beam radiotherapy for prostate cancer, comparing results with publicly available transcriptional data in surgically treated patients.

RESULTS

Following radiotherapy, overall recurrence-free survival was shorter in patients whose tumours contained high total, cytoplasmic and internalised (nuclear/cytoplasmic) IGF-1R. High total IGF-1R associated with high primary Gleason grade and risk of metastasis, and cytoplasmic and internalised IGF-1R with biochemical recurrence, which includes patients experiencing local recurrence within the radiation field indicating radioresistance. In multivariate analysis, cytoplasmic, internalised and total IGF-1R were independently associated with risk of overall recurrence, and cytoplasmic IGF-1R was an independent predictor of biochemical recurrence post radiotherapy. Insulin-like growth factor receptors expression did not associate with biochemical recurrence after radical prostatectomy.

CONCLUSIONS

These data reveal increased risk of post-radiotherapy recurrence in men whose prostate cancers contain high levels of total or cytoplasmic IGF-1R.

Dosimetric and Radiobiological Evaluation of Multiparametric MRI-Guided Dose Painting in Radiotherapy of Prostate Cancer

Radiotherapy is one of the treatment options for locally advanced prostate cancer; however, with standard radiation doses, it is not always very effective. One of the strategies to improve the efficiency of radiotherapy is increasing the dose. In this study, to increase tumor local control rates, a new radiotherapy method, known as dose painting (DP), was investigated. To compare 3-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiotherapy (IMRT) plans with DP for prostate cancer. Twenty-four consecutive patients with locally advanced prostate cancer who underwent an multiparametric-magnetic resonance imaging (MP-MRI) (T₂w, diffusion weighted image, dynamic contrast enhancement, and MRS) scan before a diagnostic biopsy from September 2015 to April 2016 were invited to take part in this study. The tumor local control probability (TCP) values for 3D-CRT, IMRT, and DP techniques were 45, 56, and 77%, respectively. The DP technique had a 37.5 and 71% higher TCP than IMRT and 3D-CRT, and these differences were statistically significant (P = 0.001). The mean normal tissue complication probability (NTCP) values of the organ at risks for 3D-CRT, IMRT, and DP showed that there were statistically significant differences among them in three plans (P = 0.01). DP by contours using MP-MRI is technically feasible. This study evaluated biological modeling based on both MP-MRI defined subvolumes and pathologically defined subvolumes. The MP-MRI-guided DP results in better TCP/NTCP than 3D-CRT and IMRT.

PSA nadir as a predictive factor for biochemical disease-free survival and overall survival following whole-gland salvage HIFU following radiotherapy failure

Background:

Treatment options for radio-recurrent prostate cancer are either androgen-deprivation therapy or salvage prostatectomy. Whole-gland high-intensity focussed ultrasound (HIFU) might have a role in this setting.

Methods:

An independent HIFU registry collated consecutive cases of HIFU. Between 2005 and 2012, we identified 50 men who underwent whole-gland HIFU following histological confirmation of localised disease following prior external beam radiotherapy (2005–2012). No upper threshold was applied for risk category, PSA or Gleason grade either at presentation or at the time of failure. Progression was defined as a composite with biochemical failure (Phoenix criteria (PSA>nadir+2 ng ml⁻¹)), start of systemic therapies or metastases.

Results:

Median age (interquartile range (IQR)), pretreatment PSA (IQR) and Gleason score (range) were 68 years (64–72), 5.9 ng ml⁻¹ (2.2–11.3) and 7 (6–9), respectively. Median follow-up was 64 months (49–84). In all, 24/50 (48%) avoided androgen-deprivation therapies. Also, a total of 28/50 (56%) achieved a PSA nadir <0.5 ng ml⁻¹, 15/50 (30%) had a nadir ⩾0.5 ng ml⁻¹ and 7/50 (14%) did not nadir (PSA non-responders). Actuarial 1, 3 and 5-year progression-free survival (PFS) was 72, 40 and 31%, respectively. Actuarial 1, 3 and 5-year overall survival (OS) was 100, 94 and 87%, respectively. When comparing patients with PSA nadir <0.5 ng ml⁻¹, nadir ⩾0.5 and non-responders, a statistically significant difference in PFS was seen (P<0.0001). Three-year PFS in each group was 57, 20 and 0%, respectively. Five-year OS was 96, 100 and 38%, respectively. Early in the learning curve, between 2005 and 2007, 3/50 (6%) developed a fistula. Intervention for bladder outlet obstruction was needed in 27/50 (54%). Patient-reported outcome measure questionnaires showed incontinence (any pad-use) as 8/26 (31%).

Conclusions:

In our series of high-risk patients, in whom 30–50% may have micro-metastases, disease control rates were promising in PSA responders, however, with significant morbidity. Additionally, post-HIFU PSA nadir appears to be an important predictor for both progression and survival. Further research on focal salvage ablation in order to reduce toxicity while retaining disease control rates is required.

Synergistic action of image-guided radiotherapy and androgen deprivation therapy

The combined use of androgen deprivation therapy (ADT) and image-guided radiotherapy (IGRT) can improve overall survival in aggressive, localized prostate cancer. However, owing to the adverse effects of prolonged ADT, it is imperative to identify the patients who would benefit from this combined-modality therapy relative to the use of IGRT alone. Opportunities exist for more personalized approaches in treating aggressive, locally advanced prostate cancer. Biomarkers--such as disseminated tumour cells, circulating tumour cells, genomic signatures and molecular imaging techniques--could identify the patients who are at greatest risk for systemic metastases and who would benefit from the addition of systemic ADT. By contrast, when biomarkers of systemic disease are not present, treatment could proceed using local IGRT alone. The choice of drug, treatment duration and timing of ADT relative to IGRT could be predicated on these personalized approaches to prostate cancer medicine. These novel treatment intensification and reduction strategies could result in improved prostate-cancer-specific survival and overall survival, without incurring the added expense of metabolic syndrome and other adverse effects of ADT in all patients.

Single session of high-intensity focused ultrasound for localized prostate cancer: treatment outcomes and potential effect as a primary therapy

Purpose

To investigate the treatment outcomes of a single-session high-intensity focused ultrasound (HIFU) using the Sonablate^® for patients with localized prostate cancer.

Methods

Biochemical failure was defined according to the Stuttgart definition [a rise of 1.2 ng/ml or more above the nadir prostate-specific antigen (PSA)] and the Phoenix definition (a rise of 2 ng/ml or more above the nadir PSA). Disease-free survival rate was defined using the Phoenix criteria and positive follow-up biopsy.

Results

A total of 171 patients were identified. Fifty-two (30.4 %) patients were identified to be with D’Amico low risk, 47 (27.5 %) with intermediate risk, and 72 (42.1 %) with high risk. In the median follow-up time of 43 months, there was 44 (25.7 %) and 36 (21.1 %) patients experienced biochemical failure for Stuttgart and Phoenix definition with mean (±SD) time to failure of 17.8 ± 2.1 and 19.4 ± 2.3 months, respectively. A total of 44 (25.7 %) patients were diagnosed as disease failure. Cox multivariate analysis revealed PSA nadir level (PSA cutoff = 0.2 ng/ml; HR = 9.472, 95 % CI 4.527–19.820, p < 0.001) and D’amico risk groups [HR = 3.132 (95 % CI 1.251–6.389), p = 0.033] were the predictor for failure in single-session HIFU.

Conclusions

Single-session HIFU treatment using the Sonablate^® seems to be potentially curative approach. When treated carefully with neoadjuvant hormonal therapy or preoperative transurethral resection of the prostate, higher-risk disease might be able to choose this minimally invasive procedure as primary therapy.

Radiotherapy with rectangular fields is associated with fewer clinical failures than conformal fields in the high-risk prostate cancer subgroup: results from a randomized trial

OBJECTIVE

High-risk prostate cancer patients are at risk for subclinical disease and micro-metastasis at the time of treatment. Nowadays, tight margins reduce dose to periprostatic areas compared to earlier techniques. We investigated whether rectangular fields were associated with fewer failures compared to conformal fields (with lower extraprostatic dose).

METHODS

We selected 164 high-risk patients from the trial population of 266 T1-T4N0M0 patients, randomized between rectangular (n=79) and conformal fields (n=85). Prescribed dose was 66 Gy to the prostate and seminal vesicles plus 15 mm margin. We compared clinical failure rates (in- and excluding local failures), between both arms. Dose differences around the prostate were calculated based on an inter-patient mapping method.

RESULTS

Median follow-up was 34 months. There were 9 clinical failures in the rectangular arm versus 24 in the conformal arm (p=0.012). Number of failures outside the prostate was 7 and 19, respectively (p=0.025). We observed average dose differences of 5-35 Gy between the arms in the regions around the prostate.

CONCLUSIONS

We found a significantly lower risk of early tumor progression for patients treated with rectangular fields. Treatment failure can probably in part be prevented by irradiation of areas suspected of subclinical disease in high-risk prostate cancer.

Single application of high-intensity focused ultrasound as a first-line therapy for clinically localized prostate cancer: 5-year outcomes

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? High-intensity focused ultrasound (HIFU) therapy has been proposed for the treatment of localized prostate cancer (PCa) for all risk levels of tumour recurrence. The study adds data on the efficacy of a single HIFU application in the treatment of PCa with different risks of recurrence. Durable cancer control was achieved in 81.7% of patients with low-risk disease, with rates of efficacy declining in intermediate- and high-risk tumours. The data suggest that the principal domain for minimal invasive HIFU should be low-risk disease.

OBJECTIVE

• To report cancer control results after a single application of high-intensity focused ultrasonography (HIFU) in patients with localized prostate cancer (PCa), stratified by tumour recurrence risk according to D'Amico risk classification.

PATIENTS AND METHODS

• In a retrospective single-centre study, we analysed the outcomes of patients with localized PCa who were treated with curative intent between December 2002 and October 2006 using an Ablatherm HIFU device (EDAP-TMS, France). • Transurethral resection of the prostate or adenomectomy were performed before HIFU to downsize large prostate glands. • Oncological failure was determined by the occurrence of biochemical relapse, positive biopsy and/or metastasis. Biochemical relapse was defined as a PSA nadir +1.2 ng/mL (Stuttgart definition), or as a rise in PSA level to ≥ 0.5 ng/mL if PSA doubling time was ≤ 6 months. Kaplan-Meier analysis was performed for survival estimates.

RESULTS

• A total of 191 consecutive patients were included in the study. The median (range) patient age was 69.7 (51-82) years, and 38, 34 and 28% of these patients were in the low-, intermediate- and high-risk groups, respectively. • The median (range) follow-up was 52.8 (0.2-79.8) months. • At 5 years, overall and cancer-specific survival rates were 86.3% and 98.4%, respectively. • Stratified by risk group, negative biopsy rates were 84.2%, 63.6%, and 67.5% (P = 0.032), 5-year biochemical-free survival rates were 84.8%, 64.9% and 54.9% (P< 0.01), and 5-year disease-free survival rates were 81.7%, 53.2% and 51.2% (P < 0.01), respectively.

CONCLUSION

• Single-session HIFU is recommended as a curative approach in elderly patients with low-risk PCa. Patients at higher risk of tumour progression should be counselled regarding the likely need for salvage therapy, including repeat HIFU.

Young age under 60 years is not a contraindication to treatment with definitive dose escalated radiotherapy for prostate cancer

BACKGROUND

It is widely believed that younger prostate cancer patients are at greater risk of recurrence following radiotherapy (RT).

METHODS

From 1992 to 2007, 2168 (395 age ≤ 60) men received conformal RT alone for prostate cancer at our institution (median dose=76 Gy, range: 72-80). Multivariable analysis (MVA) was used to identify significant predictors for BF and PCSM. Cumulative incidence was estimated using the competing risk method (Fine and Gray) for BF (Phoenix definition) and PCSM to account for the competing risk of death.

RESULTS

With a median follow-up of 72.2 months (range: 24.0-205.1), 8-year BF was 27.1% for age ≤ 60 vs. 23.7% for age >60 (p=0.29). Eight-year PCSM was 3.0% for age ≤ 60 vs. 2.0% for age >60 (p=0.52). MVA for BF identified initial PSA [adjusted HR=1.7 (PSA 10-20), 2.6 (PSA >20), p<0.01], Gleason score [adjusted HR=2.1 (G7), 1.9 (G8-10), p<0.01], T-stage [adjusted HR=1.7 (T2b-c), 2.6 (T3-4), p<0.01], and initial androgen deprivation therapy (ADT) [adjusted HR=0.38 (ADT >12 months), p<0.01] as significant, but not age or ADT <12 months. MVA for PCSM identified Gleason score [adjusted HR=3.0 (G8-10), p=0.01] and T-stage [adjusted HR=8.7 (T3-4), p<0.01] as significant, but not age, PSA, or ADT.

CONCLUSION

This is the largest, most mature study of younger men treated with RT for prostate cancer that confirms young age is not prognostic for BF.

Long-term survival after radical prostatectomy versus external-beam radiotherapy for patients with high-risk prostate cancer

BACKGROUND

The long-term survival of patients with high-risk prostate cancer was compared after radical prostatectomy (RRP) and after external beam radiation therapy (EBRT) with or without adjuvant androgen-deprivation therapy (ADT).

METHODS

In total, 1238 patients underwent RRP, and 609 patients received with EBRT (344 received EBRT plus ADT, and 265 received EBRT alone) between 1988 and 2004 who had a pretreatment prostate-specific antigen (PSA) level ≥ 20 ng/mL, a biopsy Gleason score between 8 and 10, or clinical tumor classification ≥ T3. The median follow-up was 10.2 years, 6.0 years, and 7.2 years after RRP, EBRT plus ADT, and EBRT alone, respectively. The impact of treatment modality on systemic progression, cancer-specific survival, and overall survival was evaluated using multivariate Cox proportional hazard regression analysis and a competing risk-regression model.

RESULTS

The 10-year cancer-specific survival rate was 92%, 92%, and 88% after RRP, EBRT plus ADT, and EBRT alone, respectively (P = .06). After adjustment for case mix, no significant differences in the risks of systemic progression (hazard ratio [HR], 0.78; 95% confidence interval [CI], 0.51-1.18; P = .23) or prostate cancer death (HR, 1.14; 95% CI, 0.68-1.91; P = .61) were observed between patients who received EBRT plus ADT and patients who underwent RRP. The risk of all-cause mortality, however, was greater after EBRT plus ADT than after RRP (HR, 1.60; 95% CI, 1.25-2.05; P = .0002).

CONCLUSIONS

RRP alone and EBRT plus ADT provided similar long-term cancer control for patients with high-risk prostate cancer. The authors concluded that continued investigation into the differing impact of treatments on quality-of-life and noncancer mortality will be necessary to determine the optimal management approach for these patients.

Prolongation of total treatment time because of infrequently missed days of treatment is not associated with inferior biochemical outcome after dose-escalated radiation therapy for prostate cancer

PURPOSE

Prolongation of treatment time with radiation therapy (RT) is associated with inferior disease control for many rapidly proliferating tumors, but it is uncertain whether the same effect is seen in prostate cancer.

METHODS AND MATERIALS

596 patients underwent with curative-intent RT for adenocarcinoma of the prostate. By National Comprehensive Cancer Network criteria, men were classified as having low-risk (30%), medium-risk (40%), or high-risk (30%) disease. The median RT dose was 72 Gy. Androgen-deprivation therapy (ADT) was used in 45%. The idealized treatment time was defined as the total elapsed time (including weekends) to complete treatment if started on a Monday. Missed days of treatment, defined as the number of days beyond the idealized treatment time, was recorded for all patients. Missed days were added to the end of therapy resulting in a longer treatment time. Analysis was conducted for missed days and other standard prognostic variables against freedom from biochemical failure (FFBF).

RESULTS

The median number of missed days was 2 (range, -3 to 22). With a median follow-up of 51 months, men with 5 or more missed days had similar 4-year FFBF rates (79% vs. 83% in men with <5 missed days, p = 0.0809), especially in the subset of men receiving 74 Gy or greater (89% for both groups, p = 0.8008). Analysis of missed days was performed for the subsets of dose, ADT, and risk category. Men without ADT had a lower FFBF rate with more missed days (p = 0.0030), but this association was not seen in men treated to a dose of 74 Gy or greater (p = 0.7425). On multivariate analysis, dose (p = 0.0010), T stage (p = 0.0145), and prostate-specific antigen level (p < 0.0001) were associated with FFBF, but Gleason score (p = 0.1351) and missed days (p = 0.3767) were not.

CONCLUSIONS

Slight prolongation of treatment time (e.g., ≤7 days) was not associated with inferior FFBF, especially in men receiving an RT dose of 74 Gy or greater.

Locally recurrent prostate cancer after external beam radiation therapy: diagnostic performance of 1.5-T endorectal MR imaging and MR spectroscopic imaging for detection

PURPOSE

To determine if performing magnetic resonance (MR) spectroscopic imaging, compared with performing T2-weighted MR imaging alone, improves the detection of locally recurrent prostate cancer after definitive external beam radiation therapy.

MATERIALS AND METHODS

This retrospective single-institution study was approved by the committee on human research, with a waiver of informed consent, and was compliant with HIPAA requirements. Sixty-four men who underwent endorectal MR imaging, MR spectroscopic imaging, and transrectal ultrasonographically guided biopsy for suspected local recurrence of prostate cancer after definitive external beam radiation therapy were retrospectively identified. Thirty-three patients had also received androgen therapy. Recurrent cancer was determined to be present or absent in the left and right sides of the prostate at T2-weighted MR imaging and MR spectroscopic imaging by a radiologist and a spectroscopist, respectively. Area under the receiver operating characteristic curve (A(Z)) was calculated for T2-weighted MR imaging alone and combined T2-weighted MR imaging and MR spectroscopic imaging by using generalized estimating equations and by using biopsy results as the reference standard.

RESULTS

Recurrent prostate cancer was identified at biopsy in 37 (58%) of the 64 men. Recurrence was unilateral in 28 patients and bilateral in nine (total of 46 affected prostate sides). A(Z) analysis revealed that use of combined T2-weighted MR imaging and MR spectroscopic imaging (A(Z) = 0.79), as compared with T2-weighted MR imaging alone (A(Z) = 0.67), significantly improved the detection of local recurrence (P = .001).

CONCLUSION

The addition of MR spectroscopic imaging to T2-weighted MR imaging significantly improves the diagnostic accuracy of endorectal MR imaging in the detection of locally recurrent prostate cancer after definitive external beam radiation therapy.

Outcome of patients with localized prostate cancer treated by radiotherapy after confirming the absence of lymph node invasion

Objective

Management of lymph nodes in radiotherapy for prostate cancer is an issue for curative intent. To find the influence of lymph nodes, patients with T1–T3 prostate cancer and surgically confirmed negative nodes were treated with radiotherapy.

Methods

After lymphadenectomy, 118 patients received photon beam radiotherapy with 66 Gy to the prostate. No adjuvant treatment was performed until biochemical failure. After failure, hormone therapy was administered. Follow-up period was 57 months (mean).

Results

Biochemical failure occurred in 47 patients. Few failures were observed in patients with low (24%) and intermediate risks (14%). In contrast, 64% of high-risk patients experienced failure, 97% of whom showed until 36 months. Most patients with failure responded well to hormone therapy. After 15 months (mean), a second biochemical failure occurred in 21% of patients who had the first failure, most of them were high risk. Factors involving failure were high initial and nadir prostate-specific antigen, advanced stage, short prostate-specific antigen-doubling time and duration between radiation and first failure. Failure showed an insufficient reduction in prostate-specific antigen after radiotherapy. Factor for second failure was prostate-specific antigen-doubling time at first failure.

Conclusions

Half of high-risk patients experienced biochemical failure, indicating one of the causes involves factors other than lymph nodes. Low-, intermediate- and the other half of high-risk patients did not need to take immediate hormone therapy after radiotherapy. After failure, delayed hormone therapy was effective. Prostate-specific antigen parameters were predictive factors for further outcome.

Metastasis after radical prostatectomy or external beam radiotherapy for patients with clinically localized prostate cancer: a comparison of clinical cohorts adjusted for case mix

PURPOSE

We assessed the effect of radical prostatectomy (RP) and external beam radiotherapy (EBRT) on distant metastases (DM) rates in patients with localized prostate cancer treated with RP or EBRT at a single specialized cancer center.

PATIENTS AND METHODS

Patients with clinical stages T1c-T3b prostate cancer were treated with intensity-modulated EBRT (> or = 81 Gy) or RP. Both cohorts included patients treated with salvage radiotherapy or androgen-deprivation therapy for biochemical failure. Salvage therapy for patients with RP was delivered a median of 13 months after biochemical failure compared with 69 months for EBRT patients. DM was compared controlling for patient age, clinical stage, serum prostate-specific antigen level, biopsy Gleason score, and year of treatment.

RESULTS

The 8-year probability of freedom from metastatic progression was 97% for RP patients and 93% for EBRT patients. After adjustment for case mix, surgery was associated with a reduced risk of metastasis (hazard ratio, 0.35; 95% CI, 0.19 to 0.65; P < .001). Results were similar for prostate cancer-specific mortality (hazard ratio, 0.32; 95% CI, 0.13 to 0.80; P = .015). Rates of metastatic progression were similar for favorable-risk disease (1.9% difference in 8-year metastasis-free survival), somewhat reduced for intermediate-risk disease (3.3%), and more substantially reduced in unfavorable-risk disease (7.8% in 8-year metastatic progression).

CONCLUSION

Metastatic progression is infrequent in men with low-risk prostate cancer treated with either RP or EBRT. RP patients with higher-risk disease treated had a lower risk of metastatic progression and prostate cancer-specific death than EBRT patients. These results may be confounded by differences in the use and timing of salvage therapy.

Neoadjuvant LHRH analog plus estramustine phosphate combined with three-dimensional conformal radiotherapy for intermediate- to high-risk prostate cancer: a randomized study

OBJECTIVE

The objective of this study is to assess the safety and efficacy of a treatment regimen comprising neoadjuvant conventional androgen deprivation therapy (ADT) plus estramustine phosphate (EMP) combined with three-dimensional conformal radiotherapy (3D-CRT) for patients with intermediate- to high-risk prostate cancer.

METHODS

Thirty-nine patients with intermediate- to high-risk prostate cancer classified according to the NCCN practice guidelines recurrence risk group were randomly allocated into two groups: neoadjuvant LHRH agonist plus EMP for 6 months until completion of the 3D-CRT (EMP group, n = 20), or neoadjuvant LHRH agonist alone (LHRH group, n = 19). Both groups received 3D-CRT in daily fractions of 2 Gy for a total dose of 70 Gy. PSA relapse was defined according to the Phoenix definition.

RESULTS

The median duration of follow-up was 27.1 months. None of the patients died during the follow-up period, but three patients in the LHRH group developed distant metastasis. The 4-year PSA relapse-free survival outcomes for the EMP group and LHRH group were 61.2 and 49.4%, respectively (P = 0.04). Multivariate Cox regression model analyses of the pretreatment PSA level (>20 ng/ml n = 16 vs. < or =20 ng/ml n = 23), grade (G8 or more n = 11 vs. G7 or less n = 28) and modality (LHRH group n = 19 vs. EMP group n = 20) revealed these factors to be independent predictors of PSA relapse after treatment: pretreatment PSA had a relative risk of 3.84 (95% CI: 1.003-14.722), grade had a relative risk of 4.29 (95% CI: 1.093-16.824), and modality had a relative risk of 8.01 (95% CI: 1.867-34.361). No severe toxicities were observed in either group.

CONCLUSIONS

The present results indicate that the combination of neoadjuvant ADT plus EMP combined with 3D-CRT sustains freedom from PSA relapse in patients with intermediate- to high-risk prostate cancer. However, this regimen is insufficient for preventing biochemical failure, and an additional intervention such as adjuvant ADT, radiation dose escalation, or both, is required, especially for patients with a pretreatment PSA level of more than 20 ng/ml and high-grade cancer.

Does treatment duration affect outcome after radiotherapy for prostate cancer?

PURPOSE

The protraction of external beam radiotherapy (RT) time is detrimental in several disease sites. In prostate cancer, the overall treatment time can be considerable, as can the potential for treatment breaks. We evaluated the effect of elapsed treatment time on outcome after RT for prostate cancer.

METHODS AND MATERIALS

Between April 1989 and November 2004, 1,796 men with prostate cancer were treated with RT alone. The nontreatment day ratio (NTDR) was defined as the number of nontreatment days divided by the total elapsed days of RT. This ratio was used to account for the relationship between treatment duration and total RT dose. Men were stratified into low risk (n = 789), intermediate risk (n = 798), and high risk (n = 209) using a single-factor model.

RESULTS

The 10-year freedom from biochemical failure (FFBF) rate was 68% for a NTDR <33% vs. 58% for NTDR >/=33% (p = 0.02; BF was defined as a prostate-specific antigen nadir + 2 ng/mL). In the low-risk group, the 10-year FFBF rate was 82% for NTDR <33% vs. 57% for NTDR >/=33% (p = 0.0019). The NTDR was independently predictive for FFBF (p = 0.03), in addition to T stage (p = 0.005) and initial prostate-specific antigen level (p < 0.0001) on multivariate analysis, including Gleason score and radiation dose. The NTDR was not a significant predictor of FFBF when examined in the intermediate-risk group, high-risk group, or all risk groups combined.

CONCLUSIONS

A proportionally longer treatment duration was identified as an adverse factor in low-risk patients. Treatment breaks resulting in a NTDR of >/=33% (e.g., four or more breaks during a 40-fraction treatment, 5 d/wk) should be avoided.

Secondary therapy, metastatic progression, and cancer-specific mortality in men with clinically high-risk prostate cancer treated with radical prostatectomy

OBJECTIVES

Commonly used definitions for high-risk prostate cancer identify men at increased risk of PSA relapse after radical prostatectomy (RP). We assessed how accurately these definitions identify patients likely to receive secondary cancer therapy, experience metastatic progression, or die of prostate cancer.

MATERIALS AND METHODS

Among 5960 men with clinically localized or locally advanced prostate cancer who underwent RP, we identified eight different high-risk subsets, each comprising 4-40% of the study population. Estimates of freedom from radiation therapy, hormonal therapy, and metastatic progression after surgery were generated for each high-risk cohort with the Kaplan-Meier method, and hazard ratios (HR) were calculated with a Cox proportional hazards regression. The cumulative incidence and HR for prostate cancer-specific mortality (PCSM) were estimated with competing risk analysis.

RESULTS

Each of the studied high-risk criteria was associated with increased hazard of secondary cancer therapy (HR=1.3-5.2, p<0.05) and metastatic progression (HR=2.1-6.9, p<0.05). However, depending on the definition, the probability of freedom from additional therapy 10 yr after surgery ranged from 35% to 76%. The 10-yr cumulative incidence of PCSM in high-risk patients ranged from 3% to 11% (HR=3.2-10.4, p<0.0005).

CONCLUSIONS

Commonly used definitions for high-risk prostate cancer identify men at increased risk of secondary cancer therapy, metastatic progression, and PCSM following RP. However, a substantial proportion of high-risk patients remain free from additional therapy or metastatic disease many years after surgery. The risk of PCSM within 10 yr of treatment is remarkably low, even for patients at the highest risk of recurrent disease.

Effect of increasing radiation doses on local and distant failures in patients with localized prostate cancer

PURPOSE

To study the effect of radiation dose on local failure (LF) and distant metastasis (DM) in prostate cancer patients treated with external beam radiotherapy.

METHODS AND MATERIALS

The study sample consisted of 919 Stage T1-T3N0M0 patients treated with radiotherapy alone. Three separate dose groups were analyzed: <72 Gy (n = 552, median dose, 68.4 Gy), > or =72 but <82 Gy (n = 215, median dose, 78 Gy), and > or =82 Gy (n = 152, median dose, 83 Gy). The median follow-up period for all patients and those receiving <72 Gy, > or =72 but <82 Gy, and > or =82 Gy was 97, 112, 94, and 65 months, respectively.

RESULTS

For all patients, the LF rate at 10 and 15 years was 6% and 13%, respectively. The 7-year LF rate stratified by dose group (<72 Gy, > or =72 but <82 Gy, and > or =82 Gy) was 6%, 2%, and 2%, respectively (p = 0.012). For all patients, the DM rate at 10 and 15 years was 10% and 17%, respectively. The 7-year DM rate stratified by dose group (<72 Gy, > or =72 but <82 Gy, and > or =82 Gy) was 9%, 6%, and 1%, respectively (p = 0.008). Multivariate analysis revealed T stage (p < 0.001), pretreatment prostate-specific antigen level (p = 0.001), Gleason score (p < 0.001), and dose (p = 0.018) to be independent predictors of DM. For all 919 patients, multivariate analysis revealed only Gleason score (p = 0.009) and dose (p = 0.004) to be independent predictors of LF.

CONCLUSION

Although the effect of increasing radiation doses has been documented mostly for biochemical failure rates, the results of our study have shown a clear association between greater radiation doses and lower LF and DM rates.