Perineural invasion associated with increased cancer-specific mortality after external beam radiation therapy for men with low- and intermediate-risk prostate cancer

Evolution of definitive external beam radiation therapy in the treatment of prostate cancer

PURPOSE

Although the clinical significance of a diagnosis of prostate cancer for some men is debated, for many men it leads to significant morbidity and mortality. Radical treatment of clinically localized prostate cancer has been shown to improve survival in men with intermediate or high-risk disease. There is no high level evidence to support the superiority of radical prostatectomy, with or without adjuvant or salvage external beam radiotherapy in comparison to definitive radiotherapy with or without androgen deprivation, and the choice should be individualized. External beam radiation therapy practices are in constant evolution, and numerous strategies have been investigated to improve either efficacy or reduce toxicity, or both.

METHODS

Randomized controlled trials investigating strategies to improve efficacy, reduce toxicity, or both of external beam radiotherapy have been reviewed in men with prostate cancer without nodal or distant metastases. These strategies include the use of neo-adjuvant and adjuvant androgen deprivation, dose-escalation, hypofractionation, whole pelvic radiation therapy, incorporation of improved imaging, image- guided radiation therapy, and adjuvant systemic therapy. The evidence to date for these strategies is discussed, noting limitations in applying the results of reported trials to men treated in contemporary settings.

RESULTS

A number of strategies have shown improvements in biochemical control using external beam radiotherapy. To date, only with the use of androgen deprivation therapy has this translated into improvements in disease specific and overall survival. This may reflect the long natural history of prostate cancer and high incidence of competing risks. Technological advances have enabled dose escalation with reduced toxicity, of paramount importance given the long natural history.

RESULTS

The use of external beam radiation therapy in prostate cancer is evolving with numerous strategies incorporated to improve outcomes. The optimum dose and fractionation and use of androgen deprivation or systemic adjuvants for each man is unclear based on current evidence and prognostic and predictive parameters. Patient preferences play an important role in chosen therapy. It is hoped that future studies better capture all prostate cancer- and treatment- related morbidity to clarify the optimal therapy choices for each man with prostate cancer.

Both acute and chronic inflammation are associated with less perineural invasion in men with prostate cancer on repeat biopsy

OBJECTIVES

To evaluate the association between acute and chronic inflammation with the presence of perineural invasion (PNI) in prostate biopsies positive for prostate cancer (PCa).

MATERIAL AND METHODS

We conducted a retrospective analysis of 1 399 prostate biopsies positive for PCa in the Reduction by Dutasteride of PCa Events (REDUCE) study. PCa, acute and chronic prostate inflammation and PNI were assessed by central pathology review. The association between acute and chronic inflammation with PNI was evaluated using chi-squared and Kruskal-Wallis tests, and logistic regression adjusting for clinicopathological and biochemical variables.

RESULTS

The presence of PNI was identified in 133 biopsies (9.5%). In all, 267 biopsies (19.1%) had acute inflammation, 1 038 (74.2%) had chronic inflammation, and 255 (18.2%) had both. The presence of both acute and chronic inflammation had a mutual association (P < 0.001). Chronic inflammation was associated with a lower Gleason score (P = 0.009) and lower tumour volume (P < 0.001), while acute inflammation was associated with lower Gleason score (P = 0.04), lower tumour volume (P = 0.004) and higher prostate-specific antigen levels (P = 0.05). In both univariable and multivariable analyses, chronic prostate inflammation was significantly associated with less PNI (univariable odds ratio [OR] 0.54, 95% confidence interval [CI] 0.37-0.79, P = 0.001; multivariable OR 0.65, 95% CI 0.43-0.99, P = 0.045). Acute prostate inflammation was associated with less PNI only in univariable analysis (univariable OR 0.51, 95% CI 0.29-0.89, P = 0.018; multivariable OR 0.63, 95% CI 0.35-1.13, P = 0.12).

CONCLUSION

Acute and chronic prostate inflammation were both associated with a lower prevalence of PNI in prostate biopsies positive for PCa. If confirmed, this suggests that inflammation and immunomodulation can serve as areas of potential therapeutic design to mitigate PNI in patients with PCa.

Effects of perineural invasion on biochemical recurrence and prostate cancer-specific survival in patients treated with definitive external beam radiotherapy

OBJECTIVES

Perineural invasion (PNI) has not yet gained universal acceptance as an independent predictor of adverse outcomes for prostate cancer treated with external beam radiotherapy (EBRT). We analyzed the prognostic influence of PNI for a large institutional cohort of prostate cancer patients who underwent EBRT with and without androgen deprivation therapy (ADT).

MATERIAL AND METHODS

We, retrospectively, reviewed prostate cancer patients treated with EBRT from 1993 to 2007 at our institution. The primary endpoint was biochemical failure-free survival (BFFS), with secondary endpoints of metastasis-free survival (MFS), prostate cancer-specific survival (PCSS), and overall survival (OS). Univariate and multivariable Cox proportional hazards models were constructed for all survival endpoints. Hazard ratios for PNI were analyzed for the entire cohort and for subsets defined by NCCN risk level. Additionally, Kaplan-Meier survival curves were generated for all survival endpoints after stratification by PNI status, with significant differences computed using the log-rank test.

RESULTS

Of 888 men included for analysis, PNI was present on biopsy specimens in 187 (21.1%). PNI was associated with clinical stage, pretreatment PSA level, biopsy Gleason score, and use of ADT (all P<0.01). Men with PNI experienced significantly inferior 10-year BFFS (40.0% vs. 57.8%, P = 0.002), 10-year MFS (79.7% vs. 89.0%, P = 0.001), and 10-year PCSS (90.9% vs. 95.9%, P = 0.009), but not 10-year OS (67.5% vs. 77.5%, P = 0.07). On multivariate analysis, PNI was independently associated with inferior BFFS (P<0.001), but not MFS, PCSS, or OS. In subset analysis, PNI was associated with inferior BFFS (P = 0.04) for high-risk patients and with both inferior BFFS (P = 0.01) and PCSS (P = 0.05) for low-risk patients. Biochemical failure occurred in 33% of low-risk men with PNI who did not receive ADT compared to 8% for low-risk men with PNI treated with ADT (P = 0.01).

CONCLUSION

PNI was an independently significant predictor of adverse survival outcomes in this large institutional cohort, particularly for patients with NCCN low-risk disease. PNI should be carefully considered along with other standard prognostic factors when treating these patients with EBRT. Supplementing EBRT with ADT may be beneficial for select low-risk patients with PNI though independent validation with prospective studies is recommended.

Perineural Invasion and Risk of Lethal Prostate Cancer

Background: Prostate cancer has a propensity to invade and grow along nerves, a phenomenon called perineural invasion (PNI). Recent studies suggest that the presence of PNI in prostate cancer has been associated with cancer aggressiveness.Methods: We investigated the association between PNI and lethal prostate cancer in untreated and treated prostate cancer cohorts: the Swedish Watchful Waiting Cohort of 615 men who underwent watchful waiting, and the U.S. Health Professionals Follow-Up Study of 849 men treated with radical prostatectomy. One pathologist performed a standardized histopathologic review assessing PNI and Gleason grade. Patients were followed from diagnosis until metastasis or death.Results: The prevalence of PNI was 7% and 44% in the untreated and treated cohorts, respectively. PNI was more common in high Gleason grade tumors in both cohorts. PNI was associated with enhanced tumor angiogenesis, but not tumor proliferation or apoptosis. In the Swedish study, PNI was associated with lethal prostate cancer [OR 7.4; 95% confidence interval (CI), 3.6-16.6; P < 0.001]. A positive, although not statistically significant, association persisted after adjustment for age, Gleason grade, and tumor volume (OR 1.9; 95% CI, 0.8-5.1; P = 0.17). In the U.S. study, PNI predicted lethal prostate cancer independent of clinical factors (HR 1.8; 95% CI, 1.0, 3.3; P =0.04).Conclusions: These data support the hypothesis that perineural invasion creates a microenvironment that promotes cancer aggressiveness.Impact: Our findings suggest that PNI should be a standardized component of histopathologic review, and highlights a mechanism underlying prostate cancer metastasis. Cancer Epidemiol Biomarkers Prev; 26(5); 719-26. ©2017 AACR.

The relationship between perineural invasion, tumor grade, reactive stroma and prostate cancer-specific mortality: A clinicopathologic study on a population-based cohort

BACKGROUND

In vitro and in vivo studies have shown that nerves, tumor epithelium, and stroma interact and promote prostate cancer (PC) progression. Perineural invasion (PNI) is established amidst these interactions and may therefore indicate an aggressive PC phenotype. The purpose of the present study was to determine the relationship between PNI, tumor grade, reactive stroma, and PC-specific mortality.

METHODS

A population-based study on 318 patients, encompassing all cases of PC diagnosed by needle biopsies and without evidence of systemic metastasis at the time of diagnosis in Aust-Agder County in the period of 1991-1999. Patients were identified by cross-referencing the Cancer Registry of Norway. Clinical data were obtained by review of medical charts. Diagnostic prostate needle biopsies were reviewed with respect to presence of PNI, percentage of biopsy cores with PNI, Gleason score (GS), and reactive stromal grade (RSG). The endpoint was PC-specific mortality.

RESULTS

The presence of PNI was significantly associated with high tumor grade and abundant reactive stroma. The 10-year PC-specific survival for patients with and without PNI was 72% and 91%, respectively (P = 0.001, log rank). PNI predicted PC-specific mortality independently of clinical factors, though the effect of PNI was attenuated when adjusting for GS and RSG. However, a percentage of biopsy cores with PNI >50% was found to predict PC-specific mortality independently of other clinicopathologic parameters.

CONCLUSIONS

The present population-based study shows that PNI on diagnostic prostate needle biopsy is associated with increased risk of PC-specific mortality. Our findings demonstrate that the prognostic effect of PNI is dependent on an association with high grade carcinoma and reactive stroma. However; the impact of PNI on clinical outcome becomes stronger and independent of other clinicopathologic factors upon increased percentage of PNI positive biopsy cores. Thus, our study highlights the importance of PNI and microenvironmental interactions for the long-term outcome of PC.

Baseline Perineural Invasion is Associated with Shorter Time to Progression in Men with Prostate Cancer Undergoing Active Surveillance: Results from the REDEEM Study

PURPOSE

We evaluated the association of perineural invasion with disease progression in men with prostate cancer on active surveillance.

MATERIALS AND METHODS

We retrospectively analyzed the records of 302 men on active surveillance for low risk prostate cancer (T1c-T2a), Gleason 6 or less, 3 or fewer positive cores, 50% or less of any core involved and prostate specific antigen 11 ng/ml or less in the REduction by Dutasteride of clinical progression Events in Expectant Management (REDEEM) study. Patients underwent study mandated biopsies 18 and 36 months after enrollment. Disease progression was divided into pathological (4 or greater positive cores, 50% or greater core involvement, or Gleason greater than 6 on followup biopsy), therapeutic (any therapeutic prostate cancer intervention) or clinical (pathological or therapeutic progression). Time to disease progression was analyzed with Cox models adjusting for patient age, race, baseline prostate specific antigen, number of sampled and involved cores, tumor length and treatment.

RESULTS

A total of 11 patients (4%) had perineural invasion on baseline biopsy. Perineural invasion was not associated with any baseline features (each p >0.05). During the study clinical progression developed in 125 patients (41%), including pathological progression in 95. One, 2 and 3-year clinical progression-free survival for men with vs without perineural invasion was 82%, 27% and 27% vs 93%, 67% and 58%, respectively (p <0.05). On multivariable analyses perineural invasion was associated with clinical (HR 2.39, 95% CI 1.16-4.94, p = 0.019) and pathological progression (HR 2.21, 95% CI 0.92-5.33, p = 0.076).

CONCLUSIONS

Among patients with prostate cancer on active surveillance perineural invasion was associated with an increased risk of clinical progression. The 2-year risk of clinical progression with perineural invasion was 73%. If these results are confirmed, patients with perineural invasion may not be good active surveillance candidates.

Neoadjuvant chemoradiation followed by interstitial prostate brachytherapy for synchronous prostate and rectal cancer

PURPOSE

To describe outcomes with the use of neoadjuvant pelvic chemoradiation followed by prostate interstitial brachytherapy for the treatment of synchronous prostate and rectal cancers.

METHODS AND MATERIALS

An Internal Review Board approved retrospective review was undertaken of 4 patients with synchronous prostate and rectal cancer treated between 2006 and 2008. Patients underwent pelvic chemoradiation followed by prostate brachytherapy, then low anterior resection of the rectum with diverting loop ileostomy and adjuvant chemotherapy. Follow-up evaluation included imaging and laboratory analysis of cancer markers in addition to routine interval history and physical examination.

RESULTS

At 38-62 months postdiagnosis (24-53 months post-treatment), 6 of 8 cancers remained without evidence of relapse. One patient had rising carcinoembryonic antigen levels but no clinically evident rectal cancer relapse; another developed bony metastasis of his high-risk prostate cancer. Three patients experienced grade 1-2 treatment-related toxicity; one patient had grade 3 gastrointestinal toxicity from radiation and surgery, which precluded his receiving adjuvant chemotherapy and ileostomy reversal.

CONCLUSIONS

Chemoradiation followed by prostate brachytherapy, surgery, and adjuvant chemotherapy may be utilized to manage patients with synchronous prostate and rectal cancers.

Factors implicated in radiation therapy failure and radiosensitization of prostate cancer

Tissue markers may be helpful in enhancing prediction of radiation therapy (RT) failure of prostate cancer (PCa). Among the various biomarkers tested in Phase III randomized trials conducted by the Radiation Therapy Oncology Group, p16, Ki-67, MDM2, COX-2, and PKA yielded the most robust data in predicting RT failure. Other pathways involved in RT failure are also implicated in the development of castration-resistant PCa, including the hypersensitive androgen receptor, EGFR, VEGF-R, and PI3K/Akt. Most of them are detectable in PCa tissue even at the time of initial diagnosis. Emerging evidence suggests that RT failure of PCa results from a multifactorial and heterogeneous disease process. A number of tissue markers are available to identify patients at high risk to fail RT. Some of these markers have the promise to be targeted by drugs currently available to enhance the efficacy of RT and delay disease progression.

Perineural invasion predicts increased recurrence, metastasis, and death from prostate cancer following treatment with dose-escalated radiation therapy

PURPOSE

To assess the prognostic value of perineural invasion (PNI) for patients treated with dose-escalated external-beam radiation therapy for prostate cancer.

METHODS AND MATERIALS

Outcomes were analyzed for 651 men treated for prostate cancer with EBRT to a minimum dose ≥75 Gy. We assessed the impact of PNI as well as pretreatment and treatment-related factors on freedom from biochemical failure (FFBF), freedom from metastasis (FFM), cause-specific survival (CSS), and overall survival.

RESULTS

PNI was present in 34% of specimens at biopsy and was significantly associated with higher Gleason score (GS), T stage, and prostate-specific antigen level. On univariate and multivariate analysis, the presence of PNI was associated with worse FFBF (hazard ratio = 1.7, p <0.006), FFM (hazard ratio = 1.8, p <0.03), and CSS (HR = 1.4, p <0.05) compared with absence of PNI; there was no difference in overall survival. Seven-year rates of FFBF, FFM, and CCS were 64% vs. 80%, 84% vs. 92%, and 91% vs. 95% for those patients with and without PNI, respectively. On recursive partitioning analysis, PNI predicted for worse FFM and CSS in patients with GS 8-10, with FFM of 67% vs. 89% (p <0.02), and CSS of 69% vs. 91%, (p <0.04) at 7 years for those with and without PNI, respectively.

CONCLUSIONS

The presence of PNI in the prostate biopsy predicts worse clinical outcome for patients treated with dose-escalated external-beam radiation therapy. Particularly in patients with GS 8-10 disease, the presence of PNI suggests an increased risk of metastasis and prostate cancer death.

A novel signaling axis of matriptase/PDGF-D/ß-PDGFR in human prostate cancer

Increasing evidence indicates the significance of platelet-derived growth factor receptor-β (β-PDGFR) signaling in prostate cancer (PCa). Accordingly, preclinical studies suggest the potential of β-PDGFR as a therapeutic target in metastatic PCa. However, a ligand responsible for β-PDGFR activation in PCa was unknown, and recent clinical trials with imatinib mesylate showed limited success due to normal tissue toxicity. Similarly, in spite of mounting evidence indicating the significance of matriptase in PCa, little is known about its substrates or molecular actions during PCa progression. Here, we identified PDGF-D as a ligand for β-PDGFR in PCa and discovered matriptase as its regulator. Matriptase activates PDGF-D by proteolytic removal of the CUB domain in a 2-step process, creating a hemidimer, followed by growth factor domain dimer (GFD-D) generation. Matriptase can deactivate PDGF-D by further proteolytic cleavage within the GFD, revealing its biphasic regulation. Importantly, PDGF-D/matriptase colocalization is accompanied with β-PDGFR phosphorylation in human PCa tissues. This study unveiled a novel signaling axis of matriptase/PDGF-D/β-PDGFR in PCa, providing new insights into functional interplay between serine protease and growth factor signaling networks.

Adenocarcinoma of the prostate involving the lumbosacral plexus: MRI evidence to support direct perineural spread

BACKGROUND

Prostate adenocarcinoma, which may recur despite aggressive treatment, has the potential to spread to the lumbosacral plexus. This intraneural involvement is not widely known and is thought to be from direct perineural spread. We hypothesized that high-resolution imaging could provide supportive evidence for this mechanism.

METHODS

The clinical data and imaging studies (magnetic resonance imaging, MRI, and positron emission tomography/computed tomography, PET/CT) of patients evaluated at our institution between 2004 and 2009 for lumbosacral plexopathy due to intraneural prostate carcinoma were retrospectively reviewed.

RESULTS

Four patients presenting with painful lumbosacral plexopathy were found to have intraneural lumbosacral prostate adenocarcinoma. Two patients had involvement of the lumbosacral plexus ipsilateral to the lobe of the prostate most involved with adenocarcinoma at prostatectomy. High-resolution MRI and PET/CT studies revealed similar findings: abnormal soft tissue signal was followed from the prostate (n = 1) or prostatic bed (n = 3) area along the expected course of the pelvic plexus to the level of the sciatic notch, where it involved the sacral spinal nerves and sciatic nerve. Imaging findings were consistent with neoplastic infiltration, which was confirmed at biopsy in three patients.

CONCLUSIONS

The potential for prostate adenocarcinoma to spread to the lumbosacral plexus has, to our knowledge, not been readily appreciated. Because the imaging findings are often subtle, we believe that intraneural lumbosacral plexus involvement may not be uncommon. This study, with the use of high-resolution MRI and PET/CT studies, supports the direct perineural spread of prostate adenocarcinoma via the pelvic plexus to the lumbosacral plexus. This mechanism could also explain cases of leptomeningeal and/or dural-based prostate metastases.

The impact of perineural invasion on biochemical outcome after permanent prostate iodine-125 brachytherapy

PURPOSE

Perineural invasion (PNI) in prostate biopsies is associated with increased risk of higher Gleason score and worse pathologic stage. We report the influence of PNI in biochemical no evidence of disease (bNED) survival after (125)I prostate brachytherapy (BT).

METHODS AND MATERIALS

Pathology reports of 700 men with localized prostate cancer who underwent (125)I prostate BT in 1999-2008 were reviewed. The presence or absence of PNI in the biopsy was documented in 339 men. Clinical, treatment, and dosimetric parameters, along with PNI status, were evaluated for bNED survival, defined by "nadir+2" definition.

RESULTS

Of the 339 patients, 87% had favorable risk and 13% intermediate risk. PNI was present in 89 patients (26%). After a median followup of 32 months, there were five biochemical failures (4: +PNI and 1: -PNI), of which one was local failure (+PNI). Actuarial 5-year bNED survival for the entire group was 97.0% (92.9% for +PNI; 99.2% for -PNI). In univariate analysis age, pretreatment prostate-specific antigen, Gleason score 7, and intermediate risk group predicted for worse biochemical outcome, whereas the presence of PNI showed a trend toward significance (p=0.06). Some of the regression algorithms failed to converge because of low event rates.

CONCLUSIONS

We report excellent biochemical control in 339 men treated with (125)I prostate BT. The presence of PNI showed a trend toward significance in predicting 5-year bNED survival but did not impact on local control and should not influence the decision to recommend BT for localized prostate cancer.

The clinical significance and therapeutic implications of extraprostatic invasion

Invasion of the prostatic margin by cancer establishes a higher risk of disease progression and treatment failure depending upon its extent and other clinical factors. Pathological stage is the most important single prognostic indicator, but determined reliably only in patients having radical prostatectomy. Tumour beyond the prostatic margin or its invasion into the seminal vesicle defines the local stage category as T3, and when confirmed by pathological examination the extent of prostatic margin involvement has prognostic significance. Prediction of extraprostatic invasion may influence therapeutic decisions, but can be difficult to determine for the individual patient prior to treatment. In some individuals having radical prostatectomy, the finding of extraprostatic invasion is unsuspected, and fortunately for the majority of these men the treatment remains curative. On the other hand, when extraprostatic invasion is suspected prior to or at surgery, wide excision may be necessary to achieve negative surgical margins, with other factors contributing independently to the likelihood of subsequent progression. Radiotherapy is an effective alternative treatment for clinical stage T3 and high-risk clinically localized cancer. Recent technological advances and use of combination modality treatment with radiation and hormone manipulation have improved survival outcomes and reduced side-effects. Radiation also has its place as adjuvant treatment following radical prostatectomy in high-risk disease, or as salvage following PSA recurrence, with ongoing trials evaluating potential benefit and toxicity. For clinically localised stage T3 prostate cancer, treatment with surgery or radiotherapy may be highly effective, but multimodality interventions are increasingly being used for primary treatment where clinical assessment indicates that there would otherwise be a high risk for disease progression and therapeutic failure.

Definitive radiotherapy for prostate cancer

The probability of extraprostatic disease may be estimated based on clinical T-stage, pretreatment prostatic-specific antigen, Gleason score, and percent positive core biopsies. Patients with disease confined to the prostate may be treated with either prostatectomy or radiotherapy (RT). Patients with extraprostatic disease without evidence of distant metastases are best managed with RT. RT consisting of either external beam and/or brachytherapy results in a relatively high likelihood of cure, particularly for those with low- and intermediate-risk disease. The impact of elective nodal RT on survival is unclear. Dose escalation results in improved biochemical relapse-free survival compared with standard dose RT. Androgen deprivation therapy likely improves the probability of disease control in patients with high-risk cancers.

Expression of microRNAs and protein-coding genes associated with perineural invasion in prostate cancer

BACKGROUND

Perineural invasion (PNI) is the dominant pathway for local invasion in prostate cancer. To date, only few studies have investigated the molecular differences between prostate tumors with PNI and those without it.

METHODS

To evaluate the involvement of both microRNAs and protein-coding genes in PNI, we determined their genome-wide expression with a custom microRNA microarray and Affymetrix GeneChips in 50 prostate adenocarcinomas with PNI and 7 without it. In situ hybridization (ISH) and immunohistochemistry was used to validate candidate genes.

RESULTS

Unsupervised classification of the 57 adenocarcinomas revealed two clusters of tumors with distinct global microRNA expression. One cluster contained all non-PNI tumors and a subgroup of PNI tumors. Significance analysis of microarray data yielded a list of microRNAs associated with PNI. At a false discovery rate (FDR)<10%, 19 microRNAs were higher expressed in PNI tumors than in non-PNI tumors. The most differently expressed microRNA was miR-224. ISH showed that this microRNA is expressed by perineural cancer cells. The analysis of protein-coding genes identified 34 transcripts that were differently expressed by PNI status (FDR<10%). These transcripts were down-regulated in PNI tumors. Many of those encoded metallothioneins and proteins with mitochondrial localization and involvement in cell metabolism. Consistent with the microarray data, perineural cancer cells tended to have lower metallothionein expression by immunohistochemistry than nonperineural cancer cells.

CONCLUSIONS

Although preliminary, our findings suggest that alterations in microRNA expression, mitochondrial function, and cell metabolism occur at the transition from a noninvasive prostate tumor to a tumor with PNI.

Perineural invasion affects biochemical recurrence-free survival in patients with prostate cancer treated with definitive external beam radiotherapy

OBJECTIVES

To assess the prognostic effect of perineural invasion (PNI) for patients undergoing external beam radiotherapy for prostate cancer.

METHODS

We evaluated 657 consecutive patients who had undergone external beam radiotherapy for clinically localized prostate cancer. The clinical/treatment parameters used for analysis included PNI, clinical stage, biopsy Gleason score, pretreatment prostate-specific antigen, radiation dose, and androgen deprivation. The primary endpoint was biochemical recurrence defined by the Radiation Therapy Oncology Group-American Society for Therapeutic Radiology Oncology Phoenix consensus; the secondary endpoint was prostate cancer death.

RESULTS

Of 586 men with a minimum of 24 months of follow-up, 112 (19.1%) had PNI present in the biopsy specimen. When patients were stratified into risk groups using the National Comprehensive Cancer Network criteria, PNI was more prevalent in patients within higher risk groups (6.8% in low-risk versus 18.3% in intermediate-risk versus 30.1% in high-risk groups; P <0.001). The presence of PNI was associated with lower biochemical recurrence-free (P = 0.003) and cancer-specific (P = 0.040) survival rates by Kaplan-Meier analysis. Cox regression analysis showed that PNI was a statistically significant prognostic factor of biochemical recurrence on both univariate (hazard ratio [HR] 1.71, 95% confidence interval [CI] 1.19 to 2.46, P = 0.004) and multivariate (HR 1.57, 95% CI 1.06 to 2.32, P = 0.025) analyses. Regression analysis after stratification by risk group and adjustment for treatment covariates demonstrated a significant association between PNI and the risk of biochemical recurrence for low-risk (HR 4.14, 95% CI 1.55 to 11.02, P = 0.005) and intermediate/high-risk patients (HR 1.53, 95% CI 1.02 to 2.29, P = 0.040).

CONCLUSIONS

The results of our study have shown that the presence of PNI is an independent risk factor associated with an increased risk of biochemical recurrence in patients with prostate cancer undergoing external beam radiotherapy.

Analysis of biochemical control and prognostic factors in patients treated with either low-dose three-dimensional conformal radiation therapy or high-dose intensity-modulated radiotherapy for localized prostate cancer

PURPOSE

To identify prognostic factors and evaluate biochemical control rates for patients with localized prostate cancer treated with either high-dose intensity-modulated radiotherapy (IMRT) or conventional-dose three-dimensional conformal radiotherapy 3D-CRT.

METHODS

Four hundred sixteen patients with a minimum follow-up of 3 years (median, 5 years) were included. Two hundred seventy-one patients received 3D-CRT with a median dose of 68.4 Gy (range, 66-71 Gy). The next 145 patients received IMRT with a median dose of 75.6 Gy (range, 70.2-77.4 Gy). Biochemical control rates were calculated according to both American Society for Therapeutic Radiology and Oncology (ASTRO) consensus definitions. Prognostic factors were identified using both univariate and multivariate analyses.

RESULTS

The 5-year biochemical control rate was 60.4% for 3D-CRT and 74.1% for IMRT (p < 0.0001, first ASTRO Consensus definition). Using the ASTRO Phoenix definition, the 5-year biochemical control rate was 74.4% and 84.6% with 3D-RT and IMRT, respectively (p = 0.0326). Univariate analyses determined that PSA level, T stage, Gleason score, perineural invasion, and radiation dose were predictive of biochemical control. On multivariate analysis, dose, Gleason score, and perineural invasion remained significant.

CONCLUSION

On the basis of both ASTRO definitions, dose, Gleason score, and perineural invasion were predictive of biochemical control. Intensity-modulated radiotherapy allowed delivery of higher doses of radiation with very low toxicity, resulting in improved biochemical control.

Perineural invasion is a marker for pathologically advanced disease in localized prostate cancer

PURPOSE

To determine if perineural invasion (PNI) should be included in addition to prostate-specific antigen (PSA), biopsy Gleason score, and clinical T-stage for risk-stratification of patients with localized prostate cancer.

METHODS AND MATERIALS

We analyzed prostatectomy findings for 1550 patients, from a prospectively collected institutional database, to determine whether PNI was a significant predictor for upgrading of Gleason score or pathologic T3 disease after patients were stratified into low-, intermediate-, and high-risk groups (on the basis of PSA, biopsy Gleason score, and clinical T-stage).

RESULTS

For the overall population, PNI was associated with a significantly increased frequency of upgrading and of pathologic T3 disease. After stratification, PNI was still associated with significantly increased odds of pathologic T3 disease within each risk group. In particular, for low-risk patients, there was a markedly increased risk of extraprostatic extension (23% vs. 7%), comparable to that of intermediate-risk patients. Among high-risk patients, PNI was associated with an increased risk of seminal vesicle invasion and lymph node involvement. Furthermore, over 80% of high-risk patients with PNI were noted to have an indication for postoperative radiation.

CONCLUSIONS

Perineural invasion may be useful for risk-stratification of prostate cancer. Our data suggest that low-risk patients with PNI on biopsy may benefit from treatment typically reserved for those with intermediate-risk disease. In addition, men with high-risk disease and PNI, who are contemplating surgery, should be informed of the high likelihood of having an indication for postoperative radiation therapy.