Pathologic evidence of dose-response and dose-volume relationships for prostate cancer treated with combined external beam radiotherapy and high-dose-rate brachytherapy

Two-years Postradiotherapy Biopsies: Lessons from MRC RT01 Trial

BACKGROUND

The importance of 2-yr postradiotherapy prostate biopsy status remains uncertain.

OBJECTIVE

To assess the value of 2 year post treatment biopsies in a randomised trial of radiotherapy dose escalation.

DESIGN, SETTING, AND PARTICIPANTS

Between 1998 and 2001, 843 men with localised prostate cancer were randomised to receive either control-64Gy or escalated-74Gy conformal radiotherapy (CFRT) in the MRC RT01 trial in combination with 3-6-mo neoadjuvant androgen deprivation therapy. Prostate biopsies were planned at 2 yr from start of CFRT in suitable men.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Prostate biopsy results and prostate-specific antigen (PSA) levels performed at 2 yr post-CFRT were evaluated with long-term biochemical progression free survival (bPFS) and overall survival. Outcome measures were timed from the 2-yr biopsy using a landmark approach.

RESULTS AND LIMITATIONS

A 2-yr biopsy was performed in 312/843 patients. One hundred and seventy-seven patients were included in the per-protocol group with median follow-up of 7.8 yr from biopsy. Median PSA at biopsy was 0.5ng/ml. Sixty-four bPFS events were reported: 46/145 (32%) in patients with negative, 6/18 (33%) suspicious, and 12/14 (86%) positive biopsies. A positive biopsy was prognostic of worse bPFS, going forward, compared with negative and suspicious biopsies, hazard ratio (HR)=4.81 (95% confidence interval [CI]: 2.50-9.26, p<0.001). The estimate for survival was HR=1.58 (95% CI: 0.52-4.78, p=0.42). PSA values at 2 yr between 1.01ng/ml and 2.09ng/ml were also associated with subsequent PSA failures (HR=2.71, 95% CI: 1.98-3.71), bPFS events (HR=2.45, 95% CI: 1.81-3.32), and prostate cancer-specific survival (HR=2.87, 95% CI: 1.08-7.64) compared with PSA ≤1.0ng/ml.

CONCLUSIONS

Two-year postradiotherapy prostate biopsies have limited value in patients with PSA control but both positive biopsy and higher PSA status are strongly associated with future bPFS events. A policy of selected biopsy may provide an opportunity for early salvage interventions.

PATIENT SUMMARY

Routine 2-yr postradiotherapy biopsy is not recommended but can be considered in selected patients with unfavourable post-treatment prostate-specific antigen levels who are suitable for early salvage treatments.

The evolution of brachytherapy for prostate cancer

Brachytherapy (BT), using low-dose-rate (LDR) permanent seed implantation or high-dose-rate (HDR) temporary source implantation, is an acceptable treatment option for select patients with prostate cancer of any risk group. The benefits of HDR-BT over LDR-BT include the ability to use the same source for other cancers, lower operator dependence, and - typically - fewer acute irritative symptoms. By contrast, the benefits of LDR-BT include more favourable scheduling logistics, lower initial capital equipment costs, no need for a shielded room, completion in a single implant, and more robust data from clinical trials. Prospective reports comparing HDR-BT and LDR-BT to each other or to other treatment options (such as external beam radiotherapy (EBRT) or surgery) suggest similar outcomes. The 5-year freedom from biochemical failure rates for patients with low-risk, intermediate-risk, and high-risk disease are >85%, 69-97%, and 63-80%, respectively. Brachytherapy with EBRT (versus brachytherapy alone) is an appropriate approach in select patients with intermediate-risk and high-risk disease. The 10-year rates of overall survival, distant metastasis, and cancer-specific mortality are >85%, <10%, and <5%, respectively. Grade 3-4 toxicities associated with HDR-BT and LDR-BT are rare, at <4% in most series, and quality of life is improved in patients who receive brachytherapy compared with those who undergo surgery.

Importance of Local Control in Early-Stage Prostate Cancer: Outcomes of Patients With Positive Post-Radiation Therapy Biopsy Results Treated in RTOG 9408

PURPOSE

The purpose of this study was to assess the association between positive post-radiation therapy (RT) biopsy results and subsequent clinical outcomes in males with localized prostate cancer.

METHODS AND MATERIALS

Radiation Therapy Oncology Group study 94-08 analyzed 1979 males with prostate cancer, stage T1b-T2b and prostate-specific antigen concentrations of ≤ 20 ng/dL, to investigate whether 4 months of total androgen suppression (TAS) added to RT improved survival compared to RT alone. Patients randomized to receive TAS received flutamide with luteinizing hormone releasing hormone (LHRH) agonist. According to protocol, patients without evidence of clinical recurrence or initiation of additional endocrine therapy underwent repeat prostate biopsy 2 years after RT completion. Statistical analysis was performed to evaluate the impact of positive post-RT biopsy results on clinical outcomes.

RESULTS

A total of 831 patients underwent post-RT biopsy, 398 were treated with RT alone and 433 with RT plus TAS. Patients with positive post-RT biopsy results had higher rates of biochemical failure (hazard ratio [HR] = 1.7; 95% confidence interval [CI] = 1.3-2.1) and distant metastasis (HR = 2.4; 95% CI = 1.3-4.4) and inferior disease-specific survival (HR = 3.8; 95% CI = 1.9-7.5). Positive biopsy results remained predictive of such outcomes after correction for potential confounders such as Gleason score, tumor stage, and TAS administration. Prior TAS therapy did not prevent elevated risk of adverse outcome in the setting of post-RT positive biopsy results. Patients with Gleason score ≥ 7 with a positive biopsy result additionally had inferior overall survival compared to those with a negative biopsy result (HR = 1.56; 95% CI = 1.04-2.35).

CONCLUSIONS

Positive post-RT biopsy is associated with increased rates of distant metastases and inferior disease-specific survival in patients treated with definitive RT and was associated with inferior overall survival in patients with high-grade tumors.

Salvage radical prostatectomy after external beam radiation therapy: a systematic review of current approaches

BACKGROUND

Radical external beam radiotherapy (EBRT) is a standard treatment for prostate cancer patients. Despite this, the rate of intraprostatic relapses after primary EBRT is still not negligible. There is no consensus on the most appropriate management of these patients after EBRT failure. For these patients, local salvage therapy such as radical prostatectomy, cryotherapy, and brachytherapy may be indicated.

OBJECTIVE

The objectives of this review were to analyze the eligibility criteria for careful selection of appropriate patients and to evaluate the oncological results and complications for each method.

METHODS

A review of the literature was performed to identify studies of local salvage therapy for patients who had failed primary EBRT for localized prostate cancer.

RESULTS

Most studies demonstrated that local salvage therapy after EBRT may provide long-term local control in appropriately selected patients, although toxicity is often significant.

CONCLUSIONS

Our results suggest that for localized prostate cancer recurrence after EBRT, the selection of a local treatment modality should be made on a patient-by-patient basis. An improvement in selection criteria and an integrated definition of biochemical failure for all salvage methods are required to determine which provides the best oncological outcome and least comorbidity.

Multiparametric 3T endorectal mri after external beam radiation therapy for prostate cancer

PURPOSE

To determine the best combination of magnetic resonance imaging (MRI) parameters for the detection of locally recurrent prostate cancer after external beam radiation therapy.

MATERIALS AND METHODS

Our Institutional Review Board approved this study with a waiver of informed consent. Twenty-six patients with suspected recurrence due to biochemical failure were part of this research. The MR protocol included T2-weighted, MR spectroscopy, and diffusion-weighted MRI. Transrectal ultrasound-guided biopsy was the standard of reference. We used logistic regression to model the probability of a positive outcome and generalized estimating equations to account for clustering. The diagnostic performance of imaging was described using receiver operating characteristic (ROC) curves.

RESULTS

The area under the ROC curve of MR spectroscopic imaging (MRSI) was 83.0% (95% confidence interval [CI] = 75.5-89.1). The combination of all MR techniques did not significantly improve the performance of imaging beyond the accuracy of MRSI alone, but a trend toward improved discrimination was noted (86.9%; 95% CI = 77.6-93.4; P = 0.09).

CONCLUSION

Incorporation of MRSI to T2-weighted and/or diffusion-weighted MRI significantly improves the assessment of patients with suspected recurrence after radiotherapy and a combined approach with all three modalities may have the best diagnostic performance.

Endorectal MRI after radiation therapy: questioning the sextant analysis

PURPOSE

To evaluate whether the information gained by three coregistration systems (sextant, hemi-prostate, and whole gland) differs significantly, suggesting that one approach should be routinely favored over the others. Despite its known limitations, sextant is the generally accepted standard for magnetic resonance imaging (MRI) and biopsy coregistration; nevertheless, depending on the magnitude of localization errors, other options may be adequate.

MATERIALS AND METHODS

Institutional Review Board approval was obtained and the study was Health Insurance Portability and Accountability Act (HIPAA)-compliant. We identified 70 patients who underwent 1.5 T endorectal MRI of the prostate between 1999 and 2008 after external beam radiotherapy for prostate cancer. A single reader reviewed all T2-weighted images for the presence or absence of tumor. The performance of each approach was quantified using receiver operating characteristic (ROC) curve analysis. Transrectal ultrasound-guided sextant biopsies were used as a standard of reference.

RESULTS

The areas under the ROC curve indicating accuracy for each MRI approach were 0.63 (sextant), 0.68 (hemi-prostate), and 0.71 (whole gland). There was no statistically significant difference among these approaches.

CONCLUSION

As expected, the point estimate was higher for the whole-gland approach, but not significantly. Reliable assessment of locally recurrent prostate cancer after external beam radiotherapy by endorectal MRI may be made using a sextant, hemi-prostate, or whole gland approach. The option for one or another approach should not be solely based on estimations of imaging accuracy, but on the purpose of the procedure.

Histopathologic effects of hypofractionated robotic radiation therapy on malignant and benign prostate tissue

We describe the first histopathologic analysis of prostatic tissue following hypofractionated robotic radiation therapy. A 66 year-old man presented with stage II, low risk adenocarcinoma of the prostate and underwent elective conformal hypofractionated radiation therapy. His pretreatment evaluation revealed T1c adenocarcinoma, Gleason's grade 3 + 3 = 6 and a prostate specific antigen (PSA) level of 4.87 ng/ml. Hypofractionated radiation therapy (37.5 Gy in five daily fractions of 7.5 Gy) was completed on an Internal Review Board approved protocol. One year later, he developed progressive urinary retention. Transurethral prostatic resection was performed to alleviate obstructive symptoms. Bilobar hypertrophy was observed without evidence of stricture. Histolopathologic analyses of resected prostate tissues revealed changes consistent with radiation treatment, including cellular changes, inflammation, glandular atrophy and hyperplasia. There was no evidence of residual cancer, fibrosis or necrosis. The patient's postoperative course was uneventful with post-treatment PSA of 0.5 ng/ml and residual grade 1 stress incontinence.

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.

T2-Weighted endorectal magnetic resonance imaging of prostate cancer after external beam radiation therapy

PURPOSE

To retrospectively determine the accuracy of T2-weighted endorectal MR imaging in the detection of prostate cancer after external beam radiation therapy and to investigate the relationship between imaging accuracy and time since therapy.

MATERIALS AND METHODS

Institutional review board approval was obtained and the study was HIPPA compliant. We identified 59 patients who underwent 1.5 Tesla endorectal MR imaging of the prostate between 1999 and 2006 after definitive external beam radiation therapy for biopsy-proven prostate cancer. Two readers recorded the presence or absence of tumor on T2-weighted images. Logistic regression and Fisher's exact tests for 2x2 tables were used to determine the accuracy of imaging and investigate if accuracy differed between those imaged within 3 years of therapy (n = 25) and those imaged more than 3 years after therapy (n = 34). Transrectal biopsy was used as the standard of reference for the presence or absence of recurrent cancer.

RESULTS

Thirty-four of 59 patients (58%) had recurrent prostate cancer detected on biopsy. The overall accuracy of T2-weighted MR imaging in the detection cancer after external beam radiation therapy was 63% (37/59) for reader 1 and 71% for reader 2 (42/59). For both readers, logistic regression showed no difference in accuracy between those imaged within 3 years of therapy and those imaged more than 3 years after therapy (p = 0.86 for reader 1 and 0.44 for reader 2).

CONCLUSION

T2-weighted endorectal MR imaging has low accuracy in the detection of prostate cancer after external beam radiation therapy, irrespective of the time since therapy.

Disseminated tumor cells in bone marrow following definitive radiotherapy for intermediate or high-risk prostate cancer

BACKGROUND

The purpose of this study was to explore the prevalence of disseminated tumor cells (DTCs) in bone marrow (BM) of clinically progression-free prostate cancer (PC) patients at least 2 years after curatively intended radiotherapy (RT) with or without adjuvant hormone treatment.

METHODS

All patients were T(1-3)N(0)M(0) with intermediate or high risk of progression. Median time from RT to BM sampling was 5 years (2-8). A standardized immunocytochemical method applying the anticytokeratin antibodies AE1/AE3 was used for DTCs detection in 130 patients. Morphological characterization of immunostained cells was performed to exclude false positive cells. The post-treatment BM was explored in relation to pre-treatment risk factors, treatment strategy and serum levels of Testosterone and PSA at the time of BM sampling. Longitudinal changes in BM status were studied in a sub-group of 109 patients who also had donated BM prior to treatment.

RESULTS

Post-treatment BM-aspirates were positive for DTCs in 17% of cases without correlation to any of the tested variables. Out of 14 patients who had DTCs in BM prior to treatment, all but one had become post-treatment negative. Out of 95 patients with pre-treatment negative BM status, 18 (19%) had become post-treatment positive.

CONCLUSIONS

DTCs in BM were found in 17% of clinically progression-free PC patients following RT. The detection of these cells may provide PSA-independent prognostic information remaining to be explored by prolonged follow-up.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN, SETTING, AND PARTICIPANTS

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

INTERVENTION

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

MEASUREMENTS

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

RESULTS

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

CONCLUSION

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

The predictive value of 2-year posttreatment biopsy after prostate cancer radiotherapy for eventual biochemical outcome

PURPOSE

To determine the value of a 2-year post-radiotherapy (RT) prostate biopsy for predicting eventual biochemical failure in patients who were treated for localized prostate cancer.

METHODS AND MATERIALS

This study comprised 164 patients who underwent a planned 2-year post-RT prostate biopsy. The independent prognostic value of the biopsy results for forecasting eventual biochemical outcome and overall survival was tested with other factors (the Gleason score, 1992 American Joint Committee on Cancer tumor stage, pretreatment prostate-specific antigen level, risk group, and RT dose) in a multivariate analysis. The current nadir + 2 (CN + 2) definition of biochemical failure was used. Patients with rising prostate-specific antigen (PSA) or suspicious digital rectal examination before the biopsy were excluded.

RESULTS

The biopsy results were normal in 78 patients, scant atypical and malignant cells in 30, carcinoma with treatment effect in 43, and carcinoma without treatment effect in 13. Using the CN + 2 definition, we found a significant association between biopsy results and eventual biochemical failure. We also found that the biopsy status provides predictive information independent of the PSA status at the time of biopsy.

CONCLUSION

A 2-year post-RT prostate biopsy may be useful for forecasting CN + 2 biochemical failure. Posttreatment prostate biopsy may be useful for identifying patients for aggressive salvage therapy.

Prediagnosis Prostate Specific Antigen Velocity is Associated With Risk of Prostate Cancer Progression Following Brachytherapy and External Beam Radiation Therapy

PURPOSE

Prostate specific antigen velocity 2.0 ng/ml per year or greater in the year before prostate cancer diagnosis is associated with cancer specific survival following radical prostatectomy and radiation therapy. We evaluated the relationship between prediagnosis prostate specific antigen velocity and cancer progression following primary radiation therapy.

MATERIALS AND METHODS

We analyzed the records of 24,893 men from a community based prostate cancer screening study and identified 237 with clinically localized prostate cancer who elected primary radiation therapy. Our final cohort consisted of 130 men, including 83 treated with external beam radiation and 47 treated with brachytherapy. Patient specific variables at diagnosis were analyzed for their value in predicting biochemical progression using American Society for Therapeutic and Radiation Oncology criteria.

RESULTS

Mean followup +/- SD was 64 +/- 35 months. Prostate specific antigen at diagnosis, family history of prostate cancer and prediagnosis prostate specific antigen velocity 2.0 ng/ml per year or greater were associated with cancer progression following brachytherapy or external beam radiation. Of men with prostate specific antigen velocity 2.0 ng/ml per year or greater 38% had cancer progression compared to 12% with prostate specific antigen velocity less than 2.0 ng/ml per year (OR 4.3, p = 0.003). The 6-year progression-free survival estimate was 57% in men with prostate specific antigen velocity 2.0 ng/ml per year or greater and 82% in men with prostate specific antigen velocity less than 2.0 ng/ml per year (p < 0.001). On multivariate analysis absolute prostate specific antigen at diagnosis and prostate specific antigen velocity 2.0 ng/ml per year or greater were independently associated with cancer progression in men treated with external beam radiation therapy or brachytherapy.

CONCLUSIONS

Men with a prediagnosis prostate specific antigen velocity of 2.0 ng/ml per year or greater are at increased risk for cancer progression following brachytherapy or external beam radiation compared to men with a prostate specific antigen velocity of less than 2.0 ng/ml per year.

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.

When Prostate Brachytherapy Fails: A Case Report and Discussion

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

Acute genitourinary toxicity after high-dose-rate (HDR) brachytherapy combined with hypofractionated external-beam radiation therapy for localized prostate cancer: Correlation between the urethral dose in HDR brachytherapy and the severity of acute genitourinary toxicity

PURPOSE

Several investigations have revealed that the alpha/beta ratio for prostate cancer is atypically low, and that hypofractionation or high-dose-rate (HDR) brachytherapy regimens using appropriate radiation doses may be expected to yield tumor control and late sequelae rates that are better or at least as favorable as those achieved with conventional radiation therapy. In this setting, we attempted treating localized prostate cancer patients with HDR brachytherapy combined with hypofractionated external beam radiation therapy (EBRT). The purpose of this study was to evaluate the feasibility of using this approach, with special emphasis on the relationship between the severity of acute genitourinary (GU) toxicity and the urethral dose calculated from the dose-volume histogram (DVH) of HDR brachytherapy.

METHODS AND MATERIALS

Between September 2000 and December 2003, 70 patients with localized prostate cancer were treated by iridium-192 HDR brachytherapy combined with hypofractionated EBRT at the Gunma University Hospital. Hypofractionated EBRT was administered in fraction doses of 3 Gy, three times per week; a total dose of 51 Gy was delivered to the prostate gland and the seminal vesicles using the four-field technique. No elective pelvic irradiation was performed. After the completion of EBRT, all the patients additionally received transrectal ultrasonography (TRUS)-guided HDR brachytherapy. The fraction size and the number of fractions in HDR brachytherapy were prospectively changed, whereas the total radiation dose for EBRT was fixed at 51 Gy. The fractionation in HDR brachytherapy was as follows: 5 Gy x 5, 7 Gy x 3, 9 Gy x 2, administered twice per day, although the biologic effective dose (BED) for HDR brachytherapy combined with EBRT, assuming that the alpha/beta ratio is 3, was almost equal to 138 in each fractionation group. The planning target volume was defined as the prostate gland with 5-mm margin all around, and the planning was conducted based on computed tomography images. The number of patients in each fractionation group was as follows: 13 in the 5-Gy group; 19 in the 7-Gy group, and 38 in the 9-Gy group. The tumor stage was T1 in 10 patients, T2 in 36 patients, and T3 in 24 patients. The Gleason score was 2-6 in 11 patients, 7 in 34 patients, and 8-10 in 25 patients. Androgen ablation was performed in all the patients. The median follow-up duration was 14 months (range 3-42 months). The toxicities were graded based on the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity criteria.

RESULTS

The main symptoms of acute GU toxicity were dysuria and increase in urinary frequency or nocturia. The grade distribution of acute GU toxicity in the patients was as follows: Grade 0-1, 39 patients (56%), and Grade 2-4, 31 patients (44%). One patient who developed acute urinary obstruction was classified as having Grade 4 toxicity. Comparison of the distribution of the grade of acute GU toxicity among the different fractionation groups revealed no statistically significant differences among the groups. The urethral dose in HDR brachytherapy was evaluated using the following DVH parameters: V30 (percentage of the urethral volume receiving 30% of the prescribed radiation dose), V80, V90, V100, V110, V120, V130, and V150. The V30-110 values in the patients with Grade 2-4 acute GU toxicity were significantly higher than those in patients with Grade 0-1 toxicity. On the other hand, there were no significant differences in the V120-150 values between patients with Grade 0-1 and Grade 2-4 toxicity. Regarding the influence of the number of needles implanted for the radiation therapy, patients with 11 needles or less showed a significantly higher incidence of Grade 2-4 acute GU toxicity compared with those with 12 needles or more (p < 0.05).

CONCLUSIONS

It was concluded that HDR brachytherapy combined with hypofractionated EBRT is feasible for localized prostate cancer when considered from the viewpoint of acute toxicity. Increase in the fraction dose or reduction in the number of fractions in HDR brachytherapy did not affect the severity of acute GU toxicity, and the volume of urethra receiving an equal or lower radiation dose than the prescribed dose was more closely associated with the grade severity of acute GU toxicity than that receiving a higher than the prescribed dose.

Optimal treatment of intermediate-risk prostate carcinoma with radiotherapy

The clinical heterogeneity of intermediate-risk prostate carcinoma presents a challenge to urologic oncology in terms of prognosis and management. There is controversy regarding whether patients with intermediate-risk prostate carcinoma should be treated with dose-escalated external beam radiotherapy (EBRT) (e.g., doses > 74 gray [Gy]), or conventional-dose EBRT (e.g., doses < 74 Gy) combined with androgen deprivation (AD). Data for this review were identified through searches for articles in MEDLINE and in conference proceedings, indexed from 1966 to 2004. Currently, the intermediate-risk prostate carcinoma grouping is defined on the basis of prostate-specific antigen (PSA), tumor classification (T classification), and Gleason score. Emerging evidence suggests that additional prognostic information may be derived from the percentage of positive core needle biopsies at the time of diagnosis and/or from the pretreatment PSA doubling time. Novel prognostic biomarkers include protein expression relating to cell cycle control, cell death, DNA repair, and intracellular signal transduction. Preclinical data support dose escalation or combined AD with radiation as a means to increase prostate carcinoma cell kill. There is Level I evidence that patients with intermediate-risk prostate carcinoma benefit from dose-escalated EBRT or AD plus conventional-dose EBRT. However, clinical evidence is lacking to support the uniform use of AD plus dose-escalated EBRT. Patients in the intermediate-risk group should be entered into well designed, randomized clinical trials of dose-escalated EBRT and AD with sufficient power to address biochemical failure and cause-specific survival endpoints. These studies should be stratified by novel prognostic markers and accompanied by strong translational endpoints to address clinical heterogeneity and to allow for individualized treatment.