Acute Toxicity in Definitive Versus Postprostatectomy Image-Guided Radiotherapy for Prostate Cancer

A feasibility study of adaptive radiation therapy for postprostatectomy prostate cancer

Postoperative prostate radiotherapy requires large planning target volume (PTV) margins to account for motion and deformation of the prostate bed. Adaptive radiation therapy (ART) can incorporate image-guidance data to personalize PTVs that maintain coverage while reducing toxicity. We present feasibility and dosimetry results of a prospective study of postprostatectomy ART. Twenty-one patients were treated with single-adaptation ART. Conventional treatments were delivered for fractions 1 to 6 and adapted plans for the remaining 27 fractions. Clinical target volumes (CTVs) and small bowel delineated on fraction 1 to 4 CBCT were used to generate adapted PTVs and planning organ-at-risk (OAR) volumes for adapted plans. PTV volume and OAR dose were compared between ART and conventional using Wilcoxon signed-rank tests. Weekly CBCT were used to assess the fraction of CTV covered by PTV, CTV D99, and small bowel D1cc. Clinical metrics were compared using a Student's t-test (p < 0.05 significant). Offline adaptive planning required 1.9 ± 0.4 days (mean ± SD). ART decreased mean adapted PTV volume 61 ± 37 cc and bladder wall D50 compared with conventional treatment (p < 0.01). The CTV was fully covered for 96% (97%) of fractions with ART (conventional). Reconstructing dose on weekly CBCT, a nonsignificant reduction in CTV D99 was observed with ART (94%) compared to conventional (96%). Reduced CTV D99 with ART was significantly correlated with large anterior-posterior rectal diameter on simulation CT. ART reduced the number of fractions exceeding our institution's small bowel D1c limit from 14% to 7%. This study has demonstrated the feasibility of offline ART for post-prostatectomy cancer. ART facilitates PTV volume reduction while maintaining reasonable CTV coverage and can reduce the dose to adjacent normal tissues.

Toxicity reduction required for MRI-guided radiotherapy to be cost-effective in the treatment of localized prostate cancer

OBJECTIVE

To determine the toxicity reduction required to justify the added costs of MRI-guided radiotherapy (MR-IGRT) over CT-based image guided radiotherapy (CT-IGRT) for the treatment of localized prostate cancer.

METHODS

The costs of delivering prostate cancer radiotherapy with MR-IGRT and CT-IGRT in conventional 39 fractions and stereotactic body radiotherapy (SBRT) 5 fractions schedules were determined using literature values and cost accounting from two institutions. Gastrointestinal and genitourinary toxicity rates associated with CT-IGRT were summarized from 20 studies. Toxicity-related costs and utilities were obtained from literature values and cost databases. Markov modeling was used to determine the savings per patient for every 1% relative reduction in acute and chronic toxicities by MR-IGRT over 15 years. The costs and quality adjusted life years (QALYs) saved with toxicity reduction were juxtaposed with the cost increase of MR-IGRT to determine toxicity reduction thresholds for cost-effectiveness. One way sensitivity analyses were performed. Standard $100,000 and $50,000 per QALY ratios were used.

RESULTS

The added cost of MR-IGRT was $1,459 per course of SBRT and $10,129 per course of conventionally fractionated radiotherapy. Relative toxicity reductions of 7 and 14% are required for SBRT to be cost-effective using $100,000 and $50,000 per QALY, respectively. Conventional radiotherapy requires relative toxicity reductions of 50 and 94% to be cost-effective.

CONCLUSION

From a healthcare perspective, MR-IGRT can reasonably be expected to be cost-effective. Hypofractionated schedules, such a five fraction SBRT, are most likely to be cost-effective as they require only slight reductions in toxicity (7-14%).

ADVANCES IN KNOWLEDGE

This is the first detailed economic assessment of MR-IGRT, and it suggests that MR-IGRT can be cost-effective for prostate cancer treatment through toxicity reduction alone.

Impact of advanced radiotherapy techniques and dose intensification on toxicity of salvage radiotherapy after radical prostatectomy

The safety and efficacy of dose-escalated radiotherapy with intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT) remain unclear in salvage radiotherapy (SRT) after radical prostatectomy. We examined the impact of these advanced radiotherapy techniques and dose intensification on the toxicity of SRT. This multi-institutional retrospective study included 421 patients who underwent SRT at the median dose of 66 Gy in 2-Gy fractions. IMRT and IGRT were used for 225 (53%) and 321 (76%) patients, respectively. At the median follow-up of 50 months, the cumulative incidence of late grade 2 or higher gastrointestinal (GI) and genitourinary (GU) toxicities was 4.8% and 24%, respectively. Multivariate analysis revealed that the non-use of either IMRT or IGRT, or both (hazard ratio [HR] 3.1, 95% confidence interval [CI] 1.8-5.4, p < 0.001) and use of whole-pelvic radiotherapy (HR 7.6, CI 1.0-56, p = 0.048) were associated with late GI toxicity, whereas a higher dose ≥68 Gy was the only factor associated with GU toxicities (HR 3.1, CI 1.3-7.4, p = 0.012). This study suggested that the incidence of GI toxicities can be reduced by IMRT and IGRT in SRT, whereas dose intensification may increase GU toxicity even with these advanced techniques.

Does Interfraction Cone Beam Computed Tomography Improve Target Localization in Prostate Bed Radiotherapy?

Purpose:

In this prospective phase II study, we investigated whether cone beam computed tomography scan was a superior method of image-guided radiotherapy relative to 2D orthogonal kilovoltage images in the post-radical prostatectomy setting.

Methods:

A total of 419 treatment fractions were included in this analysis. The shifts required to align the patient for each treatment were performed using 3D matching between cone beam computed tomography scans and the corresponding computed tomography images used for planning. This was compared with the shifts obtained from 2D orthogonal kilovoltage images, matching with the corresponding digitally reconstructed radiographs. Patients did not have fiducials inserted to assist with localization. Interfractional changes in the bladder and rectal volumes were subsequently measured on the cone beam computed tomography images for each fraction and compared to the shift differences between orthogonal kilovoltage and cone beam computed tomography scans. The proportion of treatment fractions with a shift difference exceeding the planning target volume of 7 mm, between orthogonal kilovoltage and cone beam computed tomography scans, was calculated.

Results:

The mean vertical, lateral, and longitudinal shifts resulted from 2D match between orthogonal kilovoltage images and corresponding digitally reconstructed radiographs were 0.353 cm (interquartile range: 0.1-0.5), 0.346 cm (interquartile range: 0.1-0.5), and 0.289 cm (interquartile range: 0.1-0.4), compared to 0.388 cm (interquartile range: 0.1-0.5), 0.342 cm (interquartile range: 0.1-0.5), and 0.291 cm (interquartile range: 0.1-0.4) obtained from 3D match between cone beam computed tomography and planning computed tomography scan, respectively. Our results show a significant difference between the kilovoltage and cone beam computed tomography shifts in the anterior–posterior direction (P = .01). The proportion of treatment fractions in which the differences in kilovoltage and cone beam computed tomography shifts between exceeded the 7 mm planning target volume margin was 6%, 2%, and 3% in the anterior–posterior, lateral, and superior–inferior directions, respectively.

Conclusion:

We prospectively demonstrated that the daily use of volumetric cone beam computed tomography for treatment localization in post-radical prostatectomy patients demonstrated an increased need for a shift in patient position. This suggests that in post-radical prostatectomy patients the daily cone beam computed tomography imaging improved localization of the prostate bed and may have prevented a limited number of geographic misses, compared to daily kilovoltage imaging that was not assisted with fiducials.

Incidence and Dose-volume Analysis of Acute Bladder Toxicity following Pelvic Radiotherapy

Aims and Background

The authors performed this prospective study to evaluate the incidence of acute bladder toxicity following pelvic radiation therapy and to determine any dosimetric predictors for the toxicity.

Methods and Study Design

Acute bladder toxicity was evaluated weekly by physicians using the Common Terminology Criteria for Adverse Events (CTCAE version 4.0). At the same time, the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) were also assessed by each patient during radiation therapy. We contoured the bladder wall, solid bladder and trigone on the planning computed tomography and analyzed dose-volume histograms to determine which of these could be the most suitable dosimetric predictor.

Results

Of 92 eligible patients, 27 (29%) demonstrated CTCAE grade 2 acute bladder toxicity, with nocturia as the most frequently observed symptom. IPSS demonstrated better agreement with CTCAE than OABSS. In receiver-operating characteristic curve analysis, the largest area under the curve was observed for V20 of both the bladder wall and the bladder.

Conclusions

Acute bladder toxicity during pelvic radiation therapy is not a trivial complication and should be actively investigated. Dose-volume relationships demonstrate that both bladder wall V20 and bladder solid V20 are useful surrogates for identifying patients at high risk of toxicity. The roles of IPSS and OABSS need to be validated in a larger study.

Postoperative radiotherapy for prostate cancer : Morbidity of local-only or local-plus-pelvic radiotherapy

PURPOSE

The aim of this work was to characterise actuarial incidence and prevalence of early and late side effects of local versus pelvic three-dimensional conformal postoperative radiotherapy for prostate cancer.

MATERIALS AND METHODS

Based on a risk-adapted protocol, 575 patients received either local (n = 447) or local-plus-pelvic (n = 128) radiotherapy. Gastrointestinal (GI) and genitourinary (GU) side effects (≥grade 2 RTOG/EORTC criteria) were prospectively assessed. Maximum morbidity, actuarial incidence rate, and prevalence rates were compared between the two groups.

RESULTS

For local radiotherapy, median follow-up was 68 months, and the mean dose was 66.7 Gy. In pelvic radiotherapy, the median follow-up was 49 months, and the mean local and pelvic doses were 66.9 and 48.3 Gy respectively. Early GI side effects ≥ G2 were detected in 26% and 42% of patients respectively (p < 0.001). Late GI adverse events were detected in 14% in both groups (p = 0.77). The 5‑year actuarial incidence rates were 14% and 14%, while the prevalence rates were 2% and 0% respectively. Early GU ≥ G2 side effects were detected in 15% and 16% (p = 0.96), while late GU morbidity was detected in 18% and 24% (p = 0.001). The 5‑year actuarial incidence rates were 16% and 35% (p = 0.001), while the respective prevalence rates were 6% and 8%.

CONCLUSIONS

Despite the low prevalence of side effects, postoperative pelvic radiotherapy results in significant increases in the actuarial incidence of early GI and late GU morbidity using a conventional 4‑field box radiotherapy technique. Advanced treatment techniques like intensity-modulated radiotherapy (IMRT) or volumetric modulated arc radiotherapy (VMAT) should therefore be considered in pelvic radiotherapy to potentially reduce these side effects.

Outcomes and toxicity of 313 prostate cancer patients receiving helical tomotherapy after radical prostatectomy

Purpose

There are limited long-term data on patients treated with image guided intensity modulated radiation therapy (IG-IMRT) for prostate cancer recurrence or high-risk disease features after radical prostatectomy. We report single-institution results for patients treated with IG-IMRT and identify variables associated with outcome.

Methods and materials

This is a retrospective chart review consisting of 313 consecutive patients who were treated with adjuvant or salvage IG-IMRT from 2004 to 2013. Cox proportional hazards analysis was used to identify factors related to survival and toxicity. Toxicity was graded using the Common Terminology Criteria for Adverse Events Version 4.0.

Results

The median follow-up was 55 months (range, 6-131 months). The median pre-radiation therapy (RT) prostate-specific antigen (PSA) was 0.3 ng/mL (range, <0.01-55.4). The vast majority of patients (87%) received elective pelvic nodal irradiation (median dose: 45 Gy). Androgen deprivation therapy (ADT) was given to 39% of patients for a median of 9 months. Five-year biochemical progression-free survival and distant metastasis-free survival were 59% (95% confidence interval, 53%-66%) and 89% (95% confidence interval, 85%-93%), respectively. On multivariate analysis, higher pre-RT PSA (>0.2 ng/mL), biopsy Gleason score (≥7 [4+3]), and duration of ADT (>6 months) were significantly associated (P < .05) with biochemical progression-free survival. Actuarial late grade 3 genitourinary and gastrointestinal toxicities at 5 years were 10% and 2%, respectively.

Conclusion

Our results suggest that lower pre-RT PSA level and longer duration of ADT are associated with improved biochemical control. The incidence of late grade 3 gastrointestinal toxicity was low, but late grade 3 genitourinary toxicity was higher than anticipated.

Volumetric image-guided highly conformal radiotherapy of the prostate bed: Toxicity analysis

AIM

To evaluate toxicity of high conformal image-guided radiotherapy of the prostate bed.

BACKGROUND

Radiotherapy of the prostate bed has a pivotal role in the post-operative and salvage settings, but few clinical data are available on the use of daily image guidance in combination with highly conformal techniques, and data on long-term results are lacking.

MATERIALS AND METHODS

We analyzed 118 patients irradiated on the prostate bed using conformal plans processed with a micro-multileaf collimator, and daily checking treatment set-up with a cone-beam CT system. Correlation between toxicity and clinical-dosimetric parameters was assessed by the Cox regression model and log-rank test. Survival analyses were performed with the Kaplan-Meier method.

RESULTS

Median follow-up was 54.08 months. Late grade ≥2 gastro-intestinal (GI) and genito-urinary (GU) toxicity were 3.4% and 4.2%, respectively. Actuarial 4-year late grade ≥2 GI and GU toxicities were 4% and 6%, respectively. Four-year relapse-free survival was 87%. At log-rank test, acute grade ≥2 GI toxicity is associated with the use of antihypertensives (p = 0.03), and there is a trend toward significance between the use of anticoagulants and late grade ≥2 GI toxicity (p = 0.07). At Cox analysis, acute grade ≥2 GU toxicity is correlated with the percentage of bladder volume receiving more than 65 Gy (p = 0.02, HR 1.87 CI 1.25-2.8), and the maximal dose to the rectum is correlated to the development of late grade ≥2 GI toxicity (p = 0.03, HR 2.75 CI 1.10-6.9).

CONCLUSIONS

Conformal volumetric image-guided radiotherapy of the prostate bed leads to low toxicity rates.

Acute and late urinary toxicity following radiation in men with an intact prostate gland or after a radical prostatectomy: A secondary analysis of RTOG 94-08 and 96-01

INTRODUCTION

To estimate the contribution of the prostate gland and prostatic urethral inflammation to urinary symptoms after radiation therapy for prostate cancer, we performed a secondary analysis of urinary toxicity after primary radiation to an intact prostate vs. postprostatectomy radiation to the prostatic fossa in protocols RTOG 94-08 and 96-01, respectively.

MATERIALS AND METHODS

Patients randomized to the radiation-alone arms (without hormone therapy) of the 2 trials were evaluated, including 104 men receiving primary prostate radiation to 68.4Gy on RTOG 94-08 and 371 men receiving 64.8Gy to the prostatic fossa on RTOG 96-01. Acute and late urinary toxicity were scored prospectively by RTOG scales. Chi-square test/logistic regression and cumulative incidence approach/Fine-Gray regression model were used for analyses of acute and late toxicity, respectively.

RESULTS

Grade≥2 acute urinary toxicity was significantly higher after primary prostatic radiation compared with postprostatectomy radiation (30.8% vs. 14.0%; P<0.001), but acute grade≥3 toxicity did not differ (3.8% vs. 2.7%; P = 0.54). After adjusting for age, primary radiation resulted in significantly higher grade≥2 acute urinary toxicity (odds ratio = 3.72; 95% CI: 1.65-8.37; P = 0.02). With median follow-up of 7.1 years, late urinary toxicity was not significantly different with primary vs. postprostatectomy radiation (5-year grade≥2: 16.7% vs. 18.3%; P = 0.65; grade≥3: 6.0% vs. 3.3%; P = 0.24).

CONCLUSIONS

Primary radiation to an intact prostate resulted in higher grade≥2 acute urinary toxicity than radiation to the prostatic fossa, with no difference in late urinary toxicity. Thus, a proportion of acute urinary toxicity in men with an intact prostate may be attributable to inflammation of the prostatic gland or urethra.

[Clinical to planning target volume margins in prostate cancer radiotherapy]

The knowledge of inter- and intrafraction motion and deformations of the intrapelvic target volumes (prostate, seminal vesicles, prostatectomy bed and lymph nodes) as well as the main organs at risk (bladder and rectum) allow to define rational clinical to planning target volume margins, depending on the different radiotherapy techniques and their uncertainties. In case of image-guided radiotherapy, prostate margins and seminal vesicles margins can be between 5 and 10mm. The margins around the prostatectomy bed vary from 10 to 15mm and those around the lymph node clinical target volume between 7 and 10mm. Stereotactic body radiotherapy allows lower margins, which are 3 to 5mm around the prostate. Image-guided and stereotactic body radiotherapy with adequate margins allow finally moderate or extreme hypofractionation.

[Expected benefit of lymph node and seminal vesical dissection to decrease high-risk prostate cancer radiotherapy]

PURPOSE

In case of pelvic lymph node and seminal vesicle dissection followed by prostate cancer intensity-modulated radiotherapy, the objective of the study was to evaluate the dosimetric benefit of reducing the target volume.

PATIENTS AND METHODS

A total of 25 patients with high-risk prostate cancer had surgery first followed by intensity-modulated radiotherapy and androgen deprivation. Four treatment planning were simulated for each patient, based on two CT scans performed before and after surgery. The target volumes were: prostate-seminal vesicles-lymph nodes, prostate-lymph nodes, prostate-seminal vesicles and prostate only. The total dose was 46Gy in the seminal vesicles and lymph nodes, and 80Gy in the prostate.

RESULTS

Compared to prostate target volume only, the addition of seminal vesicles and lymph nodes multiplied by a factor of 1.6 and 6.5 the target volume, respectively. Decreasing the target volume from prostate-seminal vesicles-lymph nodes to prostate-seminal vesicles, to prostate only decreased the rectal wall mean dose from 49Gy to 42Gy, to 36Gy, and the risk of late rectal bleeding from 4.4% to 3.2%, to 2.4% (P<0.05), respectively. The bladder wall mean dose decreased from 51Gy to 40Gy, to 35Gy (P<0,05), respectively. Not irradiating the lymph nodes decreased the absolute risk of diarrhea by 11%.

CONCLUSION

Lymph node and seminal vesicle dissection before prostate cancer intensity-modulated radiotherapy allows decreasing moderately the risk of digestive toxicity.

Gaps between Evidence and Practice in Postoperative Radiotherapy for Prostate Cancer: Focus on Toxicities and the Effects on Health-Related Quality of Life

Adjuvant radiotherapy (ART) after prostatectomy for patients with high-risk features [extracapsular extension (ECE), seminal vesicle invasion (SVI), and positive margin] has been shown to be associated with improved biochemical disease-free survival in three large randomized trials and with improved overall survival in one. Similarly, salvage radiotherapy (SRT) can effectively achieve biochemical control in a significant proportion of patients with a rising PSA after surgery. Nonetheless, both approaches of postoperative RT remain highly underutilized. This might be partly due to concerns with overtreatment inherent to adjuvant approaches, and/or hesitance about causing radiation toxicities and their subsequent effects on the patient's quality of life. Herein, we review the literature lending evidence to these arguments. We show recent series of ART/SRT and their low rates of acute and long-term toxicities, translating only in transient decline in quality-of-life (QoL) outcomes. We conclude that concerns with side effects should not preclude the recommendation of an effective and curative-intent therapy for men with prostate cancer initially treated with radical surgery.

A prospective comparison of acute intestinal toxicity following whole pelvic versus small field intensity-modulated radiotherapy for prostate cancer

Purpose

To compare the acute intestinal toxicity of whole pelvic (WP) and small field (SF) intensity-modulated radiotherapy (IMRT) for prostate cancer using dosimetric and metabolic parameters as well as clinical findings.

Methods

Patients who received IMRT in either a definitive or postoperative setting were prospectively enrolled. Target volume and organs at risk including intestinal cavity (IC) were delineated in every patient by a single physician. The IC volume that received a 10–50 Gy dose at 5-Gy intervals (V10–V50) and the percentage of irradiated volume as a fraction of total IC volume were calculated. Plasma citrulline levels, as an objective biological marker, were checked at three time points: baseline and after exposure to 30 Gy and 60 Gy.

Results

Of the 41 patients, only six experienced grade 1 acute intestinal toxicity. Although all dose–volume parameters were significantly worse following WP than SF IMRT, there was no statistically significant relationship between these dosimetric parameters and clinical symptoms. Plasma citrulline levels did not show a serial decrease by radiotherapy volume difference (WP versus SF) and were not relevant to the irradiated doses.

Conclusion

Given that WP had comparable acute intestinal toxicities to those associated with SF, WP IMRT appears to be a feasible approach for the treatment of prostate cancer despite dosimetric disadvantages.

Helical tomotherapy for cancer treatment: a rapid health technology assessment

OBJECTIVES

Helical tomotherapy (HT) can be applied to treat complex malignant cancer with high-precise radiotherapy, and it can reduce the damage to normal tissues and improve treatment effects. But the procurement of HT must be approved by relevant departments of administration affairs. This study, appointed by the National Health and Family Planning Commission of China and undertook by the National Health Development Research Center and the Chinese Evidence-Based Medicine Centre, was aimed to rapidly assess the effectiveness, safety, costs, and applicability of HT, so as to provide currently available best evidence for decision-makers of health policies.

METHODS

We electronically searched databases including PubMed, EMbase, The Cochrane Library, CNKI, WanFang Data, VIP, CBM, and other professional websites. Two reviewer independently screened literature according to the inclusion and exclusion criteria, extracted data, assessed quality, and then performed descriptive analysis.

RESULTS

(i) We finally included 150 studies, encompassing 5 HTAs, 18 CCTs, and 127 observational studies. (ii) The included HTAs were published during 2006-2009, providing fairly less evidence of low quality and the results of 145 primary studies showed that: HT had been used mainly in the treatments of 14 kinds of cancer, with low total toxicity and high survival rates. Although the quality of the included studies was poor, there was much evidence about prostate cancer, head and neck cancer, nasopharynx cancer, cervical cancer, lung cancer and liver cancer, with enough sample and fairly reliable results in HT efficacy and safety. And (iii) a total of 56 clinical trials were registered in Clinicaltrials.gov, most of which were registered by the occident. Among them, 9 were completed but the results had not been published yet.

CONCLUSIONS

The evidence of this study showed that, HT is safe and effective in clinic. But the abovementioned conclusion needs to be verified by conducting more high-quality studies with long-term follow-up. The costs of HT in procurement, maintenance, and application are high; and the skills, training, and qualification of operators are required. We suggest that the procurement of HT should be reduced; it should be allocated rationally and effectively used after comprehensive assessment in China's cancer epidemiology characteristics, health resource allocation, disease burden, medical service level, etc.; and also high-quality studies with long-term follow-up should be financially supported on the basis of establishing projects, so as to provide local evidence and consistently guide and improve scientific decision-making.

Prostate bed motion may cause geographic miss in post-prostatectomy image-guided intensity-modulated radiotherapy

INTRODUCTION

There is little data to guide radiation oncologists on appropriate margin selection in the post-prostatectomy setting. The aim of this study was to quantify interfraction variation in motion of the prostate bed to determine these margins.

METHODS

The superior and inferior surgical clips in the prostate bed were tracked on pretreatment cone beam CT images (n = 377) for 40 patients who had received post-prostatectomy radiotherapy. Prostate bed motion was calculated for the upper and lower segments by measuring the position of surgical clips located close to midline relative to bony anatomy in the axial (translational) and sagittal (tilt) planes. The frequency of potential geographic misses was calculated for either 1 cm or 0.5 cm posterior planning target volume margins.

RESULTS

The mean magnitude of movement of the prostate bed in the anterior-posterior, superior-inferior and left-right planes, respectively, were as follows: upper portion, 0.50 cm, 0.28 cm, 0.10 cm; lower portion, 0.18 cm, 0.18 cm, 0.08 cm. The random and systematic errors, respectively, of the prostate bed motion in the anterior-posterior, superior-inferior and left-right planes, respectively, were as follows: upper portion, 0.47 cm and 0.50 cm, 0.28 cm and 0.27 cm, 0.11 cm and 0.11 cm; lower portion, 0.17 cm and 0.18 cm, 0.17 cm and 0.19 cm, 0.08 cm and 0.10 cm. Most geographic misses occurred in the upper prostate bed in the anterior-posterior plane. The median prostate bed tilt was 1.8° (range -23.4° to 42.3°).

CONCLUSIONS

Variability was seen in all planes for the movement of both surgical clips. The greatest movement occurred in the anterior-posterior plane in the upper prostate bed, which could cause geographic miss of treatment delivery. The variability in the movement of the superior and inferior clips indicates a prostate bed tilt that would be difficult to correct with standard online matching techniques. This creates a strong argument for using anisotropic planning target volume margins in post-prostatectomy radiotherapy.

Salvage intensity modulated radiotherapy using endorectal balloon after radical prostatectomy: clinical outcomes

OBJECTIVES

To evaluate biochemical non-evidence of disease and adverse events of salvage intensity-modulated radiotherapy using an endorectal balloon for prostate cancer patients after radical prostatectomy.

METHODS

Data of 107 patients (median age 65 years) with persistent (>0.1 ng/mL) or rising prostate-specific antigen after radical prostatectomy were retrospectively analyzed. The mean dose to clinical target volume was 70 Gy in 32 fractions (the equivalent dose in 2 Gy fraction is 73.2 Gy based on α:β = 2). Biochemical non-evidence of disease and predictive factors were assessed. Genitourinary toxicity and gastrointestinal toxicity were also evaluated using the Radiation Therapy Oncology Group toxicity criteria.

RESULTS

The median follow up was 37 months (range 6-126 months). A total of 48 patients developed biochemical recurrence. The 3- and 5-year biochemical non-evidence of disease rates of all patients were 52.6% and 48.8%, respectively. The Gleason score (≥4 + 3, ≤3 + 4) and pre-intensity-modulated radiotherapy prostate-specific antigen level (≥0.5 ng/mL, <0.5 ng/mL) were significant predictive factors for biochemical non-evidence of disease in univariate analysis. In multivariate analysis, only the Gleason score was detected as a significant variable. The highest late genitourinary toxicities were grade 2 in 13% and grade 3 in 6% of patients. The highest late gastrointestinal toxicities were grade 2 in 6% and grade 3 in 3% of patients.

CONCLUSION

Despite a relatively high radiation dose, intensity-modulated radiotherapy with an endorectal balloon can be delivered with acceptable toxicity and efficacy for patients developing biochemical recurrence after radical prostatectomy.

Role of early proctoscopy in predicting late symptomatic proctitis after external radiation therapy for prostate carcinoma

PURPOSE

To determine whether acute radiation-proctitis, diagnosed by proctoscopy after radiation therapy for prostate cancer, can predict late clinical proctitis.

METHODS AND MATERIALS

A prospective study of 130 patients who underwent external radiation therapy (RT) for stage T1 to T4 prostate cancer between 1997 and 2008 was performed. Treatments were conventional (2-dimensional [2D]) in 61 patients and 3D conformal in 69, with a median target dose of 72 Gy (70-74 Gy). Within 1 week after RT, proctoscopy was performed to detect possible acute endoscopic proctitis (AEP). Acute clinical proctitis (ACP) and late clinical proctitis (LCP) were also evaluated. The median follow-up was 84 months (20-180 months). The influence of AEP and ACP on LCP occurrence was studied using the Cox model controlling for age, dose, prostatectomy, RT technique (2D vs 3D), and hormone therapy.

RESULTS

AEP was detected in 15 patients (11.5%) and ACP in 67 (51.5%); in 13 cases (10%) AEP and ACP occurred simultaneously. Thirty-five cases of LCP were recorded. The 5-year probability of developing LCP was highest in patients with AEP and ACP (77%, 95% confidence interval [CI] 53%-94%) and lowest in asymptomatic patients (14%, 95% CI 7%-26%; P<.001). Compared to asymptomatic patients, the 5-year probability also was slightly increased in patients with ACP only (26%, 95% CI 16%-40%; P=.052). In multivariable analysis, the combination of AEP and ACP was the main predictor of LCP: compared to asymptomatic patients, the hazard ratio was 5.6 (2.1-15.2) in patients with AEP plus ACP (P=.001) and 2.1 (0.9-4.9) in those with ACP only (P=.103).

CONCLUSIONS

In patients with AEP and ACP, the risk of LCP was more than 5-fold increased compared to those who were asymptomatic, while a much smaller increase in risk occurred in patients with ACP only. Early proctoscopy can provide valuable information regarding the likelihood of late proctitis.

[Image guidance for the evaluation of setup accuracy]

Information obtained by different methods of image-guided radiotherapy now allows us to reposition the target volume. This evolution causes a change in practice and positioning control. In order to control positioning errors, a systematic control during the first three to five sessions is required. Random repositioning errors and clinical target volume motions can be mastered only by performing a daily imaging. Finally, image-guided radiotherapy allows assessing anatomical changes occurring during treatment, and opens the field of adaptive radiotherapy.

Use of fractional dose-volume histograms to model risk of acute rectal toxicity among patients treated on RTOG 94-06

BACKGROUND AND PURPOSE

For toxicities occurring during the course of radiotherapy, it is conceptually inaccurate to perform normal-tissue complication probability analyses using the complete dose-volume histogram. The goal of this study was to analyze acute rectal toxicity using a novel approach in which the fit of the Lyman-Kutcher-Burman (LKB) model is based on the fractional rectal dose-volume histogram (DVH).

MATERIALS AND METHODS

Grade ≥2 acute rectal toxicity was analyzed in 509 patients treated on Radiation Therapy Oncology Group (RTOG) protocol 94-06. These patients had no field reductions or treatment-plan revisions during therapy, allowing the fractional rectal DVH to be estimated from the complete rectal DVH based on the total number of dose fractions delivered.

RESULTS

The majority of patients experiencing Grade ≥2 acute rectal toxicity did so before completion of radiotherapy (70/80=88%). Acute rectal toxicity depends on fractional mean rectal dose, with no significant improvement in the LKB model fit when the volume parameter differs from n=1. The incidence of toxicity was significantly lower for patients who received hormone therapy (P=0.024).

CONCLUSIONS

Variations in fractional mean dose explain the differences in incidence of acute rectal toxicity, with no detectable effect seen here for differences in numbers of dose fractions delivered.

Post-prostatectomy image-guided radiation therapy: evaluation of toxicity and inter-fraction variation using online cone-beam CT

PURPOSE

The purpose of this study is to assess the acute and late genitourinary (GU) and gastrointestinal (GI) toxicities of cone-beam computed tomography (CBCT) guided conformal adjuvant and salvage post-prostatectomy radiotherapy (RT) compared with RT with port films.

MATERIALS AND METHODS

Sixty-eight patients (group 1) were treated with RT following radical prostatectomy (RP) using CBCT-guided conformal RT to a median dose of 68.4Gy. CBCT images were acquired three to five times weekly and were automatically co-registered to a reference CT. A comparative group (group 2) included 150 patients who received post-RP RT with weekly port films to a median dose of 64.8Gy. GU and GI toxicities were graded in both the acute and late settings using Radiation Therapy Oncology Group criteria. Associations between toxicity and study variables were evaluated by odds ratios (ORs) estimated by logistic regression.

RESULTS

Grades 2 and 3 acute GU toxicity were experienced by 13% (n=9) and 2% (n=1) of patients in group 1, respectively, while 13% (n=19) had grade 2 acute GU toxicity in the control group (group 2). Grade 2 acute GI toxicity was experienced by 13% (n=9) and 15% (n=23) in groups 1 and 2, respectively. Acute GU (P=0.67) and GI (P =0.84) toxicities were not significantly different between the two groups. There were no associations detected between CBCT and acute GI toxicity (OR 0.76, P=0.57) or acute GU (OR 1.16, P=0.75). Increased odds of acute GU toxicity were observed for doses>68.4Gy (OR 12.81, P=0.04), which were only delivered in the CBCT group. CBCT mean variations (standard deviation) for 1053 fractions were 2.8mm (2.8), 2.0mm (2.4) and 3.1mm (2.9) in the left-to-right, anterior-to-posterior (AP) and superior-to-inferior (SI) axes, respectively. Corrective shifts for variance≥5mm were required for 15%, 6% and 19% of fractions in the left-to-right, anterior-to-posterior and superior-to-inferior axes, respectively.

CONCLUSIONS

Rates of acute toxicity with CBCT-guided post-RP RT to 68.4Gy were similar to treatment to 64.8Gy without image-guidance RT. Acceptable early toxicity profiles suggest that CBCT is a reasonable strategy for image guidance, but the value of CBCT must be weighed against potential increased risk of secondary cancers due to increased radiation exposure.

Costs of early adjuvant radiation therapy after radical prostatectomy: a decision analysis

BACKGROUND

This analysis was carried out to evaluate the cost-effectiveness of adjuvant radiation therapy (ART) versus observation, using a decision analysis model based primarily upon the published results of the Southwest Oncology Group prospective trial (SWOG 8794).

PATIENTS AND METHODS

A decision analysis model was designed to compare ART versus observation over a 10-year time horizon. Probabilities of treatment success, utilization of salvage treatments, and rates of adverse events were taken from published results of SWOG 8794. Cost inputs were based on 2010 Medicare reimbursement rates. Primary outcome measure was incremental cost per prostate-specific antigen (PSA) success (i.e. serum PSA level <0.4 ng/ml).

RESULTS

ART results in a higher PSA success rate than observation with probability of 0.43 versus 0.22. The mean incremental cost per patient for ART versus observation was $6023. The mean incremental cost-effectiveness ratio was $26,983 over the 10-year period.

CONCLUSIONS

ART appears cost effective compared with observation based upon this decision analysis model. Future research should consider more costly radiation therapy (RT) approaches, such as intensity-modulated RT, and should evaluate the cost-effectiveness of ART versus early salvage RT.

Acute toxicity in prostate cancer patients treated with and without image-guided radiotherapy

BACKGROUND

Image-guided radiotherapy (IGRT) increases the accuracy of treatment delivery through daily target localisation. We report on toxicity symptoms experienced during radiotherapy treatment, with and without IGRT in prostate cancer patients treated radically.

METHODS

Between 2006 and 2009, acute toxicity data for ten symptoms were collected prospectively onto standardized assessment forms. Toxicity was scored during radiotherapy, according to the Common Terminology Criteria Adverse Events V3.0, for 275 prostate cancer patients before and after the implementation of a fiducial marker IGRT program and dose escalation from 74 Gy in 37 fractions, to 78 Gy in 39 fractions. Margins and planning constraints were maintained the same during the study period. The symptoms scored were urinary frequency, cystitis, bladder spasm, urinary incontinence, urinary retention, diarrhoea, haemorrhoids, proctitis, anal skin discomfort and fatigue. Analysis was conducted for the maximum grade of toxicity and the median number of days from the onset of that toxicity to the end of treatment.

RESULTS

In the IGRT group, 14228 toxicity scores were analysed from 249 patients. In the non-IGRT group, 1893 toxicity scores were analysed from 26 patients. Urinary frequency ≥G3 affected 23% and 7% in the non-IGRT and IGRT group respectively (p = 0.0188). Diarrhoea ≥G2 affected 15% and 3% of patients in the non-IGRT and IGRT groups (p = 0.0174). Fatigue ≥G2 affected 23% and 8% of patients in the non-IGRT and IGRT groups (p = 0.0271). The median number of days with a toxicity was higher for ≥G2 (p = 0.0179) and ≥G3 frequency (p = 0.0027), ≥G2 diarrhoea (p = 0.0033) and ≥G2 fatigue (p = 0.0088) in the non-IGRT group compared to the IGRT group. Other toxicities were not of significant statistical difference.

CONCLUSIONS

In this study, prostate cancer patients treated radically with IGRT had less severe urinary frequency, diarrhoea and fatigue during treatment compared to patients treated with non-IGRT. Onset of these symptoms was earlier in the non-IGRT group. IGRT results in less acute toxicity during radiotherapy in prostate cancer.

Two-year clinical experience with tomotherapy: the French national cancer institute project on implementing new technology

The pooled 2-year clinical experience using three tomotherapy units installed in France in 2007 is presented. Treatment indications and protocols were devised for each disease site and were the result of a consensus. A total of 642 patients were treated for central nervous system, head and neck, thoracic, abdominal, and pelvic tumors. Overall, grade 3, 4, and 5 acute toxicity was 10.7%, 0.3%, and 0.2%, respectively. Grade 3 chronic toxicity was 1.2%. There was no grade 4 or 5 chronic toxicity. The use of tomotherapy in a broad clinical practice is safe, and acute and chronic toxicity both are acceptable for all anatomical locations.

Improved toxicity profile following high-dose postprostatectomy salvage radiation therapy with intensity-modulated radiation therapy

BACKGROUND

With salvage radiation therapy (SRT) in the postprostatectomy setting, the need to deliver sufficient radiation doses to achieve a high probability of tumor control is balanced with the risk of increased toxicity. Intensity-modulated radiation therapy (IMRT) in the postprostatectomy salvage setting is gaining interest as a treatment strategy.

OBJECTIVE

Compare acute and late toxicities in patients treated with IMRT and three-dimensional conformal radiation therapy (3D-CRT) in the postprostatectomy salvage setting.

DESIGN, SETTING, AND PARTICIPANTS

A total of 285 patients who were treated at our institution between 1988 and 2007 with SRT after radical prostatectomy for biochemical recurrence were identified. All medical records were reviewed and toxicity recorded. Median follow-up was 60 mo.

INTERVENTION

All patients were treated with SRT with either 3D-CRT (n=109) or IMRT (n=176). A total of 205 patients (72%) were treated with doses ≥70Gy.

MEASUREMENTS

Late gastrointestinal (GI) and genitourinary (GU) toxicities were recorded using the Common Terminology Criteria for Adverse Events v. 3.0 definition.

RESULTS AND LIMITATIONS

The 5-yr actuarial rates of late grade ≥2 GI and GU toxicity were 5.2% and 17.0%, respectively. IMRT was independently associated with a reduction in grade ≥2 GI toxicity compared with 3D-CRT (5-yr IMRT, 1.9%; 5-yr 3D-CRT, 10.2%; p=0.02). IMRT was not associated with a reduction in risk of grade ≥2 GU toxicity (5-yr IMRT, 16.8%; 5-yr 3D-CRT, 15.8%; p=0.86), urinary incontinence (5-yr IMRT, 13.6%; 5-yr 3D-CRT, 7.9%; p=0.25), or grade 3 erectile dysfunction (5-yr IMRT, 26%; 5-yr 3D-CRT, 30%; p=0.82). Of patients who developed late grade ≥2 GI or GU toxicity, 38% and 44%, respectively, experienced resolution of their symptoms prior to the last follow-up.

CONCLUSIONS

Our experience with high-dose IMRT in the postprostatectomy salvage setting demonstrates that the treatment can be delivered safely with an associated reduction in late GI toxicity.

Comparison of daily cone-beam computed tomography and kilovoltage planar imaging for target localization in prostate cancer patients following radical prostatectomy

PURPOSE

To review our initial clinical experience with image-guided radiation therapy (IGRT) using cone-beam computed tomography (CBCT) for prostate bed localization in post-radical prostatectomy (RP) patients and to compare shift and acute toxicity results to our previously published IGRT experience with daily kV planar imaging.

METHODS AND MATERIALS

Fifty patients treated with intensity modulated radiation therapy (IMRT) who had image guidance using either CBCT (n = 23) or kV planar imaging (n = 27) following RP were analyzed. Shifts were recorded in anterior-posterior, superior-inferior, and left-right axes. Total error was defined as the shift from initial setup based on skin markings to isocenter. Prostate bed motion (PBM) was defined as the change in prostate bed position relative to bones. Acute toxicity was graded according to the Radiation Therapy Oncology Group morbidity criteria.

RESULTS

Total error (TE) was measured in 752 CBCTs and 725 kV planar image pairs. PBM was measured in 585 CBCTs and 384 kV planar image pairs. The average magnitudes of TE and PBM in the anterior-posterior, superior-inferior, and left-right axes were greater with kV planar imaging compared to CBCT. Frequencies of acute grade 2 gastrointestinal (13% vs 7%, P = .7) and genitourinary (9% vs 11%, P = 1.0) were similar for CBCT and kV planar imaging patients. No toxicities greater than grade 2 were seen.

CONCLUSIONS

These results suggest that although the magnitudes of TE and PBM were larger with kV planar compared to CBCT, the levels of acute toxicity were acceptable and comparable between the two. The reasons for the differences are unclear, but we postulate that discernment of the prostate bed on the CBCT is more difficult. Further investigation is necessary to determine the reason for the shift differences and to evaluate the benefits and risks of CBCT in this setting.

Dosimetric effect of online image-guided anatomical interventions for postprostatectomy cancer patients

PURPOSE

To assess daily variations in delivered doses in postprostatectomy patients, using kilovoltage cone-beam CT (CBCT) datasets acquired before and after interventions to correct for observed distortions in volume/shape of rectum and bladder.

METHODS AND MATERIALS

Seventeen consecutive patients treated with intensity-modulated radiotherapy to the prostate bed were studied. For patients with large anatomical variations, quantified by either a rectal wall displacement of >5 mm or bladder volume change of >50% on the CBCT compared with the planning CT, an intervention was performed to adjust the rectum and/or bladder filling. Cumulative doses over the pre- and post-intervention fractions were calculated by tracking the position of the planning CT voxels on different CBCTs using a deformable surface-mapping algorithm. Dose and displacements vectors were projected on two-dimensional maps, the minimal dose received by the highest 95% of the planing target volume (PTV D95) and the highest 10% of the rectum volume (D10) as well as the bladder volume receiving >2 Gy (V2) were evaluated.

RESULTS

Of 544 fractions, 96 required intervention. Median (range) number of interventions per patient was 5 (2-12). Compared with the planning values, the mean (SD) pre- vs. postintervention value for PTV D95 was -2% (2%) vs. -1% (2%) (p < 0.12), for rectum D10 was -1% (4%) vs. +1% (4%) (p < 0.24), and for bladder V2 was +6% vs. +20% (p < 0.84).

CONCLUSIONS

Interventions to reduce treatment volume deformations due to bladder and rectum fillings are not necessary when patients receive daily accurate CBCT localization, and the frequency of those potential interventions is low. However, for hypofractionated treatments, the relative frequency can significantly increase, and interventions can become more dosimetrically beneficial.

Impact of anatomical interventions on the localization of post-prostatectomy cancer patients

PURPOSE

Anatomical deformations of prostate-bed, rectum, and bladder can compromise the targeting accuracy in post-prostatectomy cancer patients. In this work, the impact of anatomical interventions on the localization data from post-prostatectomy patients who received image-guided IMRT was analyzed.

METHODS

Patients were localized daily with online kilovoltage cone-beam computed tomography (kV-CBCT). The target and the organs at risk (OARs) positional and volumetric changes were evaluated and couch shifts were applied. For patients with large target or OAR volumetric changes, quantified by either a rectal or bladder wall displacement of >5 mm on the CBCT sagittal images compared to the planning CT, repeated localization CBCT scans were performed following an interventional procedure. The procedure involves insertion of a catheter to deflate the rectum, evacuation of stools, and/or adjustment of bladder filling. The required shifts were then evaluated, and the IMRT treatment was subsequently delivered after proper patient positioning. The pre- and post-intervention shifts were compared in the lateral [left-right (LR)], longitudinal [superior-inferior (SI)], and vertical [anterior-posterior (AP)] directions. The percentage of shifts larger than 5 mm in all directions was also compared. Clinical target volume to planning target volume (CTV-to-PTV) expansion margins were estimated based on the pre- and post-intervention localization data.

RESULTS

Intervention was performed on all patients (n=17) treated between October 2008 and March 2009. The number of interventions ranged from 2 to 12 with a median number of 5, resulting in a total of 96 pairs of pre- and post-intervention shifts. The mean value (sigma) and standard deviation (sigma) of the shifts from pre- versus post-intervention data were LR, 0.0 +/- 3.0 mm vs. 0.5 +/- 2.8 mm; SI, 0.2 +/- 3.1 mm vs. -1.0 +/- 2.1 mm; and AP, -2.6 +/- 5.8 mm vs. 1.7 +/- 3.9 mm. The mean 3D shift distance was 7.0 +/- 3.1 mm vs. 5.0 +/- 2.6 mm. The percentage of pre-intervention shifts larger than 5 mm were 7%, 7%, and 45% in the LR, SI, and AP directions, respectively, compared to 8%, 4%, and 21% for post-intervention. Localization data from pre- and post-intervention procedures suggest that treatments that do not include intervention to correct for rectum/bladder anatomical variations require an additional 3.3 mm CTV-to-PTV margin.

CONCLUSIONS

Anatomical interventions reduced the localization errors arising from large volume and shape changes in the rectum and/or bladder compared to treatments without interventions.

Clinical comparative study of dose-volume and equivalent uniform dose based predictions in post radiotherapy acute complications

BACKGROUND

Single points placed on Dose-Volume Histograms (DVHs) for treatment plan acceptance are still widely used compared to the Equivalent Uniform Dose (EUD). The aim of this work is to retrospectively measure and compare the ability of both criteria in correctly predicting two clinical outcomes, RTOG grade 2 acute gastrointestinal (GI) and genitourinary (GU) complications in 137 patients treated for prostate cancer.

MATERIAL AND METHODS

For both complications,the best predictions have been achieved by fitting the EUD parameter and a tolerance dose (for a varying DVH point) by maximization of the Area Under the Receiver Operating Curve (AUROC). A complementary likelihood fitting of the Lyman's Normal Tissue Complication Probability (NTCP) allowed a graphical comparison between expected and observed frequencies, and to derive the associated parameters.

RESULTS AND DISCUSSION

No significant differences were found in the AUROC values obtained by using dose-volume or EUD criteria, but all the results highlighted the role of high doses. Limiting V65 (for grade 2 GI) or V73 (for grade 2 GU) was as predictive as limiting EUD value, with n equal to 0.09 or 0.06 respectively, but in all cases AUROC values were low (< 0.7). Likelihood fitting gave m = 0.195 and TD50=72.5 Gy (fixing n=0.06 for acute GU) and m=0.19 and TD50=66 Gy (fixing n=0.09 for acute GI). Both AUROC and likelihood values revealed a better fit for acute GI than for acute GU. The use of a fractionation correction, new clinical contours or previous risk factors could improve these values.

Toxicity analysis of postoperative image-guided intensity-modulated radiotherapy for prostate cancer

PURPOSE

To report on the acute and late gastrointestinal (GI) and genitourinary (GU) toxicity associated with a unique technique of image-guided radiotherapy (IGRT) in patients undergoing postprostatectomy irradiation.

METHODS AND MATERIALS

Fifty patients were treated with intensity-modulated radiation therapy (IMRT) after radical prostatectomy. Daily image guidance was performed to localize the prostate bed using kilovoltage imaging or cone-beam computed tomography. The median prescription dose was 68 Gy (range, 62-68 Gy). Toxicity was graded every 3 to 6 months according to the Common Terminology Criteria for Adverse Events version 3.0.

RESULTS

The median follow-up was 24 months (range, 13-38 months). Grade 2 acute GI and GU events occurred in 4 patients (8%) and 7 patients (14%), respectively. No Grade 3 or higher acute GI or GU toxicities were observed. Late Grade 2 GI and GU events occurred in 1 patient (2%) and 8 patients (16%), respectively. Only a single (2%) Grade 3 or higher late toxicity was observed.

CONCLUSIONS

Image-guided IMRT in the postprostatectomy setting is associated with a low frequency of acute and late GI/GU toxicity. These results compare more favorably to radiotherapy techniques that do not use in-room image-guidance, suggesting that daily prostate bed localization may reduce the incidence of adverse events in patients undergoing postprostatectomy irradiation.

Report from the Radiation Therapy Committee of the Southwest Oncology Group (SWOG): Research Objectives Workshop 2008

Strategic planning for the Radiation Therapy Committee of the Southwest Oncology Group (SWOG) is comprehensively evaluated every six years in an effort to maintain a current and relevant scientific focus, and to provide a standard platform for future development of protocol concepts. Participants in the 2008 Strategic Planning Workshop included clinical trial experts from multiple specialties, industry representatives from both pharmaceuticals and equipment manufacturers, and basic scientists. High-priority research areas such as image-guided radiation therapy for control of limited metastatic disease, analysis of biomarkers for treatment response and late toxicity, assessment of novel agents in combination with radiation, standardization of radiation target delineation, and the assessment of new imaging techniques to individualize cancer therapy, were discussed. Research priorities included clinical study designs featuring translational end points that identify patients most likely to benefit from combined modality therapy; intervention including combination radiation with standard chemotherapy; radiation with radiosensitizing molecular-targeted therapies; and stereotactic radiation for treatment of patients with regard to asymptomatic metastasis and radiation-induced tumor autoimmunity. The Committee concluded that the future research opportunities are among the most exciting to have developed in the last decade, and work is in progress to embark on these plans.

Sooner or later? Outcome analysis of 431 prostate cancer patients treated with postoperative or salvage radiotherapy

PURPOSE

To evaluate the outcome of postoperative radiotherapy (PORT) and salvage RT (SART) using a three-dimensional conformal two-dynamic arc (3D-ART) or 3D six-field technique in 431 prostate cancer patients.

METHODS AND MATERIALS

Of the 431 patients, 258 underwent PORT (started <6 months after radical prostatectomy) and 173 underwent SART because of biochemical failure after radical prostatectomy. The median patient age, preoperative prostate-specific antigen level, and Gleason score was 66 years, 9.4 ng/mL, and 7, respectively. The median radiation dose was 70 Gy in 35 fractions for both PORT and SART. The 3D six-field and 3D-ART techniques were used in 25.1% and 74.9% of patients, respectively. Biochemical failure was defined as a post-RT prostate-specific antigen nadir plus 0.1 ng/mL.

RESULTS

Acute toxicity included rectal events (PORT, 44.2% and 0.8% Grade 1-2 and Grade 3, respectively; SART, 42.2% and 1.2% Grade 1-2 and Grade 3, respectively) and urinary events (PORT, 51.2% and 2.3% Grade 1-2 and Grade 3-4, respectively; SART, 37.6% and 0% Grade 1-2 and Grade 3, respectively). Late toxicity also included rectal events (PORT, 14.7% and 0.8% Grade 1-2 and Grade 3-4, respectively; SART, 15.0% and 0.6% Grade 1-2 and Grade 3, respectively) and urinary events (PORT, 28.3% and 3.7% Grade 1-2 and Grade 3-4, respectively; SART, 19.3% and 0.6% Grade 1-2 and Grade 3, respectively). After a median follow-up of 48 months, failure-free survival, including biochemical and clinical failure, was significantly longer in the PORT patients (79.8% vs. 60.5%, p < 0.0001). Multivariate analysis showed that a prostate-specific antigen level postoperatively but before RT of >/=0.2 ng/mL (p < 0.001), Gleason score >6 (p = 0.025) and use of preoperative androgen deprivation (p = 0.002) correlated significantly with shorter failure-free survival. Multivariate analysis showed that PORT and the 3D-ART technique correlated with greater late urinary toxicity.

CONCLUSION

PORT and early referral for SART offer better disease control after radical prostatectomy. The greater urinary toxicity occurring after PORT and 3D-ART requires further investigation to improve the therapeutic index.