The role of whole pelvic radiotherapy in locally advanced prostate cancer

Prostate only radiotherapy using external beam radiotherapy: A clinician’s perspective

Prostate-only radiotherapy (PORT) is widely used as the definitive treatment for localized prostate cancer. Prostate cancer has an α/β ratio; therefore, radiotherapy (RT) with a large fraction size is biologically effective for tumor control. The current external beam RT technique for PORT has been improved from three-dimensional conformal RT to intensity-modulated, stereotactic body, and image-guided RTs. These methods are associated with reduced radiation exposure to normal tissues, decreasing urinary and bowel toxicity. Several trials have shown improved local control with dose escalation through the aforementioned methods, and the efficacy and safety of intensity-modulated and stereotactic body RTs have been proven. However, the management of RT in patients with prostate cancer has not been fully elucidated. As a clinician, there are several concerns regarding the RT volume and dose considering the patient’s age and comorbidities. Therefore, this review aimed to discuss the radiobiological basis and external beam technical advancements in PORT for localized prostate cancer from a clinician’s perspective.

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation

Background

Although there are some controversies regarding whole pelvic radiation therapy (WPRT) due to its gastrointestinal and hematologic toxicities, it is considered for patients with gynecological, rectal, and prostate cancer. To effectively spare organs-at-risk (OAR) doses using multi-leaf collimator (MLC)’s optimal segments, potential dosimetric benefits in volumetric modulated arc therapy (VMAT) using a half-beam technique (HF) were investigated for WPRT.

Methods

While the size of a fully opened field (FF) was decided to entirely include a planning target volume in all beam’s eye view across arc angles, the HF was designed to use half the FF from the isocenter for dose optimization. The left or the right half of the FF was alternatively opened in VMAT-HF using a pair of arcs rotating clockwise and counterclockwise. Dosimetric benefits of VMAT-HF, presented with dose conformity, homogeneity, and dose–volume parameters in terms of modulation complex score, were compared to VMAT optimized using the FF (VMAT-FF). Consequent normal tissue complication probability (NTCP) by reducing the irradiated volumes was evaluated as well as dose–volume parameters with statistical analysis for OAR. Moreover, beam-on time and MLC position precision were analyzed with log files to assess plan deliverability and clinical applicability of VMAT-HF as compared to VMAT-FF.

Results

While VMAT-HF used 60%–70% less intensity modulation complexity than VMAT-FF, it showed superior dose conformity. The small intestine and colon in VMAT-HF showed a noticeable reduction in the irradiated volumes of up to 35% and 15%, respectively, at an intermediate dose of 20–45 Gy. The small intestine showed statistically significant dose sparing at the volumes that received a dose from 15 to 45 Gy. Such a dose reduction for the small intestine and colon in VMAT-HF presented a significant NTCP reduction from that in VMAT-FF. Without sacrificing the beam delivery efficiency, VMAT-HF achieved effective OAR dose reduction in dose–volume histograms.

Conclusions

VMAT-HF led to deliver conformal doses with effective gastrointestinal-OAR dose sparing despite using less modulation complexity. The dose of VMAT-HF was delivered with the same beam-on time with VMAT-FF but precise MLC leaf motions. The VMAT-HF potentially can play a valuable role in reducing OAR toxicities associated with WPRT.

Outcomes and Prediction Models for Exclusive Prostate Bed Salvage Radiotherapy among Patients with Biochemical Recurrence after Radical Prostatectomy

BACKGROUND

The addition of androgen-deprivation therapy (ADT) or pelvic radiation to prostate bed salvage radiotherapy (SRT) has been debated for prostate cancer patients with biochemical recurrence (BCR) after radical prostatectomy. This study aimed to assess the outcomes and propose prediction models for exclusive prostate bed SRT.

METHODS

This is a prospective observational cohort study with patients who underwent SRT with a pre-SRT PSA < 1.5 ng/mL after radical prostatectomy. Patients were treated with 70-Gy SRT to the prostate bed exclusively. Kaplan-Meier survival analyses and Cox regression analyses were applied for depicting and predicting BCR-free survival, ADT-free survival, and metastasis-free survival (MFS). Regression-based coefficients were used to develop nomograms.

RESULTS

A total of 105 patients were included and 91 patients were eligible. The median follow-up period was 39 months. The 5-year BCR-free survival, ADT-free survival, and MFS were 37%, 50%, and 66%, respectively. Multivariable analysis showed that a pre-SRT PSA < 0.45 ng/mL was the only independent factor associated with longer BCR-free survival (p = 0.034), while a PSA-DT > 8 months had better ADT-free survival (p = 0.008). Patients with a PSA-DT > 8 months showed a 100% MFS and a 43% 5-year absolute benefit in MFS than a PSA-DT ≤ 8 months. All patients with a pre-SRT PSA < 0.45 ng/mL and PSA-DT > 8 months were free from subsequent ADT and any metastasis.

CONCLUSIONS

In patients with a PSA < 0.45 ng/mL and PSA-DT > 8 months for post-prostatectomy BCR, prostate bed SRT provided excellent outcomes without the need for concomitant ADT or pelvic radiotherapy.

Late toxicity and quality of life with prostate only or whole pelvic radiation therapy in high risk prostate cancer (POP-RT): A randomised trial

AIM

To report toxicity and quality of life (QOL) outcomes from a randomised trial of prostate only versus whole pelvic radiotherapy in high risk, node negative prostate cancer.

MATERIALS/METHODS

Patients with localised prostate adenocarcinoma and nodal involvement risk > 20%, were randomised to prostate only (PORT, 68 Gy/25# to prostate) and whole pelvis (WPRT, 68 Gy/25# to prostate and 50 Gy/25# to pelvis) arms with stratification for TURP, Gleason score, baseline PSA, and type of androgen deprivation therapy (ADT). Image guided intensity modulated radiotherapy (IG-IMRT) and two years of ADT were mandatory. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicities were graded using RTOG grading. QOL was assessed using EORTC QLQ-C30 and PR-25 questionnaire pre-treatment and every 3-6 months post RT.

RESULTS

Total 224 patients were randomised (PORT 114, WPRT 110) from November 2011 to August 2017. Median follow up was 44.5 months. No RTOG grade IV toxicity was observed. Acute GI and GU toxicities were similar between both the arms. Cumulative ≥ grade II late GI toxicity was similar for WPRT and PORT (6.5% vs. 3.8%, p = 0.39) but GU toxicity was higher (17.7% vs. 7.5%, p = 0.03). Dosimetric analysis showed higher bladder volume receiving 30-40 Gy in the WPRT arm (V30, 60% vs. 36%, p < 0.001; V40, 41% vs. 25%, p < 0.001). There was no difference in QOL scores of any domain between both arms.

CONCLUSION

Pelvic irradiation using hypofractionated IG-IMRT resulted in increased grade II or higher late genitourinary toxicity as compared to prostate only RT, but the difference was not reflected in patient reported QOL. CLINICALTRIALS.GOV NCT02302105: Prostate Only or Whole Pelvic Radiation Therapy in High Risk Prostate Cancer (POP-RT).

Risk-adapted moderate hypofractionation of prostate cancer : A prospective analysis of acute toxicity, QOL and outcome in 221 patients

Purpose

Prostate cancer (PCA) is highly heterogeneous in terms of its oncologic outcome. We therefore aimed to tailor radiation treatment to the risk status by using three different hypofractionated radiation regimen differing in applied dose, use of rectum spacer, inclusion of pelvic lymph nodes (pLN) and use of androgen deprivation therapy (ADT). Here we report on acute toxicity, quality of life (QOL) and oncologic outcome at a median follow-up of 12 months.

Methods

A total of 221 consecutive PCA patients received hypofractionated intensity-modulated radiotherapy (IMRT). Low-risk (LR) patients were planned to receive 60 Gy in 20 fractions (EQD2^α/β1.5 = 77.1 Gy), intermediate-risk (IR) patients 63 Gy in 21 fractions (EQD2^α/β1.5 = 81 Gy), and high-risk (HR) patients 67.5 Gy in 25 fractions (EQD2^α/β1.5 = 81 Gy) to the prostate and 50 Gy in 25 fractions to the pLN. Acute rectal toxicity was assessed by endoscopy. In addition, toxicity was scored using CTC-AE 4.0 and IPSS score, while QOL was assessed using QLQ-PR25 questionnaires.

Results

Acute CTC reactions were slightly higher in the HR regimen but reverted to baseline at 3 months. GI G2 toxicity was 4%, 0% and 12% for the LR, IR and HR regimen. Compared to IR patients, the increase in toxicity in HR patients was statistically significant (p = 0.002) and mainly caused by a higher incidence of diarrhea presumably due to pelvic EBRT. QOL scores of all domains were worse for the HR regimen (not significant).

Conclusion

Risk-adapted moderate hypofractionation is associated with low GI/GU toxicity. Given the higher rate of pelvic metastases in HR patients, slightly higher transient acute reactions should be outweighed by possible oncological benefits.

Conformal Radiotherapy of Clinically Localized Prostate Cancer: Analysis of Rectal and Urinary Toxicity and Correlation with Dose-Volume Parameters

Aims and background

Rectal and urinary toxicities are the principal limiting factors in delivering a high target dose to patients affected by prostate cancer. The verification of such toxicity is an important step before starting a dose-escalation program. The present observational study reports on the acute and late rectal and urinary toxicity in relation with dose-volume parameters in 104 patients with localized prostate cancer treated with 3-dimensional conformal radiation therapy.

Methods and study design

One hundred and four patients with stage T1b-T3b prostate cancer were treated with three-dimensional conformal radiation therapy to a total dose of 74 Gy, 2 Gy per fraction. Rigid dose constraints were applied for rectum and bladder. Acute and late rectal and urinary toxicities were analyzed also in relation to dose-volume histograms. Biochemical relapse-free survival was defined according to the American Society of Therapeutic Radiation Oncology (ASTRO) criteria and to the RTOG-ASTRO Phoenix Consensus Conference Recommendations using the Kaplan-Meier method.

Results

No grade 3 toxicity was observed. Acute and late grade 2 toxicity rates were 5.8% and 9.0% for rectum and 12.5% and 2.0% for bladder, respectively. Rectal V70 influenced the occurrence of late grade 2 toxicity. A relationship between acute and late urinary toxicity was also found. After a median follow-up of 30 months (range, 20–50), the actuarial overall and biochemical relapse-free survival rates were 84% and 77%, respectively, with a significant difference between low-intermediate and high-risk patients.

Conclusions

Conformal radiotherapy to the dose of 74 Gy was administered with good compliance. The incidence of acute and late toxicity was relatively low in accord with our dose constraints. Rectal V70 proved to be a reliable prognosticator of late toxicity. Overall survival and biochemical relapse-free survival rates were more favorable for low and intermediate-risk and significantly less favorable for high-risk patients.

Advanced optimization methods for whole pelvic and local prostate external beam therapy

PURPOSE

Radiation treatment planning inherently involves multiple conflicting planning goals, which makes it a suitable application for multicriteria optimization (MCO). This study investigates a MCO algorithm for VMAT planning (VMAT-MCO) for prostate cancer treatments including pelvic lymph nodes and uses standard inverse VMAT optimization (sVMAT) and Tomotherapy planning as benchmarks.

METHODS

For each of ten prostate cancer patients, a two stage plan was generated, consisting of a stage 1 plan delivering 22Gy to the prostate, and a stage 2 plan delivering 50.4Gy to the lymph nodes and 56Gy to the prostate with a simultaneous integrated boost. The single plans were generated by three planning techniques (VMAT-MCO, sVMAT, Tomotherapy) and subsequently compared with respect to plan quality and planning time efficiency.

RESULTS

Plan quality was similar for all techniques, but sVMAT showed slightly better rectum (on average Dmean -7%) and bowel sparing (Dmean -17%) compared to VMAT-MCO in the whole pelvic treatments. Tomotherapy plans exhibited higher bladder dose (Dmean +42%) in stage 1 and lower rectum dose (Dmean -6%) in stage 2 than VMAT-MCO. Compared to manual planning, the planning time with MCO was reduced up to 12 and 38min for stage 1 and 2 plans, respectively.

CONCLUSION

MCO can generate highly conformal prostate VMAT plans with minimal workload in the settings of prostate-only treatments and prostate plus lymph nodes irradiation. In the whole pelvic plan manual VMAT optimization led to slightly improved OAR sparing over VMAT-MCO, whereas for the primary prostate treatment plan quality was equal.

Individualized image-based lymph node irradiation for prostate cancer

Controversy surrounds the benefit of whole pelvis radiotherapy (WPRT) over prostate-only radiotherapy (PORT) for intermediate-risk and high-risk patients with prostate cancer. In the PSA screening era, two large randomized trials as well as multiple retrospective studies comparing WPRT with PORT have been performed, albeit with contradictory results. Data regarding the use of WPRT in patients with biochemical recurrence after prostatectomy are scarce. As a consequence, the practice of WPRT varies worldwide. Advanced highly accurate imaging methods for the detection of lymph node metastases in patients with prostate cancer have been developed, such as PET, single photon emission computed tomography (SPECT), diffusion-weighted MRI and magnetic resonance lymphography (MRL). The use of these new imaging methods might improve nodal irradiation, as they can be used not only for selection of patients, but also for accurately determining the target volume to reduce geographical miss. Furthermore, these new techniques can enable dose escalation to involved lymph nodes.

Results of combined radiotherapy and hormonal treatment of prostate cancer patients with initial PSA value >40 ng/ml

AIM

To evaluate the outcome of prostate cancer patients with initial PSA value >40 ng/ml.

BACKGROUND

The outcome of prostate cancer patients with very high initial PSA value is not known and patients are frequently treated with palliative intent. We analyzed the outcome of radical combined hormonal treatment and radiotherapy in prostate cancer patients with initial PSA value >40 ng/ml.

METHODS

Between January 2003 and December 2007 we treated, with curative intent, 56 patients with non-metastatic prostate cancer and initial PSA value >40 ng/ml. The treatment consisted of two months of neoadjuvant hormonal treatment (LHRH analog), radical radiotherapy (68-78 Gy, conformal technique) and an optional two-year adjuvant hormonal treatment.

RESULTS

The median time of follow up was 61 months. 5-Year overall survival was 90%. 5-Year biochemical disease free survival was 62%. T stage, Gleason score, PSA value, and radiotherapy dose did not significantly influence the outcome. Late genitourinal and gastrointestinal toxicity was acceptable.

CONCLUSION

Radical treatment in combination with hormonal treatment and radiotherapy can be recommended for this subgroup of prostate cancer patients with good performance status and life expectancy.

Ferumoxtran-10 MR lymphography for target definition and follow-up in a patient undergoing image-guided, dose-escalated radiotherapy of lymph nodes upon PSA relapse

PURPOSE

Evaluation of the lymph node situation in patients with prostate cancer is essential for effective radiotherapy. Using magnet resonance imaging (MRI) of the lymph nodes with ferumoxtran-10 (MR lymphography), it is possible to detect lymph node metastasis. We present our initial experience with ferumoxtran-10 MR lymphography as the basis for image-guided, dose-escalated lymph node radiotherapy and for early follow-up after radiotherapy.

PATIENTS AND METHODS

A patient with suspicion for lymph node metastasis after radical prostatectomy was examined with MR lymphography with the lymph node-specific contrast media ferumoxtran-10. Radiotherapy was performed as intensity-modulated radiotherapy with a total dose of 44 Gy to the whole lymphatic drainage, 60 Gy to the area of affected lymph nodes, 71 Gy to the prostate bed, and 75 Gy to the anastomosis region. 8 weeks after completion of radiotherapy, a follow-up MR lymphography with ferumoxtran-10 was performed.

RESULTS

In the first MRI with ferumoxtran-10, 5 metastatic lymph nodes were found in the iliac region. The scan 8 weeks postradiotherapy no longer showed lymph nodes suspicious for metastases. PSA (prostate-specific antigen) decreased from 2.06 ng/ml pretherapeutically to 0.02 ng/ml at 2 weeks after treatment and was no longer detectable at 8 months after treatment.

CONCLUSIONS

Lymph node staging with ferumoxtran-10 and subsequent dose escalation with intensity-modulated radiotherapy led to the elimination of positive lymph nodes and a decrease in the PSA value.

Predictors of acute bowel toxicity in patients treated with IMRT whole pelvis irradiation after prostatectomy

PURPOSE/OBJECTIVE

Whole pelvis irradiation with IMRT (WPRT-IMRT) after prostatectomy is efficient in reducing acute toxicity: however, a number of patients still experience moderate acute bowel toxicity.

MATERIALS AND METHODS

Ninety-six patients treated with WPRT-IMRT after prostatectomy with adjuvant or salvage intent were analysed. A number of parameters were individually recovered, including the DVHs of the intestinal cavity outside PTV and of the loops referred to both the WPRT phase and the whole treatment. Correlation between clinical-dosimetric parameters and acute bowel toxicity was investigated by logistic analyses. Best predictive cut-off values for continuous variables were assessed by ROC curves.

RESULTS

15/96 (15.6%) Patients experienced grade 2 toxicity (no grade 3). Best dose-volume predictors were the fraction of loops receiving more than 45, 50 and 55 Gy (respectively, V45TL ≥ 50cc, V50TL ≥ 13cc, V55TL ≥ 3cc; p-values ranging from 0.005 to 0.027). Age, GU acute toxicity, rectal acute toxicity and time between prostatectomy and IMRT were also predictors of acute bowel toxicity. Multivariate analysis showed that the most predictive independent parameters were age (OR: 1.13; 95%CI: 1.02-1.25; p=0.021) and V50TL (≥ 13cc, OR: 8.2; 95%CI: 1.7-40; p=0.009).

CONCLUSIONS

The risk of moderate acute uGI toxicity during WPRT-IMRT for post-operatively treated patients increases with age; the risk is substantially reduced in patients with small overlap between PTV and loops.

Benefit of whole pelvic radiotherapy combined with neoadjuvant androgen deprivation for the high-risk prostate cancer

AIM

To study whether use of neoadjuvant androgen deprivation therapy (N-ADT) combined with whole pelvic radiotherapy (WPRT) for high-risk prostate cancer patients was associated with survival benefit over prostate radiotherapy (PORT) only.

MATERIAL AND METHODS

Between 1999 and 2004, 162 high-risk prostate cancer patients were treated with radiotherapy combined with long-term androgen deprivation therapy (L-ADT). Patients were prospectively assigned into two groups: A (N-ADT + WPRT + L-ADT) n = 70 pts, B (PORT + L-ADT) n = 92 pts.

RESULTS

The 5-year actuarial overall survival (OS) rates were 89% for A and 78% for B (P = .13). The 5-year actuarial cause specific survival (CSS) rates were A = 90% and B = 79% (P = .01). Biochemical progression-free survival (bPFS) rates were 52% versus 40% (P = .07), for groups A and B, respectively.

CONCLUSIONS

The WPRT combined with N-ADT compared to PORT for high-risk patients resulted in improvement in CSS and bPFS; however no OS benefit was observed.

Helical Tomotherapy with Simultaneous Integrated Boost for High-Risk and Lymph Node-Positive Prostate Cancer: Early Report on Acute and Late Toxicity

The use of whole pelvic radiotherapy (WPRT) for high-risk and lymph node-positive prostate cancer (PC) remains controversial. The purpose of this study was to evaluate the acute toxicity associated with helical tomotherapy in the treatment of high-risk and lymph node-positive prostate cancer. To do so, twenty-eight patients were treated to a dose of 54 Gy in daily fractions of 1.8 Gy to the pelvic lymph node area, while the prostate and the seminal vesicles received a simultaneous integrated boost (SIB) to a dose of 70.5 Gy. A SIB to a dose of 60 Gy was delivered to the involved lymph node region(s) in 8 patients with pelvic lymph node metastases. All patients received concurrent hormonal treatment. The incidence of grade 2 and 3 acute gastrointestinal (GI) toxicity was 7% and 0% respectively. Grade 2 and 3 acute genito-urinary (GU) side effects were observed in 14% and 4% of the patients respectively. No grade 4 side effects occurred. No increased toxicity was observed in the 8 lymph node-positive patients receiving a simultaneous pelvic nodal dose escalation. In conclusion, WPRT with a SIB to the prostate and seminal vesicles by helical tomotherapy resulted in a favourable toxicity profile. Pelvic nodal dose escalation in node-positive patients is feasible without increasing toxicity.

Physics aspects of prostate tomotherapy: planning optimization and image-guidance issues

PURPOSE

To review planning and image-guidance aspects of more than 3 years experience in the treatment of prostate cancer with Helical Tomotherapy (HT).

METHODS AND MATERIALS

Planning issues concerning two Phase I-II clinical studies were addressed: in the first one, 58 Gy in 20 fractions were delivered to the prostatic bed for post-prostatectomy patients: in the second one, a simultaneous integrated boost (SIB) approach was applied for radical treatment, delivering 71.4-74.2 Gy to the prostate in 28 fractions. On-line daily MVCT image guidance was applied: bone match was used for post-operative patients while prostate match was applied for radically treated patients. MVCT data of a large sample of both categories of patients were reviewed.

RESULTS

At now, more than 250 patients were treated. Planning data show the ability of HT in creating highly homogeneous dose distributions within PTVs. Organs at risk (OAR) sparing also showed to be excellent. HT was also found to favorably compare to inversely-optimized IMAT in terms of PTVs coverage and dose distribution homogeneity. In the case of pelvic nodes irradiation, a large sparing of bowel was evident compared to 3DCRT and conventional 5-fields IMRT. The analysis of MVCT data showed a limited motion of the prostate (about 5% of the fractions show a deviation > or =3 mm in posterior-anterior direction), due to the careful application of rectal emptying procedures. Based on phantom measurements and on the comparison with intra-prostatic calcification-based match, direct visualization prostate match seems to be sufficiently reliable in assessing shifts > or =3 mm.

CONCLUSIONS

HT offers excellent planning solutions for prostate cancer, showing to be highly efficient in a SIB scenario. Daily MVCT information showed evidence of a limited motion of the prostate in the context of rectal filling control obtained by instructing patients in self-administrating a rectal enema.

Whole pelvic radiotherapy versus prostate only radiotherapy in the management of locally advanced or aggressive prostate adenocarcinoma

PURPOSE

To determine whether whole pelvic radiotherapy (WPRT) or prostate-only radiotherapy (PORT) yields improved biochemical disease-free survival (BDFS) in patients with advanced or aggressive prostate adenocarcinoma.

METHODS AND MATERIALS

Between 2000 and 2007, a consecutive sample of 277 patients with prostate adenocarcinoma and at least a 15% likelihood of lymph node involvement who had undergone WPRT (n = 68) or PORT (n = 209) at two referral centers was analyzed. The median radiation dose in both arms was 75.6 Gy. The outcome measure was BDFS, as determined using the prostate-specific antigen nadir + 2 ng/mL definition of failure. BDFS was calculated using the Kaplan-Meier method and compared with the log-rank test. A multivariate analysis was performed to assess for confounding. Treatment-related toxicity was assessed using the National Cancer Institute's Common Terminology Criteria for Adverse Events guidelines. The median follow-up was 30 months.

RESULTS

WPRT patients had more advanced and aggressive disease at baseline (p < .001). The 4-year BDFS rate was 69.4% in the PORT cohort and 86.3% in the WPRT cohort (p = .02). Within the entire cohort, after adjustment for confounding variables, the pretreatment prostate-specific antigen (p < .001), Gleason score (p < .001), use of hormonal therapy (p = .002), and use of WPRT (vs. PORT, p = .006) predicted for BDFS. Patients undergoing WPRT had increased acute gastrointestinal toxicity (p = .048), but no significant difference in acute genitourinary toxicity was seen (p = .09). No difference in late toxicity was found.

CONCLUSION

WPRT may yield improved BDFS in patients with advanced or aggressive prostate adenocarcinoma, but results in a greater incidence of acute toxicity.

Dose-volume relationships for acute bowel toxicity in patients treated with pelvic nodal irradiation for prostate cancer

PURPOSE

To find correlation between dose-volume histograms (DVHs) of the intestinal cavity (IC) and moderate-severe acute bowel toxicity in men with prostate cancer treated with pelvic nodal irradiation.

METHODS AND MATERIALS

The study group consisted of 191 patients with localized prostate cancer who underwent whole-pelvis radiotherapy with radical or adjuvant/salvage intent during January 2004 to November 2007. Complete planning/clinical data were available in 175 of these men, 91 of whom were treated with a conventional four-field technique (50.4 Gy, 1.8 Gy/fraction) and 84 of whom were treated with IMRT using conventional Linac (n = 26, 50.4 Gy, 1.8 Gy/fraction) or Helical TomoTherapy (n = 58, 50-54 Gy, 1.8-2 Gy/fraction). The IC outside the planning target volume (PTV) was contoured and the DVH for the first 6 weeks of treatment was recovered in all patients. The correlation between a number of clinical and DVH (V10-V55) variables and toxicity was investigated in univariate and multivariate analyses. The correlation between DVHs for the IC outside the PTV and DVHs for the whole IC was also assessed.

RESULTS

Twenty-two patients experienced toxicity (3/22 in the IMRT/tomotherapy group). Univariate analyses showed a significant correlation between V20-V50 and toxicity (p = 0.0002-0.001), with a higher predictive value observed for V40-V50. Previous prostatectomy (p = 0.066) and abdominal/pelvic surgery (p = 0.12) also correlated with toxicity. Multivariate analysis that included V45, abdominal/pelvic surgery, and prostatectomy showed that the most predictive parameters were V45 (p = 0.002) and abdominal/pelvic surgery (p = 0.05, HR = 2.4)

CONCLUSIONS

Our avoidance IMRT approach drastically reduces the incidence of acute bowel toxicity. V40-V50 of IC and, secondarily, previous abdominal/pelvic surgery were the main predictors of acute bowel toxicity.

Linac-based or robotic image-guided stereotactic radiotherapy for isolated lymph node recurrent prostate cancer

We report on 14 patients treated with linac- or robotic image-guided stereotactic radiotherapy for isolated lymph node recurrence from prostate cancer, up to the mean dose of 30Gy/3 fractions. At the mean follow-up of 18.6months, five patients experienced clinical out-field progression. Toxicity was minimal. Further investigation is warranted in order to identify the patients that benefit most from this treatment modality and to define the optimal association of such local approach with androgen deprivation. Hopefully, effective local therapy might reduce the burden of systemic therapies given to the recurrent/metastatic prostate cancer patients.

Intensity-modulated radiotherapy of pelvic lymph nodes in locally advanced prostate cancer: planning procedures and early experiences

PURPOSE

We present planning and early clinical outcomes of a study of intensity-modulated radiotherapy (IMRT) for locally advanced prostate cancer.

METHODS AND MATERIALS

A total of 43 patients initially treated with an IMRT plan delivering 50 Gy to the prostate, seminal vesicles, and pelvic lymph nodes, followed by a conformal radiotherapy (CRT) plan delivering 20 Gy to the prostate and seminal vesicles, were studied. Dose-volume histogram (DVH) data for the added plans were compared with dose-volume histogram data for the sum of two CRT plans for 15 cases. Gastrointestinal (GI) and genitourinary (GU) toxicity, based on the Radiation Therapy Oncology Group scoring system, was recorded weekly throughout treatment as well as 3 to 18 months after treatment and are presented.

RESULTS

Treatment with IMRT both reduced normal tissue doses and increased the minimum target doses. Intestine volumes receiving more than 40 and 50 Gy were significantly reduced (e.g., at 50 Gy, from 81 to 19 cm(3); p = 0.026), as were bladder volumes above 40, 50, and 60 Gy, rectum volumes above 30, 50, and 60 Gy, and hip joint muscle volumes above 20, 30, and 40 Gy. During treatment, Grade 2 GI toxicity was reported by 12 of 43 patients (28%), and Grade 2 to 4 GU toxicity was also observed among 12 patients (28%). With 6 to 18 months of follow-up, 2 patients (5%) experienced Grade 2 GI effects and 7 patients (16%) experienced Grade 2 GU effects.

CONCLUSIONS

Use of IMRT for pelvic irradiation in prostate cancer reduces normal tissue doses, improves target coverage, and has a promising toxicity profile.

Guidelines for target volume definition in post-operative radiotherapy for prostate cancer, on behalf of the EORTC Radiation Oncology Group

The appropriate application of 3-D conformal radiotherapy, intensity modulated radiotherapy or image guided radiotherapy for patients undergoing post-operative radiotherapy for prostate cancer requires a standardisation of the target volume definition and delineation as well as standardisation of the clinical quality assurance procedures. Recommendations for this are presented on behalf of the European Organisation for Research and Treatment of Cancer (EORTC) Radiation Oncology Group and in addition to the already published guidelines for radiotherapy as the primary treatment.

Evidence-based radiation oncology: Definitive, adjuvant and salvage radiotherapy for non-metastatic prostate cancer

The standard treatment options based on the risk category (stage, Gleason score, PSA) for localized prostate cancer include surgery, radiotherapy and watchful waiting. The literature does not provide clear-cut evidence for the superiority of surgery over radiotherapy, whereas both approaches differ in their side effects. The definitive external beam irradiation is frequently employed in stage T1b-T1c, T2 and T3 tumors. There is a pretty strong evidence that intermediate- and high-risk patients benefit from dose escalation. The latter requires reduction of the irradiated normal tissue (using 3-dimensional conformal approach, intensity modulated radiotherapy, image-guided radiotherapy, etc.). Recent data suggest that prostate cancer may benefit from hypofractionation due to relatively low alpha/beta ratio; these findings warrant confirmation though. The role of whole pelvis irradiation is still controversial. Numerous randomized trials demonstrated a clinical benefit in terms of biochemical control, local and distant control, and overall survival from the addition of androgen suppression to external beam radiotherapy in intermediate- and high-risk patients. These studies typically included locally advanced (T3-T4) and poor-prognosis (Gleason score >7 and/or PSA >20 ng/mL) tumors and employed neoadjuvant/concomitant/adjuvant androgen suppression rather than only adjuvant setting. The ongoing trials will hopefully further define the role of endocrine treatment in more favorable risk patients and in the setting of the dose escalated radiotherapy. Brachytherapy (BRT) with permanent implants may be offered to low-risk patients (cT1-T2a, Gleason score <7, or 3+4, PSA <or=10 ng/mL), with prostate volume of <or=50 ml, no previous transurethral prostate resection and a good urinary function. Some recent data suggest a benefit from combining external beam irradiation and BRT for intermediate-risk patients. EBRT after radical prostatectomy improves disease-free survival and biochemical and local control rates in patients with positive surgical margins or pT3 tumors. Salvage radiotherapy may be considered at the time of biochemical failure in previously non-irradiated patients.

Significant reduction of acute toxicity following pelvic irradiation with Helical Tomotherapy in patients with localized prostate cancer

PURPOSE

To assess and quantify the possible benefit deriving from IMRT with Helical Tomotherapy (HTT) delivery to the pelvic nodal area in patients with prostate cancer in terms of reduction of acute and late toxicities.

METHODS AND MATERIALS

Thirty-five patients candidate to radical or postoperative RT on whole pelvis (WPRT) were treated with HTT, while receiving a concomitant boost to the prostate or the prostatic bed (median 74.2 and 72 Gy, respectively) within a moderately hypofractionated (28-33 fractions; median HTT duration 44 days) regimen. Median and mean doses to whole pelvis were 52 and 54 Gy, respectively. One of the major goals of planning optimisation was to minimize the dose received by the intestinal cavity (IC) outside the nodal PTV.

RESULTS

HTT resulted to be very efficient in sparing the IC even at dose levels below 30-35 Gy and guaranteed a significant sparing of bladder and rectum even at intermediate-low doses (V20-V40). No acute Grade 3 RTOG toxicity was recorded. Eighteen G1 and two G2 GU acute toxicities, 13 G1 upper GI acute toxicities, 8 G1 and 1 G2 acute proctitis were observed; no patient experienced G2 upper GI toxicity. After a median FU of 11.5 months (>10 in 18 patients) one case of late G3 GU toxicity was reported in one post-prostatectomy treated patient; no G2 late rectal bleeding or other GI toxicity was recorded.

CONCLUSIONS

WPRT with HTT resulted in a very low incidence of acute Grade 2 and in the disappearance of acute Grade 3 toxicities.

Preclinical evaluation of molecular-targeted anticancer agents for radiotherapy

The combination of molecular-targeted agents with irradiation is a highly promising avenue for cancer research and patient care. Molecular-targeted agents are in themselves not curative in solid tumours, whereas radiotherapy is highly efficient in eradicating tumour stem cells. Recurrences after high-dose radiotherapy are caused by only one or few surviving tumour stem cells. Thus, even if a novel agent has the potential to kill only few tumour stem cells, or if it interferes in mechanisms of radioresistance of tumours, combination with radiotherapy may lead to an important improvement in local tumour control and survival. To evaluate the effects of novel agents combined with radiotherapy, it is therefore necessary to use experimental endpoints which reflect the killing of tumour stem cells, in particular tumour control assays. Such endpoints often do not correlate with volume-based parameters of tumour response such as tumour regression and growth delay. This calls for radiotherapy specific research strategies in the preclinical testing of novel anti-cancer drugs, which in many aspects are different from research approaches for medical oncology.