Dynamic conformal arc radiotherapy with rectum hollow-out technique for localized prostate cancer

Effects of dose-escalated radiotherapy in combination with long-term androgen deprivation on prostate cancer

OBJECTIVE

We aimed to examine the effects of a dose escalation for prostate cancer patients receiving long-term androgen deprivation therapy (ADT).

METHODS

A retrospective analysis of 605 patients treated with radiotherapy (RT) and long-term ADT (National Comprehensive Cancer Network criteria-defined intermediate-risk, minimum 10 months; high-risk and very-high-risk, minimum 20 months) was performed. The median ADT time was 31 months. Cox's proportional hazards models were used to compare biochemical disease-free survival (bDFS), clinical relapse-free survival (cRFS) and overall survival (OS) between the ≥70, <78 Gy group and 78 Gy group in a univariate analysis and to assess the effects of the dose escalation on bDFS in a multivariate analysis.

RESULTS

After a median follow-up of 70 months, 5-year bDFS was significantly better in the 78 Gy group than in the ≥70, <78 Gy group [96 vs 83%; hazard ratio 3.6 (95% confidence interval 2.2-6.1); p < 0.001]. 5-year cRFS and OS were similar between the two groups. The multivariate analysis showed that RT dose was still an independent prognostic factor of bDFS (p = 0.005).

CONCLUSION

The results of the present study suggest that dose escalations result in significant improvements in bDFS, even when used in combination with long-term ADT. A longer follow-up is needed to clarify the effects of dose escalations on cRFS and OS. Advances in knowledge: It remains unclear whether high-dose RT is necessary for improving the outcomes of patients receiving long-term ADT. The results suggest that dose escalations result in significant improvements in biochemical control.

Very high-risk prostate cancer: stratification by outcomes of radiotherapy and long-term androgen deprivation therapy

AIM

The definition of very high-risk (VHR) prostate cancer is currently based on the study of radical prostatectomy. We aimed to identify a suitable definition for VHR group following external beam radiation therapy (EBRT) and long-term androgen-deprivation therapy (ADT).

METHODS

This retrospective study included 356 high-risk patients treated with EBRT and long-term ADT. A median follow-up time was 68 months. At first, associations of previously described prognostic factors with biochemical disease-free survival (bDFS), clinical relapse-free survival (cRFS) and prostate cancer-specific survival (CSS) were examined. Second, the combination of significant adverse factors in the first analysis served as VHR test definitions. For each factor, a Cox proportional hazards model was used to calculate their hazard ratios for bDFS and cRFS. The logrank test was used to evaluate the association between each factor and CSS.

RESULTS

Primary Gleason pattern 5, T4 and ≥ 5 or 4 cores with Gleason score 8-10 were risk factors associated with bDFS, cRFS and CSS. Eleven VHR test definitions composed of these adverse factors were associated significantly with bDFS, cRFS and CSS. The final definition was described by primary Gleason pattern 5 or T4 or ≥ 4 cores with Gleason score 8-10 because of the largest sample size of 38% among 11 test definitions. bDFS, cRFS and CSS of the VHR group were significantly lower compared with other high-risk patients (P < 0.001, P < 0.001 and P = 0.015, respectively).

CONCLUSION

These VHR criteria were best fitted following EBRT with long-term ADT.

Three-dimensional conformal arc radiotherapy using a C-arm linear accelerator with a computed tomography on-rail system for prostate cancer: clinical outcomes

Background

We report the feasibility and treatment outcomes of image-guided three-dimensional conformal arc radiotherapy (3D-CART) using a C-arm linear accelerator with a computed tomography (CT) on-rail system for localized prostate cancer.

Methods and materials

Between 2006 and 2011, 282 consecutive patients with localized prostate cancer were treated with in-room CT-guided 3D-CART. Biochemical failure was defined as a rise of at least 2.0 ng/ml beyond the nadir prostate-specific antigen level. Toxicity was scored according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0.

Results

A total of 261 patients were analyzed retrospectively (median follow-up: 61.6 months). The median prescribed 3D-CART dose was 82 Gy (2 Gy/fraction, dose range: 78–86 Gy), and 193 of the patients additionally received hormonal therapy. The 5-year overall survival rate was 93.9 %. Among low-, intermediate-, and high-risk patients, 5-year rates of freedom from biochemical failure were 100, 91.5 and 90.3 %, respectively. Rates of grade 2–3 late gastrointestinal and genitourinary toxicities were 2.3 and 11.4 %, respectively. No patient experienced late grade 4 or higher toxicity.

Conclusions

In-room CT-guided 3D-CART was feasible and effective for localized prostate cancer. Treatment outcomes were comparable to those previously reported for intensity-modulated radiotherapy.

Long-term outcomes of dynamic conformal arc irradiation combined with neoadjuvant hormonal therapy in Japanese patients with T1c-T2N0M0 prostate cancer: case series study

OBJECTIVE

There are few reports of the outcomes of external beam radiotherapy in Asian males with localized prostate cancer. The aim of this study is to evaluate the long-term outcomes of external beam irradiation using three-dimensional two-dynamic conformal arc therapy, combined with neoadjuvant hormonal therapy, in patients with T1c-T2N0M0 prostate cancer.

METHODS

Between March 2003 and August 2007, 150 Japanese patients with T1c-T2N0M0 prostate cancer were definitively treated with three-dimensional two-dynamic conformal arc therapy. The median age, pretreatment prostate-specific antigen values and neoadjuvant hormonal therapy period were 73 years, 9.4 ng/ml and 6 months, respectively. In principle, 74 Gy was delivered to the planning target volume, although the total dose was reduced to 70 Gy in patients with unfavorable risk factors, such as severe diabetes mellitus or anticoagulant therapy. No adjuvant hormonal therapy was given to any patient. Salvage hormonal therapy was started when the prostate-specific antigen value exceeded 4 ng/ml in a monotonically increasing manner.

RESULTS

The median follow-up period was 79 months. Salvage hormonal therapy was initiated in 10 patients and the median prostate-specific antigen value at the initiation was 4.7 ng/ml. The 5-year Kaplan-Meier estimates of the biochemical relapse-free survival rate, the salvage hormonal therapy -free rate and the overall survival rate were 83.3% (95% confidence interval = 77.1-89.6%), 94.3% (95% confidence interval = 90.4-98.1%) and 96.3% (95% confidence interval = 93.1-99.5%), respectively. The 5-year cumulative incidence rates of developing more than Grade 2 late rectal and urinary toxicities were 5.5 and 2.9%, respectively.

CONCLUSIONS

Three-dimensional two-dynamic conformal arc therapy, with up to 74 Gy, in patients with T1c-T2N0M0 prostate cancer with neoadjuvant hormonal therapy was well tolerated and achieved good biochemical control and survival outcomes.

Dosimetric consequences of prostate-based couch shifts on the precision of dose delivery during simultaneous IMRT irradiation of the prostate, seminal vesicles and pelvic lymph nodes

INTRODUCTION

To evaluate the impact interfraction prostate (CTV1) motion corrections on doses delivered to seminal vesicles (CTV2) and lymph nodes (CTV3), and to determine ideal planning target volume (PTV) margins for these targets with prostate-based position verification.

MATERIAL AND METHODS

Retrospective analysis based on 253 cone beam computed tomography (CBCT) studies of 28 patients. The isocenter-shift method was used to estimate the interfraction prostate and bony shift effects on the original plan coverage. Friedman's test was used to assess statistical significance between dose-volume histogram (DVH) parameters which were calculated for prostate-based sum plans, bony-based sum plans and original treatment plans. The van Herk formula was used to determine the set-up margin size for prostate-based verification.

RESULTS

The tracked shifts influenced the minimum, maximum and mean CTV2 and CTV3 doses, with a range differential of 0.17%-2.63% (prostate shifts) and 0.13%-1.92% (bony shifts) compared to the corresponding original parameters. Friedman's test revealed significant differences in the minimum doses to the CTV3 and maximum doses to both the CTV2 and CTV3. The calculated set-up margins of 1.22 cm (vertical), 0.19 cm (longitudinal) and 0.39 cm (lateral) should be added to CTV3 while performing prostate-based positioning.

CONCLUSION

To avoid geographical miss during simultaneous irradiation of independently moving targets (CTV1-3) appropriate margins should be used in accordance with the position verification method used. Based on our findings the following margin sizes should be used: 0.7 cm for the CTV1, 0.8-0.9 cm for the CTV2 , and asymmetric 1.0 cm (vertically) and 0.5 cm (other axes) for the CTV3.

Evaluation of combining bony anatomy and soft tissue position correction strategies for IMRT prostate cancer patients

BACKGROUND

Radiotherapy treatment requires delivering high homogenous dose to target volume while sparing organs at risk. That is why accurate patient positioning is one of the most important steps during the treatment process. It reduces set-up errors which have a strong influence on the doses given to the target and surrounding tissues.

AIM

The aim of this study was to investigate the efficiency of combining bony anatomy and soft tissue imaging position correction strategies for patients with prostate cancer.

MATERIALS AND METHODS

The study based on pre-treatment position verification results determined for 10 patients using kV images and CBCT match. At the same patients' position, two orthogonal kV images and set of CT scans were acquired. Both verification methods gave the information about patients' position changes in vertical, longitudinal and lateral directions.

RESULTS

For 93 verifications, the mean values of kV shifts in vertical, longitudinal and lateral directions equaled: -0.11 ± 0.54 cm, 0.26 ± 0.38 cm and -0.06 ± 0.47 cm, respectively. The same values achieved for CBCT matching equaled: 0.07 ± 0.62 cm, 0.22 ± 0.36 cm and -0.02 ± 0.45 cm. Statistically significant changes between the values of shifts received during the first week of treatment and the rest time of the irradiation process were found for 2 patients in the lateral direction and 2 patients in vertical direction among kV results and for 3 patients in the longitudinal direction among CBCT results. A significant difference between kV and CBCT match results was found in the vertical direction.

CONCLUSIONS

In clinical practice, CBCT combined with kV or even portal imaging improves precision and effectiveness of prostate cancer treatment accuracy.

Dosimetric comparison of three-dimensional conformal radiotherapy in salvage radiotherapy for PSA relapse after radical prostatectomy

The purpose of this study is to compare three-dimensional conformal radiotherapy (3D-CRT) plans in a setting of salvage radiotherapy after radical prostatectomy (RP) and to simulate whether dose escalation is possible with the most adequate 3D-CRT technique. This study included consecutive 10 patients underwent salvage radiotherapy (RT) for biochemical relapse of prostate cancer after RP. Normal structures included the rectum, bladder, and femoral head. For each patient, four different treatment plans including four fields RT (4F-RT), dynamic conformal arc radiotherapy (DCAT), six fields RT (6F-RT), and DCAT with rectum hollow-out technique (DCAT-HO), were created to entire the prostate bed. The parameters of the maximum and mean doses received by organs at risk (OAR), target coverage, dose homogeneity for the planning target volume (PTV) were compared. All plans were considered to be clinically tolerable for PTV coverage and dose homogeneity. The rectum sparing at the high dose area for DCAT-HO was considered to be the most superior to those for other three techniques by comparison of the dose delivered to a 1%, 5%, and 10% volume of the rectum. In the simulation of dose escalation to 70 Gy with DCAT-HO, OAR met a requirement of the dose-volume constraints. However, in the simulation of dose escalation to 72 Gy, the rectum that receives 60 to 65 Gy and bladder that receives 65 Gy exceeded the optimal dose-volume constraints. DCAT-HO was considered to be one of the most appropriate techniques in 3D-CRT if dose escalation to 70 Gy might be needed in a setting of salvage RT after RP in the future.

Early salvage radiotherapy for patients with PSA relapse after radical prostatectomy

PURPOSE

To assess the effectiveness of early salvage radiotherapy (RT) for patients with prostate-specific antigen (PSA) relapse after radical prostatectomy (RP) retrospectively.

METHODS

Fifty-one patients underwent salvage RT for biochemical relapse of prostate cancer initially treated with RP. All patients had persistent or rising PSA >0.20 ng/ml at some point after surgery, or three successive PSA elevations after a postoperative nadir if PSA was < or =0.20 ng/ml. Most (96%) of pre-RT PSA were less or equal to 0.50 ng/ml, and median value was 0.25 ng/ml (range, 0.05-0.90 ng/ml). Median RT dose was 60 Gy (range, 50-66 Gy). Multivariate Cox regression analysis was performed for PSA before RP and salvage RT, margin status, seminal vesicle involvement, extracapsular invasion, Gleason score, PSA doubling time (PSADT), and RT dose to identify significant predictors of biochemical outcome.

RESULTS

Median follow-up was 36 months. The 3-year biochemical no evidence of disease rate (bNED) was 55.1%. On multivariate analysis only the following factors were significantly associated with improved bNED: PSADT >3.0 months (P = 0.008), Gleason score < or =7 (P = 0.01), and RT dose > or =60 Gy (P = 0.028).

CONCLUSIONS

Although a total dose of 60 Gy was effective at a low pre-RT PSA levels with short follow-up, an RT dose > or =60 Gy resulted in superior biochemical outcomes even in patients with a pre-RT PSA < or =0.50 ng/ml.