Conventional versus hypofractionated high-dose intensity-modulated radiotherapy for prostate cancer: preliminary safety results from the CHHiP randomised controlled trial

Intermediate-risk prostate cancer patients treated with androgen deprivation therapy and a hypofractionated radiation regimen with or without image guided radiotherapy

BACKGROUND

To evaluate the efficacy of hypofractionated radiotherapy (HyRT) with or without image guided radiotherapy (IGRT) in intermediate risk prostate cancer.

METHODS

105 patients were treated with HyRT, 43,8 Gy and 54,75 Gy were delivered to the seminal vescicles and to the prostate, respectively; 3,65 Gy/fraction three times weekly. All patients underwent 9 months hormonal therapy. Patient position was verified with daily kV cone beam CT in 69 patients (IGRT group). Acute and late toxicities were evaluated according to RTOG scale. Biochemical relapse was defined using PSA nadir + 2 ng/mL. The data were prospectively collected and retrospectively analyzed to evaluate the efficacy of IGRT.

RESULTS

After a median follow-up of 31 months the actuarial 3-year bNED was 93,7%. During RT, 10.5% and 7.6% of patients developed ≥Grade 2 rectal and urinary toxicities, respectively. The cumulative incidence of ≥Grade 2 late rectal and urinary toxicities at 3 years were 6,9%, and 10,8%, respectively. The incidence of ≥Grade 2 late rectal toxicities was significant reduced in the IGRT group (1,6% vs. 14,5%, p=0,021). Two patients developed Grade 3 urethral obstruction and one patient developed grade 3 rectal bleeding.

CONCLUSIONS

HyRT represents a well-tolerated treatment able to achieve a high bNED. The use of daily IGRT is beneficial for reducing the incidence of late toxicities.

Current standards and future directions for prostate cancer radiation therapy

Definitive radiation therapy is a well-recognized curative treatment option for localized prostate cancer. A suitable technique, dose, target volume and the option of a combination with androgen deprivation therapy need to be considered. An optimal standard external beam radiotherapy currently includes intensity-modulated and image-guided radiotherapy techniques with total doses of ≥76-78 Gy in conventional fractionation. Protons or carbon ions are alternatives available only in specific centers. Data from several randomized studies increasingly support the rationale for hypofractionated radiotherapy. A simultaneous integrated boost with dose escalation focused on a computed tomography/PET- or MRI/magnetic resonance spectroscopy-detected malignant lesion is one option to increase tumor control, with potentially no additional toxicity. The application of a spacer is a promising concept for optimal protection of the rectal wall.

Proton beam therapy and localised prostate cancer: current status and controversies

Proton therapy is a promising, but costly, treatment for prostate cancer. Theoretical physical advantages exist; yet to date, it has been shown only to be comparably safe and effective when compared with the alternatives and not necessarily superior. If clinically meaningful benefits do exist for patients, more rigorous study will be needed to detect them and society will require this to justify the investment of time and money. New technical advances in proton beam delivery coupled with shortened overall treatment times and declining device costs have the potential to make this a more cost-effective therapy in the years ahead.

Radical radiotherapy for high-risk prostate cancer in older men

Historical data for older men with high-risk nonmetastatic prostate cancer treated with radiotherapy alone have demonstrated a 10-year prostate-cancer-specific mortality of around 30%. The development of dose escalation, using techniques such as intensity-modulated radiotherapy, has enabled more targeted delivery of treatment with improved efficacy and a reduction in the risk of toxicity compared with conventional radiotherapy. The combination of radiotherapy and androgen-deprivation therapy (ADT) has been shown to improve overall survival compared with radiotherapy or ADT alone without a significant increase in toxicity in patients with minimal comorbidities. There is evidence that patient age has only a marginal effect on genitourinary and gastrointestinal toxicities following radiotherapy. Further research has shown that although age does have an effect on the likelihood of sexual dysfunction after radiation therapy, there is no significant difference in the proportion of men aged ≥ 75 years who feel that sexual dysfunction is a moderate or serious problem before or 24 months after diagnosis. Radical radiotherapy is effective and well tolerated in senior men with high-risk prostate cancer and should be offered in combination with long-term ADT to patients with minimal comorbidities. In case of significant comorbid conditions, shorter durations of ADT may be considered.

Hypofractionated external-beam radiation therapy (HEBRT) versus conventional external-beam radiation (CEBRT) in patients with localized prostate cancer: a systematic review and meta-analysis

BACKGROUND

The purpose of this work was to conduct a systematic review and meta-analysis of all randomized controlled trials comparing the efficacy and side effect profile of hypofractionated versus conventional external-beam radiation therapy for prostate cancer.

METHODS

Several databases were searched, including Medline, EmBase, LiLACS, and Central. The endpoints were freedom from biochemical failure and side effects. We performed a meta-analysis of the published data. The results are expressed as the hazard ratio (HR) or risk ratio (RR), with the corresponding 95% confidence interval (CI).

RESULTS

The final analysis included nine trials comprising 2702 patients. Freedom from biochemical failure was reported in only three studies and was similar in patients who received hypofractionated or conventional radiotherapy (fixed effect, HR 1.03, 95% CI 0.88-1.20; P = 0.75), with heterogeneity [χ(2) = 15.32, df = 2 (P = 0.0005); I2 = 87%]. The incidence of acute adverse gastrointestinal events was higher in the hypofractionated group (fixed effect, RR 2.02, 95% CI 1.45-2.81; P < 0.0001). We also found moderate heterogeneity on this analysis [χ(2) = 7.47, df = 5 (P = 0.19); I2 = 33%]. Acute genitourinary toxicity was similar among the groups (fixed effect, RR 1.19, 95% CI 0.95-1.49; P = 0.13), with moderate heterogeneity [χ(2) = 5.83, df = 4 (P = 0.21); I2 = 31%]. The incidence of all late adverse events was the same in both groups (fixed effect, gastrointestinal toxicity, RR 1.17, 95% CI 0.79-1.72, P = 0.44; and acute genitourinary toxicity, RR 1.16, 95% CI 0.80-1.68, P = 0.44).

CONCLUSION

Hypofractionated radiotherapy in localized prostate cancer was not superior to conventional radiotherapy and showed higher acute gastrointestinal toxicity in this meta-analysis. Because the number of published studies is still small, future assessments should be conducted to clarify better the true role of hypofractionated radiotherapy in patients with prostate cancer.

Hypofractionated external-beam radiotherapy for prostate cancer

There are radiobiological rationales supporting hypofractionated radiotherapy for prostate cancer. The recent advancements in treatment planning and delivery allow sophisticated radiation treatments to take advantage of the differences in radiobiology of prostate cancer and the surrounding normal tissues. The preliminary results from clinical studies indicate that abbreviated fractionation programs can result in successful treatment of localized prostate cancer without escalation of late toxicity.

Systematic review of hypofractionated radiation therapy for prostate cancer

Prostate cancer is the second most prevalent solid tumor diagnosed in men in the United States and Western Europe. Conventionally fractionated external beam radiation therapy (1.8-2.0 Gy/fraction) is an established treatment modality for men in all disease risk groups. Emerging evidence from experimental and clinical studies suggests that the α/β ratio for prostate cancer may be as low as 1.5 Gy, which has prompted investigators around the world to explore moderately hypofractionated radiation therapy (2.1-3.5 Gy/fraction). We review the impetus behind moderate hypofractionation and the current clinical evidence supporting moderate hypofractionated radiation therapy for prostate cancer. Although hypofractionated radiation therapy has many theoretical advantages, there is no clear evidence from prospective, randomized, controlled trials showing that hypofractionated schedules have improved outcomes or lower toxicity than conventionally fractionated regimens. Currently, hypofractionated schedules should only be used in the context of clinical trials. High dose rate brachytherapy and stereotactic body radiation therapy (fraction size 3.5 Gy and greater) are alternative approaches to hypofractionation, but are beyond the scope of this report.

The influence of MRI scan position on image registration accuracy, target delineation and calculated dose in prostatic radiotherapy

OBJECTIVE

To investigate the necessity of performing MRI in the radiotherapy position when using MRI for prostatic radiotherapy.

METHODS

20 prostate patients received a CT, diagnostic MRI and an MRI scan in the radiotherapy position. The quality of registration between CT and MRI was compared between the two MRI set-ups. The prostate and seminal vesicles were contoured using all scans and intensity modulated radiotherapy (IMRT) plans were generated. Changes in the target volume and IMRT plans were investigated. Two-tailed paired Student's t-tests determined the statistical significance.

RESULTS

There was a decrease in the mean distance from the centre of the bony anatomy between CT and MRI (from 3.9 to 1.9 mm, p-value<0.0001) when the MRI scan was acquired in the radiotherapy position. Assuming that registering CT with an MRI scan in the radiotherapy position is the gold standard for delineating the prostate and seminal vesicles, using a planning target volume delineated on the CT with a diagnostic MRI scan viewed separately, resulted in a mean conformation number of 0.80 instead of the expected 0.98 (p<0.0001).

CONCLUSION

By registering CT with an MRI scan in the radiotherapy position, there is a statistically significant improvement in the registration and IMRT quality.

ADVANCES IN KNOWLEDGE

To achieve an acceptable registration and IMRT quality in prostatic radiotherapy, neither CT with a separate diagnostic MRI nor CT registered to a diagnostic MRI will suffice. Instead, a CT registered with an MRI in the radiotherapy position should be used.

Stereotactic body radiation therapy for prostate cancer: is the technology ready to be the standard of care?

Prostate cancer is the second most prevalent solid tumor diagnosed in men in the United States and Western Europe. Stereotactic body radiation therapy (SBRT) is touted as a superior type of external beam radiation therapy (EBRT) for the treatment of various tumors. SBRT developed from the theory that high doses of radiation from brachytherapy implant seeds could be recapitulated from advanced technology of radiation treatment planning and delivery. Moreover, SBRT has been theorized to be advantageous compared to other RT techniques because it has a treatment course shorter than that of conventionally fractionated EBRT (a single session, five days per week, for about two weeks vs. eight weeks), is non-invasive, is more effective at killing tumor cells, and is less likely to cause damage to normal tissue. In areas of the US and Europe where there is limited access to RT centers, SBRT is frequently being used to treat prostate cancer, even though long-term data about its efficacy and safety are not well established. We review the impetus behind SBRT and the current clinical evidence supporting its use for prostate cancer, thus providing oncologists and primary care physicians with an understanding of the continually evolving field of prostate radiation therapy. Studies of SBRT provide encouraging results of biochemical control and late toxicity. However, they are limited by a number of factors, including short follow-up, exclusion of intermediate- and high-risk patients, and relatively small number of patients treated. Currently, SBRT regimens should only be used in the context of clinical trials.

The impact of continuously-variable dose rate VMAT on beam stability, MLC positioning, and overall plan dosimetry

A recent control system update for Elekta linear accelerators includes the ability to deliver volumetric‐modulated arc therapy (VMAT) with continuously variable dose rate (CVDR), rather than a number of fixed binned dose rates (BDR). The capacity to select from a larger range of dose rates allows the linac to maintain higher gantry speeds, resulting in faster, smoother deliveries. The purpose of this study is to investigate two components of CVDR delivery — the increase in average dose rate and gantry speed, and a determination of their effects on beam stability, MLC positioning, and overall plan dosimetry. Initially, ten VMAT plans (5 prostate, 5 head and neck) were delivered to a Delta4 dosimetric phantom using both the BDR and CVDR systems. The plans were found to be dosimetrically robust using both delivery methods, although CVDR was observed to give higher gamma pass rates at the 2%/2 mm gamma level for prostates (p < 0.01). For the dual arc head‐and‐neck plans, CVDR delivery resulted in improved pass rates at all gamma levels (2%/2 mm to 4%/4 mm) for individual arc verifications (p < 0.01), but gave similar results to BDR when both arcs were combined. To investigate the impact of increased gantry speed on MLC positioning, a dynamic leaf‐tracking tool was developed using the electronic portal imaging device (EPID). Comparing the detected MLC positions to those expected from the plan, CVDR was observed to result in a larger mean error compared to BDR (0.13 cm and 0.06 cm, respectively, p < 0.01). The EPID images were also used to monitor beam stability during delivery. It was found that the CVDR deliveries had a lower standard deviation of the gun‐target (GT) and transverse (AB) profiles (p < 0.01). This study has determined that CVDR may offer a dosimetric advantage for VMAT plans. While the higher gantry speed of CVDR appears to increase deviations in MLC positioning, the relative effect on dosimetry is lower than the positive impact of a flatter and more stable beam profile.

PACS numbers: 87.56.bd; 87.55.km; 87.55.Qr

Nasty or Nice? Findings from a UK Survey to evaluate the impact of the National Institute for Health and Clinical Excellence (NICE) clinical guidelines on the management of prostate cancer

AIMS

Although the National Institute for Health and Clinical Excellence clinical guideline 58 (CG58) for prostate cancer management was expected to have a positive effect, several recommendations raised concern among UK physicians. We conducted a survey of UK oncologists in 2008 and a second, similar survey in 2010 to assess views on these recommendations and to evaluate the change in opinion over time.

MATERIALS AND METHODS

Two semi-structured questionnaires were issued by the British Uro-oncology Group to society members in September 2008 and October 2010.

RESULTS

In 2008, 61 UK oncologists completed the survey; 60% agreed that CG58 would make a positive contribution towards improving patient care. There was strong opposition towards active surveillance as the first-line treatment for men with low-risk localised prostate cancer (49% disagreement); implementing 5 yearly flexible sigmoidoscopy post-prostate radiotherapy (51% disagreement); offering follow-up outside of the hospital (e.g. by general practitioners in primary care) for men with a stable prostate-specific antigen for ≥2 years (44% disagreement); and recommendations against docetaxel retreatment (47% disagreement) or bisphosphonate use (58% disagreement). In 2010, 77 UK oncologists completed the survey. The results were largely consistent with 2008, although several recommendations, particularly for localised disease, seem to have promoted a change in clinical practice, suggesting that they are facilitating a standardised approach. Compared with 2008, the 2010 results indicate a shift in favour of active surveillance (80% agreement) and primary care follow-up (59% agreement), but increasing opposition for docetaxel retreatment (57% disagreement). Opinions remained divided for flexible sigmoidoscopy and bisphosphonates.

CONCLUSIONS

Despite initial concerns, the CG58 seems to have had a positive impact on prostate cancer management in the UK, with adherence likely facilitating a standardised approach. However, with new data emerging, these findings underscore the need to regularly update guidelines. A revision of the CG58 is anticipated by 2014.

Radiotherapy physics research in the UK: challenges and proposed solutions

In 2011, the Clinical and Translational Radiotherapy Research Working Group (CTRad) of the National Cancer Research Institute brought together UK radiotherapy physics leaders for a think tank meeting. Following a format that CTRad had previously and successfully used with clinical oncologists, 23 departments were asked to complete a pre-meeting evaluation of their radiotherapy physics research infrastructure and the strengths, weaknesses, opportunities and threats within their own centre. These departments were brought together with the CTRad Executive Group and research funders to discuss the current state of radiotherapy physics research, perceived barriers and possible solutions. In this Commentary, we summarise the submitted materials, presentations and discussions from the meeting and propose an action plan. It is clear that there are challenges in both funding and staffing of radiotherapy physics research. Programme and project funding streams sometimes struggle to cater for physics-led work, and increased representation on research funding bodies would be valuable. Career paths for academic radiotherapy physicists need to be examined and an academic training route identified within Modernising Scientific Careers; the introduction of formal job plans may allow greater protection of research time, and should be considered. Improved access to research facilities, including research linear accelerators, would enhance research activity and pass on developments to patients more quickly; research infrastructure could be benchmarked against centres in the UK and abroad. UK National Health Service departments wishing to undertake radiotherapy research, with its attendant added value for patients, need to develop a strategy with their partner higher education institution, and collaboration between departments may provide enhanced opportunities for funded research.

Quality of life after intensity-modulated radiotherapy for prostate cancer with a hydrogel spacer. Matched-pair analysis

BACKGROUND

Hydrogel spacer is an innovative method to protect the rectal wall during prostate cancer radiotherapy. Clinical effects are not well known.

METHODS

Patients have been surveyed before, at the last day, and 2-3 months after radiotherapy using a validated questionnaire (Expanded Prostate Cancer Index Composite). Median dose to the prostate in the spacer subgroup (SP) was 78 Gy in 2 Gy fractions. The results were independently compared with two matched-pair subgroups (treated conventionally without spacer): 3D conformal 70.2 Gy in 1.8 Gy fractions (3DCRT) and intensity-modulated radiotherapy (IMRT) 76 Gy in 2 Gy fractions. There were 28 patients in each of the three groups.

RESULTS

Baseline mean bowel bother scores were 96 points in all subgroups. Similar mean changes (SP 16, 3DCRT 14, IMRT 17 points) were observed at the end of radiotherapy. The smallest difference resulted in the spacer subgroup 2-3 months after radiotherapy (SP 2, 3DCRT 8, IMRT 6 points). Bowel bother scores were only significantly different in comparison to baseline levels in the spacer subgroup. The percentage of patients reporting moderate/big bother with specific symptoms did not increase for any item (urgency, frequency, diarrhoea, incontinence, bloody stools, pain).

CONCLUSION

Moderate bowel quality-of-life changes can be expected during radiotherapy irrespective of spacer application or total dose. Advantages with a spacer can be expected a few weeks after treatment.

Hypofractionated radiotherapy in prostate cancer

In regards to prostate cancer, the classic radiotherapy dose ranges from 70-80 Gy, administered in daily 2-Gy fractions. However, when taking into account the particular radiobiological model of prostate cancer cells, one realizes that there is a potential theoretical advantage to delivering a greater biological effective dose per treatment in a lower number of fractions. Both recent and older publications have attempted to explore this treatment option. This critical review comprehensively examines the current state of knowledge concerning hypofractionated radiotherapy in prostate cancer.

Dose-escalated hypofractionated intensity-modulated radiotherapy in high-risk carcinoma of the prostate: outcome and late toxicity

Background. The benefit of dose-escalated hypofractionated radiotherapy using intensity-modulated radiotherapy (IMRT) in prostate cancer is not established. We report 5-year outcome and long-term toxicity data within a phase II clinical trial. Materials and Methods. 60 men with predominantly high-risk prostate cancer were treated. All patients received neoadjuvant hormone therapy, completing up to 6 months in total. Thirty patients were treated with 57 Gy in 19 fractions and 30 patients with 60 Gy in 20 fractions. Acute and 2-year toxicities were reported and patients followed longitudinally to assess 5 year outcomes and long-term toxicity. Toxicity was measured using RTOG criteria and LENT/SOMA questionnaire. Results. Median followup was 84 months. Five-year overall survival (OS) was 83% and biochemical progression-free survival (bPFS) was 50% for 57 Gy. Five-year OS was 75% and bPFS 58% for 60 Gy. At 7 years, toxicity by RTOG criteria was acceptable with no grade 3 or above toxicity. Compared with baseline, there was no significant change in urinary symptoms at 2 or 7 years. Bowel symptoms were stable between 2 and 7 years. All patients continued to have significant sexual dysfunction. Conclusion. In high-risk prostate cancer, dose-escalated hypofractionated radiotherapy using IMRT results in encouraging outcomes and acceptable late toxicity.