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

Ten-year outcomes of intensity-modulated radiation therapy combined with neoadjuvant hormonal therapy for intermediate- and high-risk patients with T1c-T2N0M0 prostate cancer

BACKGROUND

We aimed to analyze the 10-year outcomes of intensity-modulated radiation therapy (IMRT) combined with neoadjuvant hormonal therapy (HT) for patients with intermediate- and high-risk T1c-T2N0M0 prostate cancer.

METHODS

Fifty patients with T1c-T2N0M0 prostate cancer, who were treated with high-dose IMRT combined with neoadjuvant HT, were evaluated. Of these patients, 19 and 31 were classified into the intermediate- and high-risk groups, respectively. Neoadjuvant HT was administered over a median duration of 6 months; 74 and 78 Gy in 2 Gy per fraction were essentially delivered to the intermediate- and high-risk cases, respectively. Adjuvant HT was not administered to any of the patients after the completion of IMRT.

RESULTS

Over a median follow-up period of 118 months, the 10-year prostate-specific antigen failure-free survival, prostate-specific antigen failure-free, salvage hormonal therapy-free, prostate cancer-specific survival, and overall survival rates were 70.2 %, 78.7 %, 89.2 %, 100 %, and 88.8 %, respectively. No grade 3 or higher acute or late toxicities were observed. The 10-year likelihoods of developing grade 2 late urinary and rectal toxicities were 13.7 % and 4.2 %, respectively. Compared with the outcomes of a cohort of historical controls who were locally irradiated with 70 Gy by three-dimensional conformal radiotherapy, the prostate-specific antigen failure-free rate was significantly better in the IMRT groups (78.7 % vs. 53.4 % at 10 years; p = 0.027).

CONCLUSIONS

High-dose IMRT combined with neoadjuvant HT achieved not only high prostate-specific antigen control, but also excellent survival outcomes with acceptable morbidities, for a Japanese cohort of intermediate- and high-risk T1c-T2N0M0 prostate cancer patients, and these results warrant further investigation.

Helical intensity-modulated radiotherapy of the pelvic lymph nodes with a simultaneous integrated boost to the prostate--first results of the PLATIN 1 trial

Background

Definitive, percutaneous irradiation of the prostate and the pelvic lymph nodes in high-risk prostate cancer is the alternative to prostatectomy plus lymphadenectomy. To date, the role of whole pelvis radiotherapy (WPRT) has not been clarified especially taking into consideration the benefits of high conformal IMRT (intensity modulated radiotherapy) of complex-shaped target volumes.

Methods

From 2009 to 2012, 40 patients of high-risk prostate cancer with an increased risk of microscopic lymph node involvement were enrolled into this prospective phase II trial. Patients received at least two months of antihormonal treatment (AT) before radiotherapy continuing for at least 2 years. Helical IMRT (tomotherapy) of the pelvic lymph nodes (51.0 Gy) with a simultaneous integrated, moderate hypofractionated boost (single dose of 2.25 Gy) to the prostate (76.5 Gy) was performed in 34 fractions. PSA levels, prostate-related symptoms and quality of life were assessed at regular intervals for 24 months.

Results

Of the 40 patients enrolled, 38 finished the treatment as planned. Overall acute toxicity rates were low and no acute grade 3 or 4 gastrointestinal (GI) and genitourinary (GU) toxicity occurred. 21.6 % of patients experienced acute grade 2 but no late grade ≥2 GI toxicity. Regarding GU side effects, results showed 48.6 % acute grade 2 and 6.4 % late grade 2 toxicity. After a median observation time of 23.4 months the PLATIN 1 trial can be considered as sufficiently safe meeting the prospectively defined aims of the trial. With 34/37 patients free of a PSA recurrence it shows promising efficacy.

Conclusion

Tomotherapy of the pelvic lymph nodes with a simultaneous integrated boost to the prostate can be performed safely and without excessive toxicity. The combined irradiation of both prostate and pelvic lymph nodes seems to be as well tolerated as the irradiation of the prostate alone.

Trial registration

Trial Numbers: ARO 2009–05, ClinicalTrials.gov: NCT01903408.

Is biochemical relapse-free survival after profoundly hypofractionated radiotherapy consistent with current radiobiological models?

AIMS

The α/β ratio for prostate cancer is thought to be low and less than for the rectum, which is usually the dose-limiting organ. Hypofractionated radiotherapy should therefore improve the therapeutic ratio, increasing cure rates with less toxicity. A number of models for predicting biochemical relapse-free survival have been developed from large series of patients treated with conventional and moderately hypofractionated radiotherapy. The purpose of this study was to test these models when significant numbers of patients treated with profoundly hypofractionated radiotherapy were included.

MATERIALS AND METHODS

A systematic review of the literature with regard to hypofractionated radiotherapy for prostate cancer was conducted, focussing on data recently presented on prostate stereotactic body radiotherapy. For the work described here, we have taken published biochemical control rates for a range of moderately and profoundly fractionated schedules and plotted these together with a range of radiobiological models, which are described.

RESULTS

The data reviewed show consistency between the various radiobiological model predictions and the currently observed data.

CONCLUSION

Current radiobiological models provide accurate predictions of biochemical relapse-free survival, even when profoundly hypofractionated patients are included in the analysis.

Moderately hypofractionated radiotherapy for localized prostate cancer: long-term outcome using IMRT and volumetric IGRT

PURPOSE

To evaluate long-term outcome after dose-escalated, moderately hypofractionated radiotherapy for prostate cancer.

METHODS

Since 2005, 150 consecutive patients were treated with primary radiotherapy for localized prostate cancer. Intensity modulated radiotherapy (IMRT) using the simultaneous integrated boost (SIB) technique was practiced in all patients and doses of 73.9 Gy (n = 41) and 76.2 Gy (n = 109) were delivered in 32 and 33 fractions, respectively. The pelvic lymph nodes were treated in 41 high-risk patients. Treatment was delivered using cone-beam CT based image-guided radiotherapy (IGRT). Toxicity was assessed prospectively using CTCAE 3.0; biochemical failure was defined according to the Phoenix definition of nadir + 2 ng/ml.

RESULTS

Median follow-up of living patients was 50 months. Gastrointestinal (GI) toxicity was mild with > 80% of the patients free from any GI toxicity during follow-up and no time trend to increased rates or to higher grade of GI toxicity. Two patients suffered from late grade 3 GI toxicity. Acute genitourinary (GU) toxicity grade 1-2 was observed in 85% of the patients; most patients recovered quickly within 6 weeks after treatment. The rate of GU toxicity grade ≥ 2 was <10% at 6-12 month but increased continuously to 22.4% at 60 months; grade 3 GU toxicity remained below 5% during follow-up. The 5-year freedom from biochemical failure (FFBF) was 82% for all patients and 88, 80, and 78% for low-, intermediate-, and high-risk disease.

CONCLUSION

Favorable FFBF with simultaneously low rates of toxicity was observed after moderately hypofractionated radiotherapy with 2 Gy-equivalent doses ≥ 80 Gy. Conformal IMRT planning and accurate IGRT treatment delivery may have contributed to these results.

[Hypofractionated radiotherapy in prostate cancer]

Radiotherapy plays a central role in the management of localized prostate cancer, but the total duration of treatment of nearly 2 months poses not only problems of fatigue related to repetitive transports, especially for older patients, but also increases the overall cost of treatment including linear accelerators occupancy and patient transportation. To address this problem, various teams have developed hypofractionated radiotherapy protocols seeking to maintain the same efficacy and toxicity while reducing the total duration of treatment. These hypofractionated protocols require recent techniques such as image-guided radiation therapy (IGRT) and intensity-modulated radiation therapy (IMRT). Single centre series have validated the feasibility of "light" hypofractionation schemes at doses per fraction less than 6 Gy Similarly, different teams have shown the possibility of stereotactic irradiation for delivering "severe" hypofractionation schemes at doses greater than 6 Gy per fraction. Whatever the dose per fraction, the current clinical data support the conclusion that hypofractionated radiotherapy does not increase mid-term toxicity and could even improve biochemical control. Studies with the objective of demonstrating non-inferiority are expected to definitively validate the role of hypofractionated irradiation in the treatment of prostate cancer.