Linac-based stereotactic body radiation therapy vs moderate hypofractionated radiotherapy in prostate cancer: propensity-score based comparison of outcome and toxicity

Photon vs proton hypofractionation in prostate cancer: A systematic review and meta-analysis

BACKGROUND

High-level evidence on hypofractionated proton therapy (PT) for localized and locally advanced prostate cancer (PCa) patients is currently missing. The aim of this study is to provide a systematic literature review to compare the toxicity and effectiveness of curative radiotherapy with photon therapy (XRT) or PT in PCa.

METHODS

PubMed, Embase, and the Cochrane Library databases were systematically searched up to April 2022. Men with a diagnosis of PCa who underwent curative hypofractionated RT treatment (PT or XRT) were included. Risk of grade (G) ≥ 2 acute and late genitourinary (GU) OR gastrointestinal (GI) toxicity were the primary outcomes of interest. Secondary outcomes were five-year biochemical relapse-free survival (b-RFS), clinical relapse-free, distant metastasis-free, and prostate cancer-specific survival. Heterogeneity between study-specific estimates was assessed using Chi-square statistics and measured with the I2 index (heterogeneity measure across studies).

RESULTS

A total of 230 studies matched inclusion criteria and, due to overlapped populations, 160 were included in the present analysis. Significant lower rates of G ≥ 2 acute GI incidence (2 % vs 7 %) and improved 5-year biochemical relapse-free survival (95 % vs 91 %) were observed in the PT arm compared to XRT. PT benefits in 5-year biochemical relapse-free survival were maintained for the moderate hypofractionated arm (p-value 0.0122) and among patients in intermediate and low-risk classes (p-values < 0.0001 and 0.0368, respectively). No statistically relevant differences were found for the other considered outcomes.

CONCLUSION

The present study supports that PT is safe and effective for localized PCa treatment, however, more data from RCTs are needed to draw solid evidence in this setting and further effort must be made to identify the patient subgroups that could benefit the most from PT.

Linac-based versus MR-guided SBRT for localized prostate cancer: a comparative evaluation of acute tolerability

AIM

This study aims to compare acute toxicity of prostate cancer (PCa) stereotactic body radiotherapy (SBRT) delivered by MR-guided radiotherapy (MRgRT) with 1.5-T MR-linac or by volumetric modulated arc (VMAT) with conventional linac.

METHODS

Patients with low-to-favorable intermediate risk class PCa were treated with exclusive SBRT (35 Gy in five fractions). Patients treated with MRgRT were enrolled in an Ethical Committee (EC) approved trial (Prot. n° 23,748), while patients treated with conventional linac were enrolled in an EC approved phase II trial (n° SBRT PROG112CESC). The primary end-point was the acute toxicity. Patients were included in the analysis if they had at least 6 months of follow-up for the primary end-point evaluation. Toxicity assessment was performed according to CTCAE v5.0 scale. International Prostatic Symptoms Score (IPSS) was also performed.

RESULTS

A total of 135 patients were included in the analysis. Seventy-two (53.3%) were treated with MR-linac and 63 (46.7%) with conventional linac. The median initial PSA before RT was 6.1 ng/ml (range 0.49-19). Globally, acute G1, G2, and G3 toxicity occurred in 39 (28.8%), 20 (14.5%), and 5 (3.7%) patients. At the univariate analysis, acute G1 toxicity did not differ between MR-linac and conventional linac (26.4% versus 31.8%), as well as G2 toxicity (12.5% versus 17.5%; p = 0.52). Acute G2 gastrointestinal (GI) toxicity occurred in 7% and 12.5% of cases in MR-linac and conventional linac group, respectively (p = 0.06), while acute G2 genitourinary toxicity occurred in 11% and 12.8% in MR-linac and conventional linac, respectively (p = 0.82). The median IPSS before and after SBRT was 3 (1-16) and 5 (1-18). Acute G3 toxicity occurred in two cases in the MR-linac and three cases in the conventional linac group (p = n.s.).

CONCLUSION

Prostate SBRT with 1.5-T MR-linac is feasible and safe. Compared to conventional linac, MRgRT might to potentially reduce the overall G1 acute toxicity at 6 months, and seems to show a trend toward a lower incidence of grade 2 GI toxicity. A longer follow-up is necessary to assess the late efficacy and toxicity.

Radiotherapy-related toxicity for localized prostate cancer: meta-analysis comparing conventional or moderately hypofractionated vs. ultrahypofractionated protocols

BACKGROUND

To compare toxicities in relation to standard radiation treatments [conventional fractionation RT (CRT) and moderate hypofractionated RT (MRT)] with ultrahypofractionated RT (URT) in the treatment of patients with localized PCa.

METHODS

A searched was performed in Medline, Embase, Cochrane CENTRAL, and LILACS to January 2020 for studies comparing URT to CRT and/or MRT in relation to genitourinary (GU) and gastrointestinal (GI) toxicity in the treatment of patients with localized PCa. URT, MRT and CRT were defined as protocols delivering a daily dose of ≥5 Gy, 2.4-4.9 Gy, and <2.4 Gy per fractions regardless total dose, respectively.

RESULTS

Eight studies with 2929 patients with localized PCa were included in the analysis. These eight studies did not find any difference between URT and MRT/CRT groups in relation to acute GU toxicity (21.0% × 23.8%, RD -0.04; 95% CI -0.13, 0.06; p = 0.46; I² = 89%) and acute GI toxicity (4.9% × 6.9%, RD -0.03; 95% CI -0.07, 0.01; p = 0.21; I² = 79%). Six studies did not find any difference between URT and MRT/CRT groups in relation to late GU toxicity (3.9% × 4.7%, RD -0.01; 95% CI -0.03, 0.00; p = 0.16; I² = 19%) and late GI toxicity (2.1% × 3.5%, RD -0.01; 95% CI -0.03, 0.00; p = 0.05; I² = 22%).

CONCLUSION

The present study suggests that acute GU/GI and late GU/GI toxicity are similar between URT and standard protocols. More studies with longer follow-ups directed to oncology outcomes are warranted before any recommendation on this topic.

Phase II study of stereotactic body radiotherapy with hydrogel spacer for prostate cancer: acute toxicity and propensity score-matched comparison

BACKGROUND

The efficacy of a hydrogel spacer in stereotactic body radiotherapy (SBRT) has not been clarified. We evaluated the safety and efficacy of SBRT in combination with a hydrogel spacer for prostate cancer.

METHODS

This is a prospective single-center, single-arm phase II study. Prostate cancer patients without lymph node or distant metastasis were eligible. All patients received a hydrogel spacer insertion, followed by SBRT of 36.25 Gy in 5 fractions with volumetric modulated arc therapy. The primary endpoint was physician-assessed acute gastrointestinal (GI) toxicity within 3 months. The secondary endpoints were physician-assessed acute genitourinary (GU) toxicity, patient-reported outcomes evaluated by the EPIC and FACT-P questionnaires, and dosimetric comparison. We used propensity score-matched analyses to compare patients with the hydrogel spacer with those without the spacer. The historical data of the control without a hydrogel spacer was obtained from our hospital's electronic records.

RESULTS

Forty patients were enrolled between February 2017 and July 2018. A hydrogel spacer significantly reduced the dose to the rectum. Grade 2 acute GI and GU toxicity occurred in seven (18%) and 17 (44%) patients. The EPIC bowel and urinary summary score declined from the baseline to the first month (P < 0.01, < 0.01), yet it was still significantly lower in the third month (P < 0.01, P = 0.04). For propensity score-matched analyses, no significant differences in acute GI and GU toxicity were observed between the two groups. The EPIC bowel summary score was significantly better in the spacer group at 1 month (82.2 in the spacer group and 68.5 in the control group).

CONCLUSIONS

SBRT with a hydrogel spacer had the dosimetric benefits of reducing the rectal doses. The use of the hydrogel spacer did not reduce physician-assessed acute toxicity, but it improved patient-reported acute bowel toxicity.

TRIAL REGISTRATION

Trial registration: UMIN-CTR, UMIN000026213. Registered 19 February 2017, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000029385 .

Moderate versus extreme hypofractionated radiotherapy: a toxicity comparative analysis in low- and favorable intermediate-risk prostate cancer patients

PURPOSE

External beam radiotherapy (EBRT) is an effective treatment option for low- and favorable intermediate-risk prostate cancer (PCa) and it is usually delivered in conventional fractionation or with moderate hypofractionation (hRT), with comparable results. In the last years, a new treatment approach with stereotactic body radiotherapy (SBRT) has shown promising results. The aim of the present study was to directly compare the toxicity and outcome between hRT and SBRT in low and favorable intermediate PCa patients.

MATERIALS AND METHODS

The hRT schedules were: 71.4 Gy or 74.2 Gy in 28 fractions for low- or favorable intermediate-risk PCa, respectively, while the SBRT schedules were: 35 Gy or 37.5 Gy in five fractions, for low or favorable intermediate risk, respectively. Toxicity assessment was performed according to CTCAE v5.0 grading. The International Prostatic Symptoms Score (IPSS) was also recorded.

RESULTS

One hundred forty-nine patients were analyzed, overall 81 (54.36%) patients were low risk and 68 (45.64%) were favorable intermediate risk. Sixty-nine (46.3%) patients were treated with hypo-RT and 80 (53.7%) with SBRT. Median follow-up was 33 months (range 11-58 months). The actuarial survival rate was 98.66%. The 3-years BFS rates were 95.5% and 100% for hRT and SBRT, respectively (p = 0.051). One case (0.6%) of acute grade 3 urinary toxicity occurred in a patient with favorable intermediate risk treated with hRT. He initially suffered gross hematuria and acute urinary retention not treatable with urinary catheter, therefore a suprapubic catheter was placed and steroids were administered. No differences in acute, late or severe toxicity were detected.

CONCLUSION

Stereotactic body radiotherapy reported a good clinical outcome and safe toxicity profile. Results are comparable to hRT, but a longer follow-up is needed to assess the late effectiveness and toxicity.