Prospective Phase II Trial of Once-weekly Hypofractionated Radiation Therapy for Low-risk Adenocarcinoma of the Prostate: Late Toxicities and Outcomes

A phase II trial of stereotactic body radiotherapy in 4 fractions for patients with localized prostate cancer

Purpose/objective(s)

To report results from our phase II study of stereotactic body radiotherapy (SBRT) delivering 36 Gy in 4 fractions for patients with localized prostate cancer.

Materials/methods

We enrolled 55 patients treated with SBRT delivering 36 Gy in 4 fractions between 2015 to 2018. All patients were categorized as low-risk (n = 4), intermediate-risk (n = 31) or high-risk (n = 20) according to National Comprehensive Cancer Network criteria. Median age was 73 years (range 54–86 years). Two-thirds of patients (n = 37) had received androgen-deprivation therapy for 3–46 months (median, 31 months). Median duration of follow-up was 36 months (range 1–54 months). We used Radiation Therapy Oncology Group and National Cancer Institute—Common Toxicity Criteria version 4 for toxicity assessments. Quality of life (QOL) outcomes were also evaluated using the Expanded Prostate Cancer Index Composite (EPIC).

Results

Protocol treatments were completed for all patients. Six patients experienced biochemical failures. Among these six patients, three patients experienced clinical failure. One patient showed bone metastasis before biochemical failure. One patient died of gastric cancer. The 3-year biochemical control rate was 89.8%. Acute grade 2 genitourinary (GU) and gastrointestinal (GI) toxicities were observed in 5 patients (9%) and 6 patients (11%), respectively. No grade 3 or higher acute toxicities were observed. Late grade 2 GU and GI toxicities were observed in 7 patients (13%) and 4 patients (7%), respectively. Late grade 3 GU and GI toxicities were observed in 1 patient (1.8%) each. EPIC scores decreased slightly during the acute phase and recovered within 3 months after treatment.

Conclusion

Our phase II study showed that SBRT delivering 36 Gy in 4 fractions was safe and effective with favorable QOL outcomes, although this regimen showed slightly more severe toxicities compared to current standards.

Ultrahypofractionated Radiotherapy versus Conventional to Moderate Hypofractionated Radiotherapy for Clinically Localized Prostate Cancer

The purpose of this study was to compare the toxicity (first endpoint) and efficacy (second endpoint) of ultrahypofractionated radiotherapy (UHF) and dose-escalated conventional to moderate hypofractionated radiotherapy (DeRT) for clinically localized prostate cancer. We compared 253 patients treated with UHF and 499 patients treated with DeRT using multi-institutional retrospective data. To analyze toxicity, we divided UHF into High-dose UHF (H-UHF; equivalent doses of 2 Gy per fraction: EQD2 > 100 Gy1.5) and low-dose UHF (L-UHF; EQD2 ≤ 100 Gy1.5). In toxicity, H-UHF elevated for 3 years accumulated late gastrointestinal and genitourinary toxicity grade ≥ 2 (11.1% and 9.3%) more than L-UHF (3% and 1.2%) and DeRT (3.1% and 4.8%, p = 0.00126 and p = 0.00549). With median follow-up periods of 32.0 and 61.7 months, the actuarial 3-year biochemical failure-free survival rates were 100% (100% and 100% in the L-UHF and H-UHF) and 96.3% in the low-risk group, 96.5% (97.1% and 95.6%) and 94.9% in the intermediate-risk group, and 93.7% (100% and 94.6%) and 91.7% in the high-risk group in the UHF and DeRT groups, respectively. UHF showed equivocal efficacy, although not conclusive but suggestive due to a short follow-up period of UHF. L-UHF using EQD2 ≤ 100 Gy1.5 is a feasible UHF schedule with a good balance between toxicity and efficacy.

The efficacy and tolerability of ultra-hypofractionated radiotherapy in low-intermediate risk prostate cancer patients: single center experience

BACKGROUND

We aimed to investigate the efficacy and tolerability of ultra-hypofractionated radiotherapy (UHRT) in the treatment of low and intermediate-risk prostate cancer patients.

METHODS

This retrospective study was conducted using data derived from 44 patients who underwent UHRT, and toxicity assessment and clinical response were investigated. Treatment consisted of 35-36.25 Gy in 5 fractions using stereotactic ablative radiotherapy (SABR) with the Linac-based delivery system.

RESULTS

The median duration of follow-up was 52 months (8-68 months) and the median age was 71.5 years (54-85 years). Twenty-seven patients were assigned as intermediate-risk, whereas 17 patients had low-risk. The 5-year overall survival rate was 87.8%, while the 5-year biochemical recurrence-free survival (bRFS) rate was 97.4%. Acute grade 3 genitourinary (GU) side effect was not observed in any patient, whereas acute gastrointestinal (GI) system grade 3 side effect was seen in 6.8% of the patients. Late grade 3 GU and GI side effects were seen in 4.6% and 6.8% of the patients, respectively. In patients with planning target volume (PTV) ≥85 ml, acute grade ≥2 GU side effects were more common (p=.034).

CONCLUSION

Our data demonstrated that UHRT administered with volumetric arc therapy (VMAT) can be recommended for selected patients with low-intermediate risk prostate cancer. Further prospective, multicentric, controlled trials on larger series are warranted to reach more accurate conclusions.

Risk of adverse pathological features for intermediate risk prostate cancer: Clinical implications for definitive radiation therapy

BACKGROUND

Intermediate risk prostate cancer represents a largely heterogeneous group with diverse disease extent. We sought to establish rates of adverse pathological features important for radiation planning by analyzing surgical specimens from men with intermediate risk prostate cancer who underwent immediate radical prostatectomy, and to define clinical pathologic features that may predict adverse outcomes.

MATERIALS AND METHODS

A total of 1552 men diagnosed with intermediate risk prostate cancer who underwent immediate radical prostatectomy between 1/1/2005 and 12/31/2015 were reviewed. Inclusion criteria included available preoperative PSA level, pathology reports of transrectal ultrasound-guided prostate biopsy, and radical prostatectomy. Incidences of various pathological adverse features were evaluated. Patient characteristics and clinical disease features were analyzed for their predictive values.

RESULTS

Fifty percent of men with high risk features (defined as PSA >10 but <20 or biopsy primary Gleason pattern of 4) had pathological upstage to T3 or higher disease. The incidence of upgrade to Gleason score of 8 or higher and the incidence of lymph node positive disease was low. Biopsy primary Gleason pattern of 4, and PSA greater than 10 but less than 20, affected adverse pathology in addition to age and percent positive biopsy cores. Older age and increased percentage of positive cores were significant risk factors of adverse pathology.

CONCLUSION

Our findings underscore the importance of comprehensive staging beyond PSA level, prostate biopsy, and CT/bone scan for men with intermediate risk prostate cancer proceeding with radiation in the era of highly conformal treatment.

Hypofractionated radiotherapy recommendations for localized prostate cancer in Brasil

OBJECTIVE

Several prospective randomized trials have shown that hypofractionation has the same efficacy and safety as the conventional fractionation in the treatment of localized prostate cancer. There are many benefits of hypofractionation, including a more convenient schedule for the patients and better use of resources, which is especially important in low- and middle-income countries like Brasil. Based on these data, the Brazilian Society of Radiotherapy (Sociedade Brasileira de Radioterapia) organized this consensus to guide and support the use of hypofractionated radiotherapy for localized prostate cancer in Brasil.

METHODS

The relevant literature regarding moderate hypofractionation (mHypo) and ultra-hypofractionation (uHypo) was reviewed and discussed by a group of experts from public and private centers of different parts of Brasil. Several key questions concerning clinical indications, outcomes and technological requirements for hypofractionation were discussed and voted. For each question, consensus was reached if there was an agreement of at least 75% of the panel members.

RESULTS

The recommendations are described in this article.

CONCLUSION

This initiative will assist Brazilian radiation oncologists and medical physicists to safely treat localized prostate cancer patients with hypofractionation.

Multi-institutional retrospective analysis of ultrahypofractionated radiotherapy for Japanese prostate cancer patients

To report outcomes and risk factors of ultrahypofractionated (UHF) radiotherapy for Japanese prostate cancer patients. This multi-institutional retrospective analysis comprised 259 patients with localized prostate cancer from 6 hospitals. A total dose of 35–36 Gy in 4–5 fractions was prescribed for sequential or alternate-day administration. Biochemical failure was defined according to the Phoenix ASTRO consensus. Toxicities were assessed using National Cancer Institute Common Toxicity Criteria version 4. Tumor control and toxicity rates were analyzed by competing risk frames. Median follow-up duration was 32 months (range 22–97 months). 2- and 3-year biochemical control rates were 97.7% and 96.4%, respectively. Initial prostate-specific antigen (p < 0.01) and neoadjuvant androgen deprivation therapy (p < 0.05) were identified as risk factors for biochemical recurrence. 2- and 3-year cumulative ≥ Grade 2 late genitourinary (GU) toxicities were 5.8% and 7.4%, respectively. Corresponding rates of gastrointestinal (GI) toxicities were 3.9% and 4.5%, respectively. Grade 3 rates were lower than 1% for both GU and GI toxicities. No grade 4 or higher toxicities were encountered. Biologically effective dose was identified as a risk factor for ≥ Grade 2 late GU and GI toxicities (p < 0.05). UHF radiotherapy offered effective, safe treatment for Japanese prostate cancer with short-term follow-up. Our result suggest higher prescribed doses are related to higher toxicity rates.

Biochemical Control and Toxicity Outcomes of Stereotactic Body Radiation Therapy Versus Low-Dose-Rate Brachytherapy in the Treatment of Low- and Intermediate-Risk Prostate Cancer

PURPOSE

Low-dose-rate (LDR) brachytherapy and stereotactic body radiation therapy (SBRT) have both shown acceptable outcomes in the treatment of low- and intermediate-risk prostate cancer. Minimal data have been published directly comparing rates of biochemical control and toxicity with these 2 modalities. We hypothesize that LDR and SBRT will provide similar rates of biochemical control.

METHODS AND MATERIALS

All low- and intermediate-risk patients with prostate cancer treated definitively with SBRT or LDR between 2010 and 2018 were captured. Phoenix definition was used for biochemical failure. Independent t tests were used to compare baseline characteristics, and repeated measure analysis of variance test was used to compare American Urologic Association (AUA) and the Expanded Prostate Cancer Index Composite (EPIC) scores between treatment arms over time. Biochemical control was estimated using the Kaplan-Meier method. Differences in acute and late toxicity were assessed via Pearson χ².

RESULTS

In the study, 219 and 118 patients were treated with LDR and SBRT. Median follow-up was 4.3 years (interquartile range, 3.1-6.1). All patients treated with LDR received 125.0 Gy in a single fraction. SBRT consisted of 42.5 Gy in 5 fractions. Five-year biochemical control for LDR versus SBRT was 91.6% versus 97.6% (P = .108). LDR patients had a larger increase in mean AUA scores at 1 month (17.2 vs 10.3, P < .001) and 3 months posttreatment (14.0 vs 9.7, P < .001), and in mean EPIC scores at 1 month (15.7 vs 13.8, P < .001). There was no significant difference between LDR and SBRT in late grade 3 genitourinary toxicity (0.9% vs 2.5%, P = .238); however, LDR had lower rates of late grade 3 gastrointestinal toxicity (0.0% vs 2.5%, P = .018).

CONCLUSIONS

Our data show similar biochemical control and genitourinary toxicity rates at 5 years for both SBRT and LDR, with slightly higher gastrointestinal toxicity with SBRT and higher AUA and EPIC scores with LDR.

Favorable Biochemical Freedom From Recurrence With Stereotactic Body Radiation Therapy for Intermediate and High-Risk Prostate Cancer: A Single Institutional Experience With Long-Term Follow-Up

Purpose/Objective(s): The current study reports long-term overall survival (OS) and biochemical freedom from recurrence (BFFR) after stereotactic body radiation therapy (SBRT) for men with intermediate and high-risk prostate cancer in a single community hospital setting with early adoption. Materials/Methods: Ninety-seven consecutive men with intermediate and high-risk prostate cancer treated with SBRT between 2007 and 2015 were retrospectively studied. Categorical variables for analysis included National Comprehensive Cancer Network risk group, race, Gleason grade group, T stage, use of androgen deprivation therapy, and planning target volume dose. Continuous variables for analysis included pretreatment prostate-specific antigen (PSA), percent cores positive, age at diagnosis, PSA nadir, prostate volume, percent prostate that received 40 Gy, and minimum dose to 0.03 cc of prostate (Dmin). BFFR was assessed using the Phoenix nadir +2 definition. OS and BFFR were estimated using Kaplan-Meier (KM) methodology with comparisons accomplished using log-rank statistics. Multivariable analysis (MVA) was accomplished with a backwards selection Cox proportional-hazards model with statistical significance taken at the p < 0.05 level. Results: Median FU is 78.4 months. Five- and ten-year OS KM estimates are 90.9 and 73.2%, respectively, with 19 deaths recorded. MVA reveals pretreatment PSA (p = 0.032), percent prostate 40 Gy (p = 0.003), and race (p = 0.031) were predictive of OS. Five- and nine-year BFFR KM estimates are 92.1 and 87.5%, respectively, with 10 biochemical failures recorded. MVA revealed PSA nadir (p < 0.001) was the only factor predictive of BFFR. Specifically, for every one-unit increase in PSA nadir, there was a 4.2-fold increased odds of biochemical failure (HR = 4.248). No significant differences in BFFR were found between favorable intermediate, unfavorable intermediate, and high-risk prostate cancer (p = 0.054) with 7-year KM estimates of 96.6, 81.0, and 85.7%, respectively. Conclusions: Favorable OS and BFFR can be expected after SBRT for intermediate and high-risk prostate cancer with non-significant differences seen for BFFR between favorable intermediate, unfavorable intermediate, and high-risk groups. Our 5-year BFFR compares favorably with the HYPO-RT-PC trial of 84%. PSA nadir was predictive of biochemical failure. This study is ultimately limited by the small absolute number of high-risk patients included.

[Moderate or extreme hypofractionation and localized prostate cancer: The times are changing]

There are many treatment options for localized prostate cancers, including active surveillance, brachytherapy, external beam radiotherapy, and radical prostatectomy. Quality of life remains a primary objective in the absence of superiority of one strategy over another in terms of specific survival with similar long-term biochemical control rates. Despite a significant decrease in digestive and urinary toxicities thanks to IMRT and IGRT, external radiotherapy remains a treatment that lasts approximately 2 months or 1.5 months, when combined with a brachytherapy boost. Given the specific radiosensitivity of this tumor, several randomized studies have shown that a hypofractionated scheme is not inferior in terms of biochemical control and toxicities, allowing to divide the number of fractions by a factor 2 to 8. Given that SBRT becomes a validated therapeutic option for a selected population of patients with localized prostate cancer, extreme hypofractionation is becoming a strong challenger of conventional external radiotherapy or brachytherapy.

Hypofractionated Radiotherapy for Localized Prostate Cancer: When and for Whom?

PURPOSE OF REVIEW

To summarize recent evidence concerning the use of moderately hypofractionated external beam radiotherapy, defined as 2.4-3.4 Gy per fraction, and ultrahypofractionated external beam radiotherapy (also known as stereotactic body radiotherapy [SBRT]), defined as at least 5 Gy per fraction, in men with localized prostate cancer.

RECENT FINDINGS

Taken together, a number of recently completed randomized trials show that moderately hypofractionated radiotherapy confers similar biochemical control compared to conventionally fractionated radiotherapy without increasing late toxicity. These effects appear to extend across all baseline clinical risk groups. Several single-arm phase II studies, as well as a recently published large-scale randomized trial comparing SBRT with conventional fractionation, show very promising biochemical control and favorable acute and late treatment-related morbidity with the use of SBRT in predominantly low- and intermediate-risk prostate cancer. As it is associated with similar prostate cancer control and toxicity while improving patient convenience and reducing cost, moderate hypofractionation is a preferred alternative to conventional fractionation in a majority of men with localized prostate cancer choosing radiotherapy as their primary treatment modality. To date, studies conducted largely in low- and intermediate-risk prostate cancer report encouraging oncologic outcomes and acceptable toxicity with SBRT. Mature results of phase III trials evaluating five-fraction SBRT regimens are eagerly awaited.

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.

Stereotactic Body Radiation Therapy for Localized Prostate Cancer: A Systematic Review and Meta-Analysis of Over 6,000 Patients Treated On Prospective Studies

PURPOSE

Utilization of stereotactic body radiation therapy (SBRT) for treatment of localized prostate cancer is increasing. Guidelines and payers variably support the use of prostate SBRT. We therefore sought to systematically analyze biochemical recurrence-free survival (bRFS), physician-reported toxicity, and patient-reported outcomes after prostate SBRT.

METHODS AND MATERIALS

A systematic search leveraging Medline via PubMed and EMBASE for original articles published between January 1990 and January 2018 was performed. This was supplemented by abstracts with sufficient extractable data from January 2013 to March 2018. All prospective series assessing curative-intent prostate SBRT for localized prostate cancer reporting bRFS, physician-reported toxicity, and patient-reported quality of life with a minimum of 1-year follow-up were included. The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Meta-analyses were performed with random-effect modeling. Extent of heterogeneity between studies was determined by the I2 and Cochran's Q tests. Meta-regression was performed using Hartung-Knapp methods.

RESULTS

Thirty-eight unique prospective series were identified comprising 6116 patients. Median follow-up was 39 months across all patients (range, 12-115 months). Ninety-two percent, 78%, and 38% of studies included low, intermediate, and high-risk patients. Overall, 5- and 7-year bRFS rates were 95.3% (95% confidence interval [CI], 91.3%-97.5%) and 93.7% (95% CI, 91.4%-95.5%), respectively. Estimated late grade ≥3 genitourinary and gastrointestinal toxicity rates were 2.0% (95% CI, 1.4%-2.8%) and 1.1% (95% CI, 0.6%-2.0%), respectively. By 2 years post-SBRT, Expanded Prostate Cancer Index Composite urinary and bowel domain scores returned to baseline. Increasing dose of SBRT was associated with improved biochemical control (P = .018) but worse late grade ≥3 GU toxicity (P = .014).

CONCLUSIONS

Prostate SBRT has substantial prospective evidence supporting its use, with favorable tumor control, patient-reported quality of life, and levels of toxicity demonstrated. SBRT has sufficient evidence to be supported as a standard treatment option for localized prostate cancer while ongoing trials assess its potential superiority.

Pelvic Complications After Prostate Cancer Radiation Therapy and Their Management: An International Collaborative Narrative Review

CONTEXT

Radiotherapy used for treating localized prostate cancer is effective at prolonging cancer-specific and overall survival. Still, acute and late pelvic toxicities are a concern, with gastrointestinal (GI) and genitourinary (GU) sequelae being most common as well as other pelvic complications.

OBJECTIVE

To present a critical review of the literature regarding the incidence and risk factors of pelvic toxicity following primary radiotherapy for prostate cancer and to provide a narrative review regarding its management.

EVIDENCE ACQUISITION

A collaborative narrative review of the literature from 2010 to present was conducted.

EVIDENCE SYNTHESIS

Regardless of the modality used, the incidence of acute high-grade pelvic toxicity is low following conventionally fractionated external beam radiotherapy (EBRT). After moderate hypofractionation, the crude cumulative incidences for late grade 3 or higher (G3+) GI and GU complications are as high as 6% and 7%, respectively. After extreme hypofractionation, the 5-yr incidences of G2+ GU and GI toxicities are 3-9% and 0-4%, respectively. Following brachytherapy monotherapy, crude rates of late G3+ GU toxicity range from 6% to 8%, while late GI toxicity is rare. With combination therapy (EBRT and brachytherapy), the cumulative incidence of late GU toxicity is high, between 18% and 31%; however, the prevalence is lower at 4-14%. Whole pelvic radiotherapy remains a controversial treatment option as there is increased G3+ GI toxicity compared with prostate-only treatment, with no overall survival benefit. Proton beam therapy appears to have similar toxicity to photon therapies currently in use. With respect to specific complications, urinary obstruction and urethral stricture are the most common severe urinary toxicities. Rectal and urinary bleeding can be recurrent long-term toxicities. The risk of hip fracture is also increased following prostate radiotherapy. The literature is mixed on the risk of in-field secondary pelvic malignancies following prostate radiotherapy. Urinary and GI fistulas are rare complications. Management of these toxicities may require invasive treatment and reconstructive surgery for refractory and severe symptoms.

CONCLUSIONS

There has been progress in the delivery of radiotherapy, enabling the administration of higher doses with minimal tradeoff in terms of slightly increased or equal toxicity. There is a need to focus future improvements in radiotherapy on sparing critical structures to reduce GU and GI morbidities. While complications such as fistulae, bone toxicity, and secondary malignancy are rare, there is a need for higher-quality studies assessing these outcomes and their management.

PATIENT SUMMARY

In this report, we review the literature regarding pelvic complications following modern primary prostate cancer radiotherapy and their management. Modern radiotherapy technologies have enabled the administration of higher doses with minimal increases in toxicity. Overall, high-grade long-term toxicity following prostate radiotherapy is uncommon. Management of late high-grade pelvic toxicities can be challenging, with patients often requiring invasive therapies for refractory cases.

Risk factors for biochemical recurrence after a tissue-ablative prostate-specific antigen <0.2 ng/mL

PURPOSE

A prostate-specific antigen (PSA) nadir <0.2 ng/mL is generally considered as tissue ablative and at low risk for recurrence. After attaining such a low PSA nadir, we analyzed risk factors for recurrence.

METHODS AND MATERIALS

We identified patients from our institutionalized database with either D'Amico low- or intermediate-risk prostate cancer that was treated with either low-dose-rate prostate brachytherapy or external beam radiotherapy as monotherapy. We compared patients who attained a nadir <0.2 ng/mL and subsequently developed biochemical failure to patients who did not experience biochemical failure by using χ² test and Student t test. Survival analysis was performed using the Kaplan-Meier method (log-rank test).

RESULTS

Of 892 patients, 560 (63%) achieved a nadir <0.2 ng/mL. Only 23 (4.1%) later developed a biochemical recurrence. The 7-year Kaplan-Meier biochemical recurrence-free survival after a PSA nadir of <0.2 ng/mL was 96%. Patients who later experienced biochemical recurrence were more likely to have Cancer of the Prostate Risk Assessment Score intermediate- or high-risk cancer: (74% vs. 40%, p < 0.001). Patients were more likely to have a diagnostic PSA >6.0 ng/mL: (66% vs. 43% p < 0.001) and have a Gleason score ≥ 3  + 4: (52% vs. 34%, p = 0.005). They were also more likely to be older (p = 0.003): mean (SD) 70.3 (6.4) vs. 66.2 (6.5) and have a time to PSA nadir that was significantly shorter (p = 0.013): mean (SD) 51.8 (29.6) vs. 65.2 (25.1).

CONCLUSIONS

Biochemical recurrence after attaining a PSA nadir <0.2 ng/mL is rare and more frequent in patients with intermediate risk cancer and older patients. These patients can benefit from a prolonged followup with specialized physicians.

Stereotactic ablative body radiotherapy in patients with prostate cancer

Prostate is the most common non-cutaneous cancer diagnosed among men in North America. Fortunately most prostate cancers are screen detected and non-metastatic on diagnosis. Treatment options for men with localized prostate cancer include surgery ± postoperative radiation or radiation ± androgen deprivation therapy (ADT). Brachytherapy ± external beam radiation treatment (EBRT) appears to have superior long-term disease control over EBRT alone likely because of higher biologic effective dose delivered. Stereotactic ablative body radiation (SABR) is a novel, non-invasive, high-precision EBRT technique that allows safe delivery of biologic doses similar to brachytherapy with similar or lower side effects [measured using toxicity or quality of life (QOL) scales]. Efficacy for SABR appears to be similar to brachytherapy including positive biopsy rates 2-3 years post treatment, biochemical failure (BF) rates out to 10-year and incidence of metastases. SABR dose escalation reduces biopsy positivity and prostate-specific antigen (PSA) nadirs but increases genitourinary (GU) and gastrointestinal (GI) toxicity-no effect on BF has been realized yet. The overall treatment time (OTT) varies in many protocols. Phase 2 randomized data shows that QOL is better in the acute setting with a weekly course of treatment compared to an every other day treatment regimen with no difference in late setting. Follow-up data are immature and likely underpowered to determine efficacy differences. SABR is cheaper and uses less resource than any other radiation technique. Given the healthcare resource challenges (including financial resources), SABR would be a welcomed addition if studies show non-inferiority to other radiation techniques. For patients with de novo or metastatic disease on relapse, there is much enthusiasm regarding the use of SABR in the setting of oligometastatic prostate cancer. SABR appears to be feasible to deliver, well tolerated and may delay the next line of therapy. However, until adequately powered randomized studies confirm a benefit, such an approach cannot be considered standard of care treatment at this time. Enrollment of eligible prostate cancer patients onto SABR clinical trials should be encouraged.

A comparison of early prostate-specific antigen decline between prostate brachytherapy and different fractionation of external beam radiation-Impact on biochemical failure

PURPOSE

The aim of this study was to compare early prostate-specific antigen (PSA) decline patterns and PSA nadirs between low-dose-rate seed prostate brachytherapy (LDR-PB) and different fractionations of external beam radiotherapy (EBRT) and their predictive importance for biochemical failure (bF).

METHODS AND MATERIALS

Patients with D'Amico low- or intermediate-risk prostate cancer who underwent a single-modality treatment without androgen deprivation were included in this study. Three different treatment groups were compared: (1) normofractionation EBRT up to 70.2-79.2 Gy/1.8-2.0 Gy, (2) LDR-PB, and (3) EBRT with hypofractionation 60 Gy/3 Gy daily or 5-7.25 Gy once a week over 9-5 weeks, to a total dose of 45-36.25 Gy, respectively. The log-rank test, Cox regression analysis, and nonparametric tests were used.

RESULTS

We analyzed 892 patients: the median followup for patients without bF was 84 months (interquartile range 60-102 months), with 12% of patients experiencing bF. The PSA decline within the first 15 months was generally exponential. LDR-PB showed a faster early exponential decline compared with EBRT treatments, but whether decline was fast or slow had no influence on recurrence. The only factors that were positive predictive factors in univariate and multivariate analyses were the time to nadir >48 months (median), PSA nadir <0.5 ng/mL, and <0.2 ng/mL (all p < 0.001).

CONCLUSIONS

Although there are significant differences in early exponential PSA decline between different treatments, only the PSA nadir and longer time to nadir were predictive factors for bF.

Hypofractionation and prostate cancer: A good option for Africa?

Cancer is an emerging public health problem in Africa. According to the World Health Organization, the numbers will be doubled by 2030 because of the ageing and the growth of the population. Prostate cancer is the most common cancer among men in most African countries. Radiotherapy machines are extremely limited in Africa and therefore prostate cancer in Africa is mostly managed by urologists. However, for a large proportion of prostate cancer patients, external-beam radiotherapy (EBRT) will be the treatment of choice in Africa because of limitations of surgical expertise in many countries. The disparity between the <em>α/β</em> ratio for late complications and the low <em>α/β</em> ratio for prostate cancer widens the therapeutic window when treating prostate cancer with hypofractionation. Because of the reduced number of treatment days, hypofractionation offers economic and logistic advantages, reducing the burden of the very limited radiotherapy resources in most African countries. It also increases patient convenience. A misleading assumption is that high-level radiotherapy is not feasible in low-income countries. The gold standard option for hypofractionation includes daily image-guided radiotherapy with 3–4 implanted gold fiducials. Acceptable methods for image guidance include ultrasound and cone-beam computed tomography (CT). CT-based treatment planning with magnetic resonance imaging fusion allows for accurate volume delineation. Volumetric modulated arc therapy or inversely planned intensity modulated radiotherapy is the ideal for treatment delivery. The most vital component is safe delivery, which necessitates accurate quality assurance measures and on-board imaging. We will review the evidence and potential utilisation of hypofractionated EBRT in Africa.