Clinical outcome and toxicity evaluation of simultaneous integrated boost pelvic IMRT/VMAT at different dose levels combined with androgen deprivation therapy in prostate cancer patients

Volumetric modulated arc therapy (VMAT): a review of clinical outcomes—what is the clinical evidence for the most effective implementation?

Modern conformal radiation therapy using techniques such as modulation, image guidance and motion management have changed the face of radiotherapy today offering superior conformity, efficiency, and reproducibility to clinics worldwide. This review assesses the impact of these advanced radiotherapy techniques on patient toxicity and survival rates reported from January 2017 to September 2020. The main aims are to establish if dosimetric and efficiency gains correlate with improved survival and reduced toxicities and to answer the question ‘What is the clinical evidence for the most effective implementation of VMAT?’. Compared with 3DCRT, improvements have been reported with VMAT in prostate, locally advanced cervical carcinoma and various head and neck applications, leading to the shift in technology to VMAT. Other sites such as thoracic neoplasms and nasopharyngeal carcinomas have observed some improvement with VMAT although not in line with improved dosimetric measures, and the burden of toxicity and the incidence of cancer related deaths remain high, signaling the need to further mitigate toxicity and increase survival. As technological advancement continues, large randomised long-term clinical trials are required to determine the way-forward and offer site-specific recommendations. These studies are usually expensive and time consuming, therefore utilising pooled real-world data in a prospective nature can be an alternative solution to comprehensively assess the efficacy of modern radiotherapy techniques.

A Systematic Review of the Treatment Outcomes among Prostate Cancer Patients in Africa

Prostate cancer (PCa) is associated with a significant public health burden in Africa. This systematic review aimed to assess treatment outcomes among PCa patients in Africa. A systematic search of the literature was conducted from 1 December 2021 to 31 March 2022 to identify relevant published studies. PubMed, EMBASE, CINAHL, and Google Scholar databases were used. Twenty-four studies met the inclusion criteria, and the mean age was 68 years. Localized and locally advanced diseases had relatively higher overall survival than metastatic diseases. In metastatic disease, the mean overall five-year survival was 42% which is shorter than the Asian population (61.9%).

68Ga-PSMA-11 PET has the potential to improve patient selection for extended pelvic lymph node dissection in intermediate to high-risk prostate cancer

INTRODUCTION

Radical prostatectomy with extended pelvic lymph node dissection (ePLND) is a curative treatment option for patients with clinically significant localised prostate cancer. The decision to perform an ePLND can be challenging because the overall incidence of lymph node metastasis is relatively low and ePLND is not free of complications. Using current clinical nomograms to identify patients with nodal involvement, approximately 75-85% of ePLNDs performed are negative. The aim of this study was to assess the added value of ⁶⁸Ga-PSMA-11 PET in predicting lymph node metastasis in men with intermediate- or high-risk prostate cancer.

METHODS

⁶⁸Ga-PSMA-11 PET scans of 60 patients undergoing radical prostatectomy with ePLND were reviewed for qualitative (visual) assessment of suspicious nodes and assessment of quantitative parameters of the primary tumour in the prostate (SUV_max, total activity (PSMA_total) and PSMA positive volume (PSMA_vol)). Ability of quantitative PET parameters to predict nodal metastasis was assessed with receiver operating characteristics (ROC) analysis. A multivariable logistic regression model combining PSA, Gleason score, visual nodal status on PET and primary tumour PSMA_total was built. Net benefit at each risk threshold was compared with five nomograms: MSKCC nomogram, Yale formula, Roach formula, Winter nomogram and Partin tables (2016).

RESULTS

Overall, pathology of ePLND specimens revealed 31 pelvic metastatic lymph nodes in 12 patients. ⁶⁸Ga-PSMA-11 PET visual analysis correctly detected suspicious nodes in 7 patients, yielding a sensitivity of 58% and a specificity of 98%. The area under the ROC curve for primary tumour SUV_max was 0.70, for PSMA_total 0.76 and for PSMA_vol 0.75. The optimal cut-off for nodal involvement was PSMA_total > 49.1. The PET model including PSA, Gleason score and quantitative PET parameters had a persistently higher net benefit compared with all clinical nomograms.

CONCLUSION

Our model combining PSA, Gleason score and visual lymph node analysis on ⁶⁸Ga-PSMA-11 PET with PSMA_total of the primary tumour showed a tendency to improve patient selection for ePLND over the currently used clinical nomograms. Although this result has to be validated, ⁶⁸Ga-PSMA-11 PET showed the potential to reduce unnecessary surgical procedures in patients with intermediate- or high-risk prostate cancer.

Retrospective study comparing MR-guided radiation therapy (MRgRT) setup strategies for prostate treatment: repositioning vs. replanning

BACKGROUND

This study compared adaptive replanning and repositioning corrections based on soft-tissue matching for prostate cancer by using the magnetic resonance-guided radiation therapy (MRgRT) system.

METHODS

A total of 19 patients with prostate cancer were selected retrospectively. Weekly magnetic resonance image (MRI) scans were acquired for 5 weeks for each patient to observe the anatomic changes during the treatment course. Initial intensity-modulated radiation therapy (IMRT) plans (iIMRT) were generated for each patient with 13 coplanar ⁶⁰Co beams on a ViewRay™ system. Two techniques were applied: patient repositioning and replanning. For patient repositioning, one plan was created: soft-tissue (prostate) matching (Soft). The dose distribution was calculated for each MRI with the beam delivery parameters from the initial IMRT plan. The replanning technique was used to generate the Adaptive plan, which was the reoptimized plan for the weekly MRI. The dose-volumetric parameters of the planning target volume (PTV), bladder, and rectum were calculated for all plans. During the treatment course, the PTV, bladder, and rectum were evaluated for changes in volume and the effect on dosimetric parameters. The differences between the dose-volumetric parameters of the plans were examined through the Wilcoxon test. The initial plan was used as a baseline to compare the differences.

RESULTS

The Adaptive plan showed better target coverage during the treatment period, but the change was not significant in the Soft plan. There were significant differences in D_98%, D_95%, and D_2% in PTV between the Soft and Adaptive plans (p < 0.05) except for D_mean. There was no significant change in D_max and D_mean as the treatment progressed with all plans. All indices for the Adaptive plan stayed the same compared to those of iIMRT during the treatment course. There were significant differences in D_15%, D_25%, D_35%, and D_50% in the bladder between the Soft and Adaptive plans. The Adaptive plan showed the worse dose sparing than the Soft plan for the bladder according to each dosimetric index. In contrast to the bladder, the Adaptive plan achieved better sparing than the Soft plan during the treatment course. The significant differences were only observed in D_15% and D_35% between the Soft and Adaptive plans (p < 0.05).

CONCLUSIONS

Patient repositioning based on the target volume (Soft plan) can relatively retain the target coverage for patients and the OARs remain at a clinically tolerance level during the treatment course. The Adaptive plan did not clinically improve for the dose delivered to OARs, it kept the dose delivered to the target volume constant. However, the Adaptive plan is beneficial when the organ positions and volumes change considerable during treatment.