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BACKGROUND: Physiological PSMA expression in the cells of the proximal renal tubules and consecutive radiopharmaceutical binding and retention could potentially lead to radioligand-therapy-induced nephrotoxicity. Thus, patients with metastatic castration-resistant prostate cancer undergo 99mTc-Mercaptoacetyltriglycine (MAG3) renal scintigraphy to assess kidney function and to exclude renal obstruction as part of their workup for PSMA-targeted radioligand therapy (RLT). 99mTc-MAG-3 renal scintigraphy often requires an additional visit to the nuclear medicine department and patients spend 30-90 min in the department, which is inconvenient and takes up camera time. In addition, the patients are subjected to a baseline 68Ga-PSMA PET/CT to assess for PSMA-positive disease prior to targeted radioligand therapy. The aim of this retrospective cross-sectional study was to compare 99mTc-MAG-3-based split renal function (SRF) with 68Ga-PSMA-derived SRF. METHODS: This retrospective cross-sectional study included 28 patients with histologically proven metastatic castration-resistant prostate cancer (mCRPC) who received 177Lu-PSMA617. A comparison between the split renal function using 68Ga-PSMA PET/CT and the 99mTc-MAG-3-derived split renal function was carried out in 56 kidneys (n = 56). The SRF on 68Ga-PSMA was calculated using the volume and the average standard uptake value (SUVmean) within each VOI calculated as previously described by Roser et al.: SRF = (VOLUMEright) ∗ SUVmeanright/(VOLUMEright ∗ SUVmeanright + VOLUMEleft ∗ SUVmeanleft). Paired tests and correlation coefficients were used to compare 68Ga-PSMA and 99mTc-MAG-3. A visual comparison of kidney morphology on both studies was also performed. RESULTS: The median SRF of the right kidney was 49.9% (range: 3-91%) using 68Ga-PSMA PET/CT and 50.5% (range: 0-94%) with 99mTc-MAG3 scintigraphy. Notably, there was a strong correlation between SRF measurements obtained from PSMA and 99mTcMAG3, with a Pearson correlation coefficient of 0.957 (p < 0.001). Both 99mTc-MAG3 and 68Ga-PSMA PET/CT studies identified morphological renal abnormalities; there were nine hydronephrotic kidneys, four shrunken kidneys and one obstructed kidney, and there was a strong positive correlation between 68Ga-PSMA kidney morphology and 99mTcMAG3 renal scintigraphy kidney morphology, with a correlation coefficient of 0.93. CONCLUSIONS: PSMA-derived split function demonstrated a high correlation with renal function assessed on diuretic 99mTc-MAG3 renograms. PET-derived split renal function may, therefore, be considered an alternative to diuretic renogram-based split function. Furthermore, both 99mTc-MAG3 and 68Ga-PSMA PET/CT studies identified morphological renal abnormalities such as hydronephrosis, shrunken and obstructed kidneys. This correlation underscores the potential utility of 68Ga-PSMA imaging as a valuable tool for assessing kidney morphology as an alternative to renogram split function in clinical practice.
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The rising cancer incidence and mortality in sub-Saharan Africa (SSA) warrants an increased focus on adopting or developing approaches that can significantly increase access to treatment in the region. One such approach recommended by the recent Lancet Oncology Commission for sub-Saharan Africa is hypofractionated radiotherapy (HFRT), which can substantially increase access to radiotherapy by reducing the overall duration of time (in days) each person spends being treated. Here we highlight challenges in adopting such an approach identified during the implementation of the HypoAfrica clinical trial. The HypoAfrica clinical trial is a longitudinal, multicentre study exploring the feasibility of applying HFRT for prostate cancer in SSA. This study has presented an opportunity for a pragmatic assessment of potential barriers and facilitators to adopting HFRT. Our results highlight three key challenges: quality assurance, study harmonisation and machine maintenance. We describe solutions employed to resolve these challenges and opportunities for longer term solutions that can facilitate scaling-up use of HFRT in SSA in clinical care and multicentre clinical trials. This report provides a valuable reference for the utilisation of radiotherapy approaches that increase access to treatment and the conduct of high-quality large-scale/multi-centre clinical trials involving radiotherapy. Trial registration: Not available yet.
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PET/CT is revolutionising radiotherapy treatment planning in many cancer sites. While its utility has been confirmed in some cancer sites, and is used in routine clinical practice, it is still at an experimental stage in many other cancer sites. This review discusses the utility of PET/CT in cancer sites where the role of PET/CT has been established in cases such as head and neck, cervix, brain, and lung cancers, as well as cancer sites where the role of PET/CT is still under investigation such as uterine, ovarian, and prostate cancers. Finally, the review touches on PET/CT utilisation in Africa.
