The Association between Tumour Markers and Meta-iodobenzylguanidine Scans in South African Children with High-risk Neuroblastoma

AIMS

Diagnostic and post-induction ¹²³I-meta-iodobenzylguanidine (¹²³I-mIBG) scans have prognostic significance in the treatment of neuroblastoma, but data from low- and middle-income countries are limited due to resource constraints. The aim of this study was to determine the association between neuroblastoma-associated tumour markers (lactate dehydrogenase [LDH], ferritin and MYCN amplification) and ¹²³I-mIBG scans (modified Curie scores and metastatic disease patterns) in predicting complete metastatic response rates (mCR) and overall survival.

MATERIALS AND METHODS

Two hundred and ninety patients diagnosed with high-risk neuroblastoma in South Africa between January 2000 and May 2018 and a subanalysis of 78 patients with diagnostic ¹²³I-mIBG scans were included. Data collection included LDH, ferritin and MYCN amplification at diagnosis. Two nuclear physicians independently determined the modified Curie scores and pattern of distribution for each diagnostic and post-induction ¹²³I-mIBG scans with high inter-rater agreement (r = 0.952) and reliability (K = 0.805). The cut-off values for the diagnostic and post-induction modified Curie scores of ≥7.0 (P = 0.026) and 3 (P = 0.009), respectively, were generated. The association between the tumour markers and the modified Curie score of the ¹²³I-mIBG scans was determined using post-induction mCR and 2-year overall survival.

RESULTS

Diagnostic LDH (P < 0.001), ferritin (P < 0.001) and the diagnostic modified Curie scores (P = 0.019) significantly predicted mCR. Only ferritin correlated with diagnostic modified Curie scores (P = 0.003) but had a low correlation coefficient of 0.353. On multivariable analysis, the only significant covariate for 2-year overall survival at diagnosis was LDH <750 U/l (P = 0.024). A post-induction chemotherapy modified Curie score ≤3.0 had a 2-year overall survival of 46.2% compared with 30.8% for a score >3.0 (P = 0.484).

CONCLUSION

LDH, ferritin and the diagnostic ¹²³I-mIBG scans significantly predicted mCR, but only LDH predicted 2-year overall survival. Ferritin and the modified Curie scores correlated with each other. MYCN amplification neither correlated with any aspect of the ¹²³I-mIBG scans nor significantly predicted mCR or 2-year overall survival. LDH and ferritin are therefore appropriate neuroblastoma tumour markers to be used in low- and middle-income countries with limited or no access to mIBG scans and/or MYCN amplification studies.

The College of Nuclear Physicians of South Africa Practice Guidelines on Peptide Receptor Radionuclide Therapy in Neuroendocrine Tumours

BACKGROUND

Peptide receptor radionuclide therapy (PRRT) for metastatic or inoperable neuroendocrine tumours (NETs) is a systemic therapy which targets somatostatin receptors overexpressed by differentiated NETs for endoradiotherapy. This guideline has been compiled by the College of Nuclear Physicians of the Colleges of Medicine of South Africa, with endorsement by the South African Society of Nuclear Medicine and the Association of Nuclear Physicians to guide Nuclear Medicine Physicians in its application during the management of these patients.

RECOMMENDATIONS

Patients with well- to moderately-differentiated NETs should be comprehensively worked-up to determine their suitability for PRRT. Treatment should be administered by a Nuclear Medicine Physician in a licensed, appropriately equipped and fully staffed facility. Patient monitoring is mandatory during and after each therapy cycle to identify and treat therapy-related adverse events. Patients should also be followed-up after completion of therapy cycles for monitoring of long-term toxicities and response assessment.

CONCLUSION

PRRT is a safe and effective therapy option in patients with differentiated NETs. Its use in appropriate patients is associated with a survival benefit.

Radionuclide therapy and integrated protocols for bone metastases

Bone metastases are responsible for most of the morbidity and mortality associated with solid malignant tumors, occurring in about 65-70% of the patients with advanced breast or prostate cancer. The pathophysiology of skeletal metastasis is a complex process that involves several biologic process leading to cellular invasion, adhesions and stimulation of osteoclasts and osteoblasts with the mediation of several factors including cytokines, serine proteases and tumor-derived factors. The clinical management of pain from bone metastasis, which is mostly due to indirect stimulation of sensory nerve endings by cytokines and other biologically-active compounds released locally in response to the presence of tumor cells in the bone marrow, includes several options that can be used either alone or in varying combinations, such as analgesic drugs, chemo- or hormonal therapy, bisphosponates, external beam radiation therapy, and surgery. Bone-seeking radiopharmaceuticals play an important role in the treatment of pain caused by multiple blastic or mixed-type skeletal lesions; they have in general a favorable toxicity profile and a high rate of overall clinical benefit, although they may differ in terms of duration of pain palliation and suitability for repeat treatments. The palliative effect can be attributed to the radiation targeted to the bone marrow space, and the overall average response ranges between about 45-80%, with complete response in 10-30% of the cases. In selected clinical conditions, radionuclide therapy can also constitute an effective systemic treatment beyond bone pain palliation, and a synergistic anti-tumour effect can be expected by the combination with other agents, such as chemotherapy or bisphosphonates. This review summarizes the current experience with bone-seeking radiopharmaceuticals used for bone pain palliation, focusing on indications, patients' selection, efficacy and toxicity. Finally, the available data on combination therapies showing encouraging results as to potential anti-tumor efficacy are also reviewed.