Evaluating the prognostic potential of the Ki67 proliferation index and tumour-infiltrating lymphocytes in olfactory neuroblastoma

AIMS

Olfactory neuroblastomas (ONBs) are rare malignant tumours that arise in the nasal vault. To date, the Hyams grade remains the only widely used histological grading system. However, it is based only on morphological criteria, and has not been updated since 1988. The objective of this study was to explore the prognostic potential of the Ki67 proliferation index (PI) and tumour-infiltrating lymphocytes (TILs) in ONB.

METHODS AND RESULTS

A retrospective study was conducted on a bicentric series of 45 cases. The Ki67 PI was determined by counting at least 1000 nuclei on whole slides. TILs were evaluated with CD20, CD4 and CD8 immunohistochemical markers on whole slides. In this series, Hyams grades I, II, III and IV accounted for 13.4%, 44.4%, 20% and 22.2% of all cases, respectively. The Ki67 PI ranged from 1 to 93; the Ki67 PI was significantly higher in Hyams grade III-IV ONBs than in Hyams grade I-II ONBs (P < 0.0001). A Ki67 PI of ≥25 was associated with poorer survival (P = 0.02). TILs were present in both stromal and intratumoral compartments, but were located predominantly in the stromal component of the tumour. The numbers of intratumoral CD8+ cells/mm² and CD4+ cells/mm² were greater in high-grade ONBs than in low-grade ONBs (P = 0.0015 and P = 0.043, respectively). The numbers of T cells/mm² and B cells/mm² were not associated with survival, but a CD4/CD8 ratio of >2 was significantly associated with shorter survival (P = 0.04).

CONCLUSION

Our findings suggest that the Ki67 PI and TILs could be used as prognostic markers, as a potential alternative to the Hyams grade.

Patient characteristics of olfactory neuroblastoma: experience from a tertiary cancer centre 2000-2016 covering Eastern Denmark

The aim of this study was to report incidence and patient characteristics of olfactory neuroblastoma (ONB) at a tertiary cancer institution during a 16-year period. A retrospective review was conducted on patients with ONB treated at Rigshospitalet, Copenhagen from 2000 to 2016 covering Eastern Denmark. Patient demographics, symptoms, stage, pathology-reports, treatment, and outcome were extracted from the patient records and the Danish pathology register. The tumours were graded both histologically and clinically using Hyam's and Kadish classifications, respectively. We identified a total of 14 patients (ten males, four females, median age 57 years, range 17-81 years). Four patients were in Kadish stage A, one stage B, and seven stage C. According to Hyam's classification, two tumours were grade I, nine grade II, and three grade III. All patients were treated with surgery, eight in combination with radiotherapy, where one received proton therapy, and one a combination with chemotherapy. At a median follow-up time of 58 months, the 5-year overall survival was 90% (95% CI 61; 99). ONB is a rare disease; complete radical surgery alone or combined with radiotherapy offered good oncologic control and outcome. Long-term follow-up of ONB should be mandatory.