Racial and ethnic differences in abdominal soft tissue sarcoma incidence in New Zealand: a retrospective audit

Soft tissue sarcomas are a rare and heterogenous group of tumours. Anecdotally there seems to be an over representation of patients of Māori ethnicity presented at the Auckland Regional Sarcoma Multidisciplinary Meeting (MDM). To date no study has reported on ethnicity demographics of abdominal and retroperitoneal sarcoma in New Zealand. The aim of this study is to characterize the ethnicity distribution of patients discussed at the regional MDM.

A retrospective audit was performed of patients presented at the Auckland Regional Sarcoma MDM between January 2015 and December 2020 with abdominal sarcoma. Ethnicity documentation for these patients was reviewed.

One hundred and twenty-four patients with intra-abdominal and retroperitoneal tumours were discussed at MDM with 61 proceeding for resection, of those 43 (70.5%) were primary tumours, 10 (16.4%) were recurrent tumours and 8 (13.1%) had metastatic disease. Liposarcoma made up 56 (45.2%) cases, Leiomyosarcoma 33 (26.6%), Other 35 (28.2%). Ethnicities for this group specifically were European 64 (51.6%), Māori 31 (25.0%), Pacific Peoples 17 (13.7%), Asian 6 (4.8%) and Other/unknown 3(2.4%). This was found to be statistically significantly different to the expected ethnicity distribution based on 2018 census data from North Island DHBs (χ²  = 19.55, p = 0.00), with Māori and Pacific Peoples being over-represented and Asian patients being under-represented. Recommendation for surgery did not appear to be related to ethnicity.

Our descriptive data shows a higher proportion of patients of Māori ethnicity discussed through the North Island regional sarcoma MDM than we would expect comparted to ethnicity distribution in the general population. It is unclear whether this represents a true difference in incidence based on ethnicity.