Background: The indigenous population represents 2.5% of the Australian population. Evidence indicates lower rates of CRC, but also has suggested delayed diagnosis and inferior outcomes with poor understanding of CRC screening programs. We report the characteristics and outcomes for indigenous Australians with mCRC in SA.

Methods: The SA Central Cancer registry and Births, Deaths and Marriages registry were used and matched to the patients on the SA mCRC registry to identify Indigenous Australians. Patient characteristics and outcomes are described. Survival outcomes were analysed using Kaplan Meier estimates, and chi square testing used for comparisons.

Results: Only 14 of 2865 (0.5%) patients on the registry we identified as indigenous. Median age 64yrs (47-85yrs) compared to 72.5 yrs (17-105yrs) overall. 50% were female compared to 43% overall. There were no significant differences in primary site, pathology, actual or patterns of organ involvement. The proportion of synchronous disease was higher although not significant. (78.6% v 64.4%, p=0.27). Twelve of 14 (86%) received chemotherapy compared to the 58.5% rate for the overall mCRC population. Three of 14 underwent liver resection. KRAS was tested in 3, all wild type. The median survival for indigenous patients was 11.8 months v 14.9 months for non-indigenous (p=0.99).

Conclusions: Only 0.5% of mCRC patients diagnosed in SA are indigenous. This observation supports prior evidence that CRC is seen less in the indigenous population. The possibility of failure of diagnosis (cases not recognized) must also be considered. Indigenous patients on the registry are younger but appear to receive standard therapy and survival is equivalent to the overall population.