Factors associated with cancer-specific and overall survival among Indigenous and non-Indigenous gynecologic cancer patients in Queensland, Australia: a matched cohort study

Abstract

Objective: Aboriginal and Torres Strait Islander women have a higher mortality rate due to gynecologic cancer compared with non-Indigenous women. For cervical cancer, Australian Indigenous women are less likely to survive 5 years following diagnoses than non-Indigenous women. This study investigates the factors associated with gynecologic cancer treatment and survival among Queensland indigenous and non-Indigenous women.

Methods: Australian Indigenous women diagnosed with uterine, cervical, ovarian, or other gynecologic cancers during 1998-2004 in the public hospital system were included. They were frequency matched on age (±5 years), residential remoteness, and cancer type to a random sample of non-Indigenous women. One- and 5-year cancer-specific survival was examined according to Indigenous status using Cox proportional hazards regression.

Results: Indigenous women (n = 137) compared with non-Indigenous women (n = 120) were less likely to be diagnosed with localized disease (49% vs 65%, P = 0.02) and had more comorbidities (52% vs 21%, P < 0.001). Indigenous women were less likely to receive any cancer treatment compared with non-Indigenous women (91% vs 98%, P = 0.01), although when excluding those with metastatic cancer, there was no significant difference in uptake of treatment (95% vs 91%, respectively, P = 0.31). Among those who did undergo treatment, there was no difference in time to treatment (median difference 0.5 days, P = 0.98). Gynecologic cancer-specific survival differences between Indigenous and non-Indigenous women were most prominent in the first year following diagnosis (hazard ratio [HR], 1.89; 95% confidence interval [CI], 1.06-3.38) and were no longer significant 5 years after diagnosis (HR, 1.47 [95% CI, 0.97-2.25]). For cervical cancer, crude 1-year survival was poorer for Indigenous women compared with non-Indigenous women (HR, 2.46 [95% CI, 1.03-5.90]), but was no different when adjusted for stage and treatment of cancer (HR, 1.00 [95% CI, 0.45-2.24]).

Conclusions: Improving the early diagnosis of cervical cancer in Indigenous women may increase cancer-specific survival in the year following diagnosis.