Treatment and Survival for Unresectable Pancreatic Adenocarcinoma in Queensland, Australia, 2018-2022

The three main chemotherapy regimens for people with unresectable pancreatic cancer include modified FOLFIRINOX (comprising oxaliplatin, irinotecan and fluorouracil, denoted mFFX), gemcitabine with nab-paclitaxel (GnP), and single-agent gemcitabine (GEM). We explored characteristics associated with the type of chemotherapy and variations in survival.

Records for people with unresected pancreatic adenocarcinoma between 2018 and 2022 treated with first-line mFFX, GnP or GEM were extracted from the population-based Queensland Oncology Repository. Multivariable Poisson models were fitted to determine factors associated with each type of chemotherapy, expressed as relative likelihoods (RLs). Variations in three-year observed survival were assessed using flexible parametric modelling and reported in terms of adjusted excess mortality hazard ratios (HRs).

Of the 766 people in the study cohort, 59% were treated with GnP, 27% with mFFX, and 15% with GEM. After adjustment, treatment with mFFX was far more likely in selected private facilities compared to public hospitals (RL = 2.33, 95% CI 1.84-2.96), whereas the GEM regimen was used more often for those from outer regional/remote areas (RL = 2.20 compared to people living in major cities, 95% CI 1.45-3.34; p < 0.001). Three-year survival was very poor at just 5% (95% CI 3%-7%). Nonetheless, adjusted mortality was higher for GnP (HR = 1.30, 95% CI 1.07-1.59) and GEM (HR = 1.53, 95% CI 1.17-2.01) compared to mFFX.

Apart from clinical indications, there should be equity in the treatment received for unresectable pancreatic cancer. Our results suggest, however, that where a person lives and the type of facility at which they are treated may influence their chemotherapy regimen.