A total of 846 eviQ protocols were searched, of which there were 625 medical oncology protocols and 221 haematology protocols. There were 955 relevant PBS codes in total. Of these, 880 returned data on services while 75 did not have any subsidised use during the study period. After removing non-PBS-listed cancer drugs, and drugs that did not have any codes that gave data from the PBS Item Reports between 2012 and 2022, there were 141 final drugs included in the analysis. The full list is presented in Table 1. The average APCs and associated 95% confidence intervals for each drug class over the 10-year period from 2012 to 2022 are presented in Table 1.

Between the end of 2011 and 2021, Australia experienced 15% population growth, with the population rising from 22.9 to 26.3 million. Concurrently, cancer rates surged from 125,813 to 160,570 diagnoses per year, marking a larger 28% increase, and the population aged 65 and above grew from 3.3 to 4.5 million: a growth of 73% (Australian Bureau of Statistics 2023; Australian Institute of Health and Welfare 2023). As a result, the population-adjusted cancer diagnosis rate surged by approximately 60.80 per 100,000 individuals during this period. This suggests a swifter rise in cancer incidence when compared with population growth, which aligns with demographic aging, as cancer is generally more prevalent among older age groups (Springer et al. 2024).

Our data analysis indicates a noticeable upward trend in the demand for PBS cancer drugs across Australia. An overall APC increase of 10.3% (95% CI = 5.4–15.2%) was observed for the services of all drugs, with some drugs exhibiting higher demand when compared with others at different points in time over the past 10 years. Average APCs for the 10-year period were positive for all drug classes, varying in magnitude from 2 to 23%, as shown by the trends depicted in Fig. 1.

Services of PBS cancer drugs by class in Australia, 2012–2022

Antimetabolites, which comprised mostly conventional chemotherapeutic drugs, had consistently high usage rates that rose from 250,000 to almost 500,000 services annually in later years (equivalent to 1000–2000 services per 100,000 head of population). This is largely due to the extensive use of fluorouracil, which was found in many protocols across different types of cancer; 1,781,098 prescriptions for fluorouracil were dispensed between 2012 and 2022, and 97 (11%) of eviQ cancer treatment protocols included the use of the drug.

Alkylating agents and topoisomerase inhibitors both showed average annual percentage changes (APCs) of approximately 4% and displayed nearly identical usage patterns, as depicted in Fig. 1. However, it is evident that the rate of increase in their usage was slower when compared with drugs in other classes and also slower when compared with the annual rate of cancer diagnoses over the same years. The use of mitotic inhibitors over the years closely resembles that of alkylating agents and topoisomerase inhibitors, except for a significant surge in 2015 following the only PBS listing this study could find for docetaxel, which occurred in 2014. Docetaxel services rose from 710 in 2014 to 31,693 in 2015 and continued to remain high alongside paclitaxel, resulting in a higher APC of 11% for mitotic inhibitors.

“Other agents” which comprised drugs outside of the named seven classes, displayed a minimal increase in use over the 10-year period, with the exception of a surge post-2020, leading to an average APC of 6.5% (Fig. 1). Throughout this period, the total services for this class generally remained below 250,000 (equivalent to 1000 per 100,000 head of population), until beyond 2020. The notable spike following 2020 can be attributed to the introduction of bortezomib, which was extensively used, onto the PBS Schedule starting from 2021. Dexamethasone was the most frequently dispensed drug within the class, representing almost 45% of the total services (1,136,192 out of 2,596,369). Within eviQ, it is primarily found in haematology treatment protocols.

Hormonal agents, though used the most, exhibited the most variability in use over the course of the study, characterised by large fluctuations between 2012 and 2017, but with the lowest overall APC of 2% (Fig. 1). The number of services in this period ranged between 625,000 and 875,000 (or 2500–3500 services per 100,000 head of population) whereas the number for every other class generally fell below 500,000 services per year (or 2000 prescriptions per 100,000 head of population). Anastrozole, letrozole, and tamoxifen emerged as the most frequently used drugs and accounted for the majority of these services (Fig. 2). Consequently, the overall changes in trend reflect the individual changes observed for these three agents.

Services of hormonal cancer agents on the PBS from 2012 to 2022

The high usage rates for these drugs are explained by their daily use as oral formulations; the recommended dosing regimen for all three hormonal agents in the eviQ protocols is long-term, once-daily use. Anastrozole when used in breast adjuvant and metastatic chemotherapy is dosed every day for up to ten years or until disease progression. Similarly, letrozole is used in adjuvant endocrine therapy and is dosed once a day for a total of 5–10 years. In contrast, the majority of other cancer medications are administered once weekly to once every three weeks.

From 2012 to 2013, the use of hormonal agents saw a drop as the total number of services decreased from 734,254 to 652,082 (Change: − 11%). The number of anastrozole services decreased from 217,089 to 185,514, contributing to most of the overall drop, while letrozole decreased from 150,315 to 138,805, and tamoxifen from 131,368 to 120,089.

In the following year (2014), hormonal agents saw their steepest increase in use, driven by a change in the use of anastrozole (26% increase), letrozole (30%), and tamoxifen (22%). In total, services rose from 652,082 to 820,506 (or from about 2800 to 3500 per 100,000 head of population); an overall increase of 25%. This occurred after the inclusion of these medications into eviQ protocols for metastatic breast cancer in June 2012, expanding their use beyond adjuvant breast cancer therapy. This also followed the expiration of their patents, which began with anastrozole in 2010 (Qin et al. 2019).

While the use of anastrozole and tamoxifen slowed considerably from 2016, there was a notable increase in the use of goserelin and exemestane, with goserelin services surpassing tamoxifen services after 2017. Also used in the treatment of breast cancer, goserelin has been found to protect against ovarian failure during adjuvant chemotherapy (Moore et al. 2015). The eviQ protocol that combined goserelin and exemestane for breast adjuvant chemotherapy was also endorsed in late 2015.

Of particular interest are the usage trends of the newer targeted therapy medicines, which comprised drugs grouped under “monoclonal antibodies” and “kinase inhibitors”. Of the 23 monoclonal antibodies listed within the eviQ protocols, 14 were PBS listed with data available from, or after, 2016. The year with the most newly listed agents was 2022. Monoclonal antibodies were the only drug class to consistently increase in the number of services without any decline throughout the entire period. Its average APC increase over the 10 years was the highest at 23%. Over the course of the analysis period, denosumab (APC: 15%), trastuzumab (APC: 12%), nivolumab (APC: 42%), pembrolizumab (APC: 26%), and bevacizumab (APC: 98%) stood out for having the most notable increases in use (Figs. 3 and 4). These surges were observed in the initial years following the availability of their PBS data, with bevacizumab becoming accessible only in 2021. In 2022, denosumab and trastuzumab recorded the number of services above 60,000 (or approximately 3000 per 100,000 head of population), while the remaining three drugs recorded services above 50,000 (approximately 2500 per 100,000 head of population).

Services of immunotherapy monoclonal antibodies for cancer on the PBS from 2012 to 2022

Services of targeted monoclonal antibodies for cancer on the PBS from 2012 to 2022

Trastuzumab was one of the earliest monoclonal antibody agents to be listed on the PBS in 2012. Aside from its consistent increase in use from 2012 to 2022, with the greatest surge between 2015 and 2016 (APC: 34%), it was also one of the most used drugs across the period. Its 521,074 services amounted for 23% of the total services (n = 2,304,533) for all monoclonal antibodies. Trastuzumab was predominantly found in eviQ treatment protocols for breast cancer (n = 32 protocols; 27% of all breast cancer protocols) and used both alone and in conjunction with other drugs. Beyond its use in multiple myeloma, denosumab was predominantly used to treat a rare bone tumour, and bone metastases arising from breast and prostate cancers. Nivolumab, pembrolizumab, and bevacizumab covered a wider range of cancer treatment protocols, including those within the respiratory, neurological, and gynaecological systems, among others.

Of the 846 cancer treatment protocols retrieved from eviQ, 194 protocols included a monoclonal antibody. Among these, only 67 protocols (35%) recommended its use as standalone therapy, which meant that they were primarily used with other agents to complement existing treatment protocols. However, as many of these combinations comprised other monoclonal antibodies and kinase inhibitors, they could be replacing drugs from other classes. For example, although the FOLFIRI (modified) protocol that included the drug aflibercept was discontinued, the drugs bevacizumab, cetuximab, and panitumumab (three targeted monoclonal antibody agents) continue to be included in three other modified FOLFIRI protocols for the treatment of metastatic colorectal cancer.

Following monoclonal antibodies, kinase inhibitors exhibited the second-highest overall APC (16%) among all the drug classes analysed. Use of drugs within this category solely increased each year from 2013 onward (Fig. 5). At the beginning of the analysis period (2012), kinase inhibitors were used the least, with only 41,596 services recorded, largely due to most agents not yet being listed on the PBS. Of the 39 kinase inhibitors listed in eviQ guidelines, 25 were PBS listed with data available from 2016, and the year 2020 saw the most newly listed agents. Subsequent years resulted in rapid increases in their use as more agents were introduced, surpassing the total services per year of topoisomerase inhibitors after 2019.

Services of kinase inhibitor cancer drugs on the PBS from 2012 to 2022

Although kinase inhibitors were not as extensively used as monoclonal antibody drugs, with services consistently below 200,000 (or 1000 per 100,000 head of population) annually, the overall usage trend mirrored that of monoclonal antibodies in this analysis. Most of the monoclonal antibodies and kinase inhibitors were listed on the PBS from the late 2010s, and this is visually reflected in the steeper rise over the 10-year period. As a result, prior to 2017, the number of services for both classes that comprised newer drugs was relatively low. From 2018, the use of drugs in both the monoclonal antibody and kinase inhibitor classes began to increase at a faster rate than was observed for the other six drug classes (Fig. 1).

Imatinib was the most frequently used kinase inhibitor in this analysis (n = 293,498 total services from 2012 to 2022) despite it being listed in only six eviQ protocols: for the treatment of acute lymphoblastic and chronic myeloid leukaemia, and gastrointestinal stomal cell tumours.

Out of the 846 cancer treatment protocols sourced from eviQ, 67 protocols incorporated a kinase inhibitor into the treatment regimen. In contrast to monoclonal antibodies, the majority of these protocols (58 out of 67; 87%) recommended its use as monotherapy, particularly in lung cancer treatment. Among the few instances where it was used in combination with other drugs, the additional drugs were predominantly monoclonal antibodies, such as lenvatinib and pembrolizumab for advanced endometrial and renal cell carcinomas.