Understanding the impact of the Cancer Drug List on clinicians' prescription patterns in Singapore: A qualitative study.

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Background: The Cancer Drug List (CDL) introduced by Singapore’s Ministry of Health in September 2022 aligns insurance reimbursement with a list of clinically proven and cost-effective oncology drugs. National spending on cancer drugs doubled between 2015 and 2019. Although most patients did not experience an increase in out-of-pocket expenses (OOPE) immediately after CDL implementation, financial distress and high financial toxicity (FT) remain prevalent among patients undergoing chemotherapy. The impact of the CDL on clinicians’ prescribing behaviour has not been well described. This study examined how CDL implementation reshaped prescribing priorities. Methods: We conducted a qualitative descriptive study using semi-structured interviews with clinicians who prescribed systemic cancer therapies. Participants were recruited at a public cancer centre in Singapore and were interviewed in English between November to December 2025. Interviews were audio-recorded, transcribed, and analysed using applied thematic analysis. Results: 12 clinicians were interviewed (median age 40 years; median 15.5 years in medical practice; 75% female). Three dominant shifts in prescribing behaviour emerged following CDL implementation: recalibration toward subsidy eligibility, heightened cost consciousness, and differential access across tumour types. Prior to CDL implementation, prescribing decisions were guided by financial considerations, adherence to clinical guidelines, strength of evidence, and toxicity profiles. Clinicians described working within insurance claim limits. Post-CDL, prescribing became closely anchored to CDL inclusion, as subsidy eligibility directly determined OOPE. Clinicians reported systematically verifying whether regimens were CDL-listed before finalising treatment plans. While first-line therapies were generally perceived as accessible, subsequent lines of therapy and non-listed indications posed greater financial challenges. Access was described as straightforward for common cancers (e.g., breast), but clinicians highlighted disproportionate financial barriers for rare cancers and tumour types not aligned with CDL indications. Increased cost awareness led to more cost-related discussions and treatment sequencing adjustments. However, limited visibility into patients’ exact out-of-pocket costs hindered precise financial counselling. Conclusions: CDL implementation anchored prescribing towards subsidy eligibility and cost alignment. In the context of persistent patient-reported FT and ongoing concerns about affordability despite stable OOPE for many patients, strengthening financial transparency tools and referral pathways may enhance clinicians’ capacity to support informed, cost-sensitive treatment decisions. Further research is underway to examine patient experiences post- CDL implementation.