Cost-effectiveness of adjuvant chemotherapy for high-risk stage II and stage III colon cancer in South Africa.

Background: Colon cancer incidence is rising in low- and middle-income countries (LMICs), where resource limitations and cost often dictate treatment decisions. In this study, we evaluate the cost-effectiveness of adjuvant chemotherapy for high-risk stage II and stage III colon cancer treatment in South Africa (ZA) and illustrate how such analyses can inform cancer treatment recommendations in a LMIC.

Methods: We created a decision-analytic Markov model to compare lifetime costs and outcomes for patients with high-risk stage II and stage III colon cancer treated with three adjuvant chemotherapy regimens in a public hospital in ZA: capecitabine and oxaliplatin (CAPOX) for 3 and 6 months, and capecitabine for 6 months, compared to no adjuvant treatment. The primary outcome was the incremental cost-effectiveness ratio (ICER) in international dollars (I$) per disability-adjusted life-year (DALY) averted, at a willingness-to-pay (WTP) threshold equal to the 2021 ZA gross domestic product per capita (I$13,764/DALY averted).

Results: CAPOX for 3 months was cost-effective for both patients with high-risk stage II and patients with stage III colon cancer (ICER = I$250/DALY averted and I$1042/DALY averted, respectively), compared to no adjuvant chemotherapy. In subgroup analyses of patients by tumor stage and number of positive lymph nodes, for patients with high-risk stage II colon cancer and T4 tumors, and patients with stage III colon cancer with T4 or N2 disease. CAPOX for 6 months was cost-effective and the optimal strategy. The optimal strategy in other settings will vary by local WTP thresholds. Decision analytic tools can be used to identify cost-effective cancer treatment strategies in resource-constrained settings.

Conclusion: Colon cancer incidence is increasing in low- and middle-income countries, including South Africa, where resource constraints can impact treatment decisions. This cost-effectiveness study evaluates three systemic adjuvant chemotherapy options, compared to surgery alone, for patients in South African public hospitals after surgical resection for high-risk stage II and stage III colon cancer. Doublet adjuvant chemotherapy (capecitabine and oxaliplatin) for 3 months is the cost-effective strategy and should be recommended in South Africa.