Combined modality therapy versus chemotherapy alone as an induction regimen for primary central nervous system lymphoma: a decision analysis

In immunocompetent patients with primary central nervous system (CNS) lymphoma, combined modality therapy (CMT) using high-dose methotrexate and whole brain radiotherapy has improved response rates compared to chemotherapy alone. The trade-off is delayed and potentially devastating treatment-related neurotoxicity. A Markov decision-analytic model compared CMT to chemotherapy alone in patients with primary CNS lymphoma. Baseline probabilities were derived from a systematic literature review. Outcomes were life expectancy and quality-adjusted life expectancy. Sensitivity analyses were performed. The life expectancy was 2.69 years for CMT and 2.77years for chemotherapy alone. The quality-adjusted life expectancies for the two strategies were 1.70 and 1.67 quality-adjusted life years (QALYs) respectively. In younger patients <60 years of age, CMT yielded a quality-adjusted life expectancy of 2.71 QALYs, compared to 2.09 QALYs for chemotherapy alone, yielding an expected benefit with CMT of 0.62 QALYs or 7.4 quality-adjusted months. There was no difference between the strategies in the older group. The model was robust to key variables for the younger group. The preferred induction strategy for younger patients appears to be CMT, maximizing life expectancy, and QALYs. This analysis confirms that the preferred strategy for older patients is chemotherapy alone.