Epidemiology of Adult Acute Lymphoblastic Leukemia in Manitoba, Canada: Does This Approximate Clinical Trial Data?.

Background: Outcomes of unselected adult ALL patients (pts) have not been well studied at a population level. Whether such pts behave differently to those in formal clinical trials is unclear. We developed a uniform therapeutic protocol as the provincial standard of care in Manitoba, a province with 1.2 million people, for adult pts since 1989 (“ALL89-1”). The aim of this retrospective study was: to ascertain the local epidemiology of adult ALL; to analyze the efficacy and toxicity of the ALL89-1 regimen and any other regimens given to pts in a population-based setting.

Methods: All pts aged ≥18 years (yrs) diagnosed with ALL in Manitoba between 01/1989 and 11/2004 were identified via the provincial cancer registry. A review of computerized and paper charts was conducted. We focused on demographics, diagnostic clinical characteristics, therapy, treatment related toxicities, and whether stem cell transplantation (SCT) was performed.

Results: There were 81 pts with a median age of 44yrs (range, 18–90). 53 (65%) pts were male. 58 pts received ALL89-1, 12 received other regimens and 11 patients received palliation only. Thirteen pts were Philadelphia chromosome positive (Ph+). Complete remission (CR) rate after one cycle of induction therapy was 74% for all pts, and 74% for ALL89-1 pts. At a median follow-up of 56 months (range 7–265), estimated overall survival (OS) and leukemia free survival (LFS) at 5 years was 26% (95% Confidence interval [C.I.], 15–36) and 24%( 95% C.I. 14–35). The 5 year OS and LFS for the ALL89–1 group was 23% (95% C.I. 11–35) and 20% (95% C.I. 8–32). There were 13 treatment related deaths in the 58 ALL 89-1 pts, 4 of whom died post SCT. In multivariate analysis for all 81 pts, attainment of CR post induction chemotherapy independently predicted improved survival (hazard ratio 0.23, 95% C.I. 0.11–0.5). In contrast, age > 55yrs, Ph+ status, and high WBC at diagnosis were not significant survival predictors. Palliative pts survived for a median of 10 days (range, 0–53) from diagnosis.

Conclusions: This comprehensive province-wide study of adult ALL pts treated at a single cancer centre shows that durable leukemia free survival is possible, but for only a small subgroup. These results appear inferior to results of published clinical trials. The reasons for the relatively poor outcomes require further analysis in this and other jurisdictions.