PRESENTATION AND CLINICAL OUTCOMES IN AL AMYLOIDOSIS PATIENTS DIAGNOSED IN SASKATCHEWAN: A POPULATION‐BASED COHORT STUDY

AL amyloidosis, a rare and complex systemic disorder characterized by the extracellular accumulation of amyloid fibrils composed of misfolded immunoglobulin light chains, presents significant diagnostic and treatment challenges. Globally, the disease has a reported incidence ranging from 5.1 to 12.8 cases per million person-years. In the U.S., there are annually between 1275 and 3200 new diagnoses, resulting in an incidence of roughly 9 to 14 cases per million person-years. According to the report from the Canada’s Drug Agency (CDA), the annual incidence is 10 per million in Canada. Although AL amyloidosis is most often a systemic disease involving multiple organ systems and tissues, localized disease may be seen that involves a single organ or tissue. Despite significant advances having been made in the understanding of the mechanisms of this disease and in new diagnostic and therapeutic strategies, there is limited knowledge about the real-world clinical presentation, treatment outcomes, and experiences of individuals affected by this condition. Currently, there are no published data for AL amyloidosis patients in Saskatchewan. A retrospective chart review of cases diagnosed with AL amyloidosis in Saskatchewan provides an opportunity to address these knowledge gaps. This study aims to bridge this gap by providing details of the presentation, treatment patterns and clinical outcomes of these patients. We did a retrospective, population-based cohort study using the Saskatchewan Cancer Agency database (SCA), which showed a total of 43 cases of AL amyloidosis diagnosed in Saskatchewan from 2010 to 2023. The statistical testing was performed after data collection using SPSS (version 27). Descriptive statistics were used to summarize quantitative and qualitative variables. For quantitative variables, summary measures were selected based on data distribution: for normally distributed variables, mean ± standard deviation (SD), minimum, and maximum were reported; for skewed variables, median with first (Q1) and third (Q3) quartiles were reported. Qualitative variables were summarized using frequencies and percentages. Kaplan-Meier analysis estimated survival rates, with group differences evaluated using the log-rank test. The significance level was set to P-values < 0.05 for the statistical tests to determine meaningful differences between groups. The results of this study showed that the population was predominantly male (67.44%), with females comprising only 32.56% which suggested potential sex-based differences in susceptibility or diagnosis. The mean age at the time of AL amyloidosis diagnosis was 65.12 ± 12.51 years and the mean age of patients was 69.71 ± 12.13 years, which suggested that AL amyloidosis mostly affects older adults. The clinical presentation was variable with many patients having multiorgan symptoms most commonly involving the cardiac and renal systems. The analysis of mortality among patients with AL amyloidosis revealed that 65.12% (28 patients) of the cohort had died, while 35% (15 patients) were alive at the time of evaluation. The treatment patterns identified in this study are representative of the treatment landscape in AL amyloidosis in this province. The treatment patterns showed a heterogeneous, selective approach to the disease. Chemotherapy was used as the most common treatment in 31 patients (72.09%). Surgical excision (2 cases, 4.65%), radiotherapy (5 cases, 11.63%) and bone marrow transplant (3 cases, 6.98%) were rarely employed, which may relate to their more focused use for complications or patient requirements. The most used first line of chemotherapy regimen was CyBorD used in 64.52% of patients. The data also indicated that many patients had evidence of raised immunoglobulin light chains, i.e., abnormal kappa, lambda, and kappa/lambda ratio. The most frequent biopsy site was bone marrow (86.05%), followed by the kidney (46.51%), fat pad (18.60%), gastrointestinal tract (9.30%) and liver (6.98%). The mean survival time was estimated at 5.15 years (median: 3.66 years) for females and 5.90 years (median: 5.39 years) for males. The mean survival was 4.51 years after chemotherapy, 7.72 years after radiotherapy, and 5.17 years after bone marrow transplant. In conclusion, this study provides an important insight into the epidemiological data on AL amyloidosis in Saskatchewan, and it emphasized the need for early diagnosis. The heterogeneity in clinical presentation within our cohort highlights the systemic nature of AL amyloidosis and different responses to the treatment. This information could inform provincial health care policy and facilitate the implementation of tailored best practice guidelines that optimize the diagnosis, treatment, and management of AL amyloidosis with the aim of improving patient outcomes and survival. Further longitudinal studies should be conducted to follow the long-term effectiveness of these existing treatments and the role of new therapies.

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