Abstract
Abstract 2956
The incidence of plasma cell myeloma (PCM) in East Asian population is known to be 3–4 times lower than that in Caucasians. This may be due to genetic or environmental factors. Migrant studies may separate these factors to some extent by determining whether the disease incidence follows the parent or destination prevalence. British Columbia (BC) has a large population of Chinese migrants and therefore, it is an ideal population for migrant studies. Hong Kong (HK) is chosen as the comparison population because it has meticulous census data and a population-based cancer registry.
Computerized records of all PCM cases diagnosed from 1975 to 2004 were retrieved from the British Columbia Cancer Agency (BCCA) and the Hong Kong Cancer Registry (HKCR). Cases with Chinese ethnicity in BC were identified by surname using a previously validated methodology and verified from electronic charts. Age distribution of HK, BC and BC Chinese populations for consecutive 5-secular year (yr.) periods were obtained from census departments from the respective governments. The crude incidence rates of PCM were calculated and 95% CI were determined using normal approximation of Poisson distribution. Projected PCM incidence rates in BC Chinese using HK and BC models were calculated and standard incidence ratios (SIR) estimated.
There was a steady increase in PCM from 1975 to 2004: from 42 to 159 cases/yr. in HK and from 86 to 207 cases/yr. in BC. This is likely due to population growth and aging. The proportion of population with age >65 grew from 5.4% to 11.2% in HK and from 9.7% to 13.2% in BC. From 1975–2004, a total of 106 cases of BC Chinese PCM were identified, increasing from 0.4 to 8 cases/yr. The BC Chinese population grew from 0.07 to 0.37 million, while the elderly subgroup (age >65) grew from 7.9% to 12.9%. Age specific mean 30-year crude incidence/100,000 person-years and 95% CI in the 3 cohorts were determined (Table 1). The standardized incidence ratio (SIR) of PCM in BC Chinese from 1975–2004 was 0.83 (95% CI 0.68–1.00) when compared to HK and 0.44 (0.36-0.53) when compared to the BC population. Cumulative SIRs of PCM in BC Chinese when compared to BC population remained low for incremental 5-year from 1975–2004 (Table 2).
The incidence of PCM in ethnic Chinese in British Columbia is lower compared to the Caucasian counterparts, but similar to the incidence seen in HK. The trend is apparent in all age groups over 45 years old. This observation suggests a strong genetic predisposition in the development of PCM.
Age specific mean crude incidence of PCM/100,000 person-years from 1975–2004.
| Age . | BC Chinese . | HK Background . | BC Background . |
|---|---|---|---|
| 0–24 | 0.00 (0.00–0.19) | 0.03 (0.02–0.05) | 0.01 (0.00–0.03) |
| 25–34 | 0.11 (0.00–0.60) | 0.14 (0.10–0.18) | 0.14 (0.09–0.21) |
| 35–44 | 0.60 (0.22–1.31) | 0.51 (0.43–0.61) | 0.61 (0.50–0.75) |
| 45–54 | 2.01 (1.15–3.27) | 1.92 (1.73–2.13) | 3.62 (3.28–3.98) |
| 55–64 | 2.67 (1.46–4.48) | 4.73 (4.37–5.10) | 9.93 (9.28–10.60) |
| >65 | 11.87 (9.23–15.02) | 13.23 (12.64–13.84) | 26.36 (25.45–27.30) |
| Overall | 1.83 (1.49–2.21) | 1.83 (1.77–1.90) | 4.62 (4.48–4.75) |
| Age . | BC Chinese . | HK Background . | BC Background . |
|---|---|---|---|
| 0–24 | 0.00 (0.00–0.19) | 0.03 (0.02–0.05) | 0.01 (0.00–0.03) |
| 25–34 | 0.11 (0.00–0.60) | 0.14 (0.10–0.18) | 0.14 (0.09–0.21) |
| 35–44 | 0.60 (0.22–1.31) | 0.51 (0.43–0.61) | 0.61 (0.50–0.75) |
| 45–54 | 2.01 (1.15–3.27) | 1.92 (1.73–2.13) | 3.62 (3.28–3.98) |
| 55–64 | 2.67 (1.46–4.48) | 4.73 (4.37–5.10) | 9.93 (9.28–10.60) |
| >65 | 11.87 (9.23–15.02) | 13.23 (12.64–13.84) | 26.36 (25.45–27.30) |
| Overall | 1.83 (1.49–2.21) | 1.83 (1.77–1.90) | 4.62 (4.48–4.75) |
Cumulative SIR of PCM for incremental 5-year periods from 1975–2004 for BC Chinese compared to HK and BC population.
| . | 1975–1979 . | 1975–1984 . | 1975–1989 . | 1975–1994 . | 1975–1999 . | 1975–2004 . |
|---|---|---|---|---|---|---|
| BC Chinese vs HK | 0.52(0.06–1.88) | 0.86(0.39–1.64) | 0.79(0.47–1.24) | 0.87(0.61–1.21) | 0.90(0.70–1.15) | 0.83(0.68–1.00) |
| BC Chinese vs BC | 0.20(0.02–0.73) | 0.33(0.15–0.63) | 0.36(0.21–0.57) | 0.43(0.30–0.59) | 0.45(0.35–0.58) | 0.44(0.36–0.53) |
| . | 1975–1979 . | 1975–1984 . | 1975–1989 . | 1975–1994 . | 1975–1999 . | 1975–2004 . |
|---|---|---|---|---|---|---|
| BC Chinese vs HK | 0.52(0.06–1.88) | 0.86(0.39–1.64) | 0.79(0.47–1.24) | 0.87(0.61–1.21) | 0.90(0.70–1.15) | 0.83(0.68–1.00) |
| BC Chinese vs BC | 0.20(0.02–0.73) | 0.33(0.15–0.63) | 0.36(0.21–0.57) | 0.43(0.30–0.59) | 0.45(0.35–0.58) | 0.44(0.36–0.53) |
No relevant conflicts of interest to declare.
Author notes
Asterisk with author names denotes non-ASH members.
