1. Cervical cancer among Asian subgroups in California, 1990-2004
Janet Bates, MD MPH
California Cancer Registry
NAACCR Annual Meeting
Denver, Colorado
June 10, 2008

2. Background
National cancer statistics show lower overall cancer rates among Asians in the US
Asians have wide variability in countries of origin, immigration history, culture, language, education and SES that influence cancer risk
Aggregated cancer statistics for Asians mask important differences among subgroups
Limited national cancer data available on Asian subgroups
One of the great challenges in cancer surveillance is to document cancer patterns and disparities across a diverse spectrum of racial and ethnic groups.
National cancer statistics show that in the US, Asians experience lower cancer rates overall compared to other racial and ethnic groups.
The Asian population is comprised of a diverse mix with respect to country of origin, immigration history, culture, language, education, and socioeconomic status, and other factors that may influence cancer burden and risk. The practice of aggregating cancer statistics for the Asian population may mask important differences among the various Asian subpopulations.
National data on cancer among subgroups is not readily available.

3. Asians in California
California has largest Asian population of any state
3.7 million Asians = 12% of state population
90% of California Asian population comprised of 6 subgroups: Chinese, Filipino, Japanese, Korean, South Asian, and Vietnamese
California has the largest Asian population of any state
In 2000, 3.7 million Asians comprised approximately 12% of the states population
90% of the California Asian population is made up of 6 subgroups: Chinese, Filipino, Japanese, Korean, South Asian, and Vietnamese

4. Study purpose
To describe patterns of cervical cancer incidence, mortality, and survival among 6 major Asian subgroups in California

5. Methods
Cervical cancer cases diagnosed among California residents
Included all 6 Asian subgroups and non-Hispanic whites (NHW)
Variables:
Age (<40, 40-64, 65+ years)
SES quintile (composite census-based measure*)
Stage (local, regional, distant, unknown)
Surgery (none, local, hysterectomy, other)
Radiation (none, any)
Chemotherapy (none, any)
Invasive cervical cancer cases diagnosed in California from were identified in the California Cancer Registry
We included all 6 Asian subgroups and non-Hispanic whites which were used as a referent group
Demographic variables included age, categorized into three groups, and socioeconomic status (SES)
Briefly, the SES variable is a composite, census based measure. A principal components analysis was used that included census indicators of education, income, occupation, housing and so forth to develop an SES score for each census block group. Quintiles of this SES score were used in the analysis.
Clinical variables included stage, categorized as local, regional, and distant according to seer summary stage criteria; and treatment information including surgery, radiation, and chemotherapy
*Yost K et al, Cancer Causes & Control, 2001

6. Methods
Cervical cancer incidence rates and trends calculated using SEERstat
Cervical cancer survival probabilities (5 and 10 year) calculated using Kaplan-Meier method
Multivariate evaluation of survival calculated using Cox proportional hazards modeling, adjusted for stage, age, SES, and treatment factors
Cervical cancer incidence and trends data were analyzed in SEERstat
Survival probabilities were calculated using Kaplan Meier

7. Results

8. Demographic characteristics: age and SES
Chinese
Filipino
Japan.
Korean
S. Asian
Viet.
NHW N
485
747
198
309 88
484
10,879 %
Age (yrs) * *
<40
17.1
18.2
24.8
14.9
6.8
29.9
40-64
47.4
58.0
51.5
57.0
56.8
68.0
48.4
65+
35.5
23.8
23.7
28.2
25.0
25.2
21.7
SES quintile *
1 (low)
11.6
17.0
8.1
19.4
20.0
12.2
5 (high)
13.0
25.3
21.4
21.6
13.6
21.2
We ended up with a total of 13,190 cases of invasive, histologically confirmed cervical cancer cases. 10,879 of those cases were diagnosed among non-Hispanic whites, and 2311 among the 6 Asian subgroups. The Asian subgroup with the largest number of cases was Filipinos at 747, and the smallest was South Asians at 88.
Overall, the age distribution among all 6 of the Asian subgroups was older than that of non-Hispanic whites, who had a higher proportion of cases diagnosed among women under age 40, 29.9% than all of the Asian subgroups, and a lower proportion diagnosed at age 65 + than all the Asian subgroups. The age distributions highlighted in orange were significantly different from NHW at p <.05 – the Chinese, Filipino, Korean, and South Asians. Note that the Chinese had a greater proportion of cases diagnosed at age 65 + years than any other group – 35.5%, and the Vietnamese had the lowest proportion of cases diagnosed at less than 40 years of age at 6.8%
There also were significant differences between the Asian subgroups and the non hispanic whites with respect to SES, highlighted in orange. For simplicity, this table only shows the proportion of cases in the lowest and highest SES quintiles, using our census based composite measure. A greater proportion of cases were diagnosed among the lowest SES group in the Filipino, Korean, and Vietnamese groups compared to whites, while among the Chinese a greater proportion of cases were diagnosed among the highest SES quintile compared to NHWs.
Cases pop
Chinese % %
Filipino % %
Japanese % %
Korean % %
South Asian % %
Vietnamese % %
* P for comparison with NHW is significant at < 0.05

9. Clinical characteristics: stage distribution
Chinese
Filipino
Japan.
Korean
S. Asian
Viet.
NHW N
485
747
198
309 88
484
10,879 %
Stage * *
Local
48.0
45.9
51.0
46.0
44.3
55.0
53.7
Regional
37.5
39.9
36.9
38.5
33.0
37.6
31.3
Distant
6.8
10.4
8.6
9.7
15.9
4.6
10.9
Unknown
7.6
3.8
3.5
5.8
2.9
4.1
The stage distribution was significantly different compared to non-Hispanic whites among Chinese, Filipino, Korean and Vietnamese
Cases pop
Chinese % %
Filipino % %
Japanese % %
Korean % %
South Asian % %
Vietnamese % %
* P for comparison with NHW is significant at < 0.05

10. Clinical characteristics: stage distribution
Chinese
Filipino
Japan.
Korean
S. Asian
Viet.
NHW N
485
747
198
309 88
484
10,879 %
Stage * *
Local
48.0
45.9
51.0
46.0
44.3
55.0
53.7
Regional
37.5
39.9
36.9
38.5
33.0
37.6
31.3
Distant
6.8
10.4
8.6
9.7
15.9
4.6
10.9
Unknown
7.6
3.8
3.5
5.8
2.9
4.1
The stage distribution was significantly different compared to non-Hispanic whites among Chinese, Filipino, Korean and Vietnamese
Lowest proportion of cases diagnosed at local stage were found among South Asian, Filipino, and Korean women; stage distribution among South Asian women not significantly different from NHW
Cases pop
Chinese % %
Filipino % %
Japanese % %
Korean % %
South Asian % %
Vietnamese % %
Lowest proportion of cases diagnosed at local stage were found among South Asian, Filipino, and Korean women; stage distribution among South Asian women not significantly different from NHW
* P for comparison with NHW is significant at < 0.05

11. Cervical cancer incidence trends: 1990-2004
Over the 15 year period , incidence rates declined for all Asian subgroups and for non Hispanic white women.

12. Cervical cancer incidence trends: 1990-2004
Vietnamese had highest incidence throughout period, as well as most dramatic decline
Vietnamese had a higher incidence throughout the 15 year period than any other group, but also experienced the most dramatic decline, with rates declining from 42.6 in to 14.0 in

13. Cervical cancer incidence trends: 1990-2004
…followed by Korean, then Filipino women
Koreans had the second highest incidence, and also a substantial decline from 16.3 to 8.3, followed by Filipino women with a decline from 12.3 to 8.4 over the period

14. Cervical cancer incidence trends: 1990-2004
Chinese women and NHW had comparable rates in …
Chinese and non-Hispanic white women had comparable rates in at 8.9 and 9.1 respectively

15. Cervical cancer incidence trends: 1990-2004
…but by incidence rates were lower among Chinese women
By , Chinese incidence rates declined to 4.8, below rates for Non Hispanic whites at 6.6
NHW
Chinese

16. Cervical cancer incidence trends: 1990-2004
Rates among Japanese and South Asian women also declined, but trend not statistically significant
Japanese
Finally, rates among Japanese and South Asian women also declined but the trends were not statistically significant
South Asian

17. Unadjusted cause-specific 5- and 10-year cervical cancer survival
Survival probability (%)
(95% Confidence Interval)
Chinese
Filipino
Japanese
Korean
S. Asian
Viet.
NHW
5-year
78.6
(74.4, 82.2)
79.0
(75.9, 81.9)
72.3
(64.9, 78.4)
85.7
(80.9, 89.6)
85.8
(75.1, 92.2)
0.79
(0.64, 1.00)
77.5
(76.7, 78.3)
10-year
77.2
(72.9, 81.0)
74.8
(71.2, 78.0)
69.5
(61.7, 76.1)
82.5
(77.1, 86.7)
79.7
(75.4, 83.3)
75.4
(74.6, 76.3)
This table shows the results of the unadjusted 5 and 10 year cervical cancer survival probabilities

18. Unadjusted cause-specific cervical cancer survival
Now I will turn to the results of the analyses of survival.
South Asian women had the highest unadjusted, cause-specific survival probabilities of 85.8% at both 5 and 10 years, followed by Korean, Vietnamese, then Chinese, Filipino, all with probabilities

19. Clinical characteristics: stage distribution
Chinese
Filipino
Japan.
Korean
S. Asian
Viet.
NHW N
485
747
198
309 88
484
10,879 %
Stage * *
Local
48.0
45.9
51.0
46.0
44.3
55.0
53.7
Regional
37.5
39.9
36.9
38.5
33.0
37.6
31.3
Distant
6.8
10.4
8.6
9.7
15.9
4.6
10.9
Unknown
7.6
3.8
3.5
5.8
2.9
4.1
Recall the stage distribution slide from earlier – we just saw a higher unadjusted cause-specific survival among South Asians and Koreans compared to other groups, despite a lower proportion of cases diagnosed at local stage.
Cases pop
Chinese % %
Filipino % %
Japanese % %
Korean % %
South Asian % %
Vietnamese % %
Lowest proportion of cases diagnosed at local stage were found among South Asian, Filipino, and Korean women; stage distribution among South Asian women not significantly different from NHW
* P for comparison with NHW is significant at < 0.05

20. Risk of death due to cervical cancer among Asian subgroups
Hazard Ratio
(95% Confidence Interval)
Chinese
Filipino
Japanese
Korean
S. Asian
Viet.
Race only
0.94
(0.78, 1.15)
0.97
(0.83, 1.13)
1.28
(0.97, 1.69)
0.61
(0.45, 0.81)
0.57
(0.32, 1.04)
0.79
(0.64, 1.00)
This table shows the results of the multivariate analysis in which variables are added in a stepwise fashion.
With only race in the model, we see similarly to the previous slide, that the lowest risk of cervical cancer death compared to non-Hispanic whites was found among South Asians and Koreans; however, the difference is only statistically significant for Koreans where the 95% confidence interval does not include 1
Referent group is Non-Hispanic Whites

21. Risk of death due to cervical cancer among Asian subgroups
Hazard Ratio
(95% Confidence Interval)
Chinese
Filipino
Japanese
Korean
S. Asian
Viet.
Race only
0.94
(0.78, 1.15)
0.97
(0.83, 1.13)
1.28
(0.97, 1.69)
0.61
(0.45, 0.81)
0.57
(0.32, 1.04)
0.79
(0.64, 1.00)
Stage
(0.79, 1.18)
0.84
(0.72, 0.98)
1.19
(0.90, 1.56)
0.49
(0.37, 0.66)
0.37
(0.20, 0.66)
0.83
(0.676, 1.03)
This table shows the results of the multivariate analysis in which variables are added in a stepwise fashion.
After adding stage at diagnosis to the model, the lowest risk of cervical cancer death is still found among So. Asians and Koreans, now statistically significant; the result for Filipinos is now significant.
Referent group is non-Hispanic whites

22. Risk of death due to cervical cancer among Asian subgroups
Hazard Ratio
(95% Confidence Interval)
Chinese
Filipino
Japanese
Korean
S. Asian
Viet.
Race only
0.94
(0.78, 1.15)
0.97
(0.83, 1.13)
1.28
(0.97, 1.69)
0.61
(0.45, 0.81)
0.57
(0.32, 1.04)
0.79
(0.64, 1.00)
Stage
(0.79, 1.18)
0.84
(0.72, 0.98)
1.19
(0.90, 1.56)
0.49
(0.37, 0.66)
0.37
(0.20, 0.66)
0.83
(0.676, 1.03)
Stage, age
0.89
(0.72, 1.09)
0.82
(0.70, 0.95)
1.15
(0.87, 1.52)
0.47
(0.35, 0.62)
0.34
(0.19, 0.62)
(0.64, 0.98)
This table shows the results of the multivariate analysis in which variables are added in a stepwise fashion.
Now with the addition of age, there is little additional change, but the confidence interval for Vietnamese no longer includes 1
Referent group is non-Hispanic whites

23. Risk of death due to cervical cancer among Asian subgroups
Chinese
Filipino
Japanese
Korean
S. Asian
Viet.
Race only
0.94
(0.78, 1.15)
0.97
(0.83, 1.13)
1.28
(0.97, 1.69)
0.61
(0.45, 0.81)
0.57
(0.32, 1.04)
0.79
(0.64, 1.00)
Stage
(0.79, 1.18)
0.84
(0.72, 0.98)
1.19
(0.90, 1.56)
0.49
(0.37, 0.66)
0.37
(0.20, 0.66)
0.83
(0.676, 1.03)
Stage, age
0.89
(0.72, 1.09)
0.82
(0.70, 0.95)
1.15
(0.87, 1.52)
0.47
(0.35, 0.62)
0.34
(0.19, 0.62)
(0.64, 0.98)
Stage, age, Rx, SES
(0.68, 1.02)
0.78
(0.67, 0.91)
1.13
(0.86, 1.50)
0.42
(0.31, 0.57)
0.31
(0.17, 0.56)
0.77
(0.62, 0.96)
Finally, with all variables in the model, the pattern we saw in the unadjusted analysis generally holds with South Asians and Koreans having the lowest risk of cervical cancer death; Risk among the Filipino and Vietnamese was also lower than that of non-Hispanic whites.
Referent group is non-Hispanic whites

24. Discussion
Higher incidence among Vietnamese, Korean, Filipino women mirror international patterns
South Asian rates relatively low despite high rates in countries of origin
Overall, we saw higher cervical cancer incidence rates among Vietnamese, Filipino, and Koreans relative to other Asian subgroups and Non-Hispanic whites. This generally mirrors international incidence patterns internationally. The exception was South Asians. Incidence rates were relatively low in this population, whereas rates in India are the highest of any Asian country. This may be related to a relatively high level of education of South Asian immigrants in California compared to other race/ethnic groups.

25. Discussion
Variability in cervical cancer incidence is largely attributed to screening
Expect populations with low screening to have higher incidence
Examined cervical cancer screening survey data from the California Health Interview Survey (CHIS)
When we look at the reasons for variability in cervical cancer incidence, cervical cancer screening is the first place to look. Because cervical cancer screening can lead to the detection and removal of pre cancerous lesions, we would expect that a highly screened population would have a lower incidence of invasive cervical cancer. So we examined the data on cervical cancer screening from the 2003 California Health Interview Survey, or CHIS among Asian subgroups in California.

26. Percent pap test in past 3 years by Asian subgroup, California
Here are the results from CHIS showing the proportion of women reporting having a pap test in the past 3 years. These survey results are for women over the age of 18 who did not report having had a hysterectomy. The lowest prevalence of screening was seen among the Koreans – 67%, followed by Chinese, Vietnamese, South Asians. Filipinos reported the highest prevalence of recent pap testing, 88%, comparable to that of NHW at 88.9%.
Source: California Health Interview Survey 2003

27. Percent pap test in past 3 years and cervical cancer incidence by Asian subgroup, California
The red lines show the 3 year age adjusted average incidence rate for superimposed over the pap test results, and we see no consistent pattern. Korean and Vietnamese women had relatively low utilization of the pap test, and relatively higher cervical cancer incidence rates, which is what we would predict. However, pap utilization reported among Chinese women was also relatively low, but they also had low incidence, which is not what we would predict. Conversely, Filipino women had high pap utilization, but also had higher incidence. So at least on initial examination, there is no obvious correlation. Clearly, these relationships would need to be teased our further with additional evaluation and data..
Source: California Health Interview Survey 2003

28. Limitations Limited number of cases in some subgroups
Misclassification of race is possible
Risk factor data (HPV subtypes, smoking, diet, co-morbidities, immigration data, etc.) not available
Before concluding, I will note some of the limitations of this study
As you saw, some of the analyses were based on a low number of cases in some subgroups
Race information is obtained from the medical record and not by self report, so misclassification with respect to subgroup is possible
Information of lifestyle factors that may influence cervical cancer risk are not avaiable

29. Summary
Distinct variations among subgroups in patterns of cervical cancer incidence and survival
Practice of aggregating statistics for Asians masks these differences
Public health programs targeting cervical cancer screening and prevention must take these differences into account
To sum up, we found distinct variations in the burden of cervical cancer among our 6 Asian subgroups. These differences are masked by the general practice of aggregating statistics for Asians. Public health programs that target cervical cancer screening and prevention must take these differences into account in order to be successful in reducing the cervical cancer burden among Asians

30. Summary
Lower risk of cervical cancer death among Vietnamese, Korean, Filipino, and South Asian women
Few studies on this
Further evaluation of reasons for this apparent survival advantage is needed
Finally, we found a lower risk of cervical cancer death among Vietnamese, Korean, Filipino and south Asian women, even after adjusting for demographic and clinical factors. There are few studies on this, and further evaluation is needed of this apparent survival advantage.

31. Acknowledgements Co-authors: Brenda Hofer, Arti Parikh-Patel
CDC Cancer supplement coordinators: Meg Watson, Mona Saraiya
CCR research and surveillance program staff: Mark Allen, Allyn Fernandez Ami, Sandy Kwong