Insurance Status, Age, and Cervical Cancer Stage at Diagnosis
Insurance Status, Age, and Cervical Cancer Stage at Diagnosis
In a large national sample of women diagnosed with cervical cancer in 2000 to 2007, the strongest predictor of late stage at diagnosis was age, followed by insurance. Late stage at diagnosis is likely attributable to underscreening as opposed to interval cancers (tumors arising between regular screenings), according to previous studies examining screening histories of women diagnosed with invasive cervical cancer. Although the risk of advanced-stage disease was highest among the oldest age group (70–85 years), the greatest change in advanced-stage disease occurred in women aged 40 to 44 years and 50 to 59 years, which coincide with, respectively, the periods in a woman's life when reproduction typically ends and menopause begins.
These changes in advanced-stage diagnoses with age corresponded with reported declines in cervical cancer screening between women aged 25 to 44 years (85.7% reported having a Pap test in the past 3 years) and women aged 45 to 54 years (81.0% had been screened). This decline was also reported in women aged 55 to 64 years (76.0%) and 65 to 74 years (61.6%). Our results suggest that interventions are needed to mitigate decreased screening compliance in middle-aged women (40–69 years), a period that saw the greatest shifts in advanced-stage diagnoses. Strengthening screening compliance in middle-aged women may offer an additional benefit in preventing advanced disease in older women (70–79 years), because it takes several years for tumors to progress. Guidelines for Pap tests vary by age; the most frequent screening (annual for conventional Pap tests and every 2 years for liquid-based Pap tests) is recommended for women aged 30 years and younger. Women aged 70 years and older who have had 3 or more normal Pap tests and no abnormal Pap tests in the past 10 years may choose to stop cervical cancer screening.
Reasons for screening noncompliance may also vary by age. In a study among women with deficient screening, postmenopausal women were more likely to report that screening was not recommended by a physician, and premenopasual women were more likely to identify procrastination as a reason for not being screened. Further study is needed to determine whether late stage at diagnosis among older women results from decreased screening attributable to patientrelated factors or is related to providers' (appropriate or inappropriate) application of the guidelines to low-risk women at older ages. In addition to variations in screening practices, clinical sampling errors, which may be caused in older women by a lack of cells in the area of the cervix (the cervical transformation zone) where cancer cells are typically found, may also play a role in increased rates of advanced-stage disease.
The risk of advanced-stage cervical cancer was higher among patients without private insurance, particularly among uninsured women and Medicaid recipients. This finding is consistent with our NHIS data on Pap tests. Previous analyses of national survey data have also documented lower cervical cancer screening compliance among women lacking insurance and women without a usual care provider. Although general patterns between late stage at diagnosis and screening are similar, the specific shifts in stage in the NCDB do not precisely match NHIS screening data because the study populations may differ and self-reported data may overestimate cancer screening.
In addition to lack of screening, uninsured and underinsured patients have higher rates of abnormal screening results and lower follow-up rates after an abnormal result. Such factors may also contribute to advanced-stage disease among these groups. Increasing the proportion of uninsured and Medicaid-insured cervical cancer patients diagnosed at an earlier stage through improved screening and follow-up after an abnormal result is not only important to lower morbidity and mortality, but may also offer cost savings, because advanced-stage cervical cancers are more expensive to treat than early-stage cancers. Even among privately insured patients, women aged 35 years and older were more likely to be diagnosed with advanced disease. Although we adjusted for education by zip code area, individual socioeconomic factors, such as lack of transportation and logistical challenges (time off of work and child care), may vary by age and negatively influence screening among women with access to care. Other studies have reported older age as the most prominent predictor of failure to screen among women within comprehensive health insurance plans, highlighting the need for increased Pap testing adherence even among middle-aged women with access to care for whom it is recommended.
Similar to previous studies, we observed higher risks of advanced-stage disease in African Americans. However, when we stratified by insurance type, only privately insured and older Medicare-insured African Americans had statistically significant higher risks of advanced-stage disease than did older Medicare-insured and privately insured Whites. Previous studies of cervical cancer screening compliance by race/ethnicity among privately insured women reported mixed results: one study found lower screening rates among privately insured African Americans than Whites, but another group noted similar rates. Among uninsured and Medicaid-insured patients, Hispanics had lower risks of advanced-stage disease than did Whites. The negative association between stage and Hispanic ethnicity among uninsured and Medicaid-insured patients accords with a study reporting lower odds of cervical cancer screening among uninsured Whites than uninsured Hispanics and African Americans. Our results, along with those of others, provide some evidence that minority women are more savvy than White women about accessing subsidized services or safety net public services. In addition, national screening programs may be more effective at reaching minority women.
Although previous investigations suggested that Pap tests are more effective in detecting squamous cell carcinomas than adenocarcinomas, we observed lower risks of advanced stage among patients with adenocarcinomas. We initially hypothesized that insurance was confounding the relationship between stage and histologic type, because the proportion of adenocarcinomas among privately insured patients was much higher than among patients with other insurance types. Yet when we stratified our multivariable results by insurance type, we observed a decreased risk of advanced disease among patients with adenocarcinomas across all insurance types. The trend of lower rates of advanced-stage disease in adenocarcinomas has been observed in SEER data.
Evidence suggests that adenocarcinomas are more likely to arise as interval cancers (developing between regular screenings). Interval cancers are more likely to be diagnosed at earlier stages than are cancers eventually detected in an underscreened population. In addition, some data indicate that the etiology of adenocarcinoma and squamous cell carcinoma differ: nulliparity and obesity may play a larger role in adenocarcinoma. How this difference affects the morphogenesis and stage progression of adenocarcinoma is unclear. More detailed studies to elucidate the paradoxical relationship between stage and histology among cervical cancers are needed.
A limitation of our data source is that it only collects data on patients diagnosed or treated at facilities accredited by the Commission on Cancer, which are more likely to be located in urban areas and tend to be larger than non-accredited facilities. However, when we compared cervical cancer case counts with North American Association of Central Cancer Registries data, the NCDB coverage rate was 85%, which is high relative to the estimated 70% NCDB coverage rate for all cancers combined. When we compared patient characteristics between the NCDB and SEER, the NCDB had fewer stage III and IV cancers, which should be considered when attempting to generalize our results to other populations. In addition, the impact of the National Breast and Cervical Cancer Early Detection Program on uninsured and Medicaid-insured patients in our study and the coverage rates are unclear. This program offers women with incomes below 250% of the federal poverty level the cervical cancer screening and treatment mandated by the federal Breast and Cervical Cancer Prevention and Treatment Act of 2000. Although the program screened more than 1.6 million women in 2004 to 2009, it reached fewer than 10% of eligible women.
A sensitivity analysis examining factors related to missing staging data revealed higher rates of missing data among patients in the oldest age category and among younger Medicare patients. We believe the potential selection bias resulting from missing staging data elements was relatively minor, because only 7% of all selected cervical cancer patients were missing stage information. An additional limitation was that no formal validation study of the insurance status data in the NCDB has been conducted. Although this variable does not reflect changes in insurance type or specific covered benefits over time, it does reflect insurance coverage during initial treatment, with the exception of Medicaid recipients.
Discussion
In a large national sample of women diagnosed with cervical cancer in 2000 to 2007, the strongest predictor of late stage at diagnosis was age, followed by insurance. Late stage at diagnosis is likely attributable to underscreening as opposed to interval cancers (tumors arising between regular screenings), according to previous studies examining screening histories of women diagnosed with invasive cervical cancer. Although the risk of advanced-stage disease was highest among the oldest age group (70–85 years), the greatest change in advanced-stage disease occurred in women aged 40 to 44 years and 50 to 59 years, which coincide with, respectively, the periods in a woman's life when reproduction typically ends and menopause begins.
These changes in advanced-stage diagnoses with age corresponded with reported declines in cervical cancer screening between women aged 25 to 44 years (85.7% reported having a Pap test in the past 3 years) and women aged 45 to 54 years (81.0% had been screened). This decline was also reported in women aged 55 to 64 years (76.0%) and 65 to 74 years (61.6%). Our results suggest that interventions are needed to mitigate decreased screening compliance in middle-aged women (40–69 years), a period that saw the greatest shifts in advanced-stage diagnoses. Strengthening screening compliance in middle-aged women may offer an additional benefit in preventing advanced disease in older women (70–79 years), because it takes several years for tumors to progress. Guidelines for Pap tests vary by age; the most frequent screening (annual for conventional Pap tests and every 2 years for liquid-based Pap tests) is recommended for women aged 30 years and younger. Women aged 70 years and older who have had 3 or more normal Pap tests and no abnormal Pap tests in the past 10 years may choose to stop cervical cancer screening.
Reasons for screening noncompliance may also vary by age. In a study among women with deficient screening, postmenopausal women were more likely to report that screening was not recommended by a physician, and premenopasual women were more likely to identify procrastination as a reason for not being screened. Further study is needed to determine whether late stage at diagnosis among older women results from decreased screening attributable to patientrelated factors or is related to providers' (appropriate or inappropriate) application of the guidelines to low-risk women at older ages. In addition to variations in screening practices, clinical sampling errors, which may be caused in older women by a lack of cells in the area of the cervix (the cervical transformation zone) where cancer cells are typically found, may also play a role in increased rates of advanced-stage disease.
The risk of advanced-stage cervical cancer was higher among patients without private insurance, particularly among uninsured women and Medicaid recipients. This finding is consistent with our NHIS data on Pap tests. Previous analyses of national survey data have also documented lower cervical cancer screening compliance among women lacking insurance and women without a usual care provider. Although general patterns between late stage at diagnosis and screening are similar, the specific shifts in stage in the NCDB do not precisely match NHIS screening data because the study populations may differ and self-reported data may overestimate cancer screening.
In addition to lack of screening, uninsured and underinsured patients have higher rates of abnormal screening results and lower follow-up rates after an abnormal result. Such factors may also contribute to advanced-stage disease among these groups. Increasing the proportion of uninsured and Medicaid-insured cervical cancer patients diagnosed at an earlier stage through improved screening and follow-up after an abnormal result is not only important to lower morbidity and mortality, but may also offer cost savings, because advanced-stage cervical cancers are more expensive to treat than early-stage cancers. Even among privately insured patients, women aged 35 years and older were more likely to be diagnosed with advanced disease. Although we adjusted for education by zip code area, individual socioeconomic factors, such as lack of transportation and logistical challenges (time off of work and child care), may vary by age and negatively influence screening among women with access to care. Other studies have reported older age as the most prominent predictor of failure to screen among women within comprehensive health insurance plans, highlighting the need for increased Pap testing adherence even among middle-aged women with access to care for whom it is recommended.
Similar to previous studies, we observed higher risks of advanced-stage disease in African Americans. However, when we stratified by insurance type, only privately insured and older Medicare-insured African Americans had statistically significant higher risks of advanced-stage disease than did older Medicare-insured and privately insured Whites. Previous studies of cervical cancer screening compliance by race/ethnicity among privately insured women reported mixed results: one study found lower screening rates among privately insured African Americans than Whites, but another group noted similar rates. Among uninsured and Medicaid-insured patients, Hispanics had lower risks of advanced-stage disease than did Whites. The negative association between stage and Hispanic ethnicity among uninsured and Medicaid-insured patients accords with a study reporting lower odds of cervical cancer screening among uninsured Whites than uninsured Hispanics and African Americans. Our results, along with those of others, provide some evidence that minority women are more savvy than White women about accessing subsidized services or safety net public services. In addition, national screening programs may be more effective at reaching minority women.
Although previous investigations suggested that Pap tests are more effective in detecting squamous cell carcinomas than adenocarcinomas, we observed lower risks of advanced stage among patients with adenocarcinomas. We initially hypothesized that insurance was confounding the relationship between stage and histologic type, because the proportion of adenocarcinomas among privately insured patients was much higher than among patients with other insurance types. Yet when we stratified our multivariable results by insurance type, we observed a decreased risk of advanced disease among patients with adenocarcinomas across all insurance types. The trend of lower rates of advanced-stage disease in adenocarcinomas has been observed in SEER data.
Evidence suggests that adenocarcinomas are more likely to arise as interval cancers (developing between regular screenings). Interval cancers are more likely to be diagnosed at earlier stages than are cancers eventually detected in an underscreened population. In addition, some data indicate that the etiology of adenocarcinoma and squamous cell carcinoma differ: nulliparity and obesity may play a larger role in adenocarcinoma. How this difference affects the morphogenesis and stage progression of adenocarcinoma is unclear. More detailed studies to elucidate the paradoxical relationship between stage and histology among cervical cancers are needed.
Limitations
A limitation of our data source is that it only collects data on patients diagnosed or treated at facilities accredited by the Commission on Cancer, which are more likely to be located in urban areas and tend to be larger than non-accredited facilities. However, when we compared cervical cancer case counts with North American Association of Central Cancer Registries data, the NCDB coverage rate was 85%, which is high relative to the estimated 70% NCDB coverage rate for all cancers combined. When we compared patient characteristics between the NCDB and SEER, the NCDB had fewer stage III and IV cancers, which should be considered when attempting to generalize our results to other populations. In addition, the impact of the National Breast and Cervical Cancer Early Detection Program on uninsured and Medicaid-insured patients in our study and the coverage rates are unclear. This program offers women with incomes below 250% of the federal poverty level the cervical cancer screening and treatment mandated by the federal Breast and Cervical Cancer Prevention and Treatment Act of 2000. Although the program screened more than 1.6 million women in 2004 to 2009, it reached fewer than 10% of eligible women.
A sensitivity analysis examining factors related to missing staging data revealed higher rates of missing data among patients in the oldest age category and among younger Medicare patients. We believe the potential selection bias resulting from missing staging data elements was relatively minor, because only 7% of all selected cervical cancer patients were missing stage information. An additional limitation was that no formal validation study of the insurance status data in the NCDB has been conducted. Although this variable does not reflect changes in insurance type or specific covered benefits over time, it does reflect insurance coverage during initial treatment, with the exception of Medicaid recipients.