Cervical Screening and Cervical Cancer Death in Older Women
Cervical Screening and Cervical Cancer Death in Older Women
Recent research suggests that cervical screening of older women is associated with a considerable decrease in cervical cancer incidence. We sought to quantify the efficacy of cervical cytology screening to reduce death from this disease. Among enrollees of 2 US health plans, we compared Papanicolaou smear screening histories of women aged 55–79 years who died of cervical cancer during 1980–2010 (cases) to those of women at risk of cervical cancer (controls). Controls were matched 2:1 to cases on health plan, age, and enrollment duration. Cytology screening during the detectable preclinical phase, estimated as the 5–7 years before diagnosis during which cervical neoplasia is asymptomatic but cytologically detectable, was ascertained from medical records. A total of 39 cases and 80 controls were eligible. The odds ratio of cervical cancer death associated with screening during the presumed detectable preclinical phase was 0.26 (95% confidence interval: 0.10, 0.63) after adjustment for matching characteristics, smoking, marital status, and race/ethnicity using logistic regression. We estimate that cervical cytology screening of all women aged 55–79 years in the United States could avert 630 deaths annually. These results provide a minimum estimate of the efficacy of human papillomavirus DNA screening—a more sensitive test—to reduce cervical cancer death among older women.
Cervical cancer screening by means of cytology, or the Papanicolaou (Pap) smear, seeks to detect precancerous or cancerous cervical lesions prior to symptom onset. Research has consistently observed that cervical cytology screening is highly efficacious against invasive cervical cancer (ICC) incidence and death among women of reproductive age. Data regarding the utility of screening older women for cervical cancer are limited. Analyses from Sweden and Finland suggest that participation in national organized cervical cancer screening programs is associated with 51%–64% reductions in cervical cancer incidence among older women. In the United States, data from Kamineni et al. suggest that cervical cancer screening among women aged 55–79 years is associated with a 77%–79% reduction in cervical cancer incidence.
Whether cytological screening reduces ICC death to a similar degree as its apparent reduction of ICC incidence has not been well evaluated in older women. Screening may preferentially detect slow-growing lesions and/or those lesions that are treatment responsive, in which case screening would not be as efficacious in reducing ICC death as its apparent reduction of incidence. However, 2 recent analyses suggest that cytology screening is associated with a substantial mortality benefit for older women. A case-only analysis of Sweden's cervical cancer screening registry found that women aged 66 years or older at diagnosis experienced a 36% increase in long-term survival if their cancers were detected by screening rather than clinically. A Finnish case-control study observed that the receipt of a negative Pap smear in the national screening program was associated with reduced cervical cancer death among women aged 55–69 years. Nonetheless, limitations in the information available from these national registries—such as lack of data on the presence of signs and/or symptoms at the time of each Pap smear, hysterectomy status, potential confounders, and the receipt of "opportunistic" smears outside national screening programs—restrict the conclusions that can be drawn from these results.
We sought to quantify the efficacy of cervical cancer screening to reduce cervical cancer death among older American women.
Abstract and Introduction
Abstract
Recent research suggests that cervical screening of older women is associated with a considerable decrease in cervical cancer incidence. We sought to quantify the efficacy of cervical cytology screening to reduce death from this disease. Among enrollees of 2 US health plans, we compared Papanicolaou smear screening histories of women aged 55–79 years who died of cervical cancer during 1980–2010 (cases) to those of women at risk of cervical cancer (controls). Controls were matched 2:1 to cases on health plan, age, and enrollment duration. Cytology screening during the detectable preclinical phase, estimated as the 5–7 years before diagnosis during which cervical neoplasia is asymptomatic but cytologically detectable, was ascertained from medical records. A total of 39 cases and 80 controls were eligible. The odds ratio of cervical cancer death associated with screening during the presumed detectable preclinical phase was 0.26 (95% confidence interval: 0.10, 0.63) after adjustment for matching characteristics, smoking, marital status, and race/ethnicity using logistic regression. We estimate that cervical cytology screening of all women aged 55–79 years in the United States could avert 630 deaths annually. These results provide a minimum estimate of the efficacy of human papillomavirus DNA screening—a more sensitive test—to reduce cervical cancer death among older women.
Introduction
Cervical cancer screening by means of cytology, or the Papanicolaou (Pap) smear, seeks to detect precancerous or cancerous cervical lesions prior to symptom onset. Research has consistently observed that cervical cytology screening is highly efficacious against invasive cervical cancer (ICC) incidence and death among women of reproductive age. Data regarding the utility of screening older women for cervical cancer are limited. Analyses from Sweden and Finland suggest that participation in national organized cervical cancer screening programs is associated with 51%–64% reductions in cervical cancer incidence among older women. In the United States, data from Kamineni et al. suggest that cervical cancer screening among women aged 55–79 years is associated with a 77%–79% reduction in cervical cancer incidence.
Whether cytological screening reduces ICC death to a similar degree as its apparent reduction of ICC incidence has not been well evaluated in older women. Screening may preferentially detect slow-growing lesions and/or those lesions that are treatment responsive, in which case screening would not be as efficacious in reducing ICC death as its apparent reduction of incidence. However, 2 recent analyses suggest that cytology screening is associated with a substantial mortality benefit for older women. A case-only analysis of Sweden's cervical cancer screening registry found that women aged 66 years or older at diagnosis experienced a 36% increase in long-term survival if their cancers were detected by screening rather than clinically. A Finnish case-control study observed that the receipt of a negative Pap smear in the national screening program was associated with reduced cervical cancer death among women aged 55–69 years. Nonetheless, limitations in the information available from these national registries—such as lack of data on the presence of signs and/or symptoms at the time of each Pap smear, hysterectomy status, potential confounders, and the receipt of "opportunistic" smears outside national screening programs—restrict the conclusions that can be drawn from these results.
We sought to quantify the efficacy of cervical cancer screening to reduce cervical cancer death among older American women.
