Cervical Cancer Screening Predictors Revealed in South African Health Survey Data

Cervical cancer screening in South Africa remains stubbornly below national and global targets, and the women least likely to be screened are those who carry the greatest burden of the disease. That is the central finding of a new nationally representative analysis of the 2016 South African Demographic and Health Survey, published in the journal Cancer Causes & Control, which for the first time ranks the relative importance of a broad range of factors driving — or failing to drive — Pap smear uptake among South African women.

Cervical cancer is the second most common cancer among women in South Africa, with an age-standardized incidence rate of 30.2 per 100,000 women in 2022. Yet that national figure conceals a stark racial divide: the incidence rate among Black African women is 35.2 per 100,000, compared with 19.8 among White women, 19.5 among women of Mixed ancestry and 10.5 among Indian/Asian women. These inequities reflect unequal exposure to human papillomavirus (HPV), the virus that causes virtually all cervical cancers, as well as unequal access to healthcare and screening. Because cervical cancer is one of the most preventable malignancies when precancerous lesions are detected early through quality-assured Papanicolaou (Pap) screening, the persistent gap in uptake is a matter of life and death.

Led by M. G. Singini of the South African Medical Research Council, the research team analyzed data from 2,789 women aged 25 to 49 years drawn from the 2016 SADHS, a nationally representative cross-sectional survey covering all nine provinces. Overall, only 45.2 percent of women reported ever having had a Pap smear — well below the 70 percent coverage target set by South Africa’s Department of Health and the World Health Organization. Among those who had been screened, 72.6 percent had done so within the previous three years, in line with recommended screening intervals.

The study’s methodological strength lies in its integrated, multifactorial approach. Rather than examining risk factors in isolation, as most previous studies have done, the researchers grouped predictors into four domains — sociodemographic characteristics, women’s autonomy and empowerment, healthcare access, and risky lifestyle behaviors — and modeled them simultaneously. Because the outcome was relatively common, the team used generalized linear regression models with a Poisson distribution and log-link function to estimate adjusted prevalence ratios (aPRs), a technique that avoids the overstatement of associations that can occur when odds ratios are applied to high-prevalence outcomes. The quasi-Poisson specification accounts for overdispersion, yielding robust standard errors. To capture the survey’s complex two-stage stratified cluster design, all analyses incorporated sampling weights, primary sampling units and stratification variables.

Crucially, the researchers then ranked the factors by their attributable fractions, a metric that combines both the strength of each association and the prevalence of the factor in the population. The attributable fraction estimates the increase in screening uptake that would occur if women shifted to the adjacent healthier category, assuming a causal relationship.

The results were unambiguous in their hierarchy. The single most important determinant was a history of HIV testing: women who had ever been tested for HIV were nearly twice as likely to have had a Pap smear (aPR 1.79; 95 percent CI 1.40–2.30), and this factor accounted for an attributable fraction of 41.7 percent. The authors interpret this as evidence that cervical cancer screening in South Africa largely happens opportunistically, whenever women come into contact with health services — and HIV testing is one of the most common such contacts. It suggests that women who engage more frequently with the healthcare system, particularly through HIV services, are far more likely to be screened as a byproduct of that engagement.

Population group ranked second, with an attributable fraction of 19.7 percent. Black African women had the lowest screening uptake of any group, at 41.0 percent, compared with 76.7 percent among White women, 70.0 percent among women of Mixed ancestry and 64.8 percent among Indian/Asian women. After adjustment, Mixed ancestry women (aPR 1.44) and White women (aPR 1.25) were significantly more likely to be screened than Black African women. Wealth came third, accounting for 15.9 percent of the attributable fraction. Women in the richest households were far more likely to be screened than those in the poorest (65.0 percent versus 31.8 percent; aPR 1.56), likely reflecting their greater ability to absorb the indirect costs of healthcare — transport, fees and lost income. Education ranked fourth, contributing 8.9 percent, with tertiary-educated women significantly more likely to be screened (aPR 1.36) than those with seven years of schooling or fewer.

Less prominent but still significant were alcohol misuse (aPR 1.23; attributable fraction 6.1 percent), private health insurance (aPR 1.27; 5.5 percent) and women’s disempowerment (aPR 1.10; 5.5 percent). The alcohol finding, which echoes equivocal results from the Netherlands and Norway, is counterintuitive; the authors speculate that women who misuse alcohol may have more frequent contact with health services for related conditions, creating more opportunities for opportunistic screening, or that residual confounding through other risky behaviors may be at play. The empowerment index, constructed by summing six decision-making variables covering contraceptive use, healthcare access, large purchases, visits to relatives and the use of a husband’s earnings, showed that highly empowered women were more likely to be screened — a result consistent with studies from Lesotho, Tanzania and Nepal linking women’s autonomy to health-seeking behavior.

Age also mattered strongly. Women aged 40 to 49 were nearly twice as likely to be screened as those aged 25 to 29 (56.0 percent versus 29.6 percent; aPR 1.86), and women aged 30 to 39 fell in between (aPR 1.57). The authors attribute this to older women’s greater engagement with health services and their longer window of opportunity for screening. Marriage was marginally associated with higher uptake, possibly because partners provide financial support for travel to clinics and reduce time constraints, and prior research has shown that male partner engagement can significantly influence women’s screening decisions.

One of the study’s more revealing analyses examined the intersection of wealth, population group and empowerment. Among Black African women, screening prevalence climbed only from 25.0 percent in the poorest wealth quintile to 55.0 percent in the richest, whereas women of Mixed ancestry showed the highest overall rates, ranging from 50.0 to 75.0 percent across the wealth spectrum. Moreover, of the women who reported both screening and possession of health insurance, 78.4 percent were White compared with just 20.0 percent Black — evidence that insurance coverage itself is unevenly distributed along racial and socioeconomic lines. A sensitivity analysis using stepwise regression confirmed the robustness of the key predictors, although it suggested the effect of wealth is partially mediated by healthcare access and autonomy.

The authors are candid about the limitations of their work. The cross-sectional design precludes causal inference, and self-reported screening history may be subject to recall or social desirability bias. The 2016 data may not reflect current behavior, the survey captured only Pap smears and not newer modalities such as HPV DNA testing or visual inspection with acetic acid, and the empowerment instrument was developed in Lesotho and may not transfer perfectly to the South African context. Wide confidence intervals around some predicted probabilities, particularly in the interaction analysis of empowerment, population group and wealth, warrant cautious interpretation.

Nevertheless, the implications are clear. Because so much screening appears to occur opportunistically through HIV services, the authors argue that integrating cervical cancer screening into HIV care — and using postnatal and immunization clinics as strategic entry points — could dramatically expand coverage. They recommend expanding the health workforce through community health workers, implementing task shifting, deploying mobile clinics and workplace screening with flexible hours and weekend availability, and running media campaigns in local languages to raise awareness among communities where knowledge of cervical cancer prevention remains low. Girls’ education also emerges as a long-term lever, given its established link to cancer awareness and screening participation.

With roughly 660,000 new cervical cancer cases worldwide in 2022 and 90 percent of them occurring in low- and middle-income countries, the South African findings carry lessons well beyond the country’s borders. The study demonstrates that closing the screening gap requires more than clinics and guidelines: it requires confronting the structural and behavioral forces — poverty, race, education and women’s autonomy — that determine who actually reaches the examination table.