Exposure Definition in Case-Control Studies of Cervical Cancer Screening: A Systematic Literature Review

The first step in evaluating the effectiveness of cervical screening is defining exposure to screening. Our aim was to describe the spectrum of screening exposure definitions used in studies of the effectiveness of cervical screening. This systematic review included case-control studies in a population-based screening setting. Outcome was incidence of cervical cancer. Three electronic databases were searched from January 1, 2012 to December 6, 2018. Articles prior to 2012 were identified from a previous review. The qualitative synthesis focused on describing screening exposure definitions reported in the literature and the methodologic differences that could have an impact on the association between screening and cervical cancer. Forty-one case-control studies were included. Six screening exposure definitions were identified. Cervical cancer risk on average decreased by 66% when screening exposure was defined as ever tested, by 77% by time since last negative test, and by 79% after two or more previous tests. Methodologic differences included composition of the reference group and whether diagnostic and/or symptomatic tests were excluded from the analysis. Consensus guidelines to standardize exposure definitions are needed to ensure evaluations of cervical cancer screening can accurately measure the impact of transitioning from cytology to human papillomavirus-based screening and to allow comparisons between programs.

Will COVID-19 Be the Tipping Point for Primary HPV Self-sampling?

Self-sampling is poised to be a disruptor for cervical screening. So far, cancer screening has been a causality of COVID-19; however, the opposite may transpire for self-sampling. Self-sampling enables socially distanced cervical screening with an outreach that extends to underserved populations. As evidence mounts that self-sampling is noninferior to clinician-taken samples, the focus for self-sampling is now as a primary screening option for all women. Now, we have evidence from a modeling study (using Australia as an exemplar) to suggest that program effectiveness with primary self-sampling would be better than the current program, even if sensitivity is lower. Regulatory issues, suitable triage strategies, and clear communication about self-sampling are hurdles yet to be overcome. Nevertheless, existing evidence coupled with COVID-19 could be the tipping point for wider introduction of self-sampling.See related article by Smith et al., p. 268.

Evaluating cytology for the detection of invasive cervical cancer

OBJECTIVE

To assess the sensitivity, the number needed to screen (NNS) and the positive predictive value (PPV) of cervical cytology for the diagnosis of cancer by age in a screening population.

METHODS

A retrospective cohort of women with invasive cervical cancer nested within a census of cervical cytology. All (c. 8 million) women aged 20-64 years with cervical cytology (excluding tests after an earlier abnormality). From April 2007 to March 2010, 3372 women had cervical cancer diagnosed within 12 months of such cytology in England. The sensitivity of cervical cytology to cancer, NNS to detect one cancer and predictive values of cytology were calculated for various 'referral' thresholds. These were calculated for ages 20-24, 25-34, 35-49 and 50-64 years.

RESULTS

The sensitivity of at least moderate dyskaryosis [equivalent to a high-grade squamous intraepithelial lesion (HSIL) or worse] for cancer of 89.4% [95% confidence interval (CI) 88.3-90.4%] in women offered screening was independent of age. At all ages, women with borderline-early recall or mild dyskaryosis on cytology (equivalent to ASC-US and LSIL, respectively, in the Bethesda system) had a similar risk of cervical cancer to the risk in all women tested. The PPV of severe dyskaryosis/?invasive and ?glandular neoplasia cytology (equivalent to squamous cell carcinoma and adenocarcinoma/adenocarcinoma in situ, respectively, in the Bethesda System) were 34% and 12%, respectively; the PPV of severe dyskaryosis (HSIL: severe dysplasia) was 4%. The NNS was lowest when the incidence of cervical cancer was highest, at ages 25-39 years, but the proportion of those with abnormal cytology who have cancer was also lowest in younger women.

CONCLUSIONS

The PPV of at least severe dyskaryosis (HSIL: severe dysplasia) for cancer was 4-10% of women aged 25-64 years, justifying a 2-week referral to colposcopy and demonstrating the importance of failsafe monitoring for such patients. The sensitivity of cytology for cervical cancer was excellent across all age groups.

Time to diagnosis of Type I or II invasive epithelial ovarian cancers: a multicentre observational study using patient questionnaire and primary care records

OBJECTIVE

To compare time to diagnosis of the typically slow-growing Type I (low-grade serous, low-grade endometrioid, mucinous, clear cell) and the more aggressive Type II (high-grade serous, high-grade endometrioid, undifferentiated, carcinosarcoma) invasive epithelial ovarian cancer (iEOC).

DESIGN

Multicentre observational study.

SETTING

Ten UK gynaecological oncology centres.

POPULATION

Women diagnosed with primary EOC between 2006 and 2008.

METHODS

Symptom data were collected before diagnosis using patient questionnaire and primary-care records. We estimated patient interval (first symptom to presentation) using questionnaire data and diagnostic interval (presentation to diagnosis) using primary-care records. We considered the impact of first symptom, referral and stage on intervals for Type I and Type II iEOC.

MAIN OUTCOME MEASURES

Patient and diagnostic intervals.

RESULTS

In all, 78% of 60 Type I and 21% of 134 Type II iEOC were early-stage. Intervals were comparable and independent of stage [e.g. median patient interval for Type I: early-stage 0.3 months (interquartile range 0.3-3.0) versus late-stage 0.3 months (interquartile range 0.3-4.5), P = 0.8]. Twenty-seven percent of women with Type I and Type II had diagnostic intervals of at least 9 months. First symptom (questionnaire) was also similar, except for the infrequent abnormal bleeding (Type I 15% versus Type II 4%, P = 0.01). More women with Type I disease (57% versus 41%, P = 0.04) had been referred for suspected gynaecological cancer. Median time from referral to diagnosis was 1.4 months for women with iEOC referred via a 2-week cancer referral to any specialty compared with 2.6 months (interquartile range 2.0-3.7) for women who were referred routinely to gynaecology.

CONCLUSION

Overall, shorter diagnostic delays were seen when a cancer was suspected, even if the primary tumour site was not recognised to be ovarian. Despite differences in carcinogenesis and stage for Type I and Type II iEOC, time to diagnosis and symptoms were similar. Referral patterns were different, implying subtle symptom differences. If symptom-based interventions are to impact on ovarian cancer survival, it is likely to be through reduced volume rather than stage-shift. Further research on histological subtypes is needed.

TWEETABLE ABSTRACT

No difference in time to diagnosis for Type I versus Type II invasive epithelial ovarian cancers.

Measuring the nature and duration of symptoms of cervical cancer in young women: developing an interview-based approach

BACKGROUND

Some young women experience delays in diagnosis of cervical cancer, but little research about ways of studying these delays has been published. A major challenge is that gynaecological symptoms are common in young women, but cervical cancer is rare. This study describes the development and testing of a measure for studying delays in diagnosis in young women with cervical cancer.

METHODS

Prospective development of an interview measure and testing of its ability to reliably and systematically collect relevant data in two large hospitals in London, UK using 27 women aged 18-40 diagnosed with cervical cancer in the previous two years. We developed a semi-structured interview schedule and data extraction form to systematically collect data on symptoms (including nature and duration) and risk factors for delayed diagnosis from young women with cervical cancer. We piloted the measure among young women with cervical cancer (audiorecording it with their permission), refining it iteratively. To complete the measure, we developed a database for managing the data and a manual for using the schedule. Two researchers extracted data from the recorded interviews to assess inter-rater reliability.

RESULTS

The final interview schedule yielded quantitative data on the nature and duration of symptoms and risk factors for delayed diagnosis. Inter-rater reliability was high. In the pilot, 12 of the 27 women were diagnosed via symptomatic presentation. Median time from the symptom triggering presentation to presentation was one month (interquartile range 0-4 months). Median time from presentation to diagnosis was three months (interquartile range 1-8.5 months).

CONCLUSIONS

We have developed a reliable tool for measuring the nature and duration of symptoms in young women with cervical cancer. Pilot data suggest that a substantial proportion of women experience delay between first presentation and diagnosis.

Characteristics and screening history of women diagnosed with cervical cancer aged 20-29 years

Background:

There was concern that failure to screen women aged 20–24 years would increase the number of cancers or advanced cancers in women aged 20–29 years. We describe the characteristics of women diagnosed with cervical cancer in England aged 20–29 years and examine the association between the period of diagnosis, screening history and FIGO stage.

Methods:

We used data on 1800 women diagnosed with cervical cancer between April 2007 and March 2012 at age 20–29 from the National Audit of Invasive Cervical Cancers.

Results:

The majority of cancers (995, or 62% of those with known stage) were stage 1A. Cancer at age 20–24 years was rare (12% of those aged 20–29 years), when compared with age 25 (24%) and age 26–29 years (63%); however, cancers in women aged 20–24 years tended to be more advanced and were more often of a rare histological type. For 59% of women under age 30, the cervical cancer was screen detected, most of them (61%) as a result of their first screening test. A three-fold increase in the number of cancers diagnosed at age 25 years was seen since the start of the study period.

Conclusion:

Cervical cancer at age 20–24 years is rare. Most cancers in women under age 30 years are screen detected as microinvasive cancer.