Risk factors for the increasing incidence of pregnancy-associated cancer in Sweden - a population-based study.

INTRODUCTION: The incidence of cancer during pregnancy and within first year post-delivery, ie pregnancy-associated cancer (PAC), is increasing in many countries, but little is known about risk factors for these trends. This study quantified incidence of PAC by trimesters and post-delivery periods, and assessed the role of maternal age, parity, immigrant status, education, smoking and body mass index for the risk and incidence trends of PAC. MATERIAL AND METHODS: We used data from the national birth and cancer registers in Sweden during 1973-2017 to define a register-based cohort of women aged 15-44 years. Incidence rates of PAC during pregnancy and up to 1 year post-delivery were calculated per 100 000 deliveries per year. Poisson regression with multiple imputation estimated incidence rate ratios with 95% confidence intervals adjusted by year, age, previous parity, immigrant status, education, smoking and BMI during 1990-2017, when information on risk factors was available. RESULTS: Among 4 557 284 deliveries, a total of 1274 (during pregnancy) and 3355 (within 1 year post-delivery) cases of PAC were diagnosed, with around 50 cases/year diagnosed during pregnancy and 110 cases/year during the first year post-delivery in the latest period 2015-2017. The most common cancer types during pregnancy were malignant melanoma, breast and cervical cancer, together accounting for 57% of cases during pregnancy and 53% during the first year post-delivery. The numbers of PAC were lower during pregnancy than during post-delivery for all tumor types with lowest numbers during first trimester. The PAC incidence rates increased over calendar time. High maternal age at diagnosis, smoking, nulliparity and non-immigrant background were associated with significantly higher risks of PAC. The increasing PAC incidence was in part explained by higher maternal age over time, but not by the other factors. CONCLUSIONS: High maternal age is the strongest risk factor for PAC. We show for the first time that smoking, nulliparity and non-immigrant background are also contributing risk factors for PAC. However, only high maternal age contributed significantly to the increasing incidence. Further studies on other potential risk factors for PAC are warranted, since our results indicate that age on its own does not fully explain the increase.

Feasibility of sending a direct send HPV self-sampling kit to long-term non-attenders in an organized cervical screening program.

INTRODUCTION: Non-participation in screening is a main risk factor for cervical cancer. Human-papillomavirus (HPV) self-sampling may be an alternative to repeated invitations for non-attenders. Several studies have concluded that participation among non-attenders increases significantly when offering self-sampling kits for HPV. However, participation rates are highly variable between settings, and therefore pilots to determine optimal implementation strategy have been recommended before routine roll out. MATERIALS AND METHODS: All women who had not participated in the organized screening program for at least 10 years aged 33-62 in one Swedish county were identified through screening registers. HPV self-sampling kits were sent to all eligible women. Participation was defined as returning a self-sample kit or attending routine screening within 6 months. Women who did not submit the kit within 8 weeks were randomized to receive a written reminder. HPV-positive women were referred directly to colposcopy without prior triage. Biopsies for histopathologic confirmation were used as gold standard. RESULTS: Among eligible women, 150/741 (20.2%) returned the self-sample kit or attended routine screening. A randomized written reminder was sent out to 319/591 non-responders and another 11 women returned the kit. In total, 23/147 (16.3%) of returned kits were HPV positive. Out of the 23 HPV-positive women, 17 (74%) attended colposcopy; 10/17 (59%) had a histopathological high-grade squamous intraepithelial lesions (HSIL) or cervical cancer. The most common HPV type was HPV 52, and 2 out of 3 women with HPV 16 had a histopathologically confirmed cancer. CONCLUSION: The direct send kit strategy and referral of all HPV-positive women to colposcopy without prior triage appears to be feasible if resources are available and should be prioritized given the high prevalence of HSIL lesions and cancer among non-attenders. A written reminder might further increase attendance.

Colposcopic performance in a birth cohort previously eligible for human papillomavirus vaccination.

BACKGROUND: Sweden started subsidized quadrivalent human papillomavirus vaccination for girls aged 13 to 17 in 2007. Since 2012, vaccination has been offered to all girls aged 10 to 12 within a school-based vaccination program, with a coverage of 80% or more. In addition, the vaccine has been offered on-demand as catch-up vaccination for girls aged 13 to 18, with a cumulative coverage of 55% to 60%. Since the first women in Sweden eligible for human papillomavirus vaccination entered the cervical screening program, questions on how to evaluate colposcopic findings among vaccinated women have arisen. Evidence is inconsistent on whether colposcopic features for the detection of cervical lesions are influenced by specific human papillomavirus genotypes and what role they can play in the prevention of invasive cervical cancer in vaccinated women. OBJECTIVE: The primary objective of the study was to compare colposcopic evaluation in vaccinated and unvaccinated women entering the organized cervical screening program. STUDY DESIGN: Women in the 1994 and 1995 birth cohorts who entered the cervical screening program at age 23 in 1 region in Sweden were identified. Colposcopy was performed within 2 to 4 months after a positive screening result in accordance with national guidelines. Colposcopic performance was evaluated according to national guidelines with the Swede score and colposcopic impression. Punch biopsies were taken from colposcopic lesions and as "random biopsies" in the absence of lesions. These biopsies were used as the gold standard for the analysis. An endocervical sample was analyzed for cytologic findings and detection of 14 high-risk human papillomavirus genotypes. All colposcopic imaging was saved digitally for re-review. Vaccination status was obtained through linkage to national vaccination registries. Results were compared between vaccinated and unvaccinated women. RESULTS: In 2018 and 2019, 160 out of 165 (98%) women with a positive screening result attended colposcopy, of which 90 (56%) were vaccinated and 70 (44%) were unvaccinated. Only 7 out of 90 (5%) women in the vaccinated group were human papillomavirus 16/18-positive, compared with 23 out of 70 (33%) in the unvaccinated group (P<.001). There was a total of 61 out of 160 (38%) women with high-grade lesions-33 out of 90 (37%) in the vaccinated group and 28 out of 70 (40%) in the unvaccinated group (P=.697). There was 64% (21/33) of vaccinated women and 75% (21/28) of unvaccinated women with high-grade squamous intraepithelial lesions who had a Swede score of 6 to 10 (indicating high-grade squamous intraepithelial lesions) (P=.124). The sensitivity was slightly higher for the detection of high-grade squamous intraepithelial lesions in unvaccinated women using both colposcopic tests (Swede score, 0.67 vs 0.75; colposcopic impression, 0.67 vs 0.68), but the difference was not statistically significant. CONCLUSION: We found no statistically significant difference between the colposcopic evaluation of vaccinated and unvaccinated women, although human papillomavirus vaccination reduced the prevalence of human papillomavirus 16/18 infection in human papillomavirus-vaccinated women. Our results indicate that colposcopic examination is still a useful tool in vaccinated women entering the organized cervical screening program.

Colposcopic and histopathologic evaluation of women with HPV persistence exiting an organized screening program.

BACKGROUND: Human papillomavirus-based screening has a higher sensitivity for precursors of cervical cancer compared with cytology-based screening. However, more evidence is needed on optimal management of human papillomavirus-positive women. OBJECTIVE: The objective of the study was to compare the risk of histopathologically confirmed cervical intraepithelial lesions grade 2 or worse after 1 and 3 years of human papillomavirus persistence, respectively, and evaluate the clinical management of human papillomavirus-positive women in the 56-60 year age group. STUDY DESIGN: This was a randomized health care policy offering human papillomavirus screening to 50% of resident women aged 56-60 years in the Stockholm/Gotland region of Sweden during January 2012 through May 2014. Women who were human papillomavirus positive/cytology negative at baseline were referred for a repeat test after 1 or 3 years. In case of human papillomavirus persistence, women were referred for colposcopy, including biopsies and endocervical sampling. RESULTS: The human papillomavirus prevalence was 5.5% (405 women of 7325 attending). Among the 405 human papillomavirus-positive women, 313 were reflex test cytology negative at baseline and were referred for a repeat human papillomavirus test, 176 women after 1 year and 137 women after 3 years. After 1 year, 91 of 176 (52%) were persistently human papillomavirus positive and after 3 years 55 of 137 (40%) (P = .042). In repeat cytology, 10 of the 91 (12%) were positive after 1 year and 15 of 55 (33%) after 3 years (P = .005). The attendance rates for colposcopy were similar: 82 of 91 (90%) in the 1 year group and 45 of 55 (82%) in the 3 year group. All women attending colposcopy were postmenopausal, and endocervical sampling and punch biopsies were performed to facilitate colposcopic management, with a positive predictive value of 43-50% and 28-31%, respectively. Histopathologically confirmed cervical intraepithelial lesions grade 2 or worse was found in 19 of 82 women (23%) and 9 of 45 women (20%) in the 1 year and 3 year groups, respectively, and registry linkage follow-up found no cancers in either group. Human papillomavirus genotyping was predictive of cervical intraepithelial lesions grade 2 or worse, and human papillomavirus 16 was the most common genotype at human papillomavirus persistence, occurring in 18% of the cases in the 1 year group and 20% in the 3 year group. CONCLUSION: It was safe to postpone repeat human papillomavirus tests for 3 years in postmenopausal women attending the organized cervical screening program. There was a high risk for cervical intraepithelial lesions grade 2 or worse at follow-up and noteworthy yields from human papillomavirus genotyping as well as endocervical sampling and random biopsies in the absence of visible colposcopic lesions.