Effect of ageing on cervical or vaginal cancer in Swedish women previously treated for cervical intraepithelial neoplasia grade 3: population based cohort study of long term incidence and mortality
BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.f7361 (Published 14 January 2014) Cite this as: BMJ 2014;348:f7361
- 1Department of Obstetrics and Gynaecology, Institute of Clinical Science, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
- 2Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
- Correspondence to: B Strander, Regional Cancer Centre, Sahlgrenska University Hospital, Göteborg SE-413 45, Sweden bjorn.strander{at}rccvast.se
- Accepted 29 November 2013
Abstract
Objective To determine factors influencing long term risks for acquiring or dying from invasive cervical or vaginal cancer in women previously treated for cervical intraepithelial neoplasia grade 3 (CIN3).
Design Population based cohort study conducted in 1958-2008, followed up until 2009 in the Swedish Cancer Registry and Swedish Cause of Death Register, linked to the Swedish Population Register. Standardised incidence and mortality ratios were calculated for the risk of acquiring or dying from vaginal or cervical cancer, with the general female population in Sweden as reference. Relative risks in multivariable regression models were also calculated, adjusting for follow-up duration, treatment period, and age at CIN3 treatment or attained age.
Setting Entire female population of Sweden.
Participants 150 883 women in Sweden diagnosed and treated with CIN3 and followed up for invasive cervical or vaginal cancer, and related mortality. The cohort comprised 3 148 222 woman years.
Main outcome measures Standardised incidence and mortality ratios, stratified by period for treatment. Relative standardised incidence ratios and standardised mortality ratios for age at acquiring or dying from cervical or vaginal cancer (attained age), adjusted for preset variables.
Results Women previously diagnosed with CIN3 had an increased risk of dying from invasive cervical or vaginal cancer, compared with the general female population (standardised mortality ratio 2.35, 95% confidence interval 2.11 to 2.61). After age 60 years, these women had an accelerated increased risk of acquiring invasive cancer; a similar steep increase in mortality risk was seen after age 70. Regression analyses indicated that the increase in risk over time is highly attributable to ageing.
Conclusions Women previously treated for CIN3 are at increased risk of developing and dying from cervical or vaginal cancer, compared with the general female population. The risk accelerates above age 60 years, suggesting a need for lifelong surveillance of these women.
Footnotes
Contributors: All authors contributed to study design, acquisition of data, and interpretation of data. JH had the main responsibility for statistical analysis but all authors contributed. BS and PS wrote the manuscript, and all authors reviewed and commented on drafts and approved the final manuscript and the decision to submit for publication. BS and PS are the guarantors of the study, accept full responsibility for the research, had access to the data and controlled the decision to publish.
Funding: This study was supported by the Halland County Scientific Board and the Swedish Cancer Society. These sources had no role in the design or conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: support from the Halland County Scientific Board and the Swedish Cancer Society for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: Data retrieval was approved by the Ethics Committee at the Karolinska Institute (Dnr 02-556, 2011/921-32).
Data sharing: Statistical code and dataset are available from par.sparen{at}ki.se.
The guarantors affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.
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