Elsevier

The Lancet

Volume 349, Issue 9057, 5 April 1997, Pages 978-980
The Lancet

Articles
Invasive cervical cancer after conservative therapy for cervical intraepithelial neoplasia

https://doi.org/10.1016/S0140-6736(96)08295-5Get rights and content

Summary

Background

Conservative outpatient therapy for cervical intraepithelial neoplasia (CIN) by ablative or excisional techniques is widely used. The main objective of this treatment is the prevention of invasive cervical cancer. We assessed the rate of invasive disease and the duration of the risk of developing invasive cervical cancer after such treatment.

Methods

Four UK centres have used life-table methods to analyse the long-term results of conservative treatment of CIN. We combined and updated data from these studies to investigate the rate of invasive disease after treatment and the duration of that risk.

Findings

The data comprised 44 699 woman-years of follow-up, with 2116 women under observation 8 years after treatment. 33 women developed invasive cancer, 14 of whom had microinvasion. The cumulative rate of invasion 8 years after treatment was 5·8 per 1000 women and the rate of invasive cancer during this period was 85 (95% CI 60-119) per 100 000 woman-years. The risk of developing cancer did not change throughout the 8 years of follow-up.

Interpretation

These data show that conservative outpatient therapy in women with CIN reduces the risk of invasive cancer of the cervix by 95% during the first 8 years after treatment. However, even with careful, long-term follow-up, the risk of invasive cervical cancer among these women is about five times greater than that among the general population of women throughout that period. Careful follow-up is essential for at least 10 years after conservative treatment of CIN.

Introduction

The objective of treatment of cervical intraepithelial neoplasia (CIN) is the prevention of invasive squamous-cell carcinoma of the cervix. Treatments have evolved over the years from inpatient surgery, such as radical hysterectomy, hysterectomy, and knife-cone biopsy, to conservative therapy for suitable outpatients with laser, cryotherapy, cold coagulation, or diathermy. Because of the risk of inadvertently treating invasive disease, ablative techniques for outpatients with CIN have given way to excisional treatment with laser or diathermy.

Long-term follow-up of women who have undergone hysterectomy or knife-cone biopsy for CIN suggests that although these procedures are effective, some patients have late recurrences.1, 2, 3, 4, 5 Few studies have used life-table methods to take account of the reducing numbers of patients as the length of follow-up increases.1, 2, 3, 4

The follow-up periods of most studies of the efficacy of conservative outpatient treatments rarely exceed 1 year. To the best of our knowledge, there have been only six long-term studies of such treatments for CIN, in which the data were analysed by life-table methods.6, 7, 8, 9, 10, 11 We combined data from the five studies in the UK6, 7, 8, 9, 10 and new, hitherto unpublished, information was added.

Section snippets

Methods

The studies were based at four UK centres in Sheffield, Gateshead, Aberdeen, and Dundee. Data from the five UK studies were made available for our analysis.6, 7, 8, 9, 10 If the number of woman-years of follow-up was not published, we calculated it by re-examining the original data. Data was obtained for the time from treatment of CIN to the development of invasive cervical cancer. We collected further follow-up data for the laser vaporisation series from Gateshead. Unpublished data for women

Results

Data were available from six groups of patients (table 1). The Sheffield series (group SV) comprised 328 women who had been treated with laser vaporisation and ten women who had undergone laser excision between 1980 and 1984.6 The Gateshead laser vaporisation series (group GV) comprised 4464 women who had been treated for CIN between 1978 and 1990. Data from 4222 of these women have been reported.7 Data from the Gateshead laser cone series (group GC) and the Gateshead loop series (group GL)

Discussion

Our study is unique because of the large number of women included in the analysis and the long duration of follow-up. Furthermore, the value of our - findings is increased by the heterogeneity of the data from four institutions in the UK that serve different populations.

Potential limitations of combining data from these studies are differences in the age distribution of the women and in the length and methods of follow-up between the studies. These data may also be affected by possible

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