Invasive Cervical Cancer After Conservative Therapy for CIN

Abstract & Commentary

Synopsis: Conservative treatment of CIN results in a 95% decrease in the occurrence of invasive cervical cancer, but the rate is still higher than for the general population.

Source: Soutter WP, et al. Lancet 1997;349:978-980.

A recent article combines the experience of four centers in the United Kingdom that treat large numbers of cases of cervical intraepithelial neoplasia (CIN). 44,699 woman-years of follow-up among 2116 women. Soutter et al report methods of treatment of CIN included laser vaporization, laser excisional conization, and various loop diathermy procedures. Although all three grades of CIN were included in the study, approximately two-thirds of the patients were treated for CIN III. All ages of women were included in the study, but there was a significant trend toward the use of excisional methods in women who were later in or beyond their reproductive years.

The overall rate of the development of invasive cervical cancer after treatment was 75 per 100,000 woman-years. Cases of invasive cancer occurred in each of the eight years of follow-up, though most of the cases were diagnosed during the first five years. Although the rate of invasive cancer of the cervix was approximately fivefold greater in these women than that expected in the general population, the rate is only about 5% of that expected had no treatment been performed. Soutter et al conclude that conservative treatment of CIN is successful, but women who have been so treated need follow-up for long periods of time.

COMMENT BY KENNETH NOLLER, MD

This is a short, well-written article that I recommend to those of you who are interested in the office treatment of CIN. Unfortunately, the study has drawbacks, as do all studies that are retrospectively combined to create a cohort. For example, there is no uniform method of treatment, the different centers managed different-aged women by different techniques, the method of ascertainment of invasive cancer varied among the centers, and the rate of follow-up varied considerably. Nonetheless, there are a few (but very few) conclusions that can be drawn from this study.

First, women who have been treated for CIN in the office are much less likely to develop invasive cancer of the cervix than women with CIN who are not treated at all. Although Soutter et al stated that the decreased rate of invasive cancer is to be on the order of 95%, they derived this number from a study that included only patients with carcinoma in situ of the cervix. Because the current study included patients with all grades of CIN, it is not clear what percent of reduction in invasive disease actually occurred.

Second, although office treatment reduces the risk of invasive cancer, women who have significant CIN— regardless of the method of treatment—have a four- to fivefold increased risk of developing invasive cervical cancer when compared to the general population.

The take-home message is that women who have been treated for CIN need to be involved in long-term Pap smear follow-up treatments for the remainder of their lives.

In the past, some authors have suggested that women with CIN should still be offered hysterectomy as a treatment choice and, thus, avoid the need for long-term cytology follow-up. Although this paper did not directly address that point, the literature shows that women who have high-grade CIN and who receive a hysterectomy are still at an increased risk for the development of squamous cancer of the vagina and, thus, must be followed. Because of this fact, office management of CIN remains the preferred method of handling this pre-cancerous disease.