Women who have been treated for cervical intraepithelial neoplasia (CIN) face an elevated risk of recurrence and invasive cervical cancer. That’s the conclusion drawn from a recent population-based study of 37,142 women who were treated for CIN 1, 2, or 3 between 1986 and 2000.
In the first 6 years after treatment, the cumulative rate of CIN 2 or 3 in this group was:
- 14.0% in women originally treated for CIN 3
- 9.3% in women originally treated for CIN 2
- 5.6% in women originally treated for CIN 1.
After 6 years, annual rates of CIN 2 or 3 were less than 1%.
The overall incidence of invasive cancer was 37 cancers for every 100,000 woman-years in the group that had a history of CIN, versus 6 cancers for every 100,000 woman-years in the comparison cohort, which comprised 71,213 women who had normal cytology and no previous diagnosis of CIN.
Cryotherapy was the least “durable” treatment
In addition to the grade of CIN, the woman’s age and type of treatment had a bearing on the likelihood of recurrence. According to the study, the risk of invasive cervical cancer and recurrent CIN 2 or 3 was highest among women who were older than 40, previously treated for CIN 3, or treated with cryotherapy.
For example, among women 40 to 49 years old, the 6-year adjusted rate of CIN 2 or 3 ranged from 2.6% for treatment of CIN 1 using the loop electrosurgical procedure (LEEP), to 34.0% for treatment of CIN 3 using cryotherapy.
Implications of the findings
The study sheds new light on the long-term risks of abnormal cell growth and invasive cancer, and should help in the development of follow-up treatment guidelines for women who have a history of treatment for abnormal cells.
“We now have a much more clear idea of the risks of recurrent abnormal cells and invasive cervical cancer over time after treatment of these cells,” said Joy Melnikow, professor of family and community medicine and associate director of the UC Davis Center for Healthcare Policy and Research, who led the study.
Melnikow said the findings may help physicians determine the optimal intensity of follow-up after treatment of CIN. The findings may also help physicians and patients select a treatment.
For example, although cryotherapy was associated with a higher risk of recurrence, it carries a lower risk of other harmful effects than cone biopsy or LEEP, procedures that have been associated with preterm delivery, Melnikow explained.
This suggests that a younger woman who has CIN 2 and who plans to start a family might opt for cryotherapy, whereas an older woman who has CIN 3—and is therefore at greatest risk of recurrence—might opt for LEEP or cone biopsy.
“These data may help inform that treatment discussion, because we know more about how age and different treatments appear to influence risks,” Melnikow said.
She also noted that the study has different implications for health policy, depending on the health system and resources. In developing countries, where cervical cancer screening and treatment are more limited and the death rate is higher for cervical cancer, cryotherapy, a simpler and less expensive treatment method, is likely to be preferred.
Melnikow said the next step is to compare different treatment and surveillance strategies in terms of cost-effectiveness.
The study was published May 12 in the online issue of the Journal of the National Cancer Institute.
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