According to the results of a study published in the British Medical Journal, women who have been treated for high-grade precancerous changes to the cervix (cervical intraepithelial neoplasia grade 3) are more likely than women in the general population to subsequently develop cervical or vaginal cancer. Furthermore, this increased risk persists for at least 25 years.
Precancerous changes to the cervix are called cervical intraepithelial neoplasia (CIN). The severity of CIN is graded on a scale of 1 to 3, with 3 being the most severe. CIN2 and CIN3 are considered “high-grade” CIN and may progress to cancer if left untreated.
Depending on the extent and severity of the CIN, women may be treated with techniques such as loop electrosurgical excision procedure (LEEP), conization, laser ablation, or cryotherapy.
Although treatment for high-grade CIN reduces the likelihood of cervical cancer, risk of cervical cancer among women with a history of CIN may remain higher than the risk in the general population.
To evaluate the risks of cervical cancer and vaginal cancer after a diagnosis of CIN3, researchers in Sweden conducted a study among 132,493 women who had been diagnosed with CIN3 between 1958 and 2002. Following their diagnosis of CIN3, 881 of these women developed cervical cancer and 111 developed vaginal cancer.
• Compared with women in the general population, women with a history of CIN3 were more than twice as likely to develop cervical cancer and more than six times as likely to develop vaginal cancer.
• Risks of cervical and vaginal cancer remained elevated for at least 25 years after the diagnosis of CIN3.
The researchers concluded that women with a history of CIN3 face persistently elevated risks of cervical cancer and vaginal cancer compared with women in the general population. These findings highlight the importance of long-term follow-up after treatment of CIN3.
Reference: Strander B, Andersson-Ellström A, Milsom I, Sparen P. Long term risk of invasive cancer after treatment for cervical intraepithelial neoplasia grade 3: population based cohort study. British Medical Journal [early online publication]. October 24, 2007.