May 12, 2009
Women diagnosed with precancerous CIN at risk for cervical cancer
Long-term risks of invasive cancer and recurrence of severe cervical
intraepithelial neoplasia (CIN) are higher among women previously
treated for CIN, compared with those with no CIN diagnosis, according
to data from a large, retrospective cohort study published in the May
12 online issue of the Journal of the National Cancer Institute.
The
study was undertaken because information on the long-term risks of
subsequent CIN or invasive cancer among women previously treated for
the disease is limited. More information on long-term risks is needed
to help guide long-term follow-up of these patients.
To
determine such risks, Joy Melnikow, M.D., of the Center for Healthcare
Policy and Research at the University of California, Davis, and
colleagues retrospectively identified a CIN cohort of 37,142 women who
were treated for CIN 1, 2, or 3 from January 1, 1986, through December
31, 2000, and compared them with a cohort of 71,213 women with no
previous CIN diagnosis. Both groups were under active surveillance
through 2004.
The researchers found that risk for subsequent
CIN or cervical cancer was associated with initial CIN grade, treatment
type, and age. The risk of invasive cervical cancer and CIN 2/3
recurrence was highest for women who were older than 40 years,
previously treated for CIN 3, or treated with cryotherapy. According to
the study, the highest rates of CIN recurrence were observed in the
first 6 years after treatment in the CIN cohort, with a majority of
those identified in the first 2 years. Recurrence rates for CIN 2 or 3
during this 6 year period ranged from 2.3 % in the lowest risk group to
35% in the highest risk group. Overall incidence of cervical cancer in
the CIN group was 37 cervical cancers per 100,000 woman-years compared
with six cervical cancers per 100,000 woman-years among women who had
not been previously diagnosed.
"This large, population-based
cohort study with more than 300,000 women-years of observation in the
CIN cohort provided important information that could contribute to
evidence-based guidelines for follow-up of women treated for CIN," the
authors write. "Future randomized trials will need longer term
follow-up to define the impact of treatment choice on subsequent CIN
and invasive cancer."
In an accompanying editorial, Edward J.
Wilkinson, M.D., of the University of Florida College of Medicine in
Gainesville, Fla., points out that these results support evidence that
active surveillance has value in identifying most incidences of CIN 2/3
recurrence and early stages of cervical cancer. He also notes that the
majority of women who were later diagnosed with CIN had their CIN 2/3
diagnosed a relatively short time later (2 years). This short interval
suggests that the subsequent CIN lesion was probably persistent CIN 2/3
rather than a new lesion.
"[T]his work provides evidence
that women with CIN who have undergone treatment need long-term
surveillance after their therapy and remain at some risk for CIN as
well as for cervical carcinoma for 20 years or more," he concludes.
Contact: Steve Graff
jncimedia@oxfordjournals.org
301-841-1285
SOURCE:
Journal of the Nationa Cancer Institute
