BMJ. 2007 Nov 24;335(7629):1077.
Long term risk of invasive cancer after treatment for cervical
intraepithelial neoplasia grade 3: population based cohort study.
Strander B, Andersson-Ellstr? A, Milsom I, Spar? P.
Department of Obstetrics and Gynecology, Sahlgren's Academy, University
of Gothenburg, SU/Ostra sjukhuset, SE-416 85, Sweden. bjorn.strander@oc.gu.se
Objectives:
To study the long term risk of invasive cancer of the cervix
or vagina after treatment for cervical intraepithelial neoplasia grade
3.
Design:
Prospective cohort study.
Setting:
Swedish cancer registry.
PARTICIPANTS: All women in Sweden with severe dysplasia or cervical
carcinoma in situ (e quivalent to cervical intraepithelial neoplasia
grade 3) treated during 1958-2002 (n=132,493) contributing 2,315,724
woman years.
Main Outcome Measures:
Standardised incidence ratios with
risk of cancer in the Swedish general female population as reference,
and relative risks in multivariable log-linear regression model, with
internal references.
Results:
Women with previous cervical
intraepithelial neoplasia grade 3 had an increased risk of invasive
cervical cancer compared with the general female population
(standardised incidence ratio 2.34, 95% confidence interval 2.18 to
2.50). The increased risk showed a decreasing trend with time since
diagnosis for women treated later than 1970 but the risk was still
increased after 25 years. An effect of age was found, with an
accentuated increase in risk for women aged more than 50. The excess
risk for cervical cancer associated with previous cervical
intraepithelial neoplasia grade 3 has steadily increased since 1958. For
vaginal cancer the standardised incidence ratio was 6.82 (5.61 to 8.21)
but this decreased to 2.65 after 25 years. Adjustments in the
multivariable log-linear regression model did not substantially alter
these results.
Conclusions:
Women previously treated for cervical
intraepithelial neoplasia grade 3 are at an increased risk of developing
invasive cervical cancer and vaginal cancer. This risk has increased
since the 1960s and is accentuated in women aged more than 50. The risk
is still increased 25 years after treatment.
  
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