P07-08Cervical screening history and rare histological types of invasive cervical cancer: a population-based nested case-control study in Sweden

02. Epidemiology and natural history
J. Lei 1, B. Andrae 2, J. Wang 1, S.N. Kleppe 1, M. Elfström 1, P. Sparén 1.
1Karolinska Institutet (Sweden), 2Karolinska Institutet; Uppsala University/Region of Gävleborg (Sweden)

Background / Objectives

The effectiveness of cervical screening on cervical cancer has been thoroughly evaluated for squamous cell carcinoma and to some extent also for adenocarcinoma of the cervix1,2. However, no studies regarding screening effectiveness have been conducted for rare histological types of invasive cervical cancer, which are considered more aggressive3-5. 


Methods

We conducted a population-based, age matched case-control study, nested within a cohort of Swedish women born 1909-1986 followed  2002-2011.  284 cases of  rare histological types of cervical cancer were identified; adenosquamous carcinoma (ASC), glassy cell carcinoma (GCC), clear cell carcinoma (CCC), cervical neuroendocrine carcinomas (CNECs), small cell carcinoma (SmCC) and undifferentiated carcinoma (UC). 


Results

Screening within the recommended interval was associated with a lower risk of rare histological types of cervical cancer (IRR:0.45, CI: 0.34-0.59; ASC IRR:0.43, CI:0.30-0.63, GCC IRR:0.57, CI: 0.19-1.70, CCC  IRR:0.22, CI: 0.08-0.60, and CNECs/SmCC/UC IRR: 0.55, CI: 0.32-0.93).  Cervical screening was particularly effective for women age 30-49 (IRR: 0.40, CI: 0.25-0.63) and 50-65 (IRR:0.26,  CI: 0.16-0.42). Screening was also effective in preventing advanced cancers (IRR: 0.31, CI: 0.20-0.47) and led to diagnosis at an earlier stage for invasive cancer, especially for young women.


Conclusion

Cervical screening with cytology can significantly reduce the risk of rare histological types of invasive cervical cancer, and downstaging also reduced the proportion of advanced cancer. Further research comparing different screening strategies with HPV and/or cytology is needed to further optimize the prevention of rare histological types of cervical cancer.


References

1. IARC, IARC handbooks of cancer prevention. Cervix cancer screening. Vol. 10. 2005, Lyon, France: International Agency for Research on Cancer Press.

2. Andrae, B., et al., Screening-preventable cervical cancer risks: evidence from a nationwide audit in Sweden. J Natl Cancer Inst, 2008. 100(9): p. 622-9.

3. Chen, J., O.K. Macdonald, and D.K. Gaffney, Incidence, mortality, and prognostic factors of small cell carcinoma of the cervix. Obstet Gynecol, 2008. 111(6): p. 1394-402.

4. Satoh, T., et al., Gynecologic Cancer InterGroup (GCIG) consensus review for small cell carcinoma of the cervix. Int J Gynecol Cancer, 2014. 24(9 Suppl 3): p. S102-8.

5. Hasegawa, K., et al., Gynecologic Cancer InterGroup (GCIG) consensus review for clear cell carcinoma of the uterine corpus and cervix. Int J Gynecol Cancer, 2014. 24(9 Suppl 3): p. S90-5.

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