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Ovarian cancer risk


With ovarian cancer (overall incidence for women aged 45 years is about 1 in 10,000) there is an element of extra risk emanating from genetic associations, for instance the BRCA1 and BRCA2 genes (see Bandolier 18 & 44 ). A new meta-analysis from Cambridge pools information to obtain estimates of the increased risk women may have from having relatives affected with ovarian cancer.

Searching and studies

MEDLINE and hand searching found 13 case-control studies and three cohort studies. One of the cohort studies was omitted because it was thought to be biased. Information was pooled where appropriate to obtain relative risks, and estimates were calculated of the lifetime risk to relatives up to age 75 years.

Results

The main results are shown in the Figure. In detail, the results for each circumstance were as follows:

Second degree relative

The pooled relative risk from three studies for having an affected second degree relative was 2.5 (95% CI 1.5 to 4.3).

First degree relative

The pooled relative risk from 15 studies for having an affected first degree relative was 3.1 (95% CI 2.6 to 3.7). The risk of developing ovarian cancer by age 75 is about 4% for women younger than 45 with an affected first degree relative. The risk falls off quite rapidly after this age.

Affected sister

The pooled relative risk from four studies for having an affected sister was 3.8 (95% CI 2.9 to 5.1). The risk of developing ovarian cancer by age 75 is about 5% for women younger than 45 with an affected sister. The risk declines after this age, but remains substantially higher than the general population.

Affected mother

The pooled relative risk from three studies for having an affected mother was 6.0 (95% CI 3.0 to 11.9). The risk of developing ovarian cancer by age 75 is about 7.5% for women younger than 45 with an affected mother. The risk declines after this age, but remains substantially higher than the general population.

More than one affected relative

The pooled relative risk from two studies for having more than one affected relative was 11.7 (95% CI 5.3 to 25.9). The risk of developing ovarian cancer by age 75 is about 14% for women younger than 45 with more than one affected relative. The risk declines after this age, but remains substantially higher than the general population.

Mother of affected daughter

Three studies looked at this. The relative risk was 1.1 (95% CI 0.8 to 1.6)

Comment

This is an interesting and useful paper, and may be helpful, as the authors say, in making decisions about the removal of ovaries at hysterectomy. Many women will find it easy to understand as well, and are likely to appreciate the information the paper contains. It presents risk information well, but Bandolier cannot immediately reproduce the pictorial methods it uses.

Reference:

  1. JF Stratton, P Pharoah, SK Smith, D Easton, B Ponder. A systematic review and meta-analysis of family history and risk of ovarian cancer. British Journal of Obstetrics and Gynaecology 1998 105: 493-9.



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