First-born’s sex has no impact on breast ca survival
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Contrary to earlier reports, there does not appear to be an association between the sex of a woman’s first child and her chances of subsequently surviving breast cancer, according to researchers.
“Given that previous reports advocated the use of the sex of the first child in making decisions related to breast cancer therapy and counseling, our findings are reassuring and clinically important,” write the researchers in the International Journal of Cancer.
A 1978 study found that breast cancer survival was higher among women whose first-born was a boy. Since then, findings have been conflicting.
Dr. Lukman Thalib, of Kuwait University, Safat, and Dr. Per Hall of the Karolinska Institute in Stockholm, Sweden, looked at the prognostic value of the sex of the first child in women with breast cancer by linking several Swedish registries, including the Swedish Cancer Registry, Cause of Death Registry, Swedish Generation Registry, and the Registry of Population and Population Changes.
They identified a population-based cohort of 32,003 women born after 1931 and diagnosed with a primary breast cancer between 1958 and 1997.
Of 27,727 women included in the final cohort, 23,476 had at least one child prior to breast cancer diagnosis whereas 4251 were delivering their first child. Among the women who had at least one child prior to breast cancer diagnosis, 2732 had only a boy and 2497 had only a girl before diagnosis.
Based on this subpopulation, the sex of the child had no significant influence on the prognosis of breast cancer, Thalib and Hall report.
Stratification by age and adjustment for age at diagnosis, calendar period, time since last birth, and age at first child did not alter the results, according to the authors.
Parity (the number of times a woman has given birth), however, had an effect. The comparison with women delivering their first child showed that the women who were diagnosed at younger ages have “worsened prognosis” if they had any child prior to diagnosis, the investigators explain.
“On the other hand, those diagnosed after 45 years of age, survival advantages exist for those who had a child compared to those who did not.”
SOURCE: International Journal of Cancer March 2006.
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