Analysis of five-year disease-free survival rates in 608 women with operable breast cancer revealed that the reproductive history is a significant prognostic determinant. Overall parous women had a significantly higher cumulative five-year disease-free survival rate (a%), compared to the nulliparous (46%) (z = 2.5, p = 0.012). Significant differences were also noted when gravidity in addition to parity was taken as the determinant. The corresponding disease-free survival rates were 61% and 50%, respectively (z = 1.98, p = 0.048). Five-year survival rates were influenced in a similar manner by these variables but the observed differences were less significant. The trend toward higher survival rates in parous and gravidae women were noted in all tumor stages but achieved statistical significance only in stage 111. The findings indicate that parity and gravidity affect not only the risk of breast cancer development but also the subsequent course of the disease. Parity seems to be a stronger risk and prognostic factor than gravidity.
Cancer 45:191-194. 1980.
CCUMULATING EVIDENCE indicates that factors
A which influence breast tumor induction, may also affect the subsequent course of the disease in the h o ~t . " ~, ' ~ Parity is an incidence-risk factor that has been extensively investigated in breast cancer.*-'O Nulliparous women have a higher incidence of breast cancer compared to parous women if the first full-term pregnancy occurred at an early age. Preliminary data indicate that parity is among the risk factors that may also affect prognosis in women with breast cancer since nulliparous women were found to have lower five-year survival rates compared to parous women.4
In order to further evaluate the effect of parity and gravidity on prognosis in breast cancer, we have examined the differences in five-year disease-free, and five-year survival rates in relation to the reproductive history in a population of 608 women with breast cancer. The tumor stage at presentation and the menopausal status of the patients were taken into consideration.