Reproductive factors and histologic subtype in relation to mortality after a breast cancer diagnosis

Abstract

Evidence suggests that certain reproductive factors are more strongly associated with the incidence of lobular than of ductal breast cancer. The mechanisms influencing breast cancer incidence histology may also affect survival. Women with invasive breast cancer (N = 22,302) diagnosed during 1986–2005 were enrolled in a series of population-based studies in three US states. Participants completed telephone interviews regarding reproductive exposures and other breast cancer risk factors. Histologic subtype was obtained from state cancer registries. Vital status and cause of death were determined through December 2006 using the National Death Index. Women were followed for 9.8 years on average with 3,050 breast cancer deaths documented. Adjusted hazard rate ratios (HR) and 95% confidence intervals (95% CI) were calculated using Cox proportional hazards regression models for breast cancer-specific and all-cause mortality. Parity was inversely associated with breast cancer-specific mortality (PTrend = 0.002). Associations were similar though attenuated for all-cause mortality. In women diagnosed with ductal breast cancer, a 15% reduction in breast cancer-specific mortality was observed in women with five or more children when compared to those with no children (HR = 0.85, 95% CI: 0.73–1.00). A similar inverse though non-significant association was observed in women with lobular subtype (HR = 0.70, 95% CI: 0.43–1.14). The trend did not extend to mixed ductal–lobular breast cancer. Age at first birth had no consistent relationship with breast cancer-specific or all-cause mortality. We found increasing parity reduced mortality in ductal and lobular breast cancer. The number of full-term births, rather than age at first birth, has an effect on both breast cancer-specific and overall mortality.

Do Reproductive Factors Influence T, N, and M Classes of Ductal and Lobular Breast Cancers? A Nation-Wide Follow-Up Study

“…Previous studies reported that nulliparity and late age at first childbirth are related to aggressive tumor behavior [37]–[40]. Our results suggest that high-T class may mediate such effects: nulliparity was associated with the risk of high-T class, particularly in premenopausal ductal carcinomas and late age at first childbirth was associated with high-T class in postmenopausal ductal and lobular carcinomas.…”

Association of Parity and Time since Last Birth with Breast Cancer Prognosis by Intrinsic Subtype

“…advanced stage, high histological grade, and high proportion of hormone receptor-negative tumors) (5, 19, 24), and consequently poor prognosis (19, 22-24). Multiparity has also been associated with higher mortality, particularly BC-specific mortality (20, 33). Our findings are in line with these previous studies.…”

“…While some studies report no association between number of births and prognosis (12-16), other studies report that multiple births are associated with a poorer prognosis (16-19), and still others show improved prognosis among multiparous women (13, 20, 21). These discrepancies may be attributed to different distributions of potential effect measure modifiers such as race and menopausal status, and a different profile of intrinsic subtypes across study populations.…”

Potentially functional polymorphisms in aminoacyl-tRNA synthetases genes are associated with breast cancer risk in a Chinese population

“…Moreover, a multiplicative interaction was observed between rs2273802 in WARS and age at first live birth on breast cancer risk. Age at first live birth has been established as risk factors for breast cancer owing to different exposure of endogenous hormones . The interaction results may suggest that the effect of rs2273802 may be different between individuals with distinct endogenous hormone levels.…”