The role of pregnancy, perinatal factors and hormones in maternal cancer risk: a review of the evidence

Abstract

An understanding of the origin of cancer is critical for cancer prevention and treatment. Complex biological mechanisms promote carcinogenesis, and there is increasing evidence that pregnancy‐related exposures influence foetal growth cell division and organ functioning and may have a long‐lasting impact on health and disease susceptibility in the mothers and offspring. Nulliparity is an established risk factor for breast, ovarian, endometrial and possibly pancreatic cancer, whilst the risk of kidney cancer is elevated in parous compared with nulliparous women. For breast, endometrial and ovarian cancer, each pregnancy provides an additional risk reduction. The associations of parity with thyroid and colorectal cancers are uncertain. The timing of reproductive events is also recognized to be important. Older age at first birth is associated with an increased risk of breast cancer, and older age at last birth is associated with a reduced risk of endometrial cancer. The risks of breast and endometrial cancers increase with younger age at menarche and older age at menopause. The mechanisms, and hormone profiles, that underlie alterations in maternal cancer risk are not fully understood and may differ by malignancy. Linking health registries and pooling of data in the Nordic countries have provided opportunities to conduct epidemiologic research of pregnancy exposures and subsequent cancer. We review the maternal risk of several malignancies, including those with a well‐known hormonal aetiology and those with less established relationships. The tendency for women to have fewer pregnancies and at later ages, together with the age‐dependent increase in the incidence of most malignancies, is expected to affect the incidence of pregnancy‐associated cancer.

Specific nutritional infections early in life as risk factors for human colon and breast cancers several decades later

“…15–23). Some of these studies reported that increased parity also reduced the risk for endometrial and ovarian cancers . For women with five or more children a 50% reduction in breast cancer risk has been reported .…”

“…Risk reduction for breast cancers after several deliveries and breast-feeding periods has been described for several decades (reviewed in Refs. [15][16][17][18][19][20][21][22][23]. Some of these studies reported that increased parity also reduced the risk for endometrial and ovarian cancers.…”

“…Some of these studies reported that increased parity also reduced the risk for endometrial and ovarian cancers. 18,19,23 For women with five or more children a 50% reduction in breast cancer risk has been reported. 24 In a large study, this figure was later slightly reduced to 36%, summarizing 47 epidemiological cohort and case-control studies involving more than 122,000 women from 30 different countries 21 (Fig.…”

MCM10 facilitates the invaded/migrated potentials of breast cancer cells via Wnt/β‐catenin signaling and is positively interlinked with poor prognosis in breast carcinoma

“…Because of socioeconomic changes and unique reproductive patterns, breast carcinoma has become one of the most extensively increasing cancers in China . Despite advances in surgical techniques and improved understanding of carcinogenesis, the prognosis for patients is still suboptimal, especially in developing countries. General risk factors of breast cancer in women include age, infertility, inherited changes in certain genes, high levels of certain hormones and obesity.…”

A Comparative Study of the Turnover of Multiciliated Cells in the Mouse Trachea, Oviduct and Brain

“…In female humans, ovarian epithelial cancer is one of the most prevalent and lethal gynecologic malignancies, and the cell of origin is likely a transformed oviduct fimbrial epithelial cell (Kindelberger et al, 2007;Siegel et al, 2016). Further, a decrease in the number of ovulationseither through pregnancy and lactation, or hormonal contraception -is correlated with a decrease in the risk of ovarian epithelial cancer (Hankinson et al, 1992;Purdie et al, 2003;Tung et al, 2005;Kindelberger et al, 2007;Havrilesky et al, 2013;Troisi et al, 2018). Therefore, recurrent exposure to ovulatory fluid is damaging to oviduct epithelial cells, which increases the risk of ovarian epithelial cancer.…”