Parity reduces a woman's lifetime risk of developing breast cancer
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Epidemiological literature demonstrates that early parity and full-term pregnancies are associated with a reduced lifetime risk of developing breast cancer for women.
The epidemiology of breast cancer was reviewed in the context of hormonal, hereditary, histologic, and dietary risk factors. Literature review. Late age at menarche and early age at first birth decrease the risk of breast cancer as does an early age at menopause. These risk factors relate to the lifetime exposure of the breast tissue to ovarian hormones. Although an early first birth is associated with a transient increase in the risk of breast cancer, perhaps as a result of the breast's exposure to high levels of hormones before terminal differentiation, in older women, parity is associated with a decreased risk of breast cancer. Among postmenopausal women, obesity is associated with higher levels of estrogens and an increased risk of breast cancer. Within the strata of breast cancer stages at diagnosis, obesity is associated with increased mortality, again supporting the influence of endogenous estrogens on this disease's incidence, recurrence, and survival rates. Consistent with these relationships, current use of estrogen therapy among postmenopausal women is associated with an increased risk of breast cancer. A family history of breast cancer is associated with approximately a two-fold increase in the risk of breast cancer, and this risk is greater if the diagnosis was made when the woman's mother was young, although even a diagnosis in an older mother is associated with an increased risk in her daughters. The follow-up of women with a history of benign breast biopsy results shows that atypical hyperplasia is associated with a fourfold increase in risk compared with a biopsy specimen without proliferative changes. Atypia doubles the risk. These data support the concept of atypia as a precursor lesion for breast cancer and may warrant its use as a marker in further studies. Consistent data from retrospective and prospective studies show a positive association between moderate alcohol intake and the risk of breast cancer. This may reflect the increase in estrogen levels observed among women who consume alcohol. Data from prospective studies do not support a relationship between dietary fat intake and the risk of breast cancer either in premenopausal or postmenopausal women. Few of these associations offer the potential for intervention to reduce the breast cancer risk.
Abstract Nulliparity and inheritance of BRCA1 or BRCA2 mutations are conditions associated with a greater risk of developing breast cancer. The knowledge that early parity reduces a woman's lifetime cancer risk and the demonstration in preclinical studies that the protective effect of pregnancy is mediated by the differentiation of the breast, which is manifested as permanent changes in the genomic/transcriptomic profile of this organ, led us to hypothesize that the transcriptomic profile of breast tissue of nulliparous BRCA1 mutation carriers would revert from high risk to lower risk after a short treatment with recombinant human chorionic gonadotropin (r-hCG). For this purpose we designed a pilot study for determining whether treatment of sexually mature, from 20 to 40 years of age, nulliparous women carriers of BRCA1 mutations with the r-hCG changes their breast epithelium's genomic profile to one similar to that identified in cancer-free postmenopausal women with a history of full term pregnancy. After signing an informed consent form, eligible candidates received 250 micrograms r-hCG applied as a subcutaneous injection 3 times a week for 12 weeks. Before initiation of treatment (T0), at the end (T12), and 24 weeks post-treatment (T24) a breast core needle biopsy (CNB) was performed by the study surgeon. In this proof of concept, tissues obtained from two volunteers were divided for histopathological and RNA analyses. Total RNA was extracted, prepared for hybridization us
There is no available data on the risk for coronary artery atherosclerosis due to OC use, even though 50% of all women die from atherosclerosis-related processes regardless of OC use. Non human primate studies, however, suggest that there may be a reduced risk, perhaps due to the presence of estrogen receptors in arterial endothelium and smooth muscles. Data clearly indicate that the overall risk of breast cancer pre and post 1950 is the same, but age may be a factor with younger OC users at risk; parity protects. The association for lifetime risk, however, cannot be determined since most use occurred in the 1960s. For cervical cancer, 8 found no increased risk and 9 did, and the suggestion is the 5 years use is related to increased risk. Biases related to sexual behavior confound control and analysis of data. The most common cancer in developing countries is cervical, which warrants greater Pap smear screening to reduce this preventable cancer. Protection from cancer of the endometrium occurs for 15 years following 12 months of OC use at a 40% reduced risk. A protected effect is also found for epithelial ovarian cancer, with a 40% risk reduction.
Abstract : An early first full-term pregnancy significantly reduces a woman's lifetime risk of developing breast cancer. As such, early first childbirth is one of the most effective naturally occurring protective events that can diminish a woman's risk of breast cancer and is a candidate for targeted chemopreventive strategies. Despite extensive epidemiological evidence in support of parity-induced protection against breast cancer, very little is known about the molecules and pathways responsible for this protective effect. Rodent carcinogenesis models mimic the epidemiology of early parity and provide a valuable system for examining its biological underpinnings. As a means of addressing the underlying molecular and cellular basis of parity induced protection, we have conducted a broad-based gene expression analysis of nulliparous and parous murine mammary glands. As a result of this analysis, we have generated a panel of genes that molecularly define the protected parous mammary gland, including differentiation markers, immune- related genes, growth, factors and TGF-beta3. We identified the upregulation of several differentiation markers for mammary epithelial cells in the parous mammary gland. Additionally, we isolated genes whose expression marks the presence of a permanent population of lymphocytes and macrophages residing in the parous mammary gland. Further analysis of major categories of genes whose expression correlates with the protected parous state revealed a downr
a risk of breast cancer that is about five times the normal risk, and a risk of ovarian cancer that is about ten to thirty times normal. The risk of breast
A BRCA mutation is a mutation in either of the BRCA1 and BRCA2 genes, which are tumour suppressor genes. Hundreds of different types of mutations in these genes have been identified, some of which have been determined to be harmful, while others have no proven impact. Harmful mutations in these genes may produce a hereditary breast–ovarian cancer syndrome in affected persons. Only 5–10% of breast
Women…
For women with a BRCA1 mutation, the woman's age when she first gives birth has no association with her risk of breast cancer. Childbearing does not protect against breast cancer, unless the woman has five or more full-term pregnancies, at which point she receives only modest protection. Similar to genetically typical women, pregnancy protects against ovarian cancer in BRCA1 women. Breastfeeding for more than one year significantly protects against breast cancer. This effect may be as high as 19% per year of breastfeeding, which is much higher than that seen among genetically typical women. The effect, if any, of long-term breastfeeding on ovarian cancer is unclear.
For women with a BRCA2 mutation, each pregnancy is paradoxically associated with a statistically significant increase in the risk for breast cancer. Unlike genetically typical women or women with BRCA1 mutations, breastfeeding has no effect on…
In a woman who has not developed breast cancer, removing the breasts may reduce her risk of ever being diagnosed with breast cancer by 90%, to a level that is approximately half the average woman's risk.
Bilateral mastectomy is the removal of both breasts by a breast surgeon. The modified radical mastectomy is only used in women diagnosed with invasive breast cancer. Techniques for prophylactic mastectomies include:
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