California Teachers Study

• A 2015 study combined data from the CTS, six other cohort studies, and four case-control studies to compare risk factors for endometrial cancer among black and white women. Endometrial cancer risk factors appeared to have similar effects for black and white study participants. Black and white participants with BMI ≥ 30 had a three times greater risk of endometrial cancer, and participants with diabetes had a 30-40% increased risk. Increasing parity (number of births) was associated with decreased risk of endometrial cancer for both black and white participants. These findings can be used to address health disparities, as differences in the number of endometrial cancer cases identified among black and white women may be due to differences in the presence of risk factors among these populations. Read more here.
   

• Using data from the Epidemiology of Endometrial Cancer Consortium (E2C2), this study investigated whether BMI in young adulthood (age 18–21), BMI at study enrollment, and weight change over time were associated with risk of endometrial cancer. Results from this study suggest that young adulthood and adulthood obesity were both associated with risk of endometrial cancer, as was weight gain over time. Read more here.

​

• ​Researchers pooled data from the CTS, 3 other cohort studies, and 14 case-control studies to examine the relationship between intrauterine devices (IUDs) and risk of endometrial cancer. Within these study populations, use of IUDs, older age (≥ 35 years) at first use, older age (≥ 45) at last use, longer duration (≥ 10 years), and recent use (within 1 year of study entry) were associated with a reduced risk of endometrial cancer. Read more here.
   

• Among California Teachers Study participants, more than 3 hours per week of strenuous recreational physical activity at study enrollment was associated with decreased endometrial cancer risk, but only among overweight/obese women (BMI ≥25 kg). Participants who participated in three or more hours of strenuous recreational physical activity at baseline had an approximately 25% lower risk of endometrial cancer than women who did less than a half hour a week per year of strenuous activity.  Read more here.

​

• A 2013 study combined data from the Epidemiology of Endometrial Cancer Consortium to examine risk factors for uterine sarcoma, a disease where cancer cells form in the muscles of the uterus or in the tissue around the uterus. For study participants, obesity, history of diabetes, and first menstrual period before age 11 were all risk factors for uterine sarcoma.  Read more here.

​

• Prevailing wisdom has suggested that type I and II endometrial cancers may have different risk factors. However, in 2013 researchers examined risk factors for type I and type II endometrial cancer among CTS participants and participants in 9 other cohort and 14 case-control studies. Among these participant populations, parity (having children), oral contraceptive use, cigarette smoking, age at menarche (first menstrual period), and diabetes were associated with type I and type II tumors to similar extents. However, participants’ BMI appeared to have a greater effect on their risk of type I tumors than type II tumors. Read more here.

​

• Researchers compiled data from the Epidemiology of Endometrial Cancer Consortium to study the relationship between age at last birth and risk of endometrial cancer. They found that within these studies, risk of endometrial cancer declined with increasing age at last birth. Read more here. 

​

• A 2010 study compared two types of obesity—visceral obesity and abdominal obesity—and found that abdominal obesity, which is characterized by excessive fat around the stomach and abdomen, was associated with risk of endometrial cancer for CTS participants who had never used hormone therapy. Abdominal obesity was not associated with endometrial cancer risk for study participants who exclusively used estrogen-plus-progestin (EPT).  Read more here.

​

• CTS participants who used menopausal estrogen therapy (ET) for 10 years or more, used sequential estrogen and progestin (EPT), or used continuous-combined EPT had an elevated risk of developing endometrial cancer.  Read more here.
   

• Germ line variation can be defined as DNA change within a reproductive cell (egg or sperm) that is passed on to every cell of the offspring’s body. Several types of variants in chromosome 8q24 have already been identified as risk factors for prostate, breast, and colorectal cancer; however, no association was found between seven variants at this region and endometrial cancer.  Read more here.
   

• The gene CYP19A provides instructions for making aromatase, an enzyme responsible for converting androgens--a male sex hormone--into different forms of estrogen. Common variants in this gene, the A alleles of rs749292 and rs727479, have been associated with a 10% to 20% increase in circulating estrogen levels in postmenopausal women. A 2009 study found these two variants were associated with greater risk of endometrial cancer, though having both at once did not compound the risk. The association was greater when age was >or= 55 years and as body mass index increased.  Read more here.
   

• Estrogen has already been established to increase endometrial cancer risk, while progesterone combats estrogen’s effects. In 2010, researchers found genetic variation in the progesterone receptor gene (PGR) to be associated with an increased risk of endometrial cancer. Haplotypes (gene groups that passed down together) containing the PROGINS allele, which stunts PGR function, were associated with 34-77% increased risk of endometrial cancer among white women.  Read more here.
   

• A 2012 study investigated genetic variations in sex steroid metabolism and their effect on the relationship between hormone therapy and risk of endometrial cancer. Allele variations in CYP11A1, a gene involved in sex steroid metabolism, may alter the risk of estrogen therapy use on risk of postmenopausal endometrial cancer; however, further research is required.  Read more here.
   

• A genome-wide association study targeting endometrial cancer found no new variants that reached genome-wide significance, but replicated previously identified associations near the locus HNF1B. The findings suggest that larger studies with specific tumor classification are necessary to find novel variants.  Read more here.
   

• Researchers investigated whether SNPs previously associated with other cancers may be additionally associated with endometrial cancer. SNP rs7679673, found upstream of gene TET2 and previously reported to be associated with prostate cancer risk, was also associated with endometrial cancer risk but in the direction opposite to that for prostate cancer.  Read more here.
   

• A 2016 genome-wide association study of women of European descent discovered one new susceptibility locus reaching genome-wide significance at chromosome 6p22.3, rs1740828, which is associated with greater risk of endometrial cancer.  Read more here.
   

• Using data from multiple studies participating in the Epidemiology of Endometrial Cancer Consortium (E2C2), this study estimated the association between full-term pregnancy and endometrial cancer risk. Researchers found that having a full-term pregnancy was associated with a 41% reduction in risk of endometrial cancer compared to never having a full-term pregnancy. Read more here.
   

• This study examined the relationship between levels of three blood lipids (low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and triglycerides), the genetic variants associated with each of the lipid levels, and risk of developing endometrial cancer. The results suggested that both LDL and HDL cholesterol may play a role in the development of non-endometrioid endometrial cancer. Read more here.
   

• Chronotype refers to an individual's circadian typology, meaning one's natural inclination for the time of day they prefer to sleep. This study examined the association between endometrial cancer risk and chronotype within the California Teachers Study. Researchers found that compared to morning types, women who were definite evening types had a statistically significantly elevated risk of endometrial cancer (OR=1.44). The association between evening type and risk of endometrial cancer was stronger among obese women than among non-obese women. Read more here.
   

• This study used previously reported protein quantitative trait loci (pQTL) for 1434 plasma proteins to examine associations between genetically predicted circulating protein concentrations and risk of endometrial cancer. The research team found nine potential endometrial cancer-associated proteins. Read more here.