The Effects of Twins, Parity and Age at First Birth on Cancer Risk in Swedish Women

A Narrative Review of the Role of Estrogen (Receptors) in Melanoma

In this narrative review, we attempt to provide an overview of the evidence regarding the role of estrogen (receptors) in cutaneous melanoma (CM). We reviewed 68 studies and 4 systematic reviews and meta-analyses published from 2002 up to and including 2022. The prevailing presence of estrogen receptor β (ERβ) instead of estrogen receptor α (ERα) in CM is notable, with ERβ potentially playing a protective role and being less frequently detected in progressive cases. While men with CM generally experience a less favorable prognosis, this distinction may become negligible with advancing age. The role of oral contraceptives (OC) and hormone replacement therapy (HRT) in CM remains controversial. However, recent studies tend to associate the use of these exogenous hormones with a heightened risk of CM, mostly only when using estrogen therapy and not in combination with progesterone. On the contrary, the majority of studies find no substantial influence of in vitro fertilization (IVF) treatment on CM risk. Reproductive factors, including younger age at first childbirth, higher parity, and shorter reproductive life, show conflicting evidence, with some studies suggesting a lower CM risk. We suggest an important role for estrogens in CM. More research is needed, but the integration of estrogens and targeting the estrogen receptors in melanoma therapy holds promise for future developments in the field.

Effects of Exogenous Hormones and Reproductive Factors on Female Melanoma: A Meta-Analysis

Epidemiological findings on the effects of hormones on melanoma risk have been inconsistent. We therefore conducted a meta-analysis to examine the relationship between exogenous hormonal and reproductive factors and the risk of melanoma in women. We performed a search of PubMed, Web of Science, and the China National Knowledge Infrastructure (CNKI) database through April 2020 for relevant studies. Based on heterogeneity, we performed the meta-analysis of the risk estimates using either fixed effect or random effect models. We identified 38 studies that met the analytical criteria, involving 3,571,910 participants. The results showed that long-term use of oral contraceptives (OC) may increase the risk of melanoma in women (≥5 years [pooled RR=1.18; 95% CI: 1.07-1.31; I²=0%] and ≥10 years [pooled RR=1.25; 95% CI: 1.06-1.48; I²=0%]). Women who first used OC 15-19 years previously were more likely to develop melanoma (pooled RR=1.52; 95% CI: 1.03-2.24; I²=0%), while the years since the last use and the age at first use were not associated with the development of melanoma in women. Hormone replacement therapy (HRT) increased the incidence of melanoma in women (pooled RR=1.12, 95% CI: 1.02-1.24; I²=50%) and was especially associated with an increased risk of superficial spreading melanoma (SSM) (pooled RR=1.26; 95% CI: 1.17-1.37; I²=0%), and estrogen and estradiol may be the main active agents that contribute to the increased risk of melanoma, but these results may be due to a combination of sun exposure factors. With regard to reproductive factors, decreased parity and being aged ≥20 years at first birth may be associated with an increased risk of melanoma in females, while menopausal status and age at menarche are not associated with the incidence of melanoma in females. Further large-scale prospective studies are necessary to reveal new pathophysiological mechanisms and new therapeutic targets for cutaneous melanoma.

The effect of marital status on endometrial cancer-related diagnosis and prognosis: a Surveillance Epidemiology and End Results database analysis

Aim: Marital status has been proved a significant prognostic factor for diagnosis and prognosis in various cancers, but the effect in endometrial cancer (EMC) is controversial. The research was designed to clarify the relationship between marital status and EMC. Methods: We identified 39,387 patients with EMC between 2004 and 2010 from the Surveillance Epidemiology and End Results database. Patients were categorized into four groups according to marital status. We used the logistic regression, the Kaplan-Meier method and Cox regression analysis to analyze the effect of marital status on EMC-related diagnosis and prognosis. Results: The study suggests that marriage benefits the diagnosis and prognosis of EMC. Widowed and unmarried patients had higher risk of mortality than other marital status.

Reproductive factors and thyroid cancer risk: Meta-analysis

BACKGROUND

Assessed pooled risk on reproductive factors and oral contraceptives (OC) on thyroid cancer (TC) using published studies (1996-2017).

METHODS

Summary odds ratio (OR) for case-control studies (n = 10) and risk ratio (RR) for cohort studies (n = 9) was done.

RESULTS

OR was 1.43 (95% CI: 1.16-1.77) for age at menarche >14 years, 1.49 (95% CI: 1.19-1.86) for parity >2, 1.38 (95% CI: 1.18-1.61) for miscarriage/abortion, and 2.05 (95% CI: 1.39-3.01) for artificial menopause. A protective effect (ORs: 0.85; 95% CI: 0.72-0.99) on TC was observed for prolonged use of OCs. RR was 1.17 (95% CI: 0.90-1.57) for age at menarche >14 years, 1.10 (95% CI: 0.94-1.27) for parity >2, 1.20 (95% CI: 1.03-1.40) for miscarriage/abortion, and 2.16 (95% CI: 1.41-3.31) for artificial menopause and protective effect (RR: 0.78; 95% CI: 0.65-0.92) for prolonged use of OCs.

CONCLUSIONS

This meta-analysis supports an association due to changes in female hormones during menstrual cycle and pregnancy with the risk of TC and explains female preponderance.

Circulating maternal and umbilical cord steroid hormone and insulin-like growth factor concentrations in twin and singleton pregnancies

In addition to being associated with a higher risk of complications during pregnancy, twinning may also be a proxy for altered hormonal exposure for mothers and twin offspring, with implications for their health later in life. We compared maternal and fetal steroid hormone and insulin-like growth factor concentrations between singleton (n=62) and twin (n=41) pregnancies. Maternal concentrations of androgens, estrogens, insulin-like growth factor (IGF)-1, IGF-binding protein (BP)-3 and prolactin were quantified during the third trimester and at delivery, as well as in the fetal circulation at birth. Geometric means accounting for gestational age were calculated for hormone concentrations and compared between matched twin and singleton pregnancies. Most maternal hormone concentrations were modestly higher in twin than in singleton pregnancies in the third trimester (ranging from 8.3% for IGF-1 to 17.1% for estradiol) and at delivery (ranging from 11.1% for IGFBP-3 to 15.2% for estriol). Cord serum hormones were generally similar in twin and singleton pregnancies, except for IGFBP-3, which was 200% lower in twins. The modest differences in maternal hormones in late gestation seem unlikely to explain alterations in hormonally related disease risk in mothers of twins compared with singletons. The large deficit of IGFBP-3 in the fetal circulation of twins at birth may allow for sufficient concentrations of IGF-2 for growth and development in an environment of shared nutritional resources.

Risk of high-grade serous ovarian cancer associated with pelvic inflammatory disease, parity and breast cancer

BACKGROUND

Ovarian carcinoma is not a single disease, but rather a collection of subtypes with differing molecular properties and risk profiles. The most common of these, and the subject of this work, is high-grade serous ovarian carcinoma (HGSC).

METHODS

In this population-based study we identified a cohort of 441,382 women resident in Western Australia who had ever been admitted to hospital in the State. Of these, 454 were diagnosed with HGSC. We used Cox regression to derive hazard ratios (HRs) comparing the risk of disease in women who had each of a range of medical diagnoses and surgical procedures with women who did not.

RESULTS

We found an increased risk of HGSC associated with a diagnosis of pelvic inflammatory disease (PID) (HR 1.47, 95% CI 1.04-2.07) but not with a diagnosis of infertility or endometriosis with HRs of 1.12 (95% CI 0.73-1.71) and 0.82 (95% CI 0.55-1.22) respectively. A personal history of breast cancer was associated with a three-fold increase in the rate of HGSC. Increased parity was associated with a reduced risk of HGSC in women without a personal history of breast cancer (HR 0.57; 95% CI 0.44-0.73), but not in women with a personal history of breast cancer (HR 1.48; 95% CI 0.74-2.95).

CONCLUSIONS

Our finding of an increased risk of HGSC associated with PID lends support to the hypothesis that inflammatory processes may be involved in the etiology of HGSC.

Menstrual and reproductive history and use of exogenous sex hormones and risk of thyroid cancer among women: a meta-analysis of prospective studies

PURPOSE

Thyroid cancer has a higher incidence in women than in men, and it has been hypothesized that hormonal factors may explain such disparity. We performed a meta-analysis of observational prospective studies to investigate the association between menstrual and reproductive variables and exogenous hormone use and the risk of thyroid cancer among women.

METHODS

We calculated summary relative risks and 95% confidence intervals (95% CI) using random effect models.

RESULTS

Overall, 5,434 thyroid cancer cases from twenty-four papers were included. Increasing age at first pregnancy/birth (SRR 1.56, 95% CI 1.01-2.42) and hysterectomy (SRR 1.43, 95% CI 1.15-1.78) were associated with thyroid cancer risk. Women that were in menopause at enrolment had a reduced thyroid cancer risk (SRR 0.79, 95% CI 0.62-1.01). No other menstrual, reproductive, and hormonal variable was associated with thyroid cancer risk.

CONCLUSIONS

Menstrual and reproductive factors may play a role in the etiology of thyroid cancer, possibly through the mediation of estrogen receptors.

Reproductive history and risk of colorectal adenocarcinoma

BACKGROUND

Sex hormones may be associated with colorectal adenocarcinoma, although the association of pregnancy history and risk of colorectal cancer is not consistent.

METHODS

We conducted a population-based nested case-control study of persons born between 1932 and 2008 who are in the Swedish Multi-Generation Register. In total, 12,915 women and 15,519 men with colorectal adenocarcinoma were identified during follow-up in the Swedish Cancer Register; 10 age- and sex-matched controls were selected for each case. Number of children and age at first and last birth were analyzed in relation to the risk of colorectal adenocarcinoma, using conditional logistic regression, to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Compared with women without children, women with 1 or 2 children had an OR of 1.02 (95% CI = 0.93-1.13) of developing adenocarcinoma in the proximal colon; those with 3 or 4 children, 1.18 (1.06-1.32); and those with ≥5 children, 1.30 (1.05-1.61) (test for trend P < 0.01). The corresponding associations in men were 0.92 (0.84-1.00), 1.02 (0.92-1.13), and 0.97 (0.78-1.20), respectively (test for trend P = 0.13).

CONCLUSIONS

Higher parity in women was associated with the risk of adenocarcinoma of the proximal colon, although not the distal colon or rectum. A similar risk with family size was not seen for fathers. Still, the influence of lifestyle factors cannot be ruled out.

A linked-registry study of gestational factors and subsequent breast cancer risk in the mother

BACKGROUND

Women who were younger at their first live birth have a reduced breast cancer risk. Other pregnancy characteristics, including complications, also may affect risk but because they are rare, require large datasets to study.

METHODS

The association of pregnancy history and breast cancer risk was assessed in a population-based study including 22,646 cases diagnosed in Washington State 1974 to 2009, and 224,721 controls, frequency matched on parity, age, calendar year of delivery, and race/ethnicity. Information on prediagnosis pregnancies derived from linked birth certificate and hospital discharge databases. Adjusted odd ratios (ORs) and 95% confidence intervals (CI) were calculated.

RESULTS

Multiple gestation pregnancies were associated with decreased breast cancer risk (OR, 0.65; 95% CI, 0.57-0.74) as was prepregnancy obesity (OR, 0.76; 95% CI, 0.65-0.90). Infant birth weight was positively associated (6% per 1,000 g; 95% CI, 3%-9%). The ORs for first trimester bleeding (OR, 3.35; 95% CI, 1.48-7.55) and placental abnormality/insufficiency (OR, 2.24; 95% CI, 1.08-4.67) were increased in women diagnosed at age 50+ years and 15+ years after the index pregnancy. Results were similar in analyses restricted to first pregnancies, those closest to diagnosis, and when excluding in situ disease.

CONCLUSION

These data suggest that multiple gestation pregnancies are protective, whereas delivering larger infants increases risk for later development of maternal breast cancer. Placental abnormalities that result in bleeding in pregnancy also may reverse the long-term protection in postmenopausal women associated with parity.

IMPACT

Certain pregnancy characteristics seem to be associated with later maternal breast cancer risk.

Twins and Their Health Cost: Consequences of Multiple Births on Parental Health and Mortality in Denmark and England and Wales

The rapid increase in twinning rates in developed countries has increased interest in the question as to whether twin mothers have higher mortality and more health problems than mothers of singletons. Here we use a national survey, the Office for National Statistics Longitudinal Study of England & Wales, and a linkage between the Danish Twin Registry and the Danish population register to examine mortality patterns after age 45 (50 for fathers) for twin parents and the whole population born from 1911 to 1950. For England and Wales, presence of limiting long-term illnesses and self-rated health status was also investigated. Overall similar health and mortality was found for twin parents and the whole population although both life table methods and survival analysis suggested a slight excess mortality among older cohorts of twin mothers in England and Wales.

Hormonal and reproductive factors in relation to melanoma in women: current review and meta-analysis

A number of studies have focused on possible relationships between characteristics of female endocrine status and melanoma (CM) risk; however, the link between melanoma, oral contraceptive (OC) and hormonal replacement therapy (HRT) use, and reproductive factors remains controversial. A comprehensive, systematic bibliographic search of the medical literature was conducted to identify relevant studies. Random effects models were used to summarise results. Subgroup, meta-regression and sensitivity analyses have been carried out to explore sources of between-study variation and bias. We included thirty-six observational studies published in the last 30 years. Summarising a total of 5626 melanoma cases, we did not find any significant melanoma risk associated with OC and HRT use. Several reproductive factors were also investigated, summarising data on 16787 melanoma cases. We found a significantly increased melanoma risk for late age at first birth, and women with more than one child may be at a lower risk for melanoma; however, socio-economic confounders were found to play a significant role in explaining this association. This study confirmed no increased risk of CM with the use of oral contraceptives and hormone replacement therapy: exogenous female hormones do not contribute to an increased risk of CM. In contrast, significant associations of CM with parity and age at first pregnancy were observed in this meta-analysis finds and warrant further research.

Cutaneous melanoma and endogenous hormonal factors: a large French prospective study

To assess the role of endogenous hormonal factors on melanoma, the authors conducted a prospective analysis of 91,972 French women, aged 40-65 years at inclusion into the Etude Epidémiologique auprès de femmes de l'Education Nationale (E3N) cohort. Between 1990 and 2005, 460 melanoma cases were ascertained. Relative risks and 95% confidence intervals were computed by using Cox proportional hazards regression models. Risks of melanoma were reduced in women with ≥ 15 years at menarche (relative risk (RR) = 0.67, 95% confidence interval (CI): 0.46, 0.97, compared with 13-14 years), irregular menstrual cycles (RR = 0.52, 95% CI: 0.31, 0.89, compared with regular cycles of 25-31 days), <48 years at natural menopause (RR = 0.70, 95% CI: 0.48, 1.02, compared with 48-51 years), and shorter ovulatory life (RR = 0.51, 95% CI: 0.28, 0.91, for <33 years compared with ≥ 39 years). Modest inverse associations were observed with parity, as well as number of pregnancies and miscarriages. There was no evidence of an association between melanoma risk and age at first birth or pregnancy, age at last birth, time since last birth, breastfeeding duration, age at menstruation regularity, or menopausal status. Results did not significantly differ according to ambient ultraviolet radiation dose and melanoma site or subtype. These findings from a large prospective cohort may suggest a reduced melanoma risk associated with decreased exposure to ovarian hormones.

Reproductive risk factors and endometrial cancer: the European Prospective Investigation into Cancer and Nutrition

Endometrial cancer risk has been associated with reproductive factors (age at menarche, age at menopause, parity, age at first and last birth, time since last birth and use of oral contraceptives (OCs)]. However, these factors are closely interrelated and whether they act independently still requires clarification. We conducted a study to examine the association of menstrual and reproductive variables with the risk of endometrial cancer among the European Prospective Investigation into Cancer and Nutrition (EPIC). Among the 302,618 women eligible for the study, 1,017 incident endometrial cancer cases were identified. A reduction in endometrial cancer risk was observed in women with late menarche, early menopause, past OC use, high parity and a shorter time since last full-term pregnancy (FTP). No association was observed for duration of breast feeding after adjustment for number of FTP or for abortion (spontaneous or induced). After mutual adjustment, late age at menarche, early age at menopause and duration of OC use showed similar risk reductions of 7-8% per year of menstrual life, whereas the decreased risk associated with cumulative duration of FTPs was stronger (22% per year). In conclusion, our findings confirmed a reduction in risk of endometrial cancer with factors associated with a lower cumulative exposure to estrogen and/or higher exposure to progesterone, such as increasing number of FTPs and shorter menstrual lifespan and, therefore, support an important role of hormonal mechanisms in endometrial carcinogenesis.

Pregnancy characteristics and maternal breast cancer risk: a review of the epidemiologic literature

The short- and long-term effects of pregnancy on breast cancer risk are well documented. Insight into potential biological mechanisms for these associations may be gained by studying breast cancer risk and pregnancy characteristics (e.g., preeclampsia, twining), which may reflect hormone levels during pregnancy. To date, no review has synthesized the published literature for pregnancy characteristics and maternal breast cancer using systematic search methods. We conducted a systematic search to identify all published studies. Using PUBMED (to 31 July 2009), 42 relevant articles were identified. Several studies suggest that multiple births may be associated with a lowered breast cancer risk of about 10-30%, but results were inconsistent across 18 studies. The majority of 13 studies suggest about a 20-30% reduction in risk with preeclampsia and/or gestational hypertension. Six of seven studies reported no association for infant sex and breast cancer risk. Data are sparse and conflicting for other pregnancy characteristics such as gestational age, fetal growth, pregnancy weight gain, gestational diabetes, and placental abnormalities. The most consistent findings in a generally sparse literature are that multiple births and preeclampsia may modestly reduce breast cancer risk. Additional research is needed to elucidate associations between pregnancy characteristics, related hormonal profiles, and breast cancer risk.

Malignant melanoma risk after exposure to fertility drugs: results from a large Danish cohort study

OBJECTIVE

The aim was to examine the effects of fertility drugs on malignant melanoma risk using data from the largest cohort of infertile women to date.

METHODS

A cohort of 54,362 women with infertility problems referred to Danish fertility clinics in the period 1963-1998 was established. A detailed data collection including information about type and amount of treatment was conducted. Using case-cohort techniques, we calculated rate ratios (RRs) of malignant melanoma associated with different fertility drugs after adjustment for parity status.

RESULTS

112 malignant melanomas were identified during follow-up through 2000. Use of clomiphene, gonadotrophins, hCG or GnRH did not affect risk of malignant melanoma significantly. When stratifying for parity, however, use of gonadotrophins (RR = 2.29; CI: 1.16-4.52) or GnRH (RR = 3.26; 95% CI: 1.50-7.09) among parous women was associated with a significant increased risk. For all groups of fertility drugs, we found no association with number of cycles of use or years since first use (latency).

CONCLUSIONS

Our findings showed no strong association between malignant melanoma risk and use of fertility drugs, although the results indicated that use of gonadotrophins or GnRH might increase risk in parous women. Longer follow-up is needed to confirm our findings.

Twin births, sex of children and maternal risk of ovarian cancer: a cohort study in Norway

In a follow-up of 1 208 001 women aged 20–74 years, no significant association was found between twin births (112 cases) and risk, though those with twin girls had a non-significantly higher risk than those with singleton births; among the latter, those with girls only had a higher risk of endometrioid tumours (incidence rate ratio 1.35; 95% confidence interval 1.03–1.76, based on 475 cases) than women with boys only.