Preeclampsia and subsequent breast cancer risk

[Does fertility treatment increase the risk of breast cancer? Current knowledge and meta-analysis]

OBJECTIVE

The objective of this review was to assess the level of risk of breast cancer for women exposed to ovulation-inducing therapy (OIT).

METHODS

The 25 selected studies were extracted from the PUBMED database from January 2000 until March 2016 with the following key-words: "fertility agents", "infertility treatments", "clomiphene citrate", "buserelin", "ovarian stimulation", "assisted reproductive technology" and "breast cancer". Our meta-analysis was performed using Review Manager software, Cochrane Collaboration, 2014. The results were calculated by type of OIT, as well as globally.

RESULTS

The analysis of these published epidemiological studies confirms that exposition to OIT is not a breast cancer risk factor, but the results are contradictory. Two studies have shown a significantly increased risk of breast cancer in a population of infertile women, while two others have found a significant decrease of this risk. The twenty others did not show any impact of IOT over this risk. Our meta-analysis of 20 selected studies has not identified a significant association between exposition to OIT and breast cancer risk (relative risk=0,96; IC 95: (0,81-1,14) for cohort studies and odds ratio=0,94; IC 95% (0,81-1,10) for case-control studies).

CONCLUSION

Exposition to OIT is not an identified risk factor for breast cancer. A message reassuring about a possible risk of OIT-related breast cancer should be given to these women. Exposition to OIT is therefore not an indication of increased breast surveillance.

A prospective study of angiogenic markers and postmenopausal breast cancer risk in the prostate, lung, colorectal, and ovarian cancer screening trial

PURPOSE

Pro-angiogenic factors are positively associated with breast tumor staging and poorer prognosis, but their role in the etiology of breast cancer has not been assessed.

METHODS

We measured serum levels of the pro-angiogenic vascular endothelial growth factor A (VEGF), and placental growth factor (PlGF) and anti-angiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) in 352 incident breast cancer cases [mean age at diagnosis 67 (range 55-83)] and 352 non-cases in the prostate, lung, colorectal, and ovarian screening trial (women enrolled 1993-2001, followed through 2005) matched on age and date of enrollment. Cases were followed on average 4.2 years from blood draw to diagnosis, range 3.9-12.8 years; 53 % were estrogen receptor positive/progesterone receptor positive (ER+/PR+), and 13 % were ER-/PR-. Quartile-specific hazard ratios (HR) and 95 % confidence intervals (CI) were estimated using weighted Cox proportional hazards regression models adjusted for known breast cancer risk factors. An ordinal variable for the angiogenic markers was used to test for trend in the HR.

RESULTS

Comparing the highest to lowest quartile, multivariable HR were 0.90 for VEGF (95 % CI 0.33-2.43, p trend = 0.88), 1.38 for sFlt-1 (95 % CI 0.63-3.04, p trend = 0.63), and 0.62 for PlGF (95 % CI 0.19-2.00, p trend = 0.73). Risk patterns were not altered when all angiogenic markers were included in the model simultaneously, or by restricting analyses to invasive breast cancers, to cases diagnosed two or more years after blood collection or to ER+ tumors.

CONCLUSIONS

There was no evidence of an increased breast cancer risk associated with circulating levels of pro-angiogenic markers VEGF and PlGF or a reduced risk with circulating levels of anti-angiogenic marker sFlt-1.

Hypertensive disorders of pregnancy and subsequent risk of solid cancer--A nationwide cohort study

Women with hypertensive disorders of pregnancy (HDP) have higher levels of antiangiogenic growth factors during pregnancy than women with normotensive pregnancies. Since angiogenesis is necessary for solid cancer growth and spread, we hypothesized that women with a history of HDP might have a reduced risk of solid cancers (cancers other than lymphomas, hematologic cancers and nonmelanoma skin cancers) later in life. In a register-based cohort study of 1.08 million women giving birth at least once between 1978 and 2011, we used Cox regression to estimate hazard ratios (HRs) comparing solid cancer rates for women with and without a history of HDP. In this cohort, 68,236 women (6.3%) had ≥1 pregnancy complicated by HDP and 42,236 women (3.9%) developed solid tumors during follow-up. A history of HDP was not associated with a clinically meaningful reduction in the overall rate of solid cancer (HR 0.96, 95% confidence interval 0.92-1.00), regardless of HDP severity or time since HDP, nor was there a general tendency toward reduced solid cancer rates across organ sites. A history of HDP was only significantly associated with decreased rates of breast and lung cancers and with increased rates of endometrial and urinary tract cancers. Overall, our results do not support the hypothesis that women with a history of HDP have a reduced overall risk of solid cancer due to a persistent post-HDP antiangiogenic state or an innate tendency toward antiangiogenesis. Observed associations with specific cancers may instead be due to other pregnancy-related mechanisms or to residual/unmeasured confounding.