Risk for upper GI cancers in women rises with menopause
MedWire News: Postmenopausal women face a higher risk for upper gastrointestinal cancers than their pre- or peri-menopausal peers of a similar age, report researchers who found that risk increased with younger menopausal age.
The findings also add to previous work showing that postmenopausal women taking hormone therapy are at lower risk for these cancers than those who are not taking such therapy.
"Cancers of the esophagus and of the stomach are both more common in men than in women and it has been suggested that this may reflect protection offered by exposure to high levels of estrogens," note Jane Green (University of Oxford, UK) and colleagues in the British Journal of Cancer.
Because of this there is interest in the possible role played by hormonal factors, including those related to menarche and menopause and to childbearing.
However, for endogenous, reproductive factors, the epidemiologic evidence is inconsistent, and results from prospective studies are limited by small numbers of cancers.
The researchers addressed this matter among 1,319,409 women (average age 56 years) enrolled in the UK Million Women Study.
During a total of 11.9 million woman-years of observation (mean 9.1 years per woman), 1186 incident cancers of the esophagus and 1194 incident cancers of the stomach were reported, with an average age at diagnosis of about 59 years.
Compared with pre- or peri-menopausal women, women who were postmenopausal at recruitment had significantly higher risks for both esophageal and gastric cancer (risk ratio [RR]=1.46 and 1.59, respectively).
For both cancers, risk in postmenopausal women was higher the younger women were at menopause, at RRs per 5 years younger at menopause of 1.18 for esophageal cancer and 1.18 for gastric cancer).
Meanwhile, for childbearing factors, only one significant association was observed: the risk for esophageal, but not for gastric, cancer was significantly higher in nulliparous than parous women, at RRs of 1.31 and 1.01, respectively.
Lastly, there was a significant decrease in risk with increasing age at menarche seen for adenocarcinoma (RR per year older, 0.89) but not for squamous cell carcinoma.
This association could reflect residual confounding by body mass index (BMI), since lower BMI has been associated with both older age at menarche, and with a lower risk for adenocarcinoma, but a higher risk of squamous cell carcinoma.
Discussing the findings, Green et al comment: "Serum estradiol levels fall rapidly at the time of the menopause… thus the changes in risk associated with menopausal status and with hormone therapy use are consistent with a hypothesis that exposure to estrogens reduces the risk of esophageal and gastric cancer."
By Andrew Czyzewski