Postpartum Breast Cancer Metastatic Risk Period Extended

Women may experience an increased risk of breast cancer metastases for 10 years after giving birth

medwireNews: The heightened risk of metastases experienced by women with postpartum breast cancer (PPBC) may last for 10 years after their last pregnancy, US researchers have found. 

PPBC has been defined as a diagnosis within 5 years of last childbirth and shown to have a significantly higher risk of metastasis and death than breast cancer diagnosed during pregnancy or in nulliparous women, explain Virginia Borges, from the University of Colorado in Aurora, and co-workers. 

However, the team now believes that “the window of risk for metastasis imparted by a postpartum diagnosis persists for longer than previously reported” after analysing information from the Colorado Young Women’s Breast Cancer Cohort for 701 women aged up to 45 years with stage I–III invasive breast cancer. 

“[T]he data highlight recent childbirth as an identifiable biomarker that may be useful for determining prognosis of young women’s breast cancers”, the authors write in JAMA Network Open

Women with a PPBC diagnosis within 5 years or within 5–10 years of their last pregnancy were a significant 2.13 and 2.23 times more likely to develop metastases than their nulliparous counterparts. 

By contrast, the risk of metastasis among women who were diagnosed with PPBC more than 10 years after their last pregnancy did not significantly differ at just 1.6 times higher than that of nulliparous patients. 

The researchers found that these associations between time from pregnancy and metastasis risk did not retain significance after adjustment for breast cancer biological subtype, age and year of diagnosis. 

But on further examination, patients diagnosed with stage I or II disease within 5 years and 5–10 years of last pregnancy did have a significantly greater risk of metastasis than those without children after adjustment, with hazard ratios of 3.5 and 5.2, respectively. 

And patients with stage III disease had “a uniformly poor prognosis” with a high risk of metastasis regardless of parity status, the team states. 

Virginia Borges et al also found that while biological subtype did not significantly differ by parity status, the risk of metastasis in women who were diagnosed within 10 years of last pregnancy was “compounded” by an oestrogen receptor (ER)-negative diagnosis, whereas ER-positive postpartum women had a similar rate to that reported for nulliparous patients with ER-negative disease. 

“[O]ur data suggest that a postpartum diagnosis and ER-negative disease may be an additive component of risk for metastasis”, they write.

Acknowledging that their study population was “largely non-Hispanic white, relatively lean and with low breast cancer mortality rates”, the authors recommend that their findings be “confirmed in other cohorts of young women with breast cancer for determination of generalizability.”

 

Reference 

Goddard ET, Bassale S, Schedin T, et al. Association between postpartum breast cancer diagnosis and metastasis and the clinical features underlying risk . JAMA Network Open; 2: e186997. Published online 11 January 2019. doi:10.1001/jamanetworkopen.2018.6997

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