IVF Treatment Not Associated with Overall Increased Rate of Breast Cancer

ASRM BULLETIN  (Reprint) 
Volume 14, Number 30   
MAY 29, 2012 

Highlights from Fertility and Sterility:  IVF Treatment not Associated with Overall Increased Rate of Breast Cancer; Some Increased Risk Found in Younger Patients.

In a large population-based study out of Western Australia, researchers have found that IVF is not associated with an overall increased risk of breast cancer. However, the analysis of 20 years' worth of linked hospital and registry records demonstrates an underlying, age-related connection between IVF treatment and breast cancer.

The effect of IVF on breast cancer rates differed depending on the age of the women at the time treatment was commenced.  In younger, but not older, patients there was an association between having IVF and an increased risk of breast cancer.   Women who first underwent IVF treatment at age 24 were about one-and-a-half times more likely to develop breast cancer than women of the same age who received a non-IVF infertility treatment.  Women who commenced IVF at 40 had no increased risk. 

The cohort study was designed to compare rates of breast cancer between women whose infertility treatment included IVF and women who received other infertility treatments and utilized data from 21,025 women undergoing investigation or treatment in hospital for infertility in Western Australia from 1983 to 2002.  Of the total, 7,381 women had IVF and 13,644 did not.  Patients were between the ages of 24 and 44 at their first admission. Women with prior breast cancer diagnoses and those who developed breast cancer within six months of their first infertility admission were excluded from the study.

The data were adjusted to account for potential confounders on record, such as age at first delivery, delivery of twins or higher-order multiples, age at entry to the cohort, and socioeconomic status.  While age at first delivery was associated with an increased breast cancer rate, the delivery of twins or higher-order multiples suggested a reduced rate of cancer.     Linda Giudice, MD, PhD, President-elect of ASRM, noted, "The development of breast cancer is linked to estrogen exposure and the longer one is exposed, the greater the risk.  In an IVF cycle, there is a short, but significant elevation in circulating estrogen, and whether this is linked to the observations found in this study is not clear at this time. Women should be reassured that, overall, IVF was not associated with an increased risk for development of breast cancer.  However, as noted in the study, women in their thirties and forties still need to be aware of the increased risk of breast cancer associated with delivering one's first child at this stage of reproductive life.  For younger women, there is the possibility that IVF is associated with increased risk, but more research is needed to confirm this." Stewart et al., In vitro fertilization and breast cancer: is there cause for concern?