High Placental Weight Indicative of Increased Risk of Breast Cancer in Mothers
According to a recent article published in the Journal of the American Medical Association, mothers who deliver children with a high placental weight have an increased risk of developing breast cancer. These women may benefit from close screening for breast cancer.
Breast cancer is diagnosed in approximately 200,000 women annually in the U.S. alone and is responsible for approximately 40,000 deaths.
Fortunately, if breast cancer is detected and treated early, prior to spread from its site of origin, cure rates remain high with standard therapeutic approaches. However, once the cancer has spread from the breast or axillary (under the arm) lymph nodes, cure rates fall dramatically. Much emphasis has been placed on breast cancer screening so that the cancer may be detected and treated in its earliest and most curable stages. In particular, researchers are focusing on understanding specific variables that may be associated with a higher risk of developing breast cancer; the goal is to identify women at higher risk and monitored them closely.
Pregnancy is associated with soaring levels of the female hormones estrogen and progesterone, as well as other hormones. The majority of breast cancers are stimulated to grow from exposure to estrogen and/or progesterone. During pregnancy, these hormones are produced primarily by the placenta, prompting researchers from Sweden to investigate possible associations between the weight of a placenta (with the assumption that larger placentas produce greater amounts of hormones) and the risk of developing breast cancer.
The study included data from the Swedish Birth Register, the Swedish Cancer Register, the Swedish Cause of Death Register, and the Swedish Register of Population and Population Changes. Participants of this study included over 314,000 women who delivered single children (versus twins or other multiple live births) between 1982 and 1989. These women were followed until the end of 2001 or until the diagnosis of breast cancer or death.
- 2,216 of these women developed breast cancer during follow-up (0.7%).
- 95% of these women were diagnosed before the age of 50.
- Women whose placentas weighed between 500 grams (g)–699 g in their first delivery and at least 700 g in their second delivery (or vice versa) had an 82% increased risk of developing breast cancer compared to women whose placentas were less than 500 g on both deliveries.
- Women whose placentas weighed more than 700 g in both deliveries had over double the risk of developing breast cancer than women whose placentas were 500 g or less on both deliveries.
The researchers concluded that it appears that high placental weight is associated with a significantly increased risk of developing breast cancer among mothers. Women who are pregnant may wish to speak with their physician regarding placental weight and risk of breast cancer.
Reference: Cnattingius S, Torrang A, Ekbom A, et al. Pregnancy Characteristics and Maternal Risk of Breast Cancer. Journal of the American Medical Association. 2005; 294:2474-2480.
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