Nonsmoking women who breastfeed for more than 6 months are safeguarded against breast cancer, according to the results of a retrospective analysis.1
Conducted in Spain, the analysis included the medical records of 504 women aged 19 to 91 years of age who had undergone treatment for breast cancer from 2004 to 2009. Relevant data included age of diagnosis, period of lactation, family history of cancer, obesity, alcohol(Drug information on alcohol) consumption, and smoking habits. Using a conditional inference tree, the researchers were able to relate the age of diagnosis with smoking habits and duration of breastfeeding.
There were significant differences found between age at diagnosis of breast cancer, smoking history, and lactation period (P<0.001), but these differences were only present in women who breastfed for more than 6 months (P=0.006). Of interest is that this protective effect occurred in women who breastfed longer than 6 months even when there was a family history of cancer.
In terms of breast cancer protection, breastfeeding for longer than 6 months seems to benefit women in that the onset of breast cancer, measured by the time of diagnosis, is approximately 10 years later than that for women who breastfed for a shorter period. Smoking seems to eliminate this protective effect. Women who smoked, even when they breastfed for longer than 6 months, had a breast cancer diagnosis at a younger age.
In an unrelated case-control study examining the relationship between reported breastfeeding history and the risk of Alzheimer’s disease, researchers found that any history of breastfeeding was associated with a lower risk of Alzheimer’s disease compared with women who had no history of breastfeeding.2 In addition, there was a negative correlation between breastfeeding and risk of Alzheimer’s disease—the longer the duration of breastfeeding, the lower the risk of Alzheimer’s disease.
Overall, the evidence in both of these studies is limited. However, should a patient inquire about maternal benefits of breastfeeding, protection against breast cancer and Alzheimer’s disease could be mentioned. Whether it should be mentioned will remain at the clinician’s discretion.
- Nonsmoking women who breastfed for longer than 6 months, including those with a family history of cancer, have a significantly longer period to first diagnosis of breast cancer than nonsmoking women who breastfed for less than 6 months.
- Breastfeeding, even when longer than 6 months, offers no protective effect against breast cancer in women who smoke.
- There is limited evidence that breastfeeding may also lower the risk of Alzheimer’s disease.