Oncologist Dr. Ricardo Caponero clarifies doubts about the relationship between breastfeeding and breast cancer.

Breast cancer is a disease that can, in some cases, be prevented. This prevention, in general, consists of removing risk factors as early as possible.

Some cases of this neoplasm have a hereditary risk component. Today, we know about 21 genes related to breast cancer. In these cases, for eligible patients, prophylactic surgeries may reduce this risk. In addition, this group of women may be candidates for screening tests started when they are younger, with more specific exams and with shorter intervals.

However, most breast neoplasms do not have a hereditary character. For these, environmental factors may be the most relevant. Exposure to tobacco and its derivatives, excessive consumption of alcoholic beverages and various chemical substances are relevant, as is exposure to hormonal (estrogenic) stimuli.

All women produce estrogens, but some factors increase their action, such as hormone replacement therapy and the use of some types of contraceptive pills (those with low risk). Hormone replacement is not prohibited, but it should be done with caution, in properly selected patients, for the shortest possible time and, most importantly, with medical supervision.

Weight gain, especially after menopause, is also a risk factor. In addition to storing estrogens, fat has a higher concentration of an enzyme, called aromatase. The increase in fat mass composition also contributes to the generation of a systemic inflammatory state, which contributes to an increased risk of neoplasms in general and, in particular, for breast and endometrial cancer.

Diet (low in fat) and regular exercise are the two main modifiable factors for cancer prevention and should be started as early as possible (preferably in childhood).

The onset of periods at a younger age, the later menopause, no
having had children or having started procreation later and not breastfeeding also contribute
for a longer time of exposure to estrogen.

Pregnancy and breastfeeding also stimulate the maturation of breast cells to produce milk, and this is a factor for the good differentiation of breast tissue

We do not recommend any method to delay the first menstruation or to anticipate menopause
as a way to prevent cancer. In the same way that we cannot recommend that
women have many children, at the lowest possible age, for the same purpose. Essa
The measure causes very lasting social and economic impacts.

Breastfeeding is related to pregnancy, obviously. There are doubts regarding
At the optimal length of the breastfeeding period, most pediatricians recommend that she
occurs in the baby's first six months and may extend up to one year of age in
poorer populations, with fewer resources to provide an adequate alternative to
child feeding. Breastfeeding is a physiological act and has effects on the immunity of
newborn and in their physical and psychological development.

Although breastfeeding contributes to the reduction in the incidence of breast cancer,
its effect is very small when compared to other risk factors. We don't know your
impact on patients with hereditary mutations and their benefit is very small in
patients with other risk factors, such as obesity, sedentary lifestyle, smoking, etc.

A review of epidemiological data shows that the protective biological mechanism of breastfeeding remains unknown, although it is posited that it results from hormonal changes, such as estrogen reduction; removal of estrogens through breast fluid; excretion of carcinogens from breast tissue through breastfeeding; physical changes in mammary epithelial cells, reflecting maximum differentiation; and delayed reestablishment of ovulation.

Although breastfeeding is a potentially modifiable behavior, the practical implication of reducing the risk of breast cancer among premenopausal women with prolonged breastfeeding duration may be of marginal importance (less than 1% impact), particularly in Western societies.

Primary prevention of breast cancer is possible, but it depends on a set of measures so that it can be as effective as possible and, very importantly, it does not require adequate screening tests, which, although they do not reduce the incidence, are essential for simpler, less mutilating treatments and with greater chances of cure.

To conclude, breastfeeding is good, it should always be recommended, but its impact as a protective factor in breast cancer is very small.

Ricardo Caponero
— CRM 51,600/SP
Clinical Oncologist at the German Hospital Oswaldo Cruz