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The Normal Cyclical Changes in the Breast Tissue are Disturbed in Cancer
On the basis of the influence of the different sex hormones, namely estrogen, progesterone, luteal hormone and follicular stimulating hormone, the menstrual cycle has been classified into four stages. They are:
- Early Follicular Stage
It is also called as stage 1 and corresponds to day 0 to day 5 of the menstrual cycle.
- Late Follicular Stage
It is also called as stage II and corresponds to day 6 to day 15 of the menstrual cycle.
- Early Luteal Phase
It is also called as stage III and corresponds to day 16 to day 24 of the menstrual cycle.
- Late Luteal Phase
Classification of breast changes corresponding to different phases of menstrual cycle
The menstrual phase of the breast tissue is assessed on the basis of the size of the breast lobules, character of the luminal cells, vacuolation in the myoepithelium, intraluminal secretion, intralobular stroma, mitosis and apoptosis. Depending on the stage of changes in these features, the cyclical changes of the breast tissue can be classified as:
- Phase of Regression
This phase lasts from day 1 to day 8 and is characterized by atrophy of myoepithelium, condensation of intralobular stroma, and presence of an inflammatory infiltrate.
- Phase of Proliferation
This phase corresponds to the later half of the menstrual cycle. There is alveolar budding, secretions and stromal edema. Many apoptotic figures are seen towards the end of this phase.
Another commonly used method of classifying breast changes according to different phases of menstrual cycle is as follows:
- Proliferative phase
- Follicular phase of differentiation
- Luteal phase of differentiation
- Secretory phase
- Menstrual phase
Among these different phases of breast tissue changes, it is the late luteal phase which is of special interest to scientists studying the relationship of breast cancer with menstrual cycle. During this phase there a rapid proliferation of breast epithelial cells, because of a cumulative effect of both estrogen and progesterone. The breast lobules exhibit many apoptotic figures and there is an increased level of mitotic activity, which may lead to development of cancer in high risk individuals.
It is important to know about the changes that occur in the breast tissue because of two reasons:
- It helps in matching patients according to the changes in their breast tissue corresponding to their menstrual cycle, for different epidemiological studies relating to breast cancer.
- Certain studies have suggested that surgery for breast cancer, when performed in the luteal phase of the menstrual cycle, has a better prognosis.