Epidemiology



Breast cancer is the most common malignancy in women and the second most common (after lung cancer) cause of death in this group. However, to some extent, it concerns men as well.Different countries in the world have varying incidence of breast cancer. The West Europe countries and the USA have the highest incidence rates, adequately 35-60/100 000 and 65/100 000, whereas the Far East countries have the lowest rate (i.e. in Japan it is five times lower than in the USA).

Risk factors

Risk factors point to increased risk, that is at higher probability of falling ill among specimens of a given population. The most important risk factors include:

1. Woman's age

Incidence of breast cancer increases with age.

2. Ethnic/geographical factors

These factors, although they have been taken into consideration for years, are extremely difficult to interpret. High breast cancer incidence occurs in the USA and in West Europe, low - in Asian, Far East and African countries. Breast cancer is usually developed in Caucasian women living in a quite cold climate in the highly developed countries. It is dependent upon the influence of the following factors: race, climate, nutrition style, types of the undergone diseases, lifestyle and culture style, family planning, age of the first pregnancy, number of children, breastfeeding's popularity, etc. Black and yellow women become ill more rarely.

3. Family factors

The more affected relatives and the closer degree of kinship to them, the bigger probability of suffering from cancer. The risk increases, if these tumours occurred in one's mother and sister under the age of 35 . Genetically determined breast cancer, which amounts to 10% of all the breast tumours, most often being the result of BRCA1, BRCA2, p53 and ATM genes mutation. Breast cancer can also occur in the course of some inheritably associated syndromes, among others in Li-Fraumeni syndrome, Lynch II syndrome, Cowden's disease, Peutz-Jaeghers syndrome, ataxia-teleangiectasia, Klinefelter syndrome

4. Age of first menstruation and menopause

Appearance of first menses before the age of 12 significantly increases (by about 40%) the risk of breast cancer. Natural menopause appearing after age 55 increases risk of breast cancer twofold. Thus, the most important factor is the total number of years of ovulation activity.

5. Age of first pregnancy and delivery

Women who give birth to their first child in the age of between 20 and 30 have a lower risk of breast cancer. Nulliparous women are more exposed to breast cancer, by almost 50%.

6. Breastfeeding

Women with much lower risk of falling ill protected from breast cancer development by breastfeeding. Even relatively short time of breastfeeding gives some protection

7. Ionising radiation

High doses of X radiation (applied during routine "X-rays") can cause breast cancer. It is worth to stress that the contemporary mammography apparati expose a woman to a minimal dose of radiation.

8. Alcohol and diet

Excessive alcohol consumption for a long period of time increases the risk of breast cancer development, because the liver damage impairs estrogen metabolism (high estrogen concentration increases the risk of falling ill). It is suspected that one of the factors, which increases the breast cancer risk, is food with high content of saturated fat

9. Obesity

Obesity increases the risk of breast cancer development, as it is more difficult to find breast changes in obese people . moreover, fat cells produce estrogens

10. Exogenous hormones (hormone contraceptives)

It is believed that oral contraceptives (which include mainly estrogens), even if they are connected with breast cancer, act as a factor facilitating and accelerating the development of the disease, which has already appeared, rather than a factor causing genetic mutations and evoking disease. It is also believed that pills that are made only of progesterone and so called ?minipills? don't increase the breast cancer risk. The pills may increase the risk in genetically loaded women or women using oral contraceptives for at least 8 years until first pregnancy. It is believed that preparations which include progesterone alone, don't affect the risk for breast cancer appearance. However, preparations that include progesterone and estrogens may influence the tumour appearance. The risk is growing for women taking hormone medications longer than 8 years.

Treatment

Breast cancer is treated locally or generally, although some patients may undergo both types of treatment. Local treatment consists in surgical removal or destruction of the lesion. General treatment (chemotherapy, hormone therapy) aims at inhibiting the tumour process or decreasing the size of tumour before operation and it is also applied in significant disease progression instead of surgery. Surgical treatment is the most common way to treat breast cancer. Patients in I0 and II0 clinical progression are qualified for the surgical treatment . The most often performed surgery is the modified breast amputation by Patey's way (excision of the breast gland together with the axillary lymph nodes, without removing the breast muscles). Some patients are qualified for breast conserving treatment.

Such possibility exists in the following cases:

- TisN0M0

- T1N0M0

- T1N1M0

- T2N0-1M0 (tumour not bigger than 3cm in a mammographic measurement)

- Possibility of removing the tumour with a margin of healthy tissue

- Satisying cosmetic effect foreseen

- Patient's consent to breast conserving treatment

- The lack of contraindications

The absolute contraindications include:

1. Multicentric cancer

2. Cancer relapse after the previous breast conserving treatment

3. Previous undergoing of breast irradiation

4. No possibility of getting the margin of healthy tissue

The relative contraindications include:

1. Pregnancy

2. Foreseen unsatisfying cosmetic effect

3. Connective tissue disease (collagenosis)

Breast Conserving Treatment (BCT) includes replacing tumour within healthy tissues and regional axillary lymph nodes. The following ways of breast tumour removal are distinguished:

- tylectomy

- removing the tumour with a margin of at least 2cm. If the margin from the muscles' side is smaller than cm, the tumour must be removed together with fascia,

- wide excision, lumpectomy

- removing the tumour together with the bulk unchanged tissues margin of 1 cm. This margin can be smaller from the muscles side, but then fascia has to be removed.

- excisional biopsy, tumourectomy

- removing the tumour without margin, but with the intention of removing all the bulk suspected tissues. After BCT surgery, all patients are exposed to supplementing radiotherapy. Breast gland is irradiated with a total dose of 50 Gy, 2 Gy per fraction (25 fractions during 5 weeks). Additionally, the site of tumour removal is afterloaded with 192 Ir with the 10 Gy dose.

Radiotherapy - uses high energy radiation to destroy the cancer cells and to prevent them from further growth and fissions. There are two kinds of radiotherapy: exterior (source of radiation is located outside the human body) and interior (special containers with the radiation material are placed in the tumour site). Another kind of radiotherapy is brachytherapy which involves placing thin tubes in breast. The radiation is directed through these tubes straight to the tumour cells. Nowadays brachytherapy is applied after breast conserving treatment. It happens that radiotherapy is applied before surgery to decrease the size of tumour and/or to facilitate the tumour removal.

Chemotherapy involves the application of medicines that are aimed at tumour destruction. In breast cancer chemotherapy is usually composed of a few types of medicines, which are administered either directly to vein or in the form of pills. Regardless of the way of administering, the medicines get inside blood and flow with it through the whole body, which also results in negative effects for this therapy (nausea, vomiting, hair falling out, neutropenia, menstruation disorder, earlier menopause).

Copyright 2006 Radoslaw Pilarski