What is breast cancer
Breast cancer is a disease in which the disordered multiplication of breast cells generates abnormal cells, forming a tumor.
In the world, it is one of the three types of cancer with the highest incidence, alongside lung and colorectal cancer, in addition to non-melanoma skin cancer, which is the most frequent. Considering the diagnoses of both sexes, breast cancer cases represent 11.6% of the total disease. When the cut is only among women, this number rises to 24.2%.
In Brazil, breast cancer is the one that most affects women (excluding non-melanoma skin tumors). For 2020, the INCA (National Cancer Institute) estimated about 66,280,000 new cases in the country.
Men can also be surprised with breast cancer, but the incidence is very low: about 1% of all cases of the disease.
Subtypes of breast cancer
Breast cancer is composed of different subtypes, which makes the disease extremely heterogeneous, causing it to evolve in different ways.
Histologic type defines breast cancer in terms of where the tumor originates in breast tissue and how it develops. The most common types are:
- Ductal Carcinoma In Situ – is the most common type of non-invasive breast cancer. It affects the breast ducts, spreads through them and distorts their architecture; it can progress to invasive, although this is infrequent if the disease is adequately treated. It usually does not affect axillary nodes and does not have the potential to cause distant metastases;
- Invasive Ductal Carcinoma – represents between 65% and 85% of cases of invasive breast cancer. It starts in the breast ducts, crossing the membrane barrier and developing in nearby tissues.
- Invasive Lobular Carcinoma – second most common type of breast cancer. It is born in the milk-producing glands – the mammary lobules – and can develop locally, in addition to having the ability to present as a bilateral or multicentric disease or invade adjacent tissues and metastasize to distant organs;
- Lobular Carcinoma In Situ – is an uncommon histological type and accounts for only 2% to 6% of cases. It also originates from the breast lobules and does not have the ability to invade tissues. However, it can be a precursor to invasive breast cancer.
Less common types of breast cancer include:
- Inflammatory carcinoma – uncommon, representing 1% to 3% of cases. The lymph ducts of the skin over the breast tissue are blocked and invaded by tumor cells. In it, the lymphatic system acts in the defense against infections and inflammation, developing a chain reaction that causes the inflammation of the breast;
- Paget’s disease – very rare, with an incidence of 0.5% to 4% of breast cancer cases. It starts in the mammary duct, reaching the skin of the nipple and the areola. It can be both asymptomatic and manifest as crusts and inflammation on the nipple;
- Phyllodes tumor – very rare, it develops in the connective tissue of the breast (stroma), while the others develop in the breast ducts or lobules;
- Angiosarcoma – starts in the cells that line blood vessels or lymph vessels.
Symptoms and signs of breast cancer
Breast cancer has symptoms that can be noticed in the self-examination performed by the woman herself or in routine consultations with the gynecologist. In most cases, the symptoms are:
- Fixed and usually painless nodule or lump, present in about 90% of cases in which the cancer is perceived by the person herself;
- Redness of the skin of the breast accompanied by retraction and orange peel appearance;
- Changes in the nipple, such as retractions or inversion;
- Small lumps in the armpits or neck;
- Spontaneous and abnormal leakage of fluid from the nipples, including bloody fluid.
Self-examination can be done in the shower, when changing clothes or in any everyday situation, when the woman feels more comfortable. Both breasts and nipples should be palpated in search of small breast changes. The earlier it is detected, the greater the chance of curing breast cancer. Undoubtedly, self-examination can contribute to the early diagnosis of the disease.
Breast cancer diagnosis
The diagnosis of breast cancer is based on the tripod consisting of clinical examination, imaging and histopathological analysis.
After anamnesis, with clinical history performed by a specialist, it is necessary to perform the appropriate imaging tests to evaluate the breast parenchyma, breast ultrasound and mammography. Breast MRI can complement or help in specific situations. In case of suspicion of breast cancer, it is necessary to perform a biopsy of the region to confirm – or not – the diagnosis.
The main methods of breast biopsy are core biopsy, or core needle biopsy, and mammotomy, or vacuum biopsy, in which a larger sample of tissue is taken. Both biopsies are performed under local anesthesia and are minimally invasive. For cases of axillary injury, fine needle aspiration (FNA) is the most recommended alternative.
The choice of the best biopsy strategy is made by the mastologist or by the radiologist, a specialist in breast radiology. If none of these minimally invasive biopsy alternatives are feasible, surgical biopsy is an option. If the lesion is impalpable, an imaging test such as ultrasound, mammography, or MRI can serve as a guide for the procedure.
In the biopsy, the suspected breast tissue is removed and then evaluated by a pathologist using microscopy. Thus, it is possible to differentiate a benign lesion from a malignant one. Immunohistochemistry helps confirm the diagnosis and differentiate between types of breast cancer.
Treatment
The treatment of breast cancer depends on the stage of the disease (staging), the molecular type of the tumor and the clinical conditions of the patient (such as age, pre-existing conditions, if she has already gone through menopause). Among the procedures, there may be surgery, radiotherapy, chemotherapy, endocrine therapy, biological therapy (or targeted therapy) and immunotherapy.
Treatment modalities are divided into local (surgery and radiotherapy) and systemic (chemotherapy, endocrine therapy, biological therapy and immunotherapy).
Staging I and II
In the early stages of breast cancer, the usual option is to opt for surgery. It can be conservative (tumor removal) or partial or total mastectomy (breast removal), followed or not by breast reconstruction – which should be considered to reduce the negative physical and emotional impacts of treatment.
Radiotherapy is always indicated after conservative surgery. After partial mastectomy, it depends on some variables, such as the molecular type of the tumor and the presence or absence of lymph node involvement.
According to the risk of recurrence or relapse, a decision is made whether or not to indicate systemic treatment. The patient’s age, size, molecular subtype of the tumor, and axillary lymph node involvement are also taken into account.
To decide on endocrine therapy and/or biological therapy, for example, it is essential to assess the presence of hormone receptors and HER receptor by means of an immunohistochemical examination. Chemotherapy can be offered before or after surgery, taking into account the risk of future recurrence. The following criteria are evaluated: tumor size, hormone receptor expression, presence or absence of HER-2 protein overexpression, histopathological grade, patient’s age and more recently, when available, some genomic signatures, which evaluate tumor DNA and help to grade the patient’s risk.
There are patients who will not need chemotherapy during treatment, as they have a less aggressive disease.
Staging III
Here, the tumors are already larger than 5 cm or, when smaller, with the presence of regional lymph nodes affected in the armpits, for example. Systemic treatment (usually with chemotherapy) tends to be the initial option for tumor shrinkage. Then, it starts with local treatment, with surgery and radiotherapy.
Staging IV
It is the stage in which there is metastasis, that is, the cancer has already spread to other organs (most often bones, lungs, liver and brain). It is essential to find a balance between controlling the disease through available approaches, increasing patient survival and the potential side effects of treatment.
Great advances have been made in recent years in the treatment of metastatic breast cancer. Oral drugs, called cyclin inhibitors, have emerged with excellent ability to control and reduce the volume of disease. In addition, in the scenario of HER-2 positive metastatic breast cancer, there was a great improvement in the life expectancy of patients, with the emergence of some targeted drugs.
And, finally, immunotherapy, a treatment capable of activating the immune system of patients against cancer, showed excellent results in triple negative breast cancer, that is, that does not express hormone receptors or overexpression of the HER-2 protein.
Prevention
Adopting healthy lifestyle habits can prevent about 30% of breast cancer cases. It’s important to:
- Practice physical activities regularly;
- Maintain a healthy diet;
- Maintain an adequate body weight;
- Avoid the consumption of alcoholic beverages;
- Avoid using synthetic hormones (such as hormone replacement therapies);
- Breastfeed;
- Do not smoke;
- Do a mammogram, the recommended exam for breast cancer screening, from the age of 40 (according to the recommendation of the Brazilian Society of Mastology). Early diagnosis of breast cancer, associated with appropriate treatment, increases the chance of curing the disease.
