What is breast cancer?
Breast cancer is a disease in which the uncontrolled growth of abnormal cells in the breast forms a tumor.
In the world, breast cancer is one of the three most common types of cancer, along with lung and colorectal cancer, as well as non-melanoma skin cancer, which is the most frequent. Considering diagnoses in both sexes, breast cancer cases represent 11.6% of all cancer cases. When looking at women only, this number rises to 24.2%.
In Brazil, breast cancer is the most common cancer among women (excluding non-melanoma skin tumors). For 2023, the National Cancer Institute (INCA) estimated approximately 73,610 new cases in the country.
Men can also be diagnosed with breast cancer, but the incidence is very low: about 1% of all cases of the disease.
Subtypes of breast cancer
Breast cancer comprises different subtypes, making the disease extremely heterogeneous, which can lead to different outcomes and require different treatments. The most common types are:
- Ductal Carcinoma In Situ (DCIS) – it is the most common type of breast cancer, characterized by not invading the fatty tissue surrounding the mammary ducts; it can progress to invasive, although this is unlikely if the disease is properly treated. It generally does not affect axillary lymph nodes or have the potential to metastasize to other organs;
- Invasive Ductal Carcinoma – it represents between 65% and 85% of invasive breast cancer cases. It starts in the mammary ducts, surpassing the ductal membrane barrier and invading the fatty tissue surrounding the mammary ducts. It can invade structures adjacent to the breast, such as the axillary lymph nodes, or even cause metastases to other organs;
- Invasive Lobular Carcinoma – represents about 10% of breast cancer cases. It originates in the milk-producing glands – the mammary lobules – and can develop locally, as well as having the ability to present as multicentric disease (in more than one location in the breast) or invade adjacent tissues, such as the axillary lymph nodes, or even cause metastases to other organs.
- Lobular Carcinoma In Situ – it is a rare histological type and represents only 2% to 6% of cases. It originates from the mammary lobules and does not have the ability to invade tissues. However, it can be a precursor to invasive breast cancer.
The less common types of breast cancer include:
- Inflammatory carcinoma – rare, representing 1% to 3% of cases. The lymphatic ducts of the skin over the breast tissue are blocked and invaded by tumor cells. In it, the lymphatic system acts in defense against infections and inflammations, developing a chain reaction that causes the characteristic inflammatory aspect of the breast.
- Paget’s disease – very rare, with an incidence of 0.5% to 4% of breast cancer cases. It begins in the mammary duct, affecting the skin of the nipple and areola. It can be either asymptomatic or manifest as crusts and inflammation on the nipple.
- Phyllodes tumor – very rare, develops in the connective tissue of the breast (stroma), while others develop in the breast ducts or lobules.
- Angiosarcoma – begins in the cells lining the blood vessels or lymphatic vessels.
Symptoms and signs of breast cancer
Breast cancer presents symptoms that can be noticed in self-examination performed by the woman herself or during routine visits to the gynecologist. In most cases, the symptoms are
- Fixed and usually painless lump or thickening, present in about 90% of cases where cancer is detected by the person themselves;
- Redness in the skin of the breast, may or may not be 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 discharge from the nipples, including bloody discharge.
Self-examination can be done in the shower, when changing clothes, or in any everyday situation when the woman feels most comfortable. Both breasts and nipples should be palpated for small breast changes. The earlier it is detected, the greater the chance of cure for breast cancer. Undoubtedly, self-examination can contribute to the early diagnosis of the disease.
Diagnosis of breast cancer
The diagnosis of breast cancer is based on the triad composed of clinical examination, imaging exams, and histopathological analysis.
After anamnesis, with a clinical history conducted by a specialist physician, it is necessary to perform the appropriate imaging exams to evaluate the mammary parenchyma, such as breast ultrasound and mammography. Breast MRI may complement or assist in specific situations. In case of suspected breast cancer, a biopsy of the region is necessary to confirm or rule out the diagnosis.
The main methods of breast biopsy are core biopsy, or large needle biopsy, and vacuum-assisted biopsy, where a larger sample of tissue is removed. Both biopsies are performed under local anesthesia and are minimally invasive. For cases of axillary lesions, fine needle aspiration (FNA) is the most recommended alternative.
The choice of the best biopsy strategy is made by the breast specialist or the radiologist, who specializes in breast imaging. If none of these minimally invasive biopsy alternatives are viable, surgical biopsy is an option. If the lesion is impalpable, an imaging exam such as ultrasound, mammography, or MRI can serve as a guide for the procedure.
In the biopsy, the suspicious breast tissue is removed and then evaluated by a pathologist through microscopy. This allows distinguishing between a benign and a malignant lesion. Immunohistochemistry helps confirm the diagnosis and differentiate between types of breast cancer.
Treatment for breast cancer
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, menopausal status). Among the procedures, there may be surgery, radiotherapy, chemotherapy, endocrine therapy, biological therapy (or targeted therapy), and immunotherapy.
The treatment modalities are divided into local (surgery and radiotherapy) and systemic (chemotherapy, endocrine therapy, biological therapy, and immunotherapy).
Stages I and II
In the early stages of breast cancer, the usual approach is to opt for initial surgery. It can be conservative (removal of the tumor) or partial or total mastectomy (removal of the breast), followed or not by breast reconstruction – which should be considered to reduce the negative physical and emotional impacts of treatment.
Radiation therapy is always indicated after conservative surgeries. After mastectomy, the indication for radiation therapy depends on several 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, the indication for chemotherapy and/or targeted therapies is decided. The patient’s age, tumor size, molecular subtype, and axillary lymph node involvement are also taken into consideration.
To decide on endocrine therapy and/or biological therapy, for example, it is essential to assess the presence of hormone receptors and HER receptors through an immunohistochemistry test.
Chemotherapy can be offered before or after surgery, taking into account the risk of future recurrence. The following criteria are evaluated: tumor size, expression of hormone receptors, presence or absence of HER-2 protein overexpression, histopathological grade, patient’s age, and more recently, when available, some genomic signatures that assess tumor DNA and help grade the patient’s risk.
There are patients who will not require chemotherapy during treatment, as they have a less aggressive disease or one that is not very responsive to this type of treatment.
Stage III
Here, tumors are already larger than 5 cm and/or, when smaller, with the presence of affected regional lymph nodes in the armpits, for example. Systemic treatment (usually with chemotherapy) tends to be the initial option for tumor reduction. Then, local treatment with surgery and radiotherapy follows.
Stage IV
Stage IV is the stage of the disease in which metastases are detected, meaning the cancer has spread to other organs (most frequently bones, lungs, liver, and brain). It is essential to find a balance between disease control through available approaches, increasing the patient’s survival, and the potential side effects of treatment.
Significant advances have occurred in recent years regarding the treatment of metastatic breast cancer. Oral medications, called cyclin inhibitors, have emerged with excellent capacity to control and reduce the volume of disease. Additionally, in the scenario of HER-2 positive metastatic breast cancer, there has been a significant improvement in patients’ life expectancy with the emergence of some targeted drugs.
Lastly, immunotherapy, a treatment that can activate patients’ immune system against cancer, has shown excellent results in triple-negative breast cancer, which means it does not express hormonal receptors or overexpress the HER-2 protein.
Breast cancer prevention
It is believed that adopting healthy lifestyle habits can prevent about 30% of breast cancer cases. It is interesting:
- Engaging in regular physical activity;
- Maintaining a healthy diet;
- Maintaining a healthy body weight;
- Avoiding the consumption of alcoholic beverages;
- Avoiding the use of synthetic hormones (such as hormone replacement therapies);
- Breastfeeding;
- Not smoking;
- Undergoing mammography, the recommended screening test for breast cancer, starting at age 40 (according to the recommendation of the Brazilian Society of Mastology). Early diagnosis of breast cancer, combined with appropriate treatment, increases the chances of curing the disease.
