Types and Treatment of Breast Cancer
Breast cancer is the most common malignant disease among women in Croatia. According to data from the Croatian Institute of Public Health (HZJZ) Cancer Registry, 3,293 new cases of breast cancer were diagnosed in Croatia in 2023, while 697 women died from the disease in 2024.
Although coping with a breast cancer diagnosis is physically and emotionally challenging, the prospects for recovery continue to improve thanks to early detection and advances in treatment. Today, treatment is tailored to each patient, taking into account the stage of the disease, histological type, biological characteristics of the tumor such as ER, PR, and HER2 receptor status, and the patient's overall health.
On this page
- What Is Breast Cancer?
- Types of Breast Cancer
- Signs and Symptoms of Breast Cancer
- Stages and Aggressiveness of Breast Cancer
- What Causes Breast Cancer?
- How Is Breast Cancer Diagnosed?
- Breast Cancer Treatment Options
- Survival, Prognosis, and Patient Experiences of Breast Cancer
- Self-Examination, Early Detection, and Awareness of Breast Cancer
- Why Choose UPMC Hillman Cancer Center for Breast Cancer Treatment?
What Is Breast Cancer?
Breast cancer develops when abnormal cells in breast tissue grow and divide uncontrollably, forming a tumor. The breast is composed of milk-producing glands (lobules), milk ducts, and supporting fatty and connective tissue.
When abnormal cells remain confined to the area where they originated (the milk duct or gland) and have not spread into surrounding tissue, the condition is called non-invasive carcinoma (in situ). If the cells break through the basement membrane and spread into surrounding tissue, it is considered invasive breast cancer.
Incidence and Distribution of Breast Cancer by Age and Sex
The risk of developing breast cancer increases with age, and the disease is most often diagnosed after age 50. The median age of women diagnosed with breast cancer in Croatia in 2023 was 64 years.
Breast cancer also occurs in men. In Croatia, 26 new cases of male breast cancer were recorded in 2023, and the median age at diagnosis was 72 years.
Breast Cancer in Young Women and Men
Although uncommon at a younger age, breast cancer can develop in young women and girls. Dense breast tissue can sometimes make mammograms more difficult to interpret, so ultrasound is often used as an additional diagnostic tool.
In men, breast cancer most commonly presents as a change behind the nipple, a lump, or skin and nipple changes. Because routine screening is not performed in men, it is important to see a doctor if any new breast change is noticed.
Types of Breast Cancer
Breast cancer is not a single disease, but rather a group of different types and subtypes. In addition to the tumor's histological type, estrogen receptor (ER), progesterone receptor (PR), and HER2 receptor status are important factors in treatment selection.
- DCIS – Non-invasive cancer confined to the milk ducts
- IDC / NST – Most common invasive type; accounts for approximately 70–80% of cases
- ILC – Invasive lobular carcinoma; accounts for about 10% of cases
- Luminal tumors – Hormone receptor-positive; treatment often includes endocrine therapy
- HER2-positive breast cancer – Tumor with HER2 overexpression or amplification; may be treated with anti-HER2 targeted therapies
- TNBC – ER-, PR-, and HER2-negative subtype; accounts for approximately 15% of cases
- Inflammatory breast cancer – Rare and aggressive form characterized by breast swelling and redness
Non-Invasive Breast Cancer (DCIS)
Ductal carcinoma in situ (DCIS) is confined to the milk ducts and has not invaded surrounding tissue. Treatment is based on the characteristics of the lesion and may include surgery, radiation therapy, and other interventions.
Invasive Ductal Carcinoma (IDC / NST)
Invasive ductal carcinoma is the most common form of invasive breast cancer, accounting for approximately 70–80% of cases in women. It begins in the milk ducts and can spread into surrounding tissue and regional lymph nodes.
Invasive Lobular Carcinoma (ILC)
Invasive lobular carcinoma develops in the breast lobules and accounts for approximately 10% of breast cancer cases in women. It often presents not as a distinct lump but as thickening or a sensation of fullness in the breast.
Triple-Negative Breast Cancer (TNBC)
Triple-negative breast cancer does not express ER, PR, or HER2 receptors and accounts for roughly 15% of cases. Treatment may include chemotherapy, immunotherapy, and other systemic treatments, depending on the stage and characteristics of the disease.
Metastatic Breast Cancer
Metastatic breast cancer (Stage IV) occurs when the disease spreads to distant organs such as the bones, lungs, liver, or brain. Treatment is generally focused on controlling the disease, prolonging life, and maintaining quality of life.
Inflammatory Breast Cancer
Inflammatory breast cancer is a rare but aggressive form of the disease. It may cause sudden breast redness, swelling, and skin thickening that resembles an orange peel. Because these symptoms can mimic other inflammatory conditions, prompt medical evaluation is important.
Signs and Symptoms of Breast Cancer
Most breast changes are not cancerous, but any new or unusual change should be evaluated by a healthcare provider.
Early signs and symptoms
Possible signs of breast cancer include a new lump or thickening in the breast or underarm, changes in breast size or shape, and dimpling of the skin or nipple. Other possible signs include skin changes, unusual nipple discharge, and persistent or unusual pain or discomfort.
Breast cancer cannot be diagnosed based on symptoms alone.
Palpable changes in breast tissue
A lump may be a sign of breast cancer, but touch alone cannot reliably determine whether a change is benign or malignant. Attention should also be paid to changes in breast contour, skin appearance, or nipple appearance.
Lumps, nipple changes, and breast discharge
Warning signs may include newly developed nipple inversion, spontaneous nipple discharge, and skin changes.
Stages and Aggressiveness of Breast Cancer
The stage of breast cancer describes how far it has spread within the body. In addition to stage, prognosis and treatment selection are influenced by histological grade and biological characteristics, including ER, PR, HER2 status, and cell proliferation markers such as Ki-67.
Breast cancer from stage 0 to stage IV
Tumor staging is based on the TNM system, which evaluates:
- T = Primary tumor
- N = Regional lymph node involvement
- M = Presence of distant metastases
Stage 0: Non-invasive disease such as DCIS
Stage I: Localized invasive disease
Stage II: Larger localized tumor and/or limited lymph node involvement
Stage III: Locally or regionally advanced disease
Stage IV: Disease that has spread to distant organs such as bone, liver, lungs, or brain
What Is the Most Aggressive Type of Breast Cancer?
No single type of breast cancer can definitively be labeled as the most aggressive because the course of the disease depends on stage, histological grade, and biological characteristics. Although triple-negative and inflammatory breast cancers are generally considered more aggressive, prognosis and outcomes must be evaluated individually for each patient.
What Causes Breast Cancer?
Breast cancer develops as a result of multiple factors. The risk of developing breast cancer is influenced by age, genetic factors, a family history of breast cancer, hormonal and reproductive factors, breast tissue density, as well as certain lifestyle habits and environmental influences.
Risk factors and genetics
Important risk factors include older age, a family history of breast or ovarian cancer, inherited genetic mutations such as BRCA1 and BRCA2, greater lifetime exposure to hormones, dense breast tissue, obesity after menopause, physical inactivity, and alcohol consumption.
The presence of risk factors does not necessarily mean that a person will develop breast cancer.
How Fast Does Breast Cancer Progress?
Not all tumors grow at the same rate. The course of the disease may be influenced by the tumor’s biological characteristics, such as histologic grade and receptor status. Therefore, a tumor’s aggressiveness cannot be determined solely based on its size or symptoms.
Prevention, Lifestyle, and Nutrition
A healthy lifestyle can help reduce the risk of breast cancer. Regular physical activity, maintaining a healthy body weight, a balanced diet, and limiting alcohol consumption are recommended.
No food or dietary supplement can replace standard breast cancer treatment.
How Is Breast Cancer Diagnosed?
The diagnostic process combines a clinical examination, imaging studies, and, when necessary, a biopsy. A breast cancer diagnosis is confirmed through pathologic examination of tissue samples.
Mammography
Mammography is a key method for the early detection of breast cancer because it can identify changes that cannot yet be felt during a physical examination. The current National Breast Cancer Early Detection Program includes women aged 49 to 70, who are invited for a mammogram every two years.
Imaging findings are classified according to the standardized BI-RADS system. Suspicious findings, particularly those categorized as BI-RADS 4 or 5, require further diagnostic evaluation, which generally includes a biopsy.
Breast ultrasound
Ultrasound is an important complementary method for detecting breast cancer, particularly in younger women and women with dense breast tissue. It helps distinguish between cystic and solid lesions and is also used to guide needle placement during biopsy procedures.
Magnetic Resonance Imaging (MRI) and CT Imaging
Breast MRI is used in specific situations, such as in women with a high genetic risk or when additional evaluation of the disease is needed. Depending on the stage of the disease and the clinical presentation, CT and PET/CT scans may be used to assess the extent of cancer spread.
Biopsy, testing, and tumor markers for breast cancer
A biopsy involves obtaining a tissue sample for pathologic analysis. The pathology report may include information on the tumor’s histologic type and grade, ER, PR, and HER2 receptor status, and other biological markers that help guide treatment decisions.
Blood tumor marker testing cannot replace a clinical examination, imaging studies, or pathologic confirmation of a diagnosis.
Breast Cancer Treatment Options
Treatment is tailored to each patient, taking into account the type and stage of the tumor, its biological characteristics, and the patient’s overall health. Treatment may include surgery, radiation therapy, chemotherapy, hormone therapy, targeted therapy, and immunotherapy.
Breast cancer surgery and reconstructive procedures
Surgical treatment may include breast-conserving surgery, which removes the tumor while preserving the breast, or a mastectomy. Breast reconstruction is planned according to each patient’s circumstances and preferences.
A sentinel lymph node biopsy allows physicians to assess whether regional lymph nodes are involved. In appropriate patients, this procedure may reduce the need for more extensive removal of underarm lymph nodes.
Radiation therapy and chemotherapy
Radiation therapy destroys cancer cells using high-energy radiation. Depending on the patient’s needs, advanced techniques such as IMRT and DIBH may be used. DIBH (Deep Inspiration Breath Hold) is a technique in which the patient holds their breath during a deep inhalation, moving the heart away from the radiation field and reducing the risk of cardiac exposure.
Chemotherapy may be administered before surgery (neoadjuvant), after surgery (adjuvant), or for advanced disease. However, chemotherapy is not necessary for all types of breast cancer.
Immunotherapy and targeted therapy (“Smart Drugs”)
Targeted therapy is selected based on the biological characteristics of the tumor. For HER2-positive tumors, anti-HER2 medications such as trastuzumab and pertuzumab may be used when clinically indicated.
CDK4/6 inhibitors are used for certain advanced hormone receptor-positive tumors. Immunotherapy may be used in selected cases of triple-negative breast cancer.
Hormone (Endocrine) therapy for breast cancer
Endocrine (hormone) therapy is used for tumors that express hormone receptors, primarily ER and/or PR. Depending on whether the patient has undergone menopause and on the characteristics of the disease, treatment options may include tamoxifen, aromatase inhibitors such as letrozole, anastrozole, and exemestane, as well as medications that suppress ovarian function.
The duration of therapy is determined individually for each patient based on their risk profile and response to treatment.
Survival, Prognosis, and Patient Experiences of Breast Cancer
The likelihood of cure and the prognosis of breast cancer are evaluated individually for each patient and depend on the stage of disease at diagnosis, the biological characteristics of the tumor, response to treatment, and other individual factors.
According to data from the HZJZ Cancer Registry, the five-year net survival rate for breast cancer in Croatia was 87.2% during the period 2019–2023, representing an improvement from 84.5% during the period 2014–2018.
Survival in Invasive Breast Cancer
Survival in invasive breast cancer depends on the stage of disease, lymph node involvement, histologic grade, biological characteristics of the tumor, and response to treatment. Therefore, overall five-year net survival statistics for breast cancer do not necessarily apply to every subtype or stage of the disease.
HER2-Negative and HER2-Positive breast cancer: prognosis
The prognosis of breast cancer cannot be determined solely by whether a tumor is HER2-negative or HER2-positive. Other important factors include ER and PR receptor status, stage of disease, histologic grade, lymph node involvement, and other biological markers.
Targeted anti-HER2 therapies have significantly expanded treatment options for HER2-positive breast cancer. Specific medications are selected based on disease stage and clinical indications.
Breast cancer mortality in Croatia
In 2024, 697 women died from breast cancer in Croatia. According to HZJZ data, breast cancer mortality is decreasing due to earlier detection, advances in diagnostic methods, and increasingly effective treatments. One of the goals of the National Breast Cancer Early Detection Program is to reduce mortality from the disease by 25% to 30%.
Survival in metastatic breast cancer
Metastatic breast cancer is generally not considered curable. However, numerous treatment options can help control the disease, alleviate symptoms, and prolong life. Treatment selection depends on the location of metastases, prior treatment, and the biological characteristics of the tumor.
Patient experiences and the role of support
The experience of treatment varies from person to person. In addition to medical treatment, psychological support, rehabilitation, symptom management, and effective communication with a multidisciplinary team of specialists play important roles.
Survival and mortality statistics cannot predict the outcome of the disease for an individual patient.
Self-Examination, Early Detection, and Awareness of Breast Cancer
Breast self-examination helps women become familiar with the appearance and feel of their breasts, making it easier to notice changes. HZJZ recommends performing a self-examination approximately one to two weeks after the start of menstruation, when the breasts are less tender.
Self-examination is not a substitute for organized screening programs or medical examinations. If you notice a new lump or any other unusual change, consult your physician.
Raising awareness and supporting patients
October is Breast Cancer Awareness Month. The goal of the National Breast Cancer Early Detection Program is to identify as many cases as possible at an early stage and reduce mortality.
Patient rights and access to specific forms of support depend on current regulations and each patient's individual health status.
Why Choose UPMC Hillman Cancer Center for Breast Cancer Treatment?
UPMC Hillman Cancer Center in Croatia is located on the campus of Zabok General Hospital and is part of UPMC's international oncology network.
Treatment is planned individually for each patient according to the type and stage of the tumor, with the opportunity for collaboration between Croatian and U.S. specialists. Medical oncology, radiation oncology, and other diagnostic and therapeutic services are available in Croatia.
Since 2026, UPMC Hillman Cancer Center in Croatia has partnered with the Croatian Health Insurance Fund (HZZO). Certain healthcare services are available within the scope of the agreement with HZZO and in accordance with its established procedures.