Breast Cancer: Symptoms, Types, Causes and Treatment

Breast cancer is the most frequently diagnosed cancer among women worldwide, affecting millions each year. Despite vast improvements in detection, treatment, and survivorship, breast cancer remains a complex and multifaceted disease. Understanding its symptoms, types, causes, and treatment options is essential for patients, caregivers, and the broader community. In this article, we break down each key aspect of breast cancer based on the latest research, aiming to empower readers with clear, actionable knowledge.

Symptoms of Breast Cancer

Recognizing the symptoms of breast cancer early can make a significant difference in outcomes. Symptoms can vary widely, not only in type but also in severity and timing. Some symptoms are linked to the cancer itself, while others may result from treatments such as chemotherapy or surgery. Understanding the most common symptoms and how they cluster together can help patients and caregivers identify issues early and seek prompt care.

Symptom	Cluster/Context	Notable Features	Sources
Lump/mass	Primary presentation	Often painless, irregular	11 12
Fatigue	Fatigue-anorexia	Most common, persistent	1 2 4 5
Pain	Pain/neuropathy	Can be chronic, post-surgery	3 5
Anxiety	Psychological	Common after diagnosis	1 3 4 5
Nausea	GI/Emotion-nausea	Peaks post-chemotherapy	1 2
Lymphedema	Physical sequelae	Swelling after treatment	3 5
Cognitive	Neurocognition	Memory issues, attention	2 5
Changes in skin	Epithelial	Dimpling, redness, rash	1 11
Appetite loss	Nutritional	Often with fatigue	1 2 5
Depression	Psychological	Can persist long-term	3 5

Table 1: Key Symptoms of Breast Cancer

Common Presenting Symptoms

The most recognizable symptom of breast cancer is a new lump or mass in the breast, often identified during self-examination or routine screening. These lumps are usually painless, firm, and have irregular edges, though some may be soft and rounded. Other local symptoms can include changes in breast size or shape, nipple discharge (not breast milk), skin dimpling, or redness and thickening of the breast skin, sometimes described as “peau d’orange” 11 12.

Symptom Clusters During Treatment

Breast cancer patients frequently experience groups of symptoms—or “symptom clusters”—that occur together, especially during chemotherapy. Research identifies clusters such as:

• Fatigue-anorexia cluster: Fatigue, loss of appetite, and dry mouth, often peaking a few days after chemotherapy and then gradually decreasing 1 2.
• Emotion-nausea cluster: Nausea, disturbed sleep, distress, drowsiness, and sadness, which also peak early in chemotherapy cycles 2.
• Neurocognition cluster: Pain, shortness of breath, vomiting, memory problems, and numbness/tingling, reflecting both physical and cognitive impacts 2.

Long-Term and Survivorship Symptoms

Survivors may continue to experience symptoms for years post-treatment:

• Chronic pain and phantom breast pain
• Lymphedema (swelling of the arm due to lymph node removal)
• Persistent fatigue and decreased physical stamina
• Cognitive dysfunction (“chemo brain”)
• Emotional issues: anxiety, depression, body image concerns, and sexual dysfunction 3 4 5

Symptom Burden and Impact

Symptoms are most intense in the six months following diagnosis or major treatments, with fatigue being reported by up to 60% of patients. Younger age, higher cancer stage, more intensive treatments, and lower income are associated with a higher symptom burden 4.

Types of Breast Cancer

Breast cancer is not a single disease, but a collection of different types and subtypes. These distinctions are crucial for determining prognosis and tailoring treatment.

Type	Key Features	Prognosis/Treatment Implication	Sources
Invasive Ductal Carcinoma (IDC)	Most common, ~70-80% cases	Variable, depends on subtype	6 7 10
Invasive Lobular Carcinoma (ILC)	10-15% cases, diffuse growth	Slightly poorer DFS than IDC	6 7
Special histological types	Tubular, cribriform, mucinous, etc.	Tubular/cribriform: excellent prognosis	6 7 8
Molecular Subtypes (Luminal A/B, HER2+, Basal-like/TNBC)	Defined by gene/protein expression	Dictate systemic therapy	9 10 15 16 17
Triple Negative Breast Cancer (TNBC)	Lacks ER, PR, HER2 receptors	Aggressive, fewer treatment targets	15 16 19
HER2-positive	Overexpresses HER2 protein	Responsive to anti-HER2 therapy	10 16 17 18

Table 2: Major Types and Subtypes of Breast Cancer

Histological Types

The most common histological type is Invasive Ductal Carcinoma (IDC), accounting for the majority of cases. Invasive Lobular Carcinoma (ILC) is the second most common, noted for its diffuse growth pattern and subtle presentation.

There are also “special” histological types, including tubular, cribriform, mucinous, and medullary carcinomas. Tubular and cribriform carcinomas generally have an excellent prognosis, with 5-year disease-free survival rates approaching 98% 7. Mucinous carcinomas have outcomes similar to IDC, while lobular carcinoma is associated with a slightly poorer prognosis 6 7 8.

Molecular and Genetic Subtypes

Modern breast cancer classification relies heavily on molecular biology:

• Luminal A: ER/PR-positive, HER2-negative, low proliferation. Best prognosis, usually managed with endocrine therapy.
• Luminal B: ER/PR-positive, may be HER2-positive, higher proliferation. Needs combination therapies.
• HER2-enriched: HER2-positive, more aggressive, but responds to targeted anti-HER2 drugs.
• Basal-like/Triple Negative (TNBC): Lacks ER, PR, and HER2. Often aggressive, limited targeted treatments 10 15 16 17.

Further molecular stratification, especially within HR-positive/HER2-negative cancers, is being developed and may soon guide even finer therapy choices 9.

Rare and Special Types

Rare histological types (e.g., adenoid cystic, secretory, papillary) make up less than 10% of cases, each with unique genetic drivers and clinical features 8. Their rarity means optimal treatments are less well defined, but ongoing genetic research holds promise for targeted therapies 6 8.

Causes of Breast Cancer

Breast cancer is a multifactorial disease with both well-established risk factors and emerging, still-debated causes. Understanding what increases risk can support prevention and early detection efforts.

Cause/Risk Factor	Description	Nature	Sources
Female gender, age	Most significant risk factors	Non-modifiable	11 12 14
Family history/genetics	BRCA1/2 mutations, others	Non-modifiable	12 15
Hormonal factors	Early menarche, late menopause, HRT	Modifiable/somewhat	11 12 14
Childbearing patterns	Late/no pregnancies, short breastfeeding	Modifiable	14
Lifestyle	Alcohol, obesity, inactivity	Modifiable	12 14
Radiation exposure	Especially to chest	Modifiable	14
Oncogenic viruses	HPV, EBV, MMTV, BLV	Emerging evidence	13
Unknown/Other	Majority of sporadic cases	Multifactorial	14

Table 3: Key Causes and Risk Factors for Breast Cancer

Established Risk Factors

• Gender and Age: Being female and increasing age are the strongest risk factors; 80% of patients are over 50 10 11 12 14.
• Genetics: Mutations in BRCA1, BRCA2, and related genes significantly increase lifetime risk 12 15. However, most cases are not inherited.
• Reproductive/Hormonal Factors: Early menstruation, late menopause, late or no pregnancies, and use of exogenous hormones (like hormone replacement therapy) contribute to higher risk 11 12 14.

Lifestyle and Environmental Factors

• Alcohol Consumption: Even moderate alcohol use is linked to increased risk 14.
• Obesity and Physical Inactivity: Postmenopausal obesity is a significant risk factor 12 14.
• Radiation Exposure: Especially exposure to the chest area before age 30, as in certain medical treatments 14.

Emerging and Less Established Causes

• Oncogenic Viruses: Recent evidence suggests a possible role for viruses like HPV, EBV, mouse mammary tumor virus (MMTV), and bovine leukemia virus (BLV), but this link is not yet conclusive 13.
• Other Factors: The majority of sporadic breast cancer cases occur without clear exposure to known causes, highlighting the complex interplay of genetic, hormonal, and environmental elements 14.

Treatment of Breast Cancer

Breast cancer treatment has evolved into a multidisciplinary and highly personalized approach. The choice of treatment depends on cancer stage, molecular subtype, patient preferences, and overall health.

Treatment Modality	Indications/Use	Key Considerations	Sources
Surgery	Early-stage, local control	Breast-conserving or mastectomy, sentinel node biopsy	16 17 18 20
Radiation Therapy	After breast-conserving surgery	Reduces recurrence	16 17 18 20
Chemotherapy	All subtypes (esp. TNBC, HER2+)	Often before or after surgery	16 17 18 19
Endocrine Therapy	ER/PR-positive tumors	Tamoxifen, aromatase inhibitors	16 17 18 20
HER2-targeted Therapy	HER2-positive tumors	Trastuzumab, pertuzumab	16 17 18
Immunotherapy	TNBC, select subgroups	Under investigation, some approvals	17 19
Supportive Care	All stages, survivors	Manage symptoms, improve QoL	4 5 20

Table 4: Major Breast Cancer Treatments

Local Therapy: Surgery and Radiation

• Surgery remains the cornerstone for most early-stage breast cancers. Breast-conserving surgery (lumpectomy) combined with radiation is as effective as mastectomy for survival, allowing many women to preserve their breast 16 17 18 20.
• Sentinel node biopsy is used for axillary staging and helps avoid unnecessary removal of lymph nodes 20.

Systemic Therapy

Systemic treatments target cancer cells throughout the body and are tailored to the tumor's molecular subtype:

• Chemotherapy is standard for triple-negative and many HER2-positive cancers, and occasionally for high-risk hormone receptor-positive tumors. It may be given before (neoadjuvant) or after (adjuvant) surgery 16 17 18 19.
• Endocrine (Hormonal) Therapy is used for estrogen/progesterone receptor-positive tumors, often for 5-10 years. Options include tamoxifen or aromatase inhibitors 16 17 18 20.
• HER2-targeted Therapy (e.g., trastuzumab, pertuzumab) has dramatically improved outcomes for patients with HER2-positive cancers 16 17 18.

Advanced and Metastatic Disease

• Metastatic breast cancer is generally incurable, but treatment aims to prolong life and maintain quality of life. Options include all the above, plus:
  • Immunotherapy, particularly for selected triple-negative cases 17 19.
  • PARP inhibitors for BRCA-mutated cancers 15 17.
  • Bone stabilizing agents for bone metastases 17.

Supportive and Survivorship Care

Long-term management of side effects and survivorship issues is critical:

• Chronic pain, lymphedema, fatigue, cognitive changes, and emotional distress all need proactive care.
• Multidisciplinary follow-up, including physical therapy, counseling, and education, can significantly improve quality of life 4 5 20.

Conclusion

Breast cancer remains a leading health challenge, but advances in research and clinical care have transformed outcomes for many. Early recognition of symptoms, understanding the diversity of cancer types, awareness of risk factors, and access to personalized treatments are all key to improving survival and quality of life.

Main Points Covered:

• Breast cancer presents with a variety of symptoms, often in clusters, that can affect physical, emotional, and cognitive well-being.
• The disease comprises multiple types and molecular subtypes, each with unique characteristics and treatment needs.
• Causes are multifactorial, with established and emerging risk factors spanning genetics, hormones, lifestyle, and possibly viral infections.
• Treatment is multidisciplinary and increasingly personalized, incorporating surgery, systemic therapies, targeted drugs, and robust survivorship support.
• Ongoing research continues to refine prevention, diagnosis, and treatment strategies, offering hope for even better outcomes in the future.