Invasive breast cancer is a common type of cancer among women in the United States, affecting one in eight women¹ during their lifetime.
The disease starts from the ducts or glands and grows into other breast tissues, including nearby lymph nodes. Some women may experience growth beyond the lymph nodes to other parts of the breast.
Generally, breast cancer originates in the breast tissues, mainly in the lobules or ducts. But when it becomes invasive, it grows into different healthy cells within the breast.
Fortunately, there are effective treatment options, although they depend on the type and spread of the disease.
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Invasive breast cancer affects women's breasts and spreads to nearby tissues and lymph nodes. It often starts in milk ducts or milk-producing glands, called lobules, tiny sacs inside the lobes.
If cancer cells grow or spread to healthy breast tissues outside milk ducts and lobules, they are considered invasive cancer cells.
According to the American Cancer Society, about 81% of breast cancers are invasive², meaning abnormal cells have grown into surrounding breast tissues.
Also referred to as infiltrating cancer, invasive breast cancer exists in a variety of subtypes. The two main ones are invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC) that account for almost 90% of invasive breast cancers.
There is also mixed ductal/lobular, metaplastic, mutinous, tubular, medullary, and papillary.
Invasive ductal carcinoma (IDC)
Invasive ductal carcinoma is the most common type of invasive breast cancer, making up 80%³ of all cases.
It usually begins in the milk ducts' cells before breaking through the walls and invading the breast's fatty tissues. IDC can then spread to other healthy tissues, including the lymph nodes and other body parts, through the bloodstream or lymphatic system.
In most cases, it can remain near the site where the tumor began for several days before spreading to other healthy tissues.
Invasive lobular carcinoma (ILC)
Invasive lobular carcinoma is a type of invasive breast cancer, accounting for about 10%⁴ of all invasive breast cancers. It is the second most common type of invasive breast cancer that originates from the breast's milk-producing lobules or milk glands.
Like invasive ductal carcinoma, ILC spreads to most breast parts before reaching other parts of the body. However, women with invasive lobular carcinoma will feel a thickening in the breast rather than a lump.
The most common form of breast cancer, invasive ductal carcinoma, is primarily associated with particular risk factors.
It is important to note that simply having the following risk factors does not 100% mean you will develop breast cancer. In fact, some women develop breast cancer with no known risk factors.
Risk factors include:
For example, women aged 50 to 59 have a 2.4% chance of developing breast cancer vs. women aged 70 and over who have a 7% chance.
Although breast cancer incidence increases with age, age-related differences based on the frequency of tumor subtypes depend on hormone receptor status and pathological grade.
So, younger and older patients have a higher frequency of estrogen receptor-negative, which reduces their chances of developing breast cancer more than middle-aged patients with estrogen receptor-positive and low-grade tumors.
Other risk factors:
Female sex: Women are 100 times more likely to develop breast cancer
A sedentary lifestyle
Prior radiation treatment done to the chest
Dense breast tissue
Family history of breast cancer
Exposure to diethylstilbestrol (DES)
Tobacco and alcohol use
Increased height > 175cm vs those < 160cm
Use of hormone replacement therapy
Combined oral contraceptive pill - this risk returns to normal after 2-5 years of cessation
On the other hand, women that have fewer menstrual cycles during their lifetime can minimize the risk of developing invasive breast cancer⁵.
Other instances that provide protective effects on common breast cancers include:
First pregnancy at a younger age
Menstruation beginning at an older age
Women with breast cancer may experience no signs or symptoms, primarily during the early stages. But as cancer grows, you may notice some signs and symptoms. Below are the symptoms of invasive breast cancer:
A lump or stiffening in or near the breast or underarm
Nipple crusting or scaling
Redness or swelling of the breast
An inverted nipple
A sore or ulcer on the skin of the breast that doesn't heal
Changes in breast size, shape, or contours, such as one of the breasts seeming higher than the other
Clear or bloody fluid from the nipple
A change in the appearance or feeling of the skin on the breast or nipple
A spot that is exclusively different from others on either breast
Redness of the nipple or skin on the breast
A marble-like hardening section under the skin
If you suspect that you may have breast cancer, it is essential to consult your physician to diagnose and recommend the best treatment option.
During an invasive breast cancer diagnosis, your healthcare professional will perform various tests to check if you have cancer and whether it is invasive or non-invasive. Standard tests used to diagnose invasive breast cancer include:
This is a physical diagnosis where a healthcare professional feels the breasts for signs of lumps or any other changes.
A healthcare professional uses a device to press breasts together between two plates for an X-ray image during a mammogram. The images are then evaluated for signs of cancer.
When a healthcare professional needs a better visual of breast tissues, imaging tests, such as magnetic resonance imaging (MRI) or ultrasound, are useful. The images are used to screen the tissues of cancerous cells.
This involves taking a sample of breast tissue and examining it under a microscope for any signs of breast cancer.
This may help decide treatment options.
If your physician uses one or more methods above and detects cancer, additional tests can be adopted to characterize the disease and determine its stage. These tests may include:
This is done on the tissue sample taken. It will undergo various tests evaluating estrogen receptors, HER2 status, and progesterone receptors.
Lymph node biopsy
During a lymph node biopsy, a healthcare professional determines if cancer has spread to the nearby lymph nodes.
This test helps determine if cancer has grown, invaded, or spread to other parts of the breast. Some tests you may undergo are CT scans, positron emission tomography (PET) scans, X-rays, or bone scans.
To determine how fast your breast cancer is growing, a healthcare professional will grade your breast cancer through a biopsy.
The cells are often graded on a scale of 1 to 3⁶: Grade 1 being slow-growing cancer cells, grade 2 being moderately growing cells, and grade 3 involving fast-growing cancer cells different from others.
Staging invasive cancer cells involves an assessment of whether your breast cancer has spread and how far. Understanding the breast cancer stage enables your healthcare team to determine the right treatment option and how fast the cancer is spreading. Unlike grading, breast cancer involves four stages:
Stage 0: Considered non-invasive breast cancer with no proof of growth or spread.
Stage I-III: Considered invasive breast cancer that has spread to different parts of the breast.
Stage IV: Metastatic breast cancer with a significant growth rate that has spread to distant parts of the body.
Generally, treatment of invasive breast cancer depends on several factors, mainly the stage of the disease, size, and location of the tumor. Here are the most common treatment options for invasive breast cancer.
Most women prefer surgery to remove all cells and the lymph nodes that cancer has invaded. Since cancerous cells originate from milk ducts or lobules within the breast, cancer growth usually takes time to reach other healthy tissues and eventually lymph nodes and other parts of the body.
Depending on the cancer stage and location, a healthcare professional will determine the right surgery type to remove cancer. This might involve a local resection (lumpectomy) or removal of the whole breast “mastectomy”.
This invasive breast cancer treatment method involves high-energy radiation that stops the growth of cancer cells. Radiation therapy is an ideal treatment procedure administered externally or internally after surgery, ensuring cancer removal from the breast.
The intent is to get rid of any cancer cells left behind after the surgery. Some women may consider radiation therapy during the initial stages of cancer.
Systemic therapies are considered among the most effective treatment options for invasive breast cancers. It provides treatment for cancers that continually spread to healthy tissues in the body besides the breast.
A healthcare professional uses a therapy that travels through the bloodstream, destroying cancer cells within the body during treatment. Systemic therapy can be administered as an infusion or pill.
Here are typical examples of systemic therapies that treat invasive breast cancer:
Chemotherapy: This involves strong drugs engineered to prevent cancer cells from spreading, growing, or invading healthy tissues.
Targeted therapy: This form of systemic treatment involves drugs that target cancer cells specifically. The drugs have limited impacts on healthy cells, unlike radiation therapy and chemotherapy.
Hormone therapy: This involves therapy that blocks hormonal actions that initiate cancer cell growth. It is often an effective treatment when a diagnosis suggests that certain hormones such as estrogen and progesterone trigger the growth of cancer cells.
Immunotherapy: This invasive breast cancer treatment option involves stimulating immune cells that respond to cancer cells. Immunotherapy is also effective in treating some types of invasive breast cancer, for instance, triple-negative breast cancer.
Systemic therapy can be recommended before (neoadjuvant) or after surgery (adjuvant), depending on the cancer stage, lab test results, and other factors.
After surgery depending on the extent of cancer, women undergo systemic treatment to ensure all cancer cells present at the surgical site are removed entirely. Furthermore, systemic therapies effectively treat invasive breast cancers in the bloodstream, including people with metastatic breast cancer.
Cancer cells are similar to healthy cells in the body that grow through cellular division, whether non-invasive or invasive. According to the Robert W. Franz Cancer Research Center⁷, breast cancer cells divide at least 30 times before being detected in a screening or physical exam. Each division may take between 1-2 months, suggesting a detectable tumor takes between 2-5 years in the body.
Since the period varies, breast cancer grading and staging come in handy to determine how quickly invasive breast cancer can spread. For instance, grade 3 breast cancer spreads much faster than grade 1 and 2. Stage IV invasive breast cancer spreads much faster since multiple cancer cells are dividing.
Understanding survival rates for invasive breast cancer is a valuable benchmark that provides excellent insights for physicians to describe and discuss patient conclusions.
According to the American Society of Clinical Oncology (ASCO)⁸, the average five-year survival rate⁹ for non-metastatic invasive breast cancer is 90%, while the average ten-year survival rate is 84%.
If the invasive breast cancer is only in the breast, the five-year survival rate for women with the disease is 99%. If cancer has spread to the lymph nodes, the five-year survival rate is 86%, but if it has spread to distant tissues of the body, the five-year survival rate is 28%.
Statistically, the survival rate for invasive breast cancer is about 9% to 10% lower in black women than in white women.
Invasive breast cancer involves cancer cells that originate in lobules or milk ducts and spread to different breast parts, including the lymph nodes and other body parts.
Most breast cancers are invasive, although there are other less common types.
Getting early, regular screening can help catch the disease in its early stages, which makes it much more likely to be treatable.
U.S. Breast Cancer Statistics | Breastcancer.org
Breast Cancer Facts & Figures 2019-2020 | American Cancer Society
Invasive Ductal Carcinoma (IDC) | Johns Hopkins Medicine
Reproductive History and Cancer Risk | NIH: National Cancer Institute
Questions to ask about your breast cancer | Breast Cancer Now
Introducing the Robert W. Franz Cancer Center | Providence Health & Services
Where Knowledge Conquers Cancer | American Society of Clinical Oncology
Breast Cancer: Statistics | American Society of Clinical Oncology (ASCO)
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